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SilvicuKural Systems for

the Major Forest Types of

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United States

Department of

Agriculture

Forest

Service

Agriculture

Handbook

No. 445

Silvicultural Systems

for the Major Forest Types

of the United States

Russell M. Bums

Technical Compiler

Timber Management Research

U.S. Department of Agriculture Forest Service

Washington, D.C. Revised December 1983
Bums, Russell M., tech. comp. Silvicultural systems for the major forest types of the United States.

Agrie. Handb. 445. Washington, DC: U.S. Department of Agriculture, Forest Service; 1983. 191 p. .

The current trend toward the establishment and care of forests for a wide combination of uses requires

flexibility in forest culture and a knowledge of the silvicultural choices available to the resource manager.

This publication summarizes the silvicultural systems that appear biologically feasible, on the basis of

present knowledge, for each of 48 major forest types in the United States. Supporting information is given

on the occurrence of the 48 forest types, the cultural requirements of the component species, and the

biological factors that control the choice of silvicultural options.

Keywords: Silviculture, forest types, species, multiple use.

Cover photo: The results of uneven-aged management in Douglas-fir using the group selection cutting

method on Mt. Baker National Forest, Wash. F-437586.

For sale by the Superintendent of Documents. U.S. Government Printing Office

Washington, D.C. 20402
Acknowledgment

This handbook constitutes a revision, an expansion, and an updating of materials contained in the

March 1973 edition of the same title. It was prepared at the request of the Office of the General Counsel as a

cooperative, Servicewide venture.

The handbook is a compilation of 48 individual manuscripts written by research foresters at U.S.

Department of Agriculture Forest Service Experiment Stations in collaboration with foresters from State and

Private Forestry, from the National Forest System, and from academia. Individual manuscripts were

reviewed for technical accuracy and completeness by technically competent experts from forest industry,

State forestry organizations, and the university community.

Technical reviews and evaluations of all manuscripts were provided in the Washington Office of the

Forest Service by Carl Puuri and Robert Gillespie of Timber Management, Allan O. Lampi of Land

Management Planning, and Ronald E. Stewart and Russell M. Bums of Timber Management Research.

Manuscripts also were reviewed by Robert Maynard and Carl Peckinpaugh of the Office of the General

Counsel for completeness and appropriateness.

Evaluations of appropriate parts of the handbook were provided by Carl M. Bemtsen, Director of the

Science Program of the Society of American Foresters, and, in the Washington Office of the Forest Service,

by Arthur L. Schipper and Robert L. Lyon of Forest Insect and Disease Research and by Barbara H.

Honkala of Timber Management Research. Hugh C. Black of Wildlife and Fisheries prepared the lists of

common and scientific names of animals.

Robert E. Buckman

Deputy Chief for Research

John H. Ohman

Deputy Chief for State

and Private Forestry

Raymond M. Housley

Deputy Chief for

National Forest System

ni
Contents

Page

Introduction 1

Silvicultural Systems 1

Biological Factors Influencing the Choice of

Silvicultural Systems 2

Western Forest Cover Types

Western Hemlock - Sitka Spruce 5

Pacific Douglas-Fir 9

True Fir-Hemlock 13

Northwestern Ponderosa Pine and Associated

Species 16

Grand Fir, Douglas-Fir, and Associated Species

(Eastern Oregon and Washington) 19

Mixed Conifers of Southwestern Oregon 23

Red Alder 26

Southwestern Oregon-Northern California

Hardwoods 29

Interior Alaska White Spruce -Hardwoods 33

Redwood 37

Red Fir and White Fir 41

Sierra Nevada Mixed Conifers 44

Pacific Ponderosa Pine 48

Ponderosa Pine and Rocky Mountain

Douglas-Fir 53

Western Larch 56

Engelmann Spruce - Subalpine Fir 59

Lodgepole Pine 63

Mixed Conifers, Western White Pine, and

Western Redcedar 67

Southwestern Ponderosa Pine 70

Southwestern Mixed Conifers 73

Rocky Mountain Aspen 77

Interior Ponderosa Pine in the Black Hills 80

Pinyon-Juniper 84

Eastern Forest Cover Types

Red Pine 89

Jack Pine 92

Black Spruce 96

Page

Tamarack 99

Balsam Fir 102

Northern White-Cedar 105

Eastern Redcedar 109

Aspen 113

Oak-Hickory 116

Northern Hardwoods 121

Eastern Spruce -Fir 128

Eastern White Pine Including Eastern

Hemlock 131

Pitch Pine 135

Cherry —Maple 137

Appalachian Mixed Hardwoods 141

Paper Birch 145

Loblolly Pine 148

Longleaf Pine 153

Shortleaf Pine 157

Slash Pine 162

Virginia Pine 167

Sand Pine 170

Oak-Pine 172

Bottomland Hardwoods 175

Yellow-Poplar 180

Glossary 183

English to Metric Conversion

Factors 186

Lists of Common and

Scientific Names 187

Birds 187

Animals 188

Amphibians and Reptiles 189

Fishes 189

Index of Forest Cover Types 190

Index of Authors 191

IV
Introduction

The forests of the United States are coming under

increasing pressure to provide more and better products and

benefits for more and more people. This pressure has

accelerated the development of procedures for multipurpose

management planning to provide a mix of goods and services

when and where they are needed. Forest culture, in turn, is

being directed more toward the establishment and care of

forests for a wide combination of uses. This trend requires an

increasing flexibility in forest culture, and a knowledge of the

silvicultural choices available for the important forest types

of the United States. The purpose of this publication is to

summarize the silvicultural systems that appear biologically

feasible, on the basis of present knowledge, for each of 48

major forest types.

Great public interest focuses on the harvest cutting

operation. However, in a well-managed forest, harvest cutting can be done only in the context of a complete system of

forest culture. A system of forest culture must provide for

harvesting, regenerating, and maintaining desired species of

trees in a stand of suitable structure. This, in turn, can be

done only through an orderly series of treatments. Each

treatment must be performed on schedule for the system to

attain specified objectives.

Silvicultural Systems

The silvicultural systems discussed in this publication

are selection, shelterwood, seed-tree, and clearcutting. These

terms also refer to the method of harvest cutting that

characterizes each system, but it is important for the forest

manager to think in terms of a system of silviculture rather

than only the method of harvest cutting.

The selection system involves the removal of mature

and immature trees either singly or in groups at intervals.

Regeneration is established almost continuously. The objective is maintenance of an uneven-aged stand, with trees of

different ages or sizes intermingled singly or in groups.

When properly applied, the system is esthetically pleasing,

but is difficult to apply successfully in most forest types. The

two types of selection are individual tree selection and group

selection.

Individual (single) tree selection involves the removal

of individual trees rather than groups of trees. In mixed

stands it leads to an increase in the proportion of shadetolerant species in the forest.

Group selection can be used to maintain a higher

proportion of the less shade tolerant species in a mixture than

individual tree selection. For this purpose larger harvest

groups are more effective than smaller ones. In Eastern

timber types, groups a fraction of an acre in size are generally

suitable. In some Western timber types, where the stands are

open or the trees are very tall, the groups may be as large as

an acre or two. When groups are of maximum size, they

resemble small clearcut patches. The group selection system

is distinguished from clearcutting in that the intent of group

selection is ultimately to create a balance of age or size

classes in intimate mixture or in a mosaic of small contiguous

groups throughout the forest.

The remaining silvicultural systems—shelterwood, seedtree, and clearcutting— provide for even-aged management

and result in stands of trees of about the same age. In each of

these systems, it is important to plan the size, shape, and

dispersion of the harvested areas to meet multiple-purpose

management objectives.

In the shelterwood system, the mature stand is removed

in a series of cuts. Regeneration of the new stand occurs

under the cover of a partial forest canopy or shelterwood. A

final harvest cut removes the shelterwood and permits the

new stand to develop in the open as an even-aged stand. This

system provides a continuing cover of either large or small

trees. It is especially adapted to species or sites where shelter

is needed for the new reproduction, or where the shelterwood

gives the desired regeneration an advantage over undesired

competing vegetation.

The seed-tree system involves harvesting nearly all the

timber on a selected area in one cut. A few of the better trees

of the desired species are left well distributed over the area to

reseed naturally. When feasible, the seed trees are harvested

after regeneration is established. This system applies mainly

to conifers.

Clearcutting is the harvesting in one cut of all trees on

an area for the purpose of creating a new, even-aged stand.

The area harvested may be a patch, stand, or strip large

enough to be mapped or recorded as a separate age class in

planning for sustained yield under area regulation. Regeneration is obtained through natural seeding, through sprouting of

trees that were in or under the cut stand, or through planting

or direct seeding. This system requires careful location of

boundaries to fit the landscape and appropriate cleanup of

debris to improve the appearance of the harvested area. The

absence of reserved trees on the clearcut area facilitates site

preparation and other area-wide cultural treatments.

In past decades the silviculture of a number of mixed

timber types was dictated by requirements for maintaining a

high proportion of a single valuable species in the mixture,

such as western white pine. Now, nearly all species are

marketable, and silvicultural options that perpetuate any of

these species are desirable as they result in additional species

diversity.

Recent improvement in timber markets has coincided

with greatly increased public interest in recreation, esthetics,

wildlife, and other values of forests. In many places these

nontimber values strongly influence the choice of silvicultural systems and cultural treatments such as site preparation

and prescribed burning.

Perhaps the most important influences on the choice of

silvicultural systems result from certain biological factors

that silviculturists have learned about from long-term research and experience.
Biological Factors Influencing the Choice of

Silvicultural Systems

Biological factors frequently prevent the use of certain

silvicultural systems. Some of the more common of these

factors governing the choice of a silvicultural system recur in

many of the timber types.

Reproductive habits and requirements of the desired

and competitive tree species are among the most important

factors influencing the choice of a silvicultural system. If

forests are regenerated in the shade, the shade tolerant species

will be favored and sooner or later will predominate. Fastgrowing, shade-intolerant trees usually dominate stands regenerated in full light. The basic factors about requirements

for regeneration and growth of the important forest trees of

the United States are summarized in Silvias ofForest Trees of

the United States J

The choice of cultural measures and silvicultural systems must take the requirements of wildlife and their impact

on forest vitality and reproduction into consideration. Browsing animals are favored by systems that provide clearings of

appropriate size, shape, and dispersal for production and

utilization of low browse. Squirrels are favored by systems or

rotation lengths that result in abundant seed production and

mature trees for nest sites. Consumption of seed by birds and

rodents and damage to young trees by browsing and gnawing

animals are serious enough in some timber types to influence

the choice of silvicultural systems and cultural treatments.

Hazards created by insects and diseases are also

important in the choice of silvicultural systems. When stands

are heavily attacked by serious disease or insect pests, it may

be necessary to remove the affected trees or the entire stand.

Under other conditions, protecting against insects, such as

infestations by pine shoot weevils, involves maintaining a

canopy over the reproduction, as in the shelterwood system.

Use of flre in forest culture also may limit the choice of

silvicultural systems. In a few forest types, periodic use of

prescribed fire reduces hazardous accumulations of flammable debris and undesirable undergrowth. Periodic prescribed

burning is adapted chiefly to even-aged stands, because the

young regeneration present in all-aged stands is easily killed

by fire. All-aged systems, on the other hand, leave less

concentration of debris resulting from any one harvest cut

and tend to make disposal of debris less essential.

Climatic hazards are another important element in the

choice of a silvicultural system. For example, on sites subject

to heavy frost near ground level, a new seedling crop must be

' Powells, H. A., comp. Silvios of Forest Trees of the United States.

Agrie. Handb. 271. Washington, DC: U.S. Department of Agriculture;

1965. 762 p.

Started under a partial canopy of trees to protect the seedlings.

On the other hand, certain mountain and coastal sites, subject

to high wind velocities, should not be partially cut. Clearcutting

is usually required on windy sites and in shallow-rooted

forests on wet soils to avoid the risk of windthrow that occurs

in partially cut stands.

Another serious constraint is imposed by the size, age,

and vigor of the trees in the existing stand. A production

forest composed wholly of trees of advanced age and

declining vigor ordinarily requires a heavy harvest cut such

as a clearcut, seed-tree, or shelterwood. Attempts to use the

selection system in overmature even-aged stands have consistently resulted in high mortality among remaining trees. The

selection system is better suited to stands composed of trees

that vary considerably in age, size, and vigor.

Another natural factor in the choice of silvicultural

systems is the use of genetically improved trees for the next

crop. Improved strains of forest trees are coming out of the

nurseries in increasing numbers, and superior trees of many

important species will be produced in the future. With most

species, the growth potential of these improved varieties can

be realized only if they are planted and grown in properly

cultured even-aged stands.

Of course, certain factors can lead to a decision that no

harvest cutting should be done. They may include unstable

soils unsuited for road construction, shallow soils or severe

sites where a new crop cannot be started, or areas that have

unique value in the untouched state.

Finally, the ultimate choice of the system for a particular

tract involves analysis of various managerial constraints.

These include availability of personnel, equipment, capital,

and of markets for different classes of timber. These factors

have an important bearing on the efficiency of operating

under different silvicultural systems, but they vary so much

with time and place that they are beyond the scope of this

publication.

In the following pages experts briefly describe each

major forest type as it occurs in the United States, the cultural

requirements of the component species, the biological factors

that control the choice of silvicultural options, and the

silvicultural systems that are applicable.

An effort has been made to include metric equivalents of

all English measurements in the text. This presents a variety

of problems, especially in converting board feet to cubic feet

and cubic meters. Board feet measurements based on various

log rules have been converted, nonetheless, for the reader's

convenience. These conversions should be viewed as estimates,

however, rather than true measurements because of the

assumptions involved in the conversion process.

The table of conversion factors for English to metric

measurements begins on p. 186.
Western Forest Cover Types

Western Hemlock — Sítka Spruce

A. s. Harris

Pacific Northwest Forest and Range Experiment Station

David L. Johnson

Alaska Region

The western hemlock—Sitka spruce forest type (2), as

recognized by the Society of American Foresters (type 225),

is composed of stands in which western hemlock (Tsuga

heterophylla (Raf.) Sarg.) and Sitka spruce {Picea sitchensis

(Bong.) Carr.) comprise a majority of the stockmg. Also

included at various locations may be small admixtures of

Douglas-fir {Pseudotsuga menziesii (Mirb.) Franco), grand

fir {Abies grandis (Dougl. ex D. Don) Lindl.), Pacific silver

fir {Abies amabilis Dougl. ex Forbes), western redcedar

{Thuja plicata Donn ex D. Don), Alaska-cedar {Chamaecyparis

nootkatensis (D. Don) Spach), mountain hemlock {Tsuga

mertensiana (Bong.) Carr.), red alder {Alnus rubra Bong.),

black cottonwood {Populus trichocarpa Torr, and Gray),

vine maple {Acer circinatum Pursh), and bigleaf maple {Acer

macrophyllum (Pursh)) (2).

Tree species within the type change with latitude.

Douglas-fir is an important associate in Oregon and Washington;

Western redcedar is important in British Columbia and

extends into southeast Alaska. Pacific silver fir becomes an

associate north of the Columbia River and extends north

through British Columbia and into Alaska. Alaska-cedar and

mountain hemlock become associates north of central Vancouver Island. Shore pine {Pinus contorta Dougl. ex Loud,

var. contorta) is an associate on some sites from Oregon to

Alaska. Red alder and black cottonwood are important hardwood associates in serai stands throughout the range; bigleaf

maple is common only in the southern latitudes of the type.

The type occupies a coastal strip 2,000 miles (3220 km)

long from southern Oregon to south central Alaska (11). Its

greatest extent is in southeast Alaska where it reaches a width

of 130 miles (210 km) including a narrow mainland strip and

offshore islands.

Northwestward, along the Gulf of Alaska, the type

narrows greatly, limited by steep mountains and glaciers,

widening again to include islands within Prince William

Sound. In British Columbia, the Queen Charlotte Islands lie

entirely within the type, and a narrow strip extends along the

mainland and on the west coast of Vancouver Island with

stringers along major streams. In Washington and Oregon,

the type occupies a narrow coastal strip and extends inland

along streams and rivers.

The type occurs at sea level throughout its range,

extending to elevations of 3,000 feet (910 m) in British

Columbia and southeast Alaska. North and west from southeast Alaska, upper limits gradually lower to 1,500 feet (460

m) around Prince William Sound. Toward the south the type

reaches elevations of 1,800 feet (550 m) along the Oregon

coast, and as high as 3,000 feet (910 m) in especially moist

situations on the Olympic Peninsula, Wash. (11).

Soils vary by latitude. In the Coast Ranges of Oregon

and Washington, Inceptisols and Ultisols are the most

widespread. Northward through British Columbia and Alaska,

Spodosols and Histosols are more prevalent. Throughout the

type, Entisols are found along streams.

From the Olympic Peninsula northward, glaciation has

affected soil development. Soils tend to be less well developed northward. In Alaska, most Spodosols have low clay

content; colloidal organic and iron compounds are the main

source of cation exchange and water retention. They have

relatively high moisture retention capacity and relatively high

rates of water transmission. A substantial proportion of

nutrients is concentrated in the surface organic layers. Even

in the deeper soils, tree rooting is generally shallow, and,

therefore, destruction or serious disturbance of the upper soil

layers is likely to have adverse effects on tree growth (11).

The type is confined to an area of maritime climate with

abundant moisture throughout the year, relatively mild winter

temperatures, and cool summers. Lack of a pronounced

summer drought is an important factor affecting vegetation.

Length of growing season and total solar energy received

during the growing season decrease northward and account

for much of the variation in productivity, soil development,

and species composition within the type (3).

Total annual precipitation tends to be high throughout

the type, apparently little influenced by latitude; 60 to 150

inches (1525 to 3810 mm) is common with up to 300 inches

(7620 mm) in some localities. Local topography greatly

influences precipitation. Average depth of snowfall during

the winter decreases southward, ranging from 134 inches

(3400 mm) at Cordova, Alaska, to 5 inches (125 mm) at Otis,

Oreg. Summer precipitation tends to be greater toward the

north. Along the southern Alaska coast, frequent cloudiness,

light summer drizzle, and fog are common. Toward the south

where summer precipitation is less frequent, damp maritime

air helps to maintain moist conditions.

Storm winds often sweep in from the Pacific Ocean

during the fall and winter, causing frequent wind damage. In

Oregon and Washington, the greatest damage is from south

and southwest winds of approaching storms. Gale-force

winds are most common in October and November. In

southeast Alaska the most damaging winds are from the

southeast and occur most frequently from September through

November. Management strategies have been developed to

reduce wind damage in the forest, such as selecting windfirm

cutting boundaries, shaping cutting units to minimize the

length of cutting boundaries exposed to storm winds, and

laying out cutting strips perpendicular to prevailing storm

winds with progressive cutting of strips toward the wind (11).

Both western hemlock and Sitka spruce are prolific seed

producers. In Oregon and Washington, both species produce

some seed most years with heavy crops every 3 to 4 years. In

Alaska, a heavy crop occurs every 5 to 8 years. The seed is

small and is carried long distances by the wind. Western

hemlock is an especially heavy seed producer, and even

relatively poor seed crops usually produce enough seed to

insure natural restocking (16). Seed production generally is

adequate for establishment of regeneration even on large

clearcuts, so few areas fail to regenerate from lack of seed.

Failures more often are due to competing vegetation (11).

Western hemlock and Sitka spruce seed will germinate

and seedlings will grow on both organic and mineral soil

seedbeds. Establishment and subsequent growth, however,
are better on soils with a high percentage of organic matter.

In Alaska, soils stripped of surface organic material may be

unsuitable because underlying soil horizons contain few

nutrients to support growth. Exposure of mineral soil also

provides a good seedbed for red alder and brush species,

which compete with conifers (6).

Shade improves seedling establishment where low moisture or high temperature is limiting. Both duff-covered soil

and rotten wood can be good seedbeds under light shade, but

too much shade can prevent seedling establishment. Toward

the south, exposed organic seedbeds tend to dry out more

readily and few seedlings become established on them. On

the other hand, soils are deeper and better developed than in

Alaska and have more nutrients available in lower soil

horizons to support good tree growth (11).

Western hemlock is more tolerant of shade than is Sitka

spruce and dominates reproduction in old-growth forests (4).

Both species are capable of rapid growth increases if shade is

removed.

Soil and ground water conditions are important in

determining the success of tree species. Lodgepole pine

(Pinus contorta var. latifolia.), Douglas-fir, and red alder

roots can grow in soils with high bulk densities. These soils

prohibit the growth of Sitka spruce, western redcedar, and

western hemlock. Pacific silver fir ranks between these two

groups (9). Red alder, western redcedar, Sitka spruce, and

western hemlock are more tolerant of high water tables than

is Douglas-fir (8).

Western hemlock—Sitka spruce is one of the world's

most productive forest types. Yield tables are available for

unthinned even-aged stands of mixed hemlock and spruce in

Oregon, Washington, and Alaska. They show that many

stands in the southern part of the type's range produce over

200 cubic feet of wood per acre per year (14 m /ha/yr) (1,7,

12). Productivity decreases with increasing latitude (3).

Stand volumes can be impressive. One plot in a 147-year-old

stand in coastal Oregon contained, on an area basis, 76

spruce and 13 hemlock per acre (188 spruce and 32 hemlock/ha).

Total volume was 34,000 cubic feet per acre (2380 m^/ha).

Spruce averaged 210 feet (64 m) in height and 34 inches

(86.4 cm) in diameter at breast height (d.b.h.) (4).

Even-aged management is practiced throughout the

western hemlock—Sitka spruce type. The optimum rotation

age for management of hemlock—spruce depends on the

objectives of the landowner. Many hemlock—spruce forests

on industrial lands are managed on an economic rotation that

varies from about 40 years in accessible, intensively managed areas, to well over 100 years in less accessible areas.

The white pine weevil {Pissodes strobi (Peck)) is the

most serious enemy of young Sitka spruce in Oregon,

Washington, and British Columbia. It is not a problem on the

Queen Charlotte Islands nor in southeast Alaska. Within its

range, the weevil is more damaging to widely spaced trees on

drier sites located inland. Close spacing and the planting of

Sitka spruce in small blocks offers the most practical means

of minimizing damage in plantations (5). Weevil damage

limits the suitability of many sites for future management of

Sitka spruce.

The western blackheaded budworm (Acleris gloverana

(Walsingham)) is an important defoliator of western hemlock

and Sitka spruce in coastal forests of Oregon, Washington,

British Columbia, and Alaska. Another defoliator, the hemlock sawfly (Neodiprion tsugae Middleton), attacks westem hemlock. In this order, these are the two most destructive

forest insects in coastal Alaska. Other defoliators include the

western hemlock looper (Lambdina fiscellaria lugubrosa

(Hülst)), and the Saddleback looper (Ectropis crepuscularia

(Denis and Schiffermuller)) (5).

The thin bark and shallow roots of hemlock and spruce

make them particularly susceptible to logging injury, which

leads to decay, especially in hemlock. Losses from decay

fungi are high, especially in the old-growth forests of Alaska.

Conversion from old to young growth has great potential for

reducing decay, but root rots that reduce growth and vigor

then become important. Spread of Heterobasidium annosum

(FT.) Bref, from old stumps to new seedlings can lead to

damage in hemlock plantations. Extent of damage is correlated with frequency and intensity of thinnings (13). Hemlock dwarf mistletoe {Arceuthobium tsugense (Rosend.) G.

N. Jones), an important disease of western hemlock, can best

be controlled by clearcutting (11).

Fire danger is of less concern here than in drier forest

types. The greater concern is in the southern part of the

range, particularly inland in the transition zone toward

hemlock or Douglas-fir forests. Slash burning to reduce fire

hazard has been common wherever conditions were dry

enough to permit burning, but the trend now is away from

slash burning. Fire does not play an important role in the

management of coastal Alaska's forests, and slash burning

has not been practiced there (6).

Regeneration of hemlock—spruce forests can be attained with any silvicultural system or combination. The

choice depends on profit to the landowner and the need to

integrate timber harvest with other forest values.

Clearcutting is by far the most common silvicultural

system used in harvesting western hemlock-Sitka spruce

stands (11). It is recommended where timber production is

the primary use. Logging costs are lower than with other

systems. Exposure to the sun raises soil temperature, which

speeds decomposition of mor, thereby improving the productivity of northern sites. Clearcutting favors regeneration of

Sitka spruce by destroying advance hemlock regeneration

and by creating more favorable conditions for post-logging

reproduction of spruce. Eliminating residual overstory trees

infected with dwarf mistletoe prevents infection of western

hemlock in the new stand. Clearcutting also facilitates

residue management and fire protection and eliminates the

risk of blowdown in residual stands. The chance of blowdown

along cutting boundaries is increased but can be reduced

through proper design of cutting units.

Natural seedfall is generally adequate for regeneration,

and most young stands are dense. Direct seeding has been

done to supplement a poor seed crop, alter species composition,

or regenerate areas left without a natural seed source, but is

not effective if regeneration failures are caused by competing

vegetation. Restrictions on use of rodent control chemicals,

high cost of seed, and development of improved nursery and

planting techniques have made planting a better regeneration

method (11).

Planting is often done to reduce the time required for

natural regeneration on problem sites, to increase the percentage of Sitka spruce in stands, or to replace Sitka spruce with

Douglas-fir in areas subject to weevil damage. Handplanting

is required because hillsides usually are too steep for machine

planting; flat bottomland is too wet; and where old-growth

stands are logged, heavy logging residues create obstacles,

even if broadcast burning is done. Both bare-root and

container-grown stock are used. Where animal damage is a

problem, measures such as use of plastic mesh tubes,

chemical repellants, and modification of animal habitat may

be necessary to protect seedlings (11).

Clearcutting may be less esthetic than other harvesting

systems, although size, shape, and arrangement of clearcuts

can be altered to reduce the visual effect. On National Forests

in Alaska, openings are limited to 100 acres (40 ha) or less

except under specific circumstances. After clearcutting, sev-
eral years may elapse before the site is again fully utilized for

timber production, and competing vegetation tends to take

over the site more quickly than with the shelterwood or

selection systems. In extensive swampy areas, clearcutting

may reduce transpiration enough to cause an undesirable rise

in the water table. In the northern portions pf the hemlockspruce type where winter snows are deep, clearcutting extensive areas of old growth can impair the quality of deer habitat

(14).

Hemlock and spruce lend themselves to shelterwood

cutting because both species can become established under a

suitable forest canopy. Shelterwood cuttings resemble heavy

thinnings, and use of this method logically follows a series of

commercial thinnings in immature stands.

The shelterwood system may be preferable to clearcutting

where it is essential to maintain a continuous tree cover, to

reduce visual change, to reduce erosion, or to minimize

encroachment of unwanted intolerant vegetation. Shade can

be controlled, thus providing some control of species composition in the regenerating stand. In order of decreasing shade,

seedlings of western hemlock, Sitka spruce, Douglas-fir, and

red alder are able to become established (10). Logging costs

are higher with shelterwood cutting because several entries

are made into the stand. There is increased danger of wind

damage to the residual stand. Overstocking of western

hemlock regeneration can be expected, and growth rate of

seedlings is slower under shade (11). The system is not

appropriate for stands infected with dwarf mistletoe or for

old-growth stands where trees are large and defective.

The selection system has not been tested in the western

hemlock-Sitka spruce type, but in theory it appears to have

merit. With the selection system, a high uneven-aged forest

cover could be maintained, resulting in less visual change

and greater stability of environmental conditions. It may have

application in scenic areas where both forest cover and

commercial timber production are desired, and may be a

useful system for maintaining good deer habitat in the

northern portion of the type. The system might be used to

discriminate against unwanted intolerant plant species by

restricting the size of openings.

Disad\ antages of the selection system are that frequent

entries must be made into the stand to remove trees individually or in small groups, thus increasing logging costs and the

chance of logging damage. Risk of wind damage also

increases. A more extensive road system needs to be maintained to secure the same volume of timber as obtained by use

of Other systems, and this could result in increased erosion. It

would be the least desirable system where timber production

is a major goal.

Converting older, even-aged stands with trees of fairly

uniform, large diameters, or stands having several age

classes to uneven-aged stands with a progression of diameter

classes, would be a lengthy process. The selection system

would not be desirable for hemlock stands infected with

hemlock dwarf mistletoe.

The seed-tree system offers little advantage for use in

hemlock—spruce forests. Overdense regeneration usually

occurs even without seed trees; and on problem sites,

additional seed offers no guarantee of regeneration success.

Exposed trees tend to blow down, and it is costly to harvest

them at a later date. From the standpoint ofwildlife management,

the seed-tree system might be used to provide snags for

nesting or perching sites. Selection of seed trees could be

based on their suitability for wildlife habitat as well as for

seed production (11).

Both hemlock and spruce respond well to release, and

growth rates increase immediately after thinning (15). Early

precommercial thinning is recommended where stands are

overdense. Height growth of Sitka spruce and western

hemlock are nearly equal during the period of most rapid

growth, but spruce grows more rapidly in diameter.

Consequently, thinning from below tends to favor spruce.

Commercial thinning is becoming more common, but

conventional logging methods have not proved satisfactory,

and economics has limited thinning opportunities in hemlock.

Cable yarding is often preferable to use of tracked or wheeled

vehicles and is the only practical means on steep slopes. In

Alaska, commercial thinning has been limited because of the

predominance of old-growth stands, poor accessibility, and

limited markets for small material.

Multiple use management of resources is practiced to

various degrees in the western hemlock-Sitka spruce type

depending on forest ownership, suitability of the land, and

relative demands for various resources. Timber is a major

resource; recreation, scenery, wildlife, and fish are important

resources as well. Hemlock-spruce forests provide habitat

for game and nongame animals and watershed protection for

spawning and rearing habitat for anadromous fish. They

provide recreational opportunities and scenery rarely found in

any other forest type.

Clearcutting will doubtless continue to be by far the

most economical and practical silvicultural system for use

where timber production is a major objective of management.

The shelterwood and selection systems could become more

widely used in situations where the use or protection of other

resources is paramount.

Literature Cited

1. Barnes, George H. Yield of even-aged stands of western hemlock.

Tech. Bull. No. 1273. Washington, DC: U.S. Department of Agriculture;

1962. 52 p.

2. Eyre, F. H., ed. Forest cover types of the United States and Canada.

Washington, DC: Society of American Foresters; 1980. 148 p.

3. Farr, Wilbur A.; Harris, A. S. Site index of Sitka spruce along the

Pacific coast related to latitude and temperatures. For. Sei. 25(1):

145-153; 1979.

4. Fowells, H. A., comp. Silvics of forest trees of the United States.

Agrie. Handb. No. 271. Washington, DC: U.S. Department of Agriculture;

1965. 762 p.

5. Fumiss, R. L.; Carolin, V. M. Western forest insects. Misc. Publ. No.

1339. Washington, DC: U.S. Department of Agriculture; 1977. 654 p.

6. Harris, Ariand S.; Farr, Wilbur A. The forest ecosystem of southeast

Alaska. 7. Forest ecology and timber management. Gen. Tech. Rep.

PNW-25. Portland, OR: U.S. Department of Agriculture, Forest

Service, Pacific Northwest Forest and Range Experiment Station; 1974.

109 p.

7. Meyer, Walter H. Yield of even-aged stands of Sitka spruce and western

hemlock. Tech. Bull. No. 544. Washington, DC: U.S. Department of

Agriculture; 1937. 86 p.

8. Minore, Don. Seedling growth of eight northwestern tree species over

three water tables. Res. Note PNW-115. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Forest and

Range Experiment Station; 1970. 8 p.

9. Minore, Don; Smith, Clark E.; Woollard, Robert F. Effects of high soil

density on seedling root growth of seven northwestern tree species. Res.

Note PNW-112. Portland, OR: U.S. Department of Agriculture,

Forest Service, Pacific Northwest Forest and Range Experiment Station;

1969. 6 p.

10. Ruth, Robert H. Differential effect of solar radiation on seedling

establishment under a forest stand. Corvallis, OR: Oregon State

University; 1968. 165 p. Thesis.

11. Ruth, Robert H.; Harris, A. S. Management of western hemlock-Sitka

spruce forests for timber production. Gen. Tech. Rep. PNW-88.

Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific

Northwest Forest and Range Experiment Station; 1979. 197 p.
12. Taylor, R. F. Yield of second-growth western hemlock-Sitka spruce

stands in southeastern Alaska. Tech. Bull. No. 412. Washington, DC:

U.S. Department of Agriculture; 1934. 30 p.

13. Wallis, G. W.; Reynolds, G. Fomes annosus root and butt rot: A threat

in managed stands in coastal British Columbia. For. Chron. 46(3):

221-224; 1970.

14. Wallmo, Olof C; Schoen, John W. Response of deer to secondary

forest succession in southeast Alaska. For. Sei. 26(3): 448-462; 1980.

15. Wiley, Kenneth N. Thinning of western hemlock: A literature review.

Weyerhauser Forestry Pap. No. 12. Centralia, WA: Weyerhauser

Forestry Research Center; 1968. 12 p.

16. Williamson, Richard L. Natural regeneration of western hemlock. In:

Atkinson, William A.: Jasoski, Robert J., ed. Proceedings, Western

Hemlock Management Conference; 1976 May; Union, WA. Inst. For.

Prod. Contrib. No. 34. Seattle: University of Washington. College of

Forest Resources; 1976: 166-169.
Pacífíc Douglas-Fir

Richard L. Williamson

Pacific Northwest Forest and Range Experiment Station

Asa D. Twombly

Pacific Northwest Region

Pacific Douglas-fir (type 229), with associated species,

is one of the world's most productive forest cover types listed

by the Society of American Foresters (5). This type generally

is restricted in the United States to areas west of the Cascade

Range in Washington and Oregon, but it also is found on a

more limited area in northwestern California—in total, about

17 million acres (6.9 million ha).

Coast Douglas-fir {Pseudotsuga menziesii (Mirb.) Franco

var. menziesii) (24), requires moderate temperatures and

moisture regimes, as shown by its common presence on

southerly slopes in the northern portion of its range and on

northerly slopes in the southern part. The species thrives on a

variety of soils, but grows poorly on shallow soils and over

high water tables (26).

Almost pure stands of coast Douglas-fir are more

common in the central portion of its range than toward the

periphery. The principal associates, western hemlock {Tsuga

heterophylla (Raf.) Sarg.) and western redcedar {Thuja

plicata Donn ex. D. Don), appear more frequently in the

wçst and north; true firs and mountain hemlock are more

abundant at higher elevations (6). To the south the type

merges into the mixed conifers and hardwoods of southwest

Oregon and northern California and has a rather discreet

western boundary there with the redwood type.

The type occupies a mild and humid climate with dry

summers. Average annual temperatures vary from 45° to 55°

F (7.2° to 12.8° C), with extremes from about 110° to -30° F

(43.3° to -34.4° C) (6). Annual precipitation ranges from

about 35 to over 200 inches (890 to more than 5080 mm) per

year—much of that at higher elevations as snow. Elevations

occupied by the type range from sea level to about 1,500 feet

(460 m) in the northern part of the range; to about 6,000 feet

(1830 m) in the southern part.

Coast Douglas-fir is usually a subclimax species. Left

untouched, old-growth stands usually are succeeded by more

shade-tolerant species, especially western hemlock, unless

natural catastrophes such as wildfires and windthrow intervene.

Douglas-fir is called a fire species because wildfire often will

not kill thick-barked old-growth trees and fire has frequendy

been involved in its natural regeneration. Fire may stimulate

seed production, cause the release of seed from cones,

eliminate thin-barked competitors, and create suitable seedbeds.

Historically, wildfires have burned large areas, giving rise to

extensive even-aged stands.

Natural reproduction of Douglas-fir and its principal

associates is through wind-disseminated seed. Douglas-fir

seed production is irregular, but a light crop or better can be

expected about 2 years out of 3 in the central portion of the

range (18), and less frequently in the southern portion (34).

Seed can be disseminated over a wide range of distances,

depending on stand height and wind velocity (8, 15).

Germination and survival are best on mineral soil seedbeds,

but are possible on seedbeds of organic matter if temperature

and moisture regimes are suitable (18). Temperatures are

usually too high on sunlit seedbeds of organic matter (35).

Reproduction is usually scantier where slash is heavier (2).

Therefore, slash burning under typical old-growth harvest

conditions results in better natural restocking of Douglas-fir

than no burning.

Both western hemlock and western redcedar are more

prolific seed producers than Douglas-fir (10, 49). These

species prefer mineral soil seedbeds, too, but their seeds

germinate and seedlings survive better on duff and rotten

wood than do those of Douglas-fir. If slash is not burned,

seedlings of western hemlock and western redcedar are more

likely to predominate than if slash is burned.

Douglas-fir is medium in shade tolerance and much less

tolerant than its principal associates (30). Young Douglas-fir

seedlings require about one-third of full sunlight to achieve

maximum photosynthesis under optimum temperature and

moisture conditions (21). Light requirements are probably

greater under the usual moisture stress of growing season

field conditions. Western hemlock can germinate and survive

at about 2 percent of full sunlight, compared to Douglas-fir,

which requires at least 5 percent (18, 46, 50). On severe sites

where regeneration of Douglas-fir is difficult, approximately

50 percent shade produces the best survival and reasonable

growth of seedlings (18, 40, 48). Once Douglas-fir and

western hemlock are well established, height growth increases with increasing light (42, 50).

Soil surface temperatures above about 140° F (60° C)

can be lethal to very young Douglas-fir seedlings, and such

temperatures are common during the middays of late spring

and summer on south slopes (11, 14, 35). Where lethally

high temperatures can be expected, shade benefits survival of

seedlings (27, 48). Such benefits also extend to more mesic

sites (16). These temperature relations are probably the

principal reason why most clearcuts that have not restocked

naturally in a satisfactory length of time have failed to do so,

and why planting of seedlings is a standard practice. Prédation of seeds and seedlings by birds, rodents, and other

animals, and competing vegetation are also frequently listed

as causes of regeneration failures.

The principal associates of coast Douglas-fir are much

more tolerant of flooding and high water tables than is

Douglas-fir, to the practical exclusion of Douglas-fir on such

sites (26). Conversely, Douglas-fir tolerates drought much

better than western hemlock (4).

Productivity of a coast Douglas-fir site depends, in part,

on the genetic makeup of the trees. The use of local strains is

essential for planting stock because of their adaptation to

environmental conditions, though cautious genetic manipulation should improve yields somewhat (36). In the same vein,

promoting both natural and artificial regeneration could

uphold genetic diversity (44). Such practices should decrease

the chances of lower-than-expected yields caused by the use

of off site seed sources.

Controlled burning is a principal tool of forest land

managers within this type for preventing wildfire through

hazardous fuel reduction, controlling undesirable species,

and clearing harvested sites of debris for regeneration. Fire,

however, may decrease site productivity through loss of
nitrogen and through leaching of soil cations and surface

erosion (31, 33). No significant differences between burned

and unbumed forest soils in short-term growth of seedlings

and in organic matter, total N, P, K, Ca, permeability, and

wettability were found 25 years after broadcast burning on

the western flanks of the Cascade Range (20, 43).

Douglas-fir is remarkably free of pests during the

juvenile stages, though browsing of foliage by various

animals—^principally deer, elk, mountain beaver, snowshoe

hare, and various rabbits—can be a serious problem locally

(3). As stands mature, they become increasingly vulnerable

to root pathogens, the Douglas-fir beetle {Dendroctonus

pseudotsugae Hopkins), and snow and ice breakage. Mortality and loss of production caused by these agents is much

reduced if stands are maintained in a vigorous condition by

thinning (47).

Extensive trials some 30 years ago clearly showed that

the selection method used in uneven-aged management

cannot be applied successfully to old-growth coast Douglasfir (19). Slash disposal was difficult because there was risk of

killing standing trees, mortality in residual stands was high,

and insufficient light was provided for Douglas-fir reproduction.

The result was that stands were converted to more shadetolerant and less valuable species (18, 32). The uneven-aged

system may have limited applicability where resource values

other than timber production justify higher costs, changes in

species composition, and stand structure or stand conditions

associated with uneven-aged stands. Use of the selection

method of cutting may be possible without species conversion in small portions of the Douglas-fir range—in ecosystems where Douglas-fir is a climax species. These ecosystems generally occur in topographic rain shadows such as the

east side of Vancouver Island where soil and climate characteristics lead to droughty, but not xeric, soil conditions. No

recorded trials of individual tree selection with all size classes

represented have been designed and implemented for a

significant period in the Pacific Douglas-fir type.

The medium shade tolerance of coast Douglas-fir, and

the much greater tolerance of its principal associates, justify

the use of even-aged silviculture.

Among the even-aged regeneration methods, the only

one not appropriate for old-growth Douglas-fir is the seedtree method. Seed trees are too isolated and, thus, susceptible

to windthrow (17). The method should be appropriate in

young-growth stands that have been thinned throughout their

lives, with consequent increased wind firmness of individual

trees. Clearcutting is by far the most common and successful

reproduction method for coastal Douglas-fir—successful in

that logging is most efficient and artificial regeneration

practices usually result in good survival and growth of

seedlings. Most seedling failures after clearcutting are caused

by temperature extremes (16), with lesser amounts by drought

and competing vegetation. Shelterwood overstories, together

with site preparation, can be expected to mitigate such

extremes. Artificial regeneration after clearcutting may fail

frequently enough on some southerly slopes and on gentle

terrain in the midportion of the range of the species, and

increasingly on similar slopes toward the southern part of the

range, to suggest use of the shelterwood method. The choice

of which method to use should be based on evidence about

which one would provide adequate regeneration at most

reasonable cost.

Shelterwood harvesting in the Pacific Douglas-fir type,

with appropriate overstory characteristics and site preparation,

can insure adequate regeneration where evidence suggests

that regeneration after clearcutting will fail (48). This evidence includes survey data on regeneration success in nearby

existing clearcut areas of similar soil, slope, aspect, and

elevation. Lesser vegetation and soils descriptions are available as regeneration guidelines for some areas (29). Financial

considerations necessarily influence the choice since any

reproduction method could be made to work anywhere if

costs were no object.

Practices that aid regeneration and incur costs above

those arising under patch clearcutting include making clearcuts smaller or in narrow strips, eliminating concentrations of

slash, controlling brush, and providing artificial shade (7,9,

22, 23, 27, 28, 41). Eliminating concentrations of slash and

controlling brush often are accomplished together as part of

site preparation. Burning, either broadcast or of piles, is the

usual method. Yarding of unmerchantable material greatly

reduces the need for burning and should practically eliminate

hard-bum areas, including those areas where burning is

necessary for fire control or site preparation.

Under shelterwood harvesting, practices that aid regeneration and also incur costs are the shelterwood operation itself,

which is more expensive to lay out and log than a clearcut,

and site preparation, which can be accomplished in the same

manner as in clearcuts. Several precautions should be observed when using the shelterwood method within the Pacific

Douglas-fir type:

• The largest, most vigorous, and best formed individuals of desirable species should be retained until the

final cutting (37), unless some individual other trees

are retained as future habitat for cavity-nesting birds.

• Overstories should be sufficiently dense to provide

appropriate microclimate modification and resist

windthrow and dessication (48).

• Site preparation should expose mineral seedbed (39).

• Overstories should be removed when seedlings are

sufficiently dense and well established, but while still

low and limber. Doing so avoids much regeneration

mortality caused by overstory removal and relieves

seedlings from the substantial competition offered by

the overstory.

If these precautions are observed, conditions for natural

regeneration under shelterwood (except on high-site, brushthreat areas) are favorable.

The method is reliable and avoids the cost of planting

which may compensate for increased harvest and administrative costs. Since the seed providers in the overstory survived

to maturity in the presence of whatever pests or hostile

environmental conditions pertain to the site, the resultant

natural regeneration should show similar adaption (36).

Coast Douglas-fir seedlings become established slowly,

requiring 5 to 10 years to reach breast height. Once regeneration is established, growth is rapid on good sites, ranging up

to about 300 cubic feet per acre per year (21.0 m^/ha/year).

Mature yields above age 100 can be more than 17,500 cubic

feet per acre (1225.0 m^a) (25). Conventional rotation

lengths normally vary between 50 and 100 years, with final

harvest yields in natural stands on average sites from about

5,000 to 14,500 cubic feet per acre (350.0 to 1015.0 m^/ha).

Initial spacing and subsequent growing stock control with

fertilization are required for optimum yields in terms of tree

size and fiber production. Yields under growing stock control

and fertilization will generally range about 30 to 50 percent

greater than natural yields.

The foregoing suggests that clearcutting and shelterwood

will be the principal regeneration methods for the Pacific

Douglas-fir type. That these methods will differ significantly

in their impacts on water, fish, wildlife, rare and endangered

species, or recreation is unlikely. Any shelterwood stand

open enough to promote establishment of coast Douglas-fir

seedlings will generally support the same species of lesser

vegetation as clearcuts do, except for the very shade intoler10
ant red alder, with quantities and nutrients somewhat reduced

because of competition from the overstory. Even clearcutting

does not seem to have significant and adverse impacts on

streamflows (12, 13).

Clearcut areas provide forage for big game and habitat

for other species of wildlife including birds that utilize plant

communities containing predominantly pioneer plant species.

Hiding and thermal cover provided by uncut or maturing

stands are equally important to wildlife. The size and

distribution of clearcut and uncut areas influence the quality

of wildlife habitat (45).

Size, shape, and viewer position in relation to both

clearcut and shelterwood units largely determine the visual

acceptability of regeneration methods to achieve landscape

management objectives. Rotation lengths of 250 or more

years can provide the large-diameter trees that are specified

in many "foreground" visual resource management plans in

the Pacific Douglas-fir forest type (1).

Modifications of the even-aged silvicultural systems are

options for this type that may be considered where management for esthetic, watershed, or wildlife objectives require a

continuous high canopy or one with small gaps. These

options also may provide some opportunity to manage for

specific requirements of identified threatened, rare, or endangered species of plants or animals. Smaller clearcuts and

shelterwood stands adjacent to streams will inhibit stream

bank and sheet erosion into streams and mitigate the rise in

stream temperature that would otherwise occur under large

clearcuts.

The opportunities to utilize modifications of silvicultural

systems within the Pacific Douglas-fir type are limited by

willingness to accept yield reductions, increased costs, and

species conversion, as well as by physical and biological

limitations, The presence of potentially competitive vegetation capable of preventing the establishment of desired

vegetation limits the choice of silvicultural systems. The use

of chemicals to control the competing vegetation is hindered

by the existence of residual trees on an area being reforested,

especially on steep and rough topography.

The choice of specific silvicultural systems to achieve

multiple-use management objectives influences costs of layout

and administration or supervision of harvest operations. The

primary factors contributing to increased operational costs

are: increasing the variety of log sizes being harvested;

increasing the numbers of residual trees in any partial cut;

increasing the volume removed; and increasing the complexity of designating residual trees. The following comparisons

are between clearcutting and partial cutting within the Pacific

Douglas-fir type using current Forest Service appraisal and

logging system guidelines. The estimated range of increased

costs, relative to clearcutting, for preparation and harvest on

slopes less than 30 percent is 6 percent for shelterwood to 10

percent for selection cutting. Similarly the range on slopes

exceeding 30 percent is estimated to be 20 to 30 percent.

Partial cutting becomes increasingly costly with longer yarding distances and steeper terrain.

Within the Pacific Douglas-fir type, partial cutting or

clearcuts as small as 10 acres (4 ha) may require 7.5 miles of

road per mile^ (4.7 km/km^) of land whereas block clearcuts

of 100 acres (40.5 ha) may require only 6.3 miles of road per

mile^ (3.9 km/km^) (38). Any method of harvesting that

retains a portion of the timber stand requires an increased

area of land to provide a similar volume of timber for harvest.

This in turn requires a more rapid development of the

ultimate road network; an increase in miles of road use and

maintenance, with consequent erosion and siltation of streams;

and a temporary decrease in cover for wildlife.

Literature Cited

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management. Volume 2, Chapter 5, Timber. Agrie. Handb. No. 559.

Washington, DC: U.S. Department of Agriculture; n.d. 223 p.

2. Bever, Dale N. Evaluation of factors affecting natural reproduction of

forest trees in central western Oregon. Res. Bull. No. 3. Salem, OR:

Oreg. St. Board of For.; 1954. 49 p.

3. Brodie, Douglas; Black, Hugh C; Dimock, Edward J., II. [and others].

Animal damage to coniferous plantations in Oregon and Washington.

Part II. An economic evaluation. Res. Bull. 26. Corvallis, OR: Oreg.

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4. Cleary, B.D.; Greaves, R. D.; Owston, P. W. Chapter 6. Seedlings. In:

Cleary, Brian D.; Greaves, Robert D.; Hermann, Richard K., comp.,

eds. Regenerating Oregon's forests: a guide for the regeneration

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5. Eyre, F. H., ed. Forest cover types of the United States and Canada.

Washington, DC: Society of American Foresters; 1980. 148 p.

6. Fowells, H. A., comp. Silvics of forest trees of the United States.

Agrie. Handb. 271. Washington, DC: U.S. Department of Agriculture;

1965. 762 p.

7. Franklin, Jerry F. Natural regeneration of Douglas-fir and associated

species using modified clearcutting systems in the Oregon Cascades.

Res. Pap. PNW-3. Portland, OR: U.S. Department of Agriculture,

Forest Service, Pacific Northwest Forest and Range Experiment Station;

1963. 14 p.

8. Garman, E. H. Regeneration problems and their silvicultural significance in the coastal forests of British Columbia. Tech. Pub. T.41.

Vancouver, BC: British Columbia Forest Service; 1955. 67 p.

9. Gratkowski, H. Herbicides for shrub and weed tree control in western

Oregon. Gen. Tech. Rep. PNW-77. Portland, OR: U.S. Department

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10. Haig, Irvine T.; Davis, Kenneth P.; Weidman, Robert H. Natural

regeneration in the western white pine type. Tech. Bull. No. 767.

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11. Hallin, William E. Soil surface temperatures on cutovers in southwest

Oregon. Res. Note PNW-78. Portland, OR: U.S. Department of

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12. Harr, R. Dennis; Fredriksen, Richard L.; Rothacher, Jack. Changes in

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22 p.

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18. Isaac, Leo A. Reproductive habits of Douglas-fir. Charles Lathrop Pack

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794-801; 1965.

11
22. Lavender, Denis P.; Bergman, Moms H.; Calvin, Lyle D. Natural

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Service, Pacific Northwest Forest and Range Experiment Station; 1974:

D-1—D-23.

34. Roy, D. F. Douglas-fir seed production and dispersal in northwestem

Califomia. Tech. Rep. No. 49. Berkeley, CA: U.S. Department of

Agriculture, Forest Service, Pacific Southwest Forest and Range Experiment Station; 1960. 22 p.

35. Silen, Roy Ragnar. Lethal surface temperatures and their interpretation

for Douglas-fir. Corvallis, OR: Oregon State University; 1960. 170 p.

Ph.D. Thesis.

37

38

36. Silen, Roy R.; Doig, Ivan. The care and handling of the forest gene

pool. Pacific Search 10(8): 7-9; 1976.

Smith, David Martyn. The practice of silviculture. 7th ed. New York,

NY: John Wiley; 1962. 578 p.

Staebler, George R. "Clearcutting" practices on national timberlands.

In: Hearing before U.S. Senate Subcommittee on Public Lands. April 5

and 6, 1971; Committee on Interior and Insular Affairs, United States

Senate, Ninety-Second Congress. Washington, DC: U.S. Govemment

Printing Office; 1971: 241-253.

39. Stewart, R. E. Chapter 7. Site preparation. In: Cleary, Brian D.;

Greaves, Robert D.; Hermann, Richard K., comps., eds. Regenerating

Oregon's forests: a guide for the regeneration forester. Corvallis, OR:

Oregon State University Extension Service; 1978: 99-129.

40. Strothman, R. O. Regeneration of Douglas-fir cutblocks on the Six

Rivers National Forest in northwestem Califomia. Res. Pap. PSW-142.

Berkeley, CA: U.S. Department of Agriculture, Forest Service, Pacific

Southwest Forest and Range Experiment Station; 1979. 69 p.

41. Strothman, Rudolph O. Douglas-fir in northem California's effects of

shade on germination, survival, and growth. Res. Pap. PSW-84.

Berkeley, CA: U.S. Department of Agriculture, Forest Service, Pacific

Southwest Forest and Range Experiment Station; 1972. 10 p.

42. Tappeiner, John Cummings, II. Natural regeneration of Douglas-fir

(Pseudotsuga menziesii (Mirb.) Franco) on Blodgett Forest in the mixed

conifer type in the Sierra Nevada of Califomia. Berkeley: University of

Califomia; 1966. 238 p. Dissertation.

43. Tarrant, Robert F.; Wright, Emest. Growth of Douglas-fir seedlings

after slash buming. Res. Note No. 115. Portland, OR: U.S. Department

of Agriculture, Forest Service, Pacific Northwest Forest and Range

Experiment Station; 1955. 3 p.

44. Theisen, Peter A. Region 6 tree improvement training paper 14.

Portland, OR: U.S. Department of Agriculture, Forest Service; 1978.

9 p.

45. Thomas, Jack Ward. Wildlife habitats in managed forests in the Blue

Mountains of Oregon and Washington. Agrie. Handb. No. 553.

Washington, DC: U.S. Department of Agriculture; 1979. 512 p.

46. Weaver, John E.; Clements, Frederic E. Plant ecology. New York:

McGraw-Hill; 1938. 601 p.

47. Williamson, Richard L.; Price, Frank E. Initial thinning effects in 70- to

150-year-old Douglas-fir—westem Oregon and Washington. Res. Pap.

PNW-117. Portland, OR: U.S. Department of Agriculture, Forest

Service, Pacific Northwest Forest and Range Experiment Station; 1971.

15 p.

48. Williamson, Richard L. Results of shelterwood harvesting of Douglasfir in the Cascades of westem Oregon. Res. Pap. PNW-161. Portland,

OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest

Forest and Range Experiment Station; 1973. 13 p.

49. Williamson, Richard L. Natural regeneration of westem hemlock. In:

Atkinson, William A.; Zasoski, Robert J., eds. Westem hemlock

management. Institute of Forest Products Contribution Number 34.

Seattle, WA: University of Washington, College of Forest Resources;

1976: 166-169.

50. Williamson, Richard L.; Ruth, Robert H. Results of shelterwood cutting

in westem hemlock. Res. Pap. PNW-201. Portland, OR: U.S.

Department of Agriculture, Forest Service, Pacific Northwest Forest

and Range Experiment Station; 1976. 25 p.

12
True Fir -Hemlock

Jerry F. Franklin

Pacific Northwest Forest and Range Experiment Station

William Emmingham

Oregon State University

Ralph Jaszkowski

Pacific Northwest Region

The true fir-hemlock (Abies-Tsuga) type is a diverse

collection of montane and subalpine forests found on the

middle and upper slopes of the entire Cascade Range, on

higher peaks in the northern Coast Ranges of Oregon and

Washington, and throughoutthe Olympic Mountains in Washington. It covers at least 4 million acres (1.6 million ha)

over a broad spectrum of environmental conditions and incorporates many species and stand conditions (3). These forests

belong mainly to Society of American Foresters forest cover

types 226 (Coastal True Fir-Hemlock) and 205 (Mountain

Hemlock) (2) and occur within the Pasific Silver Fir and

Mountain Hemlock Zones (5). The majority oftrue fir-hemlock

forest are old growth, which often influences the choice of

silvicultural systems.

True fir-hemlock forests can be stratified into four

major geographic groups (3). One group is forests overwhelmingly dominated by Pacific silver fir (Abies amabilis

(Dougl.) ex Forbes) and western hemlock (Tsuga heterophylla

(Raf.) Sarg.) that occur in the Olympic Mountains (except for

the northeast comer) and western slopes of the Northern

Cascades. Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco)

and western redcedar (Thuja plicata Donn ex D. Don) are

associated at lower and mountain hemlock (Tsuga mertensiana

(Bong.) Carr.) and Alaska-cedar (Chamaecyparis nootkatensis

(D. Don) Spach) at higher elevations. A second group is

mixed forests dominated by Pacific silver fir, western hemlock,

noble fir (Abiesprocera Rehd.), and Douglas-fir with associated western redcedar, Alaska-cedar, and western white pine

(Pinus montícola Dougl. ex D. Don) that characterize jthe

western two-thirds of the Cascade Range from about 44° to

47.5° N. Another group is mixed forests with significant

representation of interior species, such as lodgepole pine

(Pinus contorta Dougl. ex Loud.), Engelmann spruce (Picea

engelmanmi Parry ex Engelm.), subalpine fir (Abies lasiocarpa

(Hook.) Nutt.), grand fir (Abies grandis (Dougl. ex D. Don)

Lindl.), and western larch (Larix occidentalis Nutt.), that

occur on the eastern slopes of the Washington Cascade

Range and in Oregon's High Cascades north of about

44° N. Douglas-fir, western white pine, western and

mountain hemlocks, and noble and Pacific silver firs remain major species in this region. A fourth group is

mountain hemlock forests in the southern Oregon Cascade

Range that have Shasta red fir (Abies magnifica A.

Murr. var. shastensis Lemm.) and lodgepole pine as major

associates. The Shasta red fir forests of the southern Cascade Range and Klamath Mountains with their associated

grand fir, Douglas-fir, western white pine, and mountain

hemlock resemble the California true fir types more closely

that the true fir-hemlock types discussed in this section.

Readers are referred to the "Red Fir-White Fir" section of

this handbook for a discussion of relevant sivicultural

systems.

More than 50 true fir-hemlock habitat types are recognized indicating the wide range of environmental variability.

Elevations range from about 3,500 to 6,000 feet (1075 to

1825 m) in central Oregon to 2,500 to 5,000 feet (750 to

1525 m) in northern Washington, although true fir-hemlock

forests may occur as low as 1,000 feet (300 m) in cold valley

bottoms. Topography is typically gentle in the High Cascades

and moderate to very steep in the Western and Northern

Cascades, Coast Ranges, and Olympic Mountains (3). Soils

are generally coarse textured, youthful, and most frequently

developed in colluvium, volcanic tephra, or glacial till. Mor

layers are typical but range widely in thickness, being best

developed in the Northern Cascades.

Climatic conditions can be characterized as cool, wet,

and snowy; but specifics vary with elevation, latitude, and

location in the various mountain ranges. Temperature decreases and precipitation increases with increases in elevation

and latitude; eastern slopes of mountain ranges have drier and

more continental temperature regimes than the western slopes,

since winter storms come from the west and southwest.

Summers are generally cool, but winter temperatures are

moderate for a subalpine region—subfreezing daytime maxima are not common. Frosty areas are particularly common

and severe in the gentle topography of the High Cascades due

to reradiation and poor air drainage but are also encountered

throughout the type. Precipitation generally exceeds 80

inches (2030 mm) and can be over 200 inches (5080 mm)

annually. Much of it occurs as snow which forms deep,

heavy, snowpacks 2 to 20 feet (0.6 to 6 m) in depth,

depending on elevation and aspect. These snowpacks are

present for 3 to 8 months and prevent extensive soil freezing.

Periods of dryness may occur during the summer but generally do not result in high plant moisture stresses. Clouds are

common throughout the year and may cause abundant fog

drip in mature forests. Strong southwest to west winds are

associated with winter storms, and strong dry east winds

occur occasionally throughout the year.

The most characteristic and widespread species are

Pacific silver fir, western hemlock, mountain hemlock,

Douglas-fir, and noble fir. Important constituents do vary

widely on both a large geographic scale (as indicated above)

and locally. Mixed stands of three to five species are most

common, but almost any species can dominate or form local

pure stands. Douglas-fir, noble fir, western larch, and the

pines are the most shade intolerant species and often function

as pioneers following major disturbances. Pacific silver fir

and western hemlock are very shade tolerant. The relative

importance of the two species as climax species varies with

increasing elevation favoring Pacific silver fir dominance

over the western hemlock.

Natural regeneration of trees in true fir-hemlock forest

is almost exclusively by seed. Some seed is produced almost

every year because stands are mixed and species vary in their

patterns of seed production (6). Many species produce

medium or better crops every 2 or 3 years, but Douglas-fir

produces less frequently and the pines at more frequent

intervals. Seed dissemination is by wind with the bulk of the

seed falling within one tree height of its source. The shade

intolerant species prefer mineral soil seedbeds while the

tolerant species also utilize organic seedbeds. Seed germina13
tion varies widely with species, the true firs generally having

low viability. Survival rates of seedlings differ markedly with

year, habitat type, and other factors. Mortality of germinants

can be extremely high with thousands of seeds necessary to

produce a single established seedling. Vegetative competition (from sedges, shrubs, and beargrass (Xerophyllum tenax)),

pocket gophers, and frost can be important factors reducing

survival of both planted and natural trees. Once established,

noble fir, Douglas-fir, western white pine, and shade intolerant associates require substantial light for best development;

these species are generally not able to recover following

suppression. Pacific silver fir and western hemlock can

establish themselves in heavy shade, and suppressed seedlings of these species often do recover and grow normally

following release.

Growth rates are highly variable between sites and

between species on the same site. In general, trees initially

grow slowly but sustain their growth into the second and even

third centuries. When more typically low-elevation species

(Douglas-fir and western hemlock) occur in the true fir-hemlock

type, they consistently show slower juvenile growth but more

sustained growth than at lower elevations (1). Noble fir site

indices of 60 to 160 feet (18 to 49 m) at 100 years illustrates

the range in productivity (1U- Mean annual growth of stands

can be in excess of 250 cubic feet per acre (17.5 m^/ha) at

culmination on the best sites although much lower values are

typical and many sites produce 50 cubic feet per acre (3.5

m^/ha) or less. Stand growth slows later in true fir-hemlock

stands than in lower elevation forests; culmination of mean

annual increment is at about 125 years in unmanaged stands

on noble fir site class II.

Numerous insects and diseases affect true fir-hemlock

forests (7, 10). Bark beetles such as mountain pine beetle

(Dendroctonus ponderosae Hopkins) affect the pines, and the

silver fir beetle {Pseudohylesinus sericeus (Mannerheim)) and

P. tsugae) affects true firs and hemlocks. Both insects sometimes cause epidemic losses. The exotic balsam woolly

adelgid {Adelges piceae Ratzeburg) is a serious pest of

Pacific silver and subalpine fir, especially on better sites

where it can limit their management potential (13). Dwarf

mistletoes {Arceuthobium spp.) are sometimes problems

especially in western hemlock; mistletoe limits the potential

use of advancç regeneradon on some sites. White pine blister

rust {Cronartium ribicola J. C. Fisch.) seriously limits the

management potential of western white pine by killing large

numbers of seedlings, saplings, and poles; development of

rust-resistant planting stock should make it possible to again

utilize western white pine on the many sites where it

demonstrates a superior growth rate. Trunk rots are common

in old-growth stands; true firs and hemlocks have low

resistance to rots once infected. Laminated root rot {Phellinus

weirii (Murr.) Gilb.) is the most serious root pathogen and

causes extensive mortality in mountain hemlock forests in the

high Cascades.

Fire is a significant factor in true fir-hemlock forests.

Sites have burned catastrophically at natural fire intervals of

100 to 400 years or more depending upon habitat type and

geographic location (8,9). Forests located on high ridges and

along the crest of the Cascade Range have especially high fire

risk particularly during times of dry east winds. Prescribed

fire is an important management tool to dispose of slash

accumulations, which can be very large after cutting virgin

stands, and to prepare the site for planting. True fir-hemlock

forests may be more susceptible to misuse of fire than many

other types, however, because of high proportions of nutrients found in surface organic layers on the predominantly

young soils, predominance of thin-barked species, and importance of advanced regeneration.

True fir-hemlock forests can probably be managed

either under even-aged or uneven-aged systems depending on

species composition, health of stand, topography, and management objectives, although silvicultural trials of systems

are far from complete. Where the more light-demanding

species predominate or are desired, an even-aged system is

indicated. If shade-tolerant species are the more important,

then either even-aged or uneven-aged management is possible provided the stand is not defective and topography is

favorable. Thus, the choice of silvicultural systems depends

on many factors including site, species, stand condition, and

objectives. Careful choice of species for management is

especially important on true fir-hemlock sites because of the

large local variations in environment and the large number of

potential species. Mixed stands reduce the risk of catastrophic loss due to environmental or biological agents and

may maximize productivity.

Small clearcuts of less than 20 acres (8.0 ha) and

shelterwood cuttings are the most consistently successful

systems for even-aged management. Noble fir, Douglas-fir,

western white pine, Shasta red fir, and other shade intolerant

species are well suited to both methods. The choice of

species may depend upon whether natural or artificial regeneration is desired; the choice may be further influenced by lack

of dependable methods for artificial regeneration of some

species on some sites. A two-stage shelterwood cutting is the

most dependable method and is particularly indicated on

severe sites, such as frost pockets, and when reliance is to be

placed on natural regeneration. Small clearcuts are a little

riskier for securing natural regeneration but are more suitable

on average sites which can be artificially regenerated. Natural seedlings typically volunteer on such small clearcuts

producing stands with a mixture of species (12). Clearcutting

is typically less expensive than shelterwood cutting and is

easier to use on steep or wet ground. Shelterwood cutting

creates more favorable environmental conditions for seedling

establishment, and species can be favored through the selection of leave trees and preparation of seedbeds. Clearcuts

should be avoided in situations where they could produce

frost pockets. Strip clearcuts would appear a likely alternative to small clearcuts, but results have often been unacceptable to date. An untested possibility for regeneration cutting

on very severe sites is group selection, even for the less

shade-tolerant species.

Larger clearcuts of more than 20 acres (8.0 ha) are

appropriate where available techniques have proven dependable for artificial regeneration of the desired species or,

sufficient good quality advance reproduction of acceptable

species can be preserved during logging and slash disposal.

Clearcutting with heavy reliance on residual advance regeneration is a recommended alternative in many areas and has been

effective on many ownerships in the Washington Cascade

Range. The forester needs to be aware of potential problems

with large clearcuts followed by broadcast burning of slash as

indicated by past experience. Such procedures aggravate

moisture and temperature extremes, minimize natural seedfall,

destroy advance regeneration, volatilize nitrogen, and sometimes result in brush problems. Furthermore, the selection of

potential species is limited since dependable stock or planting

techniques or both are not yet available for many upper-slope

species. Regeneration failures with large clearcuts have been

more common in the High Cascades and near the upper limits

of continuous forest. Advance regeneration, especially of

true firs, responds well to release and can serve as insurance

against reforestation failures even when planting is planned.

Selection is an alternative silvicultural system for extremely severe sites, such as those found at the upper edge of

closed forest, or where management objectives call for

14
maintenance of a continuous forest cover, as in heavily used

recreation areas. Conceptually, group selection should work

with less shade-tolerant species and single tree selection for

species such as Pacific silver fir and western hemlock.

Selection systems have not been tested, however, and have

little application to steep slopes where damage to residual

stems and soils during harvest operations would be severe.

Seed source and genetic variation are important considerations in regeneration programs reflecting high levels of

genecological variability in many species and wide environmental differences in local site conditions. Selection and

testing for genetic improvement of growth rates is currently

underway on public and private forest lands for Douglas-fir,

noble fir. Pacific silver fir, and western white pine. Western

white pine trees resistant to white pine blister rust have been

identified and their progeny are being used in reforestation

programs.

There is very little documented experience in thinning

true fir-hemlock stands. Intermediate cuttings should consider compositional as well as growth objectives, for example,

maintenance of species mixtures, especially in the face of

varying growth rates that tend to cause species stratification

by size classes. In general, desirable stocking levels have not

been determined; but they are expected to involve higher

densities than those established for Douglas-fir stands on

comparable sites; this is based on comparisons between

normally stocked stands of true firs and Douglas-fir (4).

Precommercial thinning is judged the most important type of

intermediate cutting, especially on low site stands that tend to

stagnate. Commercial thinning opportunities are limited by

the thin bark and high damage susceptibility of many

upper-slope species and their patterns of sustained growjth.

Similarly, sanitation cuttings should be avoided because of

the potential for damaging the residual stand.

The potential for fertilization is essentially unknown.

Soils are typically low in nitrogen and, sometimes, phosphorus.

Responses have been reported from fertilized western hemlock and Pacific silver fir (14).

The true fir-hemlock type is well represented in reserved (National Park and Wilderness) lands and is, therefore,

not endangered. No animal species are known to be solely

dependent on the type for their existence although it is

important to a great variety of wildlife.

Since true fir-hemlock forests occupy the upper slopes

of mountain ranges, watershed and recreational values are

major management considerations. The forests are sites for

winter snowpack accumulations, and disturbances can affect

water yields and quality. Recreational activities as varied as

downhill skiing and wilderness backpacking are common in

true fir-hemlock forests. Huckleberry picking is an historic

and valued recreational use of cutover and burned forests of

this type. Wildlife and livestock use are also important

locally in interspersed meadows and as temporary range

following forest disturbance. No-cutting options can be

considered on true fir—hemlock sites with low productivity

(despite significant standing crops) or with severe regeneration problems, and high non-timber values.

Literature Cited

1. Curtis, Robert O.; DeMars, Donald J.; Herman, Francis R. Height

growth and site index estimates for Douglas-fir {Pseudotsuga menziesii)

in high-elevation forests of the Oregon-Washington Cascades. For. Sei.

20(4): 307-316; 1974.

2. Eyre, F. H., ed. Forest cover types of the United States and Canada.

Washington, DC: Society of American Foresters; 1980: 148 p.

3. Franklin, Jerry F. Tentative ecological provinces within the true

fir-hemlock forest areas of the Pacific Northwest. Res. Pap. PNW-22.

Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific

Northwest Forest and Range Experiment Station; 1965. 31 p.

4. Franklin, Jerry F. The true fir resource. In: True fir symposium. Seattle,

WA: University of Washington College of Forest Resources; 1981: In

press.

5. Franklin, Jerry F.; Dymess, C. T. Natural vegetation of Oregon and

Washington. Gen. Tech. Rep. PNW-8. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Forest and

Range Experiment Station; 1973. 417 p.

6. Franklin, Jerry F.; Carkin, Richard; Booth, Jack. Seeding habits of

upper-slope trees species I. A 12-year record of cone production. Res.

Note PNW-213. Portland, OR: U.S. Department of Agriculture,

Forest Service, Pacific Northwest Forest and Range Experiment Station;

1974. 12 p.

7. Fumiss, R. L.; Carolin, V. M. Western forest insects. Misc. Publ.

1339. Washington, DC: U.S. Department of Agriculture; 1977. 654 p.

8. Hemstrom, Miles A. A recent disturbance history of forest ecosystems

at Mount Rainier National Park. Corvallis: Oregon State University;

1979. 67 p. Dissertation.

9. Hemstrom, Miles A. Fire in the forests of Mount Rainier National Park.

In: Proceedings Second Conference on Scientific Research in the

National Parks, Vol. 10: Fire Ecology. Washington, DC: U.S. Department of Interior, National Park Service; 1980: 119-129.

10. Hepting, George H. Diseases of forest and shade trees of the United

States. Agrie. Handb. 386. Washington, DC: U.S. Department of

Agriculture; 1971. 658 p.

11. Herman, Francis R.; Curtis, Robert O.; DeMars, Donald J. Height

growth and site index estimates for noble fir in high-elevation forests of

the Oregon-Washington Cascades. Res. Pap. PNW-243. Portland,

OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest

Forest and Range Experiment Station; 1978. 15 p.

12. Minore, Don; Dubrasich, Michael E. Regeneration after clearcutting in

subalpine stands near Windigo Pass. Oregon. J. For. 79(9): 619-621;

1981.

13. Mitchell, Rüssel G. Infestation characteristics of the balsam wooly

aphid in the Pacific Northwest. Res. Pap. PNW-35. Portland, OR:

U.S. Department of Agriculture, Forest Service, Pacific Northwest

Forest and Range Experiment Station; 1966. 18 p.

14. Scott, David R. M. The Pacific Northwest region. In: Barrett, John

W.,ed., Regional Silviculture of the United States. New York: John

Wiley; 1981: 447-493.

15
Northwestern Ponderosa Pine and Associated Species

James W. Barrett and Robert E. Martin

Pacific Northwest Forest and Range Experiment Station

Donald C. Wood

Pacific Northwest Region

The ponderosa pine type (Society of American Foresters

forest cover type 237) occupies about 7 million acres (2.8

million ha) in eastern Oregon and Washington (10). Additional areas of similar forest occur in northeastern California.

Gentle rolling hills, flat river bottoms, and steep slopes are

all vegetated by ponderosa pine, especially at intermediate

elevations from about 4,000 to 6,000 feet (1220 to 1830 m)

in southern Oregon, but lowering to about 2,000 feet (610 m)

in eastern Washington. Stands are frequently interspersed

with islands of nonforest type and can also be islands in the

grasslands.

Soils are quite varied with many of them the result of

volcanism. Pumice, ash, cinder, and basalt-derived soils,

usually with poorly differentiated horizons, have developed

over buried soils. Other soils are derived from granitic or

serpentine bases. Sedimentary rocks also account for some

soils.

The climate is modified maritime, the result of the

barrier to marine air masses provided by the Cascade Range.

The area has warm dry summers and cold wet winters with

much of the precipitation falling as snow. Growing season

temperatures average between 62° to 70° F (16.7° to 21. T C);

but the daily range of temperature can be as much as 54° F

(30° C), and frost can occur any night of the year in many

areas. Summers are especially sunny; winters have intermittent periods of sunshine and clouds. Precipitation ranges

from about 10 to 30 inches (250 to 760 mm), with only 2 to 6

inches (50 to 150 mm) falling during the growing season.

Humidity is generally quite low, especially in summer.

Lodgepole pine (Pinas contorta Dougl. ex Loud.),

western juniper (juniperus occidentalis Hook.), and western

larch {Larix occidentalis Nutt.) are common intolerant associates of ponderosa pine {Pinus ponderosa Dougl. ex Laws.),

although ponderosa pine has no prevalent associate on the

lowest, driest sites in Washington. The first two species may

be killed by light fires, but the latter may be more resistant to

fire than ponderosa pine as it becomes older.

Other associates of ponderosa pine in the area, in order

of increasing tolerance and decreasing fire resistance are

Jeffrey pine {Pinus Jeffreyi Grev. & Balf.), an important

associate in northern California; sugar pine (Pinus lambertiana

Dougl.); Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco);

incense-cedar (Libocedrus decurrens Torr.); western white

pine (Pinus monticola Dougl. ex D. Don); and true firs

(Abies grandis (Dougl. ex D. Don) Lindl.) and (A. concolor

(Gord. & Glend.) Lindl. ex Hildebr.). Lack of disturbance

such as fire on sites capable of supporting the more tolerant

trees gradually converts the site to those species.

Artificial regeneration of ponderosa pine is generally by

machine planting, although hand planting by auger and hoe

are practiced (7) where obstacles or steep slopes are present.

Adequate site preparation is necessary because of competing

shrub and herbaceous species. Direct seeding is seldom used.

Good seed crops of 200,000 seeds per acre (494 200

seeds/ha) can be expected once every 4 or 5 years, although

these years are not regularly periodic (9). Dissemination is

primarily by wind and by small mammals who cache the

seed. Poor seed years generally have a lower percent of

sound seed; occasionally almost no seed is produced in the

Northwest, perhaps because frost damages the conelets (9,

17). Barrett (2) reported little ponderosa pine seed disseminated more than 100 feet (30.8 m) from the seed source; but in

strong prevailing winds, seeds can be blown 528 feet (161m)

into a clearcut. Mineral soil is considered best for seedling

establishment. On many sites, this is needed in combination

with a shelterwood of 10 to 15 trees per acre (25 to 37/ha) to

reduce heat and frost damage. Survival of seedlings depends

on a combination of factors: availability of sound seed, good

seedbed, adequate moisture, and protection from frost, animals,

disease, and fire. If any of these is unfavorable, survival will

be poor (8).

Ponderosa pine is generally considered a shade intolerant tree, probably being more tolerant than western juniper,

about the same as lodgepole pine and western larch, and less

tolerant than all its other tree associates. Established seedlings and saplings are able to survive shade and root

competition from overstory ponderosa pine. Once established,

ponderosa pine is able to withstand the annual summer

drought, often surviving where the more tolerant mesic

species succumb. It also survives well through periodic

droughts, although it is somewhat more susceptible to insect

attack during dry periods.

Except where growing on very shallow soils, or when a

stand is opened up in a shelterwood or seedtree cut, ponderosa

pine is fairly resistant to uprooting by wind. Older trees often

break from wind damage when previously weakened by fire

scars or decay.

Snow can be damaging to ponderosa pine seedlings or

saplings when they are established on upper slopes where

snowpack is heavy. The overwinter compaction and slippage

of the snow will cause bending or breakage of the young

trees.

Ponderosa pine is able to recover from severe suppression at least to an age of 80 years. Removal of overstory,

control of shrubs, and thinning to a stocking level that will

produce a marketable product will allow rapid growth (3, 4,

14). Suppressed saplings are generally thinned to 150 to 200

trees per acre (370 to 490/ha) after overstory harvest and

frequently will respond and grow at diameter growth rates of

2.5 to 3.0 inches (6.4 to 7.6 cm) per decade. Further

reduction to only 60 trees per acre (148/ha) and control of

shrubs can promote diameter growth rates to as much as 5 or

6 inches (12.7 or 15.2 cm) per decade on some sites. Height

growth can also be substantially increased by thinning in

these suppressed stands (3, 4).

Height and diameter growth of ponderosa pine will

continue to respond to release for at least 16 years following

treatment. Natural stands often grow many years to reach

breast height (4.5 ft or 1.37 m) because of overstory

presence, and understory vegetation competition. Frequently,

many years are required for roots to reach more moist or

fertile substrata in the soil.

16
Annual growth rates may vary from 10 cubic feet per

acre (0.7 m^/ha) on sites near the desert fringe to 80 cubic

feet per acre (5.6 m^/ha) on better pine climax types. On true

fir-Douglas-fir habitat types, where ponderosa is present but

not climax, annual yields commonly vary from 50 cubic feet

per acre (3.5 m^/ha) to 150 cubic feet per acre (10.5 m^/ha).

Stocking capacity is a major factor in yields along with site

index and management practices such as thinning, vegetation

control, and amount of overstory retained (6, 11).

Culmination of mean annual increment (MAI) (rotation

age) varies from 80 to 140 years depending on site quality

and silvicultural treatment. Ponderosa pine is sometimes

allowed to grow to 200 years or older in visually sensitive

areas on public lands without an appreciable reduction in

MAI. Yield tables for natural unmanaged fully stocked

stands (13) and a first approximation (16) for managed stands

are available, but actual yield tables are commonly developed

for each local situation due to the large variation in site,

stocking capacity, and management objectives.

Insects have been a major problem in the management

of ponderosa pine and probably will continue to be so. In

contrast, diseases have been a relatively minor problem; but

the future may see an increase in such problems.

The major problem insects are three species of bark

beetles: western pine beetle (Dendroctonus brevicomis LeConte),

mountain pine beetle {Dendroctonus ponderosae Hopkins),

and pine engraver {Ips pini (Say)). Each insect attacks a

different size class, but all are favored by trees under stress

either from being overmature or overstocked. With intensive

management, the risk of damage is greatly reduced.

Other insects that have potential for damage are red

turpentine beetle {Dendroctonus valens LeConte), western

pine shoot borer {Eucosma sonomana Kearfott), and pine

butterfly {Neophasia menapia (Felder and Felder)).

In some stands, western dwarf mistletoe {Arceuthobium

campylopodum Engelm.) can cause loss of growth and poor

form in ponderosa pine in this region. Recent evidence,

however, suggests that on better sites, young moderately

infected trees can be managed.^ Overstory trees having

mistletoe must be harvested and the young infected trees

thinned to a spacing that will promote at least 10 inches (25

cm) or more of leader growth per year. This eventually

confínes most infections to the lower part of the crown.

Infected trees grow at acceptable rates and eventually produce merchantable trees. This practice frequently reduces the

necessity for clearcutting and planting areas infested with

mistletoe.

Armillaria root rot {Armillariellia mellea (Vahl. ex Fr.)

Karst.) has infected ponderosa pine stands over a long period

of time. It spreads primarily by black stringlike rhizomorphs

from root to root. At present the recommended control is to

remove infected stumps and surrounding trees and roots to

prevent spread (15). Annosus root rot {Heterobasidium

annosum (Fr.) Bref.) may become a problem in the future as

ponderosa pine is more intensively managed.

Protection from wildfire can be achieved through mechanical methods or prescribed fire. Crushing or chipping

increases fuel density thus reducing fire spread. Piling,

followed by pile burning of natural or activity fuels, is often

used to reduce the amount of fuel. These practices are usually

done in conjunction with cultural practices.

One of the best ways of protecting ponderosa pine

forests from wildfire, and to obtain other benefits, is judi-

' Barrett, James W.; Roth, Lewis F. Response of dwarf mistletoe infected

ponderosa pine saplings after thinning. Portland, OR: U.S. Department of

Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment

Station; 1982. (Manuscript in preparation)

cious use of prescribed fire (12). Ponderosa pine, throughout

its life, is one of the more resistant trees to fire. It is more

resistant than any of its associates in the Northwest except for

western larch. Historically, fires occurred as frequently as

once every 5 years in lower, drier pine sites with the period

between fires increasing as precipitation and altitude increase

and as temperature decreases. Exclusion of wildfire in many

areas has led to dangerous fuel complexes and an increase in

tolerant species. Use of prescribed fire can be a cost effective

method of reducing these fuel complexes, controlling undesirable species, and preparing the forest for other cultural

practices after the bum.

Today both even-aged and uneven-aged silvicultural

systems are used in ponderosa pine management. If a young

even-aged stand is left from previous cutting practices, it is

perpetuated. If an uneven-aged structure exists a choice

usually exists for even-aged or uneven-aged management.

Even-aged systems are popular because they are simpler to

apply and more growth information exists for determining

present and future cuts. Uneven-aged systems are sometimes

preferred for esthetics along roadways, in recreation areas,

and for wildlife habitat. It should not be inferred that the

uneven-aged system is necessarily preferable to even-aged

silviculture for achieving wildlife, recreation, and visual

objectives. Both can have a place in accomplishing these

objectives and are sometimes used alternately to give the

forest viewer variety.

Single-tree selection is generally used where esthetic

considerations are of major concern along highways. Group

selection of pine is appropriate in some areas where esthetics

are important, in lower, drier sites, or for special wildlife

considerations. Timber production can probably be maintained at an acceptable level in such situations if proper

stocking-level control is maintained in the smaller trees.

Clearcutting of units as large as 20 or 40 acres (8 or 16

ha) in size will reduce costs of logging, slash disposal, site

preparation, and planting. An exception might be where

seedling establishment and growth is hindered by edaphic

conditions or animal pests. Clearcutting allows complete

removal of trees infested with insects or disease and planting

with genetically improved stock. A major disadvantage with

clearcutting is unsightliness until trees are well established.

To temper this disadvantage, clearcuts frequently are irregular

in shape and simulate natural stand losses from fire, windthrow,

or insects.

In multiple-storied stands, overstory removal or harvesting of the overstory, while saving enough understory to

provide a satisfactory new stand, is frequently applied (5) and

is simply the final removal cut of a natural shelterwood.

Many older ponderosa pine stands have a dense understory

that responds well to release (4). Saving and thinning the

understory avoids the costs, problems, and uncertainties of

site preparation and planting, saves several years in the next

rotation, and reduces the period of unsightliness.

The seed-tree method has some of the advantages and

disadvantages of clearcutting. Four to eight high-quality seed

trees are left per acre (10 to 20/ha), and cutting and site

preparation should preferably be done as a good seed crop

matures to provide rapid regeneration. Seed trees are harvested once the new seedlings are established and a foot (0.3

m) or so in height. In some cases, one or more of the seed

trees per acre (2 or more per ha) may be left for wildlife

habitat. The method is not used extensively in the region but

has been moderately successful on the perimeter of the

Columbia Basin.

The shelterwood method removes the old stand in two or

more cuttings. Usually 10 to 15 high-quality trees are left per

acre (25 to 37/ha) to furnish seed and shelter for the new

17
stand (6). Areas are planted if natural regeneration does not

occur in a designated period of time. Ordinarily, the shelter

trees are removed once the new stand is 1 or 2 feet (0.3 or 0.6

m) high. The shelterwood system is successful on many

ponderosa pine sites. It provides a tree cover at all times and

can be applied in three or four cuts where special consideration is being given to other resource objectives.

Intermediate cuttings made between regeneration and

final harvest are usually necessary to keep the stand growing

at desirable rates. In uneven-aged management, improvement cuttings are frequently necessary to regulate species

composition and age class distribution and to sanitize insector disease-infested trees. The same may be true using

even-aged management, but usually the intermediate cuttings

thin the stand to an optimum density that will keep diameter

and height growth at desirable rates, provide early return on

invested capital, and maximize yields during the last few

decades of the rotation. Precommercial thinnings are made

from below, removing the smaller, less desirable trees from

the stand. Later commercial thinnings retain the best trees.

Ponderosa pine stands commonly reproduce prolifically

during good seed years when climatic conditions are just

right and dense thickets develop. Early thinning is necessary

to avoid stagnation. Trees are spaced far enough apart so they

will produce a salable tree before another thinning is needed.

Brush species such as greenleaf manzanita (Arctostaphylos

patula Greene), snowbrush (Ceanothus velutinus Dougl. ex

Hook.), antelope bitterbrush {Purshia tridentata Pursh DC),

and golden chinkapin {Castanopsis chrysophylla (Dougl.) A.

DC.) are significant competitors with ponderosa pine from

seedling stage until the stand averages about 10 inches (25

cm) in diameter. Recent unpublished results from the Pringle

Falls spacing study in Oregon's Deschutes National Forest

indicate that tree volume growth losses from shrubs during

this period can range from about 25 percent at commonly

used tree spacings of around 15 feet (4.6 m) to 50 percent at

wider spacings, sometimes used to promote rapid growth to

sawlog-sized trees. Shrub control in thinned natural stands

and plantations is recommended as soon as potential crop

trees can be identified. An additional shrub treatment before

trees reach sawlog size may be necessary.

The ponderosa pine forest has great potential for multiple use and is often managed for several purposes. These

forests, while not high in production of wood, are excellent

for accessibility, for recreation, and for providing habitat for

a wide variety of wildlife.

Range management is often practiced in the ponderosa

pine forest where livestock can complement timber management by reducing growth of competitive species and reduce

fuel accumulation. Prescribed burning is often helpful in

increasing the palatability and quantity of forage.

Water and fish are generally not major concerns in

ponderosa pine management. Leaving trees along stream and

lake edges can be important in keeping water temperature

down, but protection of riparian zones is more a function of

controlling livestock.

Controlling shrubs or tree stocking in pine stands can

contribute significantly to groundwater (1).

A wide variety of game and nongame wildlife use one or

rnore ponderosa pine communities and structures during their

life cycles. Some wildlife have rather narrow requirements

while others flourish under a wide range of conditions, and

changing the stand structure can favor one life form over the

other (18).

Rare and endangered species may have specific requirements in a rather restricted geographic area. For this purpose.

through the planning processes now in effect, rare and

endangered species must be considered before treatment can

be made in any area.

Literature Cited

1. Barrett, James W.; Youngberg, C. T. Effect of tree spacing and

understory vegetation on water use in a pumice soil. Soil Sei. Soc.

Amer. Proc. 29: 427-475; 1965.

2. Barrett, James W. A record of ponderosa pine seed flight. Res. Note

PNW-38. Portland, OR: U.S. Department of Agriculture, Forest

Service, Pacific Northwest Forest and Range Experiment Station; 1966.

5 p.

3. Barrett, James W. Response of ponderosa pine pole stands to thinning.

Res. Note PNW-77. Portland, OR: U.S. Department of Agriculture,

Forest Service, Pacific Northwest Forest and Range Experiment Station;

1968. 11 p.

4. Barrett, James W. Latest results from the Pringle Falls ponderosa pine

spacing study. Res. Note PNW-209. Portland, OR: U.S. Department

of Agriculture, Forest Service, Pacific Northwest Forest and Range

Experiment Station; 1973. 22 p.

5. Barrett, James W.; Tombom, Stanley S.; Sassaman, Robert W.

Logging to save ponderosa pine regeneration: A case study. Res. Note

PNW-273. Portland, OR: U.S. Department of Agriculture, Forest

Service, Pacific Northwest Forest and Range Experiment Station; 1976.

13 p.

6. Barrett, James W. Silviculture of ponderosa pine in the Pacific

Northwest: The state of our knowledge. Gen. Tech. Rep. PNW-97.

Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific

Northwest Forest and Range Experiment Station; 1979. 106 p.

7. Cleary, Brian D.; Greaves, Robert D.; Hermann, Richard K. Regenerating Oregon's forests. Corvallis, OR: Oregon State University Extension

Service; 1978. 286 p.

8. Cochran, P. H. Seeding ponderosa pine. In: Regeneration of ponderosa

pine: Proceedings of the symposium; 1969 September 11-12; School of

Forestry Paper 681. Corvallis, OR: Oregon State University; 1970:

28-35.

9. Dahms, Walter G.; Barrett, James W. Seed production of central

Oregon ponderosa and lodgepole pines. Res. Pap. PNW-191. Portland,

OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest

Forest and Range Experiment Station; 1975. 13 p.

10. Eyre, F. H., ed. Forest cover types of the United States and Canada.

Washington, DC: Society of American Foresters; 1980: 148 p.

11. Maclean, Colin D.; Bolsinger, Charles L. Estimating productivity on

sites with a low stocking capacity. Res. Pap. PNW-152. Portland, OR:

U.S. Department of Agriculture, Forest Service, Pacific Northwest

Forest and Range Experiment Station; 1973. 18 p.

12. Martin, Robert E.; Dell, John D. Planning for prescribed burning in the

Inland Northwest. Gen. Tech. Rep. PNW-76. Portland, OR: U.S.

Department of Agriculture, Forest Service, Pacific Northwest Forest

and Range Experiment Station; 1978. 67 p.

13. Meyer, Walter H. Yield of even-aged stands of ponderosa pine.

Tech. Bull. 630. Washington, DC: U.S. Department of Agriculture;

1961. 59 p. (Revised)

14. Mowat, E. L. Cutting lodgepole overstory releases ponderosa pine

reproduction. J. For. 48(10): 679-680; 1950.

15. Roth, Lewis F.; Shaw, Charles G. Ill; Rolph, Leonard. Marking

ponderosa pine to combine commercial thinning and control of armillaria

root rot. J. For. 75(10): 644-647; 1977.

16. Sassaman, Robert E.; Barrett, James W.; Twombly, Asa D.

Financial precommercial thinning guides for Northwest ponderosa

pine stands. Res. Pap. PNW-226. Portland, OR: U.S. Department of

Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment Station; 1977. 27 p.

17. Sorensen, Frank C; Miles, Richard S. Differential frost tolerance of

ponderosa and lodgepole pine megasporangiate strobili. For. Sei. 20(4):

377-378; 1974.

18. Thomas, Jack Ward, tech. ed. Wildlife habitats in managed forests: the

Blue Mountains of Oregon and Washington. Agrie. Handb. 553.

Washington, DC: U.S. Department of Agriculture; 1979. 512 p.

18
Grand Fir, Douglas-Fir, and Associated Species

(Eastern Oregon and Washington)

K. W. Seidel

Pacific Northwest Forest and Range Experiment Station

Tom Beebe

Pacific Northwest Region

The grand fir, Douglas-fir, and associated species type

of eastern Oregon and Washington occupies about 6 million

acres (2.4 million ha) on the east side of the Cascade Range

ai)d other ranges to the east.

The climax tree species in these forests are Rocky

Mountain Douglas-fir (Pseudotsuga menziesii var. glauca

(Beissn.) Franco), grand fir {Abies grandis (Dougl. ex D.

Don) Lindl.), and white fir {Abies concolor (Gord. and

Glend.) Lindl. ex Hildebr.). Both Douglas-fir and grand fir

climax forests are found on the east slopes of the Washington

Cascades south of the Entiat River. To the north, only

Douglas-fir climax forests exist. In Oregon, the usual climax

species is grand fir. ^ Major pioneer species in these forests include Douglasfir (a pioneer in grand fir forests), ponderosa pine {Pinus

ponderosa Dougl. ex Laws.), lodgepole pine {P. contorta

Dougl. ex Loud.), and western larch {Larix occidentalis

Nutt.). Other species occur in these forests only in minor

quantities or in restricted habitats, such as streamside zones.

These latter include nearly all of the tree species indigenous

to eastern Oregon and Washington.

This forest cover type includes the northwesterly portion

of the following Society of American Foresters forest cover

types (7): interior Douglas-fir (210), white fir (211), western

larch (212), and grand fir (213). It is found within the

Pseudotsuga menziesii and Abies grandis Zones (11), which

occupy a midslope position between the lower elevation

Pinus ponderosa Zone and the high elevation Abies lasiocarpa

Zone.

Stand structure and species composition of the grand fir

and Douglas-fir forests in eastern Oregon and Washington

are extremely variable, depending upon site, logging history,

insect attack, and wildfire. Both even- and uneven-aged

stands occur. Typically, light-demanding species such as

larch and pines become established in pure even-aged stands

after severe disturbances from wildfire or blowdown, while

the more shade tolerant true firs eventually form the climax

vegetation after many years of stand stability.

Volcanic activity has played a major role in shaping

much of the landscape. As a result, a great diversity in soils

exists within this complex forest cover type. Many large

areas in the Cascade Range and Blue Mountains are covered

with deposits of pumice and volcanic ash that show little

profile development because of their youth (11). Elevation is

the primary factor influencing local climate. Average annual

temperatures range from 42° to 50° F (5.6° to 10.0° C) and

extremes are from about -45° to 110° F (-42.8° to 43.3° C).

The frost-free season is relatively short and very irregular

from year to year, with freezing temperatures occurring in

any month of the year. Average annual precipitation ranges

' Grand fir and white fir form a continuously varying biological complex

in eastern Oregon and are treated alike for management purposes (11). Both

species belong to the genus Abies. Members of this genus are collectively

known as "true firs."

from about 15 inches (380 mm) at lower elevations to 50

inches (1270 mm) near the crest of the Cascade Range.

Seed production is generally adequate for natural regeneration with medium to heavy cone crops occurring at 3- to

4-year intervals (9). Species having small, light seeds such as

western larch and lodgepole pine are the best seed producers,

yielding some seed almost every year.

Heavier seeded species such as Douglas-fir and ponderosa

pine have less frequent crops. Lighter crops of all species are

especially subject to heavy insect and rodent depredations.

Seed is dispersed chiefly by wind, although rodents carry

away some seed and bury it. Much seed falls within 60 to 130

feet (18 to 40 m) of clearcut edges, with smaller amounts at

greater distances.

Mineral soil is the most favorable seedbed for all

coniferous species because it is a more stable source of water

and is cooler than litter and duff (26). True firs become

established better on mineral soil, but they also survive in

light litter and duff layers up to about 0.5 inch (1.3 cm) deep

(21). A mineral soil seedbed is more essential on south and

west aspects.

Seedling mortality is generally greatest during the first

growing season because of drought, temperature extremes,

competing vegetation (especially grass), or animal damage.

Temperature extremes can be mitigated by partial shade from

an overstory or by light amounts of slash which reduce

radiation cooling and decrease solar insolation. Severely

burned seedbeds, such as areas where slash has been piled

and burned, can also reduce seedling survival (22).

Seedlings of shade intolerant species such as western

larch, lodgepole pine, and ponderosa pine grow rapidly in

full sunlight and may reach a height of 4 feet (1.2 m) in 4

years (29). In contrast, height growth of the more shade

tolerant true firs is slower initially, but they may eventually

exceed the pioneer species in total height. Net volumes of

even-aged stands of grand fir and Douglas-fir on high sites

are impressive—yielding up to 18,940 cubic feet per acre

(1326 m^/ha) at 100 years of age (4, 5, 6).

Mixed conifer forests are attacked by a large number of

insects and diseases (12, 14). Insects causing serious damage

over large areas include the western pine beetle {Dendroctonus

brevicomis LeConte), the mountain pine beetle {D. ponderosae

Hopkins), the Douglas-fir beetle (D. pseudotsugae Hopkins),

the Douglas-fir tussock moth {Orgyia pseudotsugata

(McDunnough)), the western spruce and Modoc budworms

{Choristoneura occidentalis Freeman and C. retiniana

(Walsingham)), and the larch casebearer {Coleophora laricella

(Hubner)). The most practical silvicultural control to prevent

bark beetle outbreaks is by harvesting susceptible overmature

stands before epidemics and thinning overstocked young stands

to maintain vigorous trees (19). The Douglas-fir tussock moth is

a major defoliator of east-side mixed conifer forests, showing

equal preference for Douglas-fir, grand fir, or white fir. It

also attacks other species after the preferred hosts are

consumed (31). It may be possible to reduce the severity of

further outbreaks by maintaining pine on the more xeric sites

19
using prescribed fire (32). The larch casebearer is the most

damaging defoliator of western larch. Some foreign parasitic

wasps offer the best means of containing the casebearer (18).

The most serious diseases of mixed conifer forests are

trunk and root rots and dwarf mistletoes {Arceuthobium

spp.). The single most damaging pathogen in true firs is the

Indian paint fungus (Echinodontium tinctorium (E. & E.) E.

& E.). In the Blue Mountains, nearly 40 percent of the true fir

old-growth volume is unmerchantable because of rot from

this disease (1). In eastern Washington, an important fungal

disease of Douglas-fir and true firs is shoestring root rot

{Armillariella mellea (Vahl. ex Fr.) Karst.). Dwarf mistletoes are found on nearly every tree species in these coniferous

forests. In most cases, these parasitic plants slow the growth

of the host tree; but in the Douglas-fir forests of eastern

Washington, an infestation is often fatal.

Fire is a primary natural force in forest ecosystems and

has had a major impact on the forests in this type. Wildfire

has influenced the age structure and species composition of

the forest and produced a mosaic of even-aged stands

intermixed with uneven-aged stands. It has also affected

insect and disease populations, influenced nutrient cycles,

and determined wildlife habitats (13, 30). Fire suppression

during the past 70 years has drastically altered the natural

ecological relationships resulting in large accumulations of

residues and replacement of ponderosa pine by the shade

tolerant true firs in communities where pine is a pioneer

species. Properly used, prescribed fire can be a useful

silvicultural tool for maintaining pioneer stands of ponderosa

pine and other intolerant species, with a cycle of light,

frequent, surface fires (16, 17).

Successional trends within the mixed conifer forest

depend upon the shade tolerance of the species and have

important implications for forest management. Observations

suggest the following order of shade tolerance from most to

least tolerant species: grand or white fir, Douglas-fir, ponderosa

pine, lodgepole pine, western larch. In order to successfully

apply selected silvicultural systems, it is essential to realize

that the successional role or relative tolerance of species

differs from site to site. For example, Douglas-fir is the

climax species in the Pseudotsuga menziesii Zone but a

pioneer species in the Abies grandis Zone. Therefore, application of uneven-aged management (selection system) in the

Pseudotsuga menziesii Zone would tend to maintain Douglasfir in the stand, whereas it would be replaced by more

tolerant species in the Abies grandis Zone.

Because of the variety of species and stand conditions in

this forest type, both even- and uneven-aged silvicultural

systems can be used. In stands where timber production is an

important objective, the use of an even-aged silvicultural

system is recommended. Even-aged management is desirable

to convert overmature, old-growth stands to vigorous, fastgrowing second-growth stands and to secure regeneration of

the shade-intolerant species. It also has an economic advantage as markets for smaller material increase and the removal

of large volumes reduces logging costs by spreading fixed

costs over a greater volume removed. On the other hand,

uneven-aged management is well suited where healthy unevenaged stands exist or can be created in a reasonable time and

conversion to more shade-tolerant species is not objectionable.

Areas of high recreational or esthetic value such as near

campgrounds and roadsides may be good choices for unevenaged silviculture.

On the majority of productive forest sites in this type,

the choice between even-aged and uneven-aged silvicultural

systems depends primarily on factors other than the ecological limitations of the species (10). These factors include

economic and social considerations, esthetics of cutover

areas, and effect on soil, water, and wildlife habitat, limitations on suitable logging methods, and constraints imposed

by insects, diseases, or potential animal damage.

The clearcutting method and the shelterwood method

are recommended to create even-aged stands in this forest

type (25). The seed tree method is not recommended because

it does not commonly provide sufficient seed or protective

overstory and the isolated trees are subject to windthrow.

Clearcutting is recommended as a harvesting method in

old-growth mixed conifer stands where heavy infestations of

dwarf mistietoe exist in both overstory and understory, or

where rots are present. Clearcutting allows regeneration to

develop without suppression or possible damage from a

residual overstory and eliminates the risk of blowdown in

areas where wind damage is common. It is well suited for

regeneration of the pioneer tree species. On the other hand,

there are also disadvantages. Understory vegetation such as

greenleaf manzanita {Arctostaphylos patula Greene) and

snowbrush (Ceanothus velutinus Dougl. ex Hook.) develops

rapidly on many clearcuts, requiring measures to reduce

competition to tree regeneration. Seedlings are subjected to

greater temperature extremes resulting in frost damage or

heat stress. And animal damage to reproduction is often

greater on clearcuts than in partial cuts (3).

The primary application of clearcutting is for regeneration of mature stands on protected sites. Such sites are

located generally on northwest to east aspects, where slopes

range from 30 to 70 percent. Flatter uplands may also be

suitable for clearcutting, especially in the more moderate

environments of the grand fir climax forests. Here clearcutting

often is limited to stands where medium- or fine-textured

soils are generally over 30 inches (76 cm) deep and where

insolation and frost are moderated by slope and aspect.

A mixture of planted species may be needed to resolve

insect and disease problems common in single-species stands

and to achieve full site utilization and wildlife and esthetic

benefits. Planting should be done immediately after logging

and slash disposal operations are completed, except where

local experience shows that natural regeneration is sufficientiy reliable to reforest the area in an acceptable period.

Generally, natural regeneration is better on strip and patch

clearcuts of 10 to 20 acres (4.0 to 8.1 ha) than on large

clearcuts of 40 acres (16 ha) or more. The probability of

obtaining adequate natural regeneration in clearcuts is greatest on northwest to east aspects; strips oriented perpendicular

to the prevailing wind provide the best seed distribution and

least chance of wind damage. No studies of direct seeding

(broadcast or spot-seeding) in mixed conifer forests of

eastern Oregon and Washington have been reported, and this

practice is recommended only in more moderate environments where seed predators have been controlled and suitable

seedbeds prepared.

The shelterwood method is well suited for moderating

high and low temperatures or intense sunlight and thus

enhances natural regeneration of more shade tolerant species

such as true fir. It can also be used effectively with intolerant

species by leaving fewer trees after the seed cut and removing

them sooner after regeneration is established. It often slows

the invasion of understory vegetation, thus leaving seedbeds

more receptive to tree seedling establishment for a longer

time. It reduces the chance of soil movement on steep slopes

and decreases the probability of animal damage to regeneration.

It also temporarily improves the visual quality of harvested

units. The chief disadvantage of the shelterwood method in

old-growth forests is the chance of losing the residual

overstory by windthrow. This drawback will diminish as

more second-growth stands are managed and trees become

more windfirm.

20
Natural regeneration after shelterwood cutting, leaving a

basal area of 60 to 80 square feet per acre (13.7 to 18.4

m^/ha) in the overstory, has generally been good to excellent

in mixed conifer communities in the Oregon Cascades (23).

Suitable seedbeds are provided by the logging and slash

disposal if about 40 to 50 percent mineral soil is exposed.

Because of the high probability of obtaining natural regeneration when using the shelterwood method, planting is generally not needed after the seed cut. The most efficient use of

planting in these communities is to increase stocking if it is

below minimum standards after removing the residual overstory.

On steeper ground in Washington and eastern Oregon,

shelterwood cutting is usually recommended for the regeneration of mature stands growing on exposed sites. These are

located generally on southeast to west aspects where slopes

exceed 30 percent. Especially recommended for shelterwood

regeneration are the harsher low-elevation Douglas-fir climax

forests growing on exposed sites. Because of vegetative

competition and irregular seed production, planting is usually

necessary under such shelterwoods. The amount of shelter

provided may vary according to the harshness of the site and

the tolerance of the species planned for regeneration. Where

no suitable shelter is available (due to root rot or other

problems), small 8- to 12-acre (3.2 to 4.9 ha) clearcuts may

provide the best alternative, especially when shaped so that

trees on clearcut edges provide a maximum of shelter.

Site preparation is often a requirement of the regeneration process in Douglas-fir and grand fir forests. Although

many species of shrubs, forbs, and grasses exist in these

forests, the single most formidable competitor of planted

seedlings is pinegrass {Calamagrostis rubescens Buckl.).

The occupancy of a site by pinegrass is a slow process

(generally 3 to 5 years after clearcutting), but once established,

major site preparation efforts are required to obtain satisfactory survival of new conifer seedlings. Methods include

tractor scarification (on flat ground), hand scalping, and hand

or aerial herbicide treatment.

Many mixed conifer stands have suppressed true fir and

Douglas-fir advance reproduction established in the understory.

If sufficiently vigorous to respond rapidly to release, these

trees can be used to form the new stand after the overstory is

removed. Trees with live crown ratios of at least 50 percent

have the best potential for rapid growth after release (20, 24).

Although advance reproduction of released true fir can grow

rapidly, there is a possibility that reactivation of dormant

fungi by wounds may cause serious decay in the future (8).

Uneven-aged silviculture (single-tree and group selection)

appears to be most suitable in those stands having a multistoried or irregular structure and where dwarf mistletoe or

heart rots are not major problems. The single-tree selection

method provides maximum flexibility in choosing trees to cut

or leave and favors the shade tolerant species. In group

selection cutting, tree groups, ranging in size from a fraction

up to about 1 acre (0.4 ha) are removed. The larger sized

groups provide an opportunity for the shade intolerant species

to be maintained in the stand, although growth of the

regeneration may be suppressed by the mature trees surrounding these small openings. The application of uneven-aged

silviculture and management is difficult because information

on growth and regeneration in relation to stocking and stand

structure is lacking. Guidelines for the initiation of unevenaged management in the Rocky Mountains may prove useful

in eastern Oregon and Washington (2).

Thinnings are essential in many mixed conifer stands to

maintain or improve growth and vigor. All species benefit

from timely thinnings; but the highest priority for early

precommercial thinnings should be given to overstocked

stands of pioneer species such as larch, lodgepole pine, and

ponderosa pine growing on good sites. Such thinnings should

remove the smaller, slower growing trees, while maintaining

a mixed species composition. The greatest gains from

precommercial thinning occur when trees are about 10 to 15

feet tall (3.0 to 4.6 m), usually less than 20 years old, and

before competition reduces crown size. The residual stocking

depends on species and estimates of merchantable tree

diameter but usually varies from 200 to 400 trees per acre

(490 to 990 trees/ha).

In addition to their value as a source of timber, the

mixed conifer forests in this type are of great importance in

providing water, habitat for many species of wildlife, forage

for livestock, and recreational opportunities. Fortunately, in

most cases, timber management objectives can be a part of

the multiple-use objectives.

Water yields from forested watersheds increase as a

result of timber harvesting. Although no information is

available for this forest cover type, work in the Rocky

Mountains suggests that optimum snow accumulation may

result from patch clearcutting when patches have a diameter 5

to 8 times the height of surrounding trees and are spaced

about the same distance apart (15).

The habitat for big game and domestic livestock can be

improved by the same cutting method which optimizes water

yields—small patch clearcuts distributed throughout the mature stand (27). The clearcuts provide palatable forage for

deer, elk, and cattle; and the adjacent uncut stands provide

cover. Partial cut stands are preferred least by deer and elk

because they lack the volume and variety of forage in

clearcuts and the cover of the uncut stands. Timber management also affects the habitat of other wildlife species. The

present trends in timber management will lead to stand

diversity resulting in a greater variety of bird species, except

for those species adapted to old growth and those requiring

snags for nesting. Estimates of the number of snags needed to

maintain populations of snag-dwelling species in the Blue

Mountains are available (28).

The esthetic value of these forests is often closely tied to

the presence of scattered old-growth ponderosa pine, which

can be maintained as a second age class in managed, young

fir forests.

Literature Cited

1. Aho, Paul E. Decay of grand fir in the Blue Mountains of Oregon and

Washington. Res. Pap. PNW-229. Portland, OR: U.S. Department of

Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment Station; 1977. 18 p.

2. Alexander, Robert R.; Edminster, Carleton B. Uneven-aged management of old-growth spruce—fir forests: Cutting methods and stand

structure goals for the initial entry. Res. Pap. RM-186. Fort Collins,

CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain

Forest and Range Experiment Station; 1977. 12 p.

3. Barnes, Victor G., Jr. Pocket gophers and reforestation in the Pacific

Northwest: A problem analysis. Special Scientific Rep.—Wildlife No.

155. Denver, CO: U.S. Department of Interior, U.S. Fish and Wildlife

Service; 1973. 18 p.

4. Cochran, P. H. Gross yields for even-aged stands of Douglas-fir and

white or grand fir east of the Cascades in Oregon and Washington. Res.

Pap. PNW-263. Portland, OR: U.S. Department of Agriculture, Forest

Service, Pacific Northwest Forest and Range Experiment Station; 1979.

17 p.

5. Cochran, P. H. Site index and height growth curves for managed,

even-aged stands of Douglas-fir east of the Cascades in Oregon and

Washington. Res. Pap. PNW-251. Portland, OR: U.S. Department of

Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment Station; 1979. 16 p.

21
6. Cochran, P. H. Site index and height growth curves for managed,

even-aged stands of white or grand fir east of the Cascades in Oregon

and Washington. Res. Pap. PNW-252. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Forest and

Range Experiment Station; 1979. 13 p.

7. Eyre, F. H., ed. Forest cover types of the United States and Canada.

Washington, DC: Society of American Foresters; 1980. 148 p.

8. Filip, G. M.; Aho, P. E. Incidence of wounding and associated stain

and decay in advanced white fir regeneration on the Fremont National

Forest, Oregon. Forest Insect and Disease Management Report, Region

6. Portland, OR: U.S. Department of Agriculture, Forest Service; 1978.

22 p.

9. Franklin, Jerry F. Cone production by upper-slope conifers. Res. Pap.

PNW-60. Portland, OR: U.S. Department of Agriculture, Forest

Service, Pacific Northwest Forest and Range Experiment Station; 1968.

21 p.

10. Franklin, Jerry F.; DeBeil, Dean S. Effects of various harvesting

methods on forest regeneration. In: Even-aged management: Proceedings of the symposium. School of Forestry Pap. 843. Corvallis, OR:

Oregon State University, 1973: 29-57.

11. Franklin, Jerry F.; Dymess, C. T. Natural vegetation of Oregon and

Washington. Gen. Tech. Rep. PNW-8. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Forest and

Range Experiment Station; 1973. 417 p.

12. Fumiss, R. L.; Carolin, V. M. Western forest insects. Misc. Publ.

1339. Washington, DC: U.S. Department of Agriculture; 1977. 654 p.

13. Heinselman, Miron L. Fire in wilderness ecosystems. In: Wilderness

management. Misc. Publ. 1365. Washington, DC: U.S. Department of

Agriculture; 1978: 249-280.

14. Hepting, George H. Diseases of forest and shade trees of the United

States. Agrie. Handb. 386. Washington, DC: U.S. Department of

Agriculture; 1971. 658 p.

15. Leaf, Charles F. Watershed management in the Rocky Mountain

subalpine zone: The status of our knowledge. Res. Pap. RM-137. Fort

Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky

Mountain Forest and Range Experiment Station; 1975. 31 p.

16. LeBarron, Russell K. Silvicultural possibilities of fire in northeastern

Washington. J. For. 55(9): 627-630; 1957.

17. Martin, Robert E.; Dell, John D. Planning for prescribed burning in the

inland Northwest. Gen. Tech. Rep. PNW-76. Portland, OR: U.S.

Department of Agriculture, Forest Service, Pacific Northwest Forest

and Range Experiment Station; 1978. 67 p.

18. Ryan, R. B.; Dentón, R. E. Initial releases oí Chrysocharis laricinellae

and Dicladocerus westwoodii for biological control of the larch casebearer

in the western United States. Res. Note PNW-200. Portland, OR: U.S.

Department of Agriculture, Forest Service, Pacific Northwest Forest

and Range Experiment Station; 1973. 4 p.

19. Sartwell, Charles; Stevens, Robert E. Mountain pine beetle in ponderosa

pine, prospects for silvicultural control in second-growth stands. J. For.

73(3): 136-140; 1975.

20. Seidel, K. W. Suppressed grand fir and Shasta red fir respond well to

release. Res. Note PNW-228. Portland, OR: U.S. Department of

Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment Station; 1977. 7 p.

21. Seidel, K. W. Natural regeneration after shelterwood cutting in a grand

fir-Shasta red fir stand in central Oregon. Res. Pap. PNW-259.

Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific

Northwest Forest and Range Experiment Station; 1979. 23 p.

22. Seidel, K. W. Regeneration in mixed conifer clearcuts in the Cascade

Range and the Blue Mountains of eastern Oregon. Res. Pap. PNW-248.

Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific

Northwest Forest and Range Experiment Station; 1979. 24 p.

23. Seidel, K.W. Regeneration in mixed conifer shelterwood cuttings in the

eastern Oregon Cascades. Res. Pap. PNW-264. Portland, OR: U.S.

Department of Agriculture, Forest Service, Pacific Northwest Forest

and Range Experiment Station; 1979. 29 p.

24. Seidel, K. W. Diameter and height growth of suppressed grand fir

saplings after overstory removal. Res. Pap. PNW-275. Portland, OR:

U.S. Department of Agriculture, Forest Service, Pacific Northwest

Forest and Range Experiment Station; 1980. 9 p.

25. Seidel, K. W.; Cochran, P. H. Silviculture of mixed conifer forests in

eastern Oregon and Washington. Gen. Tech. Rep. PNW-121. Portland,

OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest

Forest and Range Experiment Station; 1981. 70 p.

26. Seidel, K. W.; Cooley, R. Natural reproduction of grand fir and

mountain hemlock after shelterwood cutting in central Oregon. Res.

Note PNW-229. Portland, OR: U.S. Department of Agriculture, Forest

Service, Pacific Northwest Forest and Range Experiment Station; 1974.

10 p.

27. Thomas, Jack Ward; Black, Hugh, Jr.; Scherzinger, Richard J. land

others]. Deer and elk. In: Wildlife habitats in managed forests. Agrie.

Handb. 553. Washington, DC: U.S. Department of Agriculture; 1979:

104-127.

28. Thomas, Jack Ward; Anderson, Ralph G.; Maser, Chris land others].

Snags. In: Wildlife habitats in managed forests. Agrie. Handb. 553.

Washington, DC: U.S. Department of Agriculture; 1979: 60-67.

29. U.S. Department of Agriculture, Forest Service. Silvics of forest trees

of the United States. Agrie. Handb. 271. Washington, DC: U.S.

Department of Agriculture; 1965. 762 p.

30. Wellner, Charles A. Fire history in the northern Rocky Mountains. In:

Proceedings on the role of fire in the Intermountain West symposium;

1970 October 27-29; Missoula, MT. Missoula, MT: University of

Montana, Intermountain Fire Research Council; 1970: 42—64.

31. Wickman, Boyd E.; Mason, Richard R.; Thompson, C. G. Major

outbreaks of the Douglas-fir tussock moth in Oregon and California.

Gen. Tech. Rep. PNW-5. Portland, OR: U.S. Department of Agriculture,

Forest Service, Pacific Northwest Forest and Range Experiment Station;

1973. 18 p.

32. Williams, Jerry T.; Martin, Robert E.; Pickford, Stewart G. Silvicultural and fire management implications from a timber type evaluation of

tussock moth outbreak areas. In: Proceedings of the 6th conference on

fire and forest meteorology; 1980 April 22-24; Seattle, WA. Washington,

DC: Society of American Foresters; 1980: 191-196.

22
Mixed Conifers of Southwestern Oregon

Don Minore

Pacific Northwest Forest and Range Experiment Station

Duane Kingsley

Rogue River National Forest

Mixed conifer forests occupy about 4 million acres (1.6

million ha), or nearly half the area of southwestern Oregon.

They extend from the Calapooya Mountains (43° 30' N.)

south into northwestern California and from the western

slopes of the Cascade Range (122° 20' W.) to the Pacific

Ocean, but are discontinuous and heterogeneous. Society of

American Foresters forest cover types 231 (Port Orfordcedar), 234 (Douglas-fir-tanoak-madrone), and 244 (Pacific

ponderosa pine-Douglas-fir) are present (4). Less defined

forest types and nonforest inclusions of grass, brush, or

agricultural land are common, however, and species composition varies with local physiography, soil, and climate.

The physiography of southwestern Oregon is complex

and varied. Mountains create differing combinations of

elevation, soil parent material, and weather that are considered here as seven subregions: the Oregon Coast Ranges in

Coos, Curry, and western Douglas Counties; the western

Siskiyous in southern Josephine County; the eastern Siskiyous

in southern Jackson County; the southern Cascades in eastern

Douglas and Jackson Counties; a pumice plateau where

ancient Mt. Mazama deposited a deep, level layer of pumice

in the Cascades; the Calapooya Mountains in northern

Douglas County; and a central valley-ridge complex in

southern Douglas, northern Josephine, and northern Jackson

Counties. Mixed conifer forests occur in all seven subregions.

Topography is steep and broken in the Coast Ranges,

Siskiyous, and central valley-ridge complex, with the most

dissected terrain occurring in the Siskiyous. Slopes are less

steep in the southern Cascades, Calapooya Mountains, and

pumice plateau.

Relatively uniform soils derived from Mazama pumice

characterize the pumice plateau. Soils derived from andesitic

tuffs, basalt, and breccias are common in the southern

Cascades. Elsewhere, the rocks and soils underlying mixed

conifer forests in southwestern Oregon are complex and

heterogeneous; with andésite, basalt, conglomerate, granite,

sandstone, mica schist, shale, and ultramafic parent materials

that are extensively folded, faulted, and metamorphosed (12,

14).

Mixed conifer stands occur at elevations as low as 500

feet (150 m) in the Coast Ranges, but are absent below 3,500

feet (1065 m) in the Cascade Range in southern Jackson

County. Upper elevation limits are about 4,000 feet (1220 m)

near the coast and about 6,000 feet (1830 m) in the southern

Cascades. Average low temperatures recorded at representative weather stations in the mixed conifer forest from June

1973 through February 1981 ranged from -2° F (-18.9 C)

in the southern Cascades to 21° F (-6.1° C) in the Coast

Ranges (17). The greatest range in high temperatures occurred

in the central valley-ridge complex, where average high temperatures ranged from 91° to 106° F (32.8° to 41.1° C).

The average frost-free period ranges from 50 (southern

Cascades) to 207 days (Coast Ranges). Annual precipitation

varies from 70 to 150 inches (1778 to 3810 mm) in the Coast

Ranges to about 25 inches (635 mm) in the eastern Siskiyous.

Most of this precipitation is winter rain, but 50 to 90 inches

(1270 to 2286 mm) of snowfall occur at elevations above

4,000 feet (1219 m). Hot, dry summers are common throughout southwestern Oregon, and summer drought conditions

are most severe in the eastern Siskiyous.

The mixed conifer forests of southwestern Oregon vary

in composition, but two or more of the following major

species are always present: Douglas-fir {Pseudotsuga menziesii

(Mirb.) Franco var. menziesii), incense-cedar (Libocedrus

decurrens Torr.), sugar pine (Pinus lambertiana Dougl.),

white fir {Abies concolor var. lowiana (Gord.) Lemm.), and

ponderosa pine {Pinus ponderosa Dougl. ex Laws. var.

ponderosa).

Several minor species are also present. Western hemlock {Tsuga heterophylla (Raf.) Sarg.) occurs on cool moist

sites in the Calapooyas, Coast Ranges, central valley-ridge,

western Siskiyous, and northern portion of the southern

Cascade subregions. Grand fir {Abies grandis (Dougl. ex D.

Don) Lindl.) replaces white fir in the Calapooya, Coast

Ranges, and central valley-ridge subregions. Elsewhere grand

fir often hybridizes with white fir and forms intermediate

populations (7). Jeffrey pine {Pinus jejfreyi Grev. & Balf.)

grows on ultramafic soils in the Siskiyous and central

valley-ridge complex. Port Orford-cedar {Chamaecyparis

lawsoniana (A. Murr.) Pari.) also grows on ultramafic soils

and along drainages where atmospheric moisture is high in

the western Siskiyous, but it is most important in the Coast

Ranges. Knobcone pine {Pinus attenuata Lemm.) sometimes

occupies recent bums in the western subregions. Western

redcedar {Thuja plicata Donn ex D. Don) grows on moist

stream bottoms in the Coast Ranges, western Siskiyous,

Calapooya, and central valley-ridge subregions. Pacific yew

{Taxus brevifolia Nutt.) is occasionally present in the understory on moist sites throughout southwestern Oregon. Hardwoods often associated with mixed conifers include Pacific

madrone {Arbutus menziesii Pursh), giant chinkapin {Castanopsis

chrysophylla (Dougl.) A. DC), California black oak {Quercus

kelloggii Newb.), Oregon white oak {Quercus garryana

Dougl. ex Hook.), canyon live oak {Quercus chrysolepis

Liebm.), California-laurel {Umbellularia californica (Hook.

& Am.) Nutt.), tanoak {Lithocarpus densiflorus (Hook. &

Am.) Rehd.), bigleaf maple {Acer macrophyllum Pursh), and

vine maple {Acer circinatum Pursh).

Natural conifer reproduction is common but erratic in

southwestem Oregon. The most shade-tolerant species (e.g.,

westem hemlock, westem redcedar, white fir, and grand fir)

tend to have seed crops more often than less tolerant species

(e.g., Douglas-fir and ponderosa pine). Westem hemlock,

westem redcedar, and Port Orford-cedar produce the largest

seed crops, followed in descending order by Douglas-fir and

Jeffrey pine, ponderosa pine, sugar pine, and white fir (15).

Mineral soil benefits the germination and survival of all

species; westem hemlock and westem redcedar are more

successful than other conifers on organic seedbeds. Bumed

seedbeds amplify unfavorable temperature extremes; but they

tend to favor Douglas-fir, grand fir, and ponderosa pine over

other conifer species.

23
Two-year-old seedlings at least 5 inches (13 cm) tall are

recommended as Douglas-fir planting stock (3, 20). Bareroot

seedlings with a minimum diameter of 0.16 inches (4 mm)

are usually used, and shoot/root ratios of 2.0 or less benefit

survival. One-year-old containerized seedlings may be more

successful on steep slopes with shallow skeletal soils, however;

where the seedlings often have to be protected from downslope

debris movement (10). Ponderosa pine seedlings are frequently planted in frost pockets. More sugar pine stock

probably will be planted as blister-rust-resistant seedlings

become more available. Conifer seedlings of all species

survive and grow most successfully on north and east aspects

in the absence of vegetative competition. South and west

aspects with shallow soils, grass and brush competition, or

sprouting madrone, maple and other hardwood trees tend to

hinder and delay conifer reproduction.

Competition from annual and perennial grasses hinders

conifer reproduction throughout southwestern Oregon. Brush

competition from Arctostaphylos, Ceanothus, Rhus, and

Rubus species is most serious in the Coast Ranges, western

Siskiyous and Calapooya Mountains. Drought adversely

impacts survival of seedlings in the eastern Siskiyous and

central valley-ridge complex. Pocket gophers and frost seriously limit conifer regeneration in the southern Cascade and

pumice plateau subregions.

The silvical characteristics of major southwestern Oregon conifer species differ greatly. Ponderosa pine is frost- and

drought resistant and intolerant of shade. Incense-cedar is

less frost- and drought-resistant but, like the faster-growing

Douglas-fir and sugar pine, grows well in partial shade.

Douglas-fir is less frost- and drought-resistant than incensecedar, more drought-resistant and slower growing than sugar

pine. White fir is more tolerant of shade and less droughtresistant than other major conifer species (15). It endures

suppression and recovers well when released.

No growth and yield data are available for managed

mixed-conifer stands in southwestern Oregon. Information

derived from an inventory of existing natural stands indicates

that site quality and yields are low, however; the average site

index for mixed conifers on the Rogue River National Forest

is 110 at age 100. Empirical net yields of unmanaged natural

stands range from 23,170 board feet (fbm) (Scribner Decimal

C) or 4,634 cubic feet^ per acre (324.4 m^/ha) at age 90 to

44,925 fbm or 8,985 cubic feet per acre (629.0 m%a) at age

320 when very low site lands and badly damaged stands are

excluded from the inventory data.^

Douglas-fir seedlings are often badly damaged by deer

and elk. Older Douglas-firs are attacked by Douglas-fir

beetles (Dendroctonus pseudotsugae Hopkins) and the flatheaded

fir borer (Melanophila drummondi (Kirby)) throughout southwestern Oregon. They are seriously infected with dwarf

mistletoe {Arceuthobium douglasii Engelm.) in the Siskiyous

and southern Cascades (5,9). Poria root rot (Phellinus weirii

(Murr.) Gilb.) also is a serious Douglas-fir pathogen. White

pine blister rust {Cronartium ribicola J. C. Fisch.) limited the

management of sugar pine for many years, but rust-resistant

sugar pine races have recently been identified and propagated

(13). Unfortunately, no root-rot resistant races of Port Orfordcedar have been found, and the root rot caused by Phytophthora

lateralis Tuck. & J. A. Milb. can be limited only by

' Cubic foot and metric conversions of measurements expressed in board

feet should be viewed as estimates because of the assumptions involved in

the conversion process.

^ Rogue River National Forest Timber Management Plan. Appendix 1979:

70-71.

sanitation measures such as the prohibition of road building

and avoidance of drainage areas.

Fire danger is highest in the southern Cascade and

eastern Siskiyou subregions, lowest in the Coast Ranges and

western Siskiyous (8). Throughout southwestern Oregon,

fires in the past tended to perpetuate serai species such as

Douglas-fir, ponderosa pine. Pacific madrone, and incensecedar. Under modem fire prevention practices, however,

natural stands are slowly converting to more shade-tolerant

species such as white fir, Port Orford-cedar, and tanoak (1).

The slash resulting from clearcutting is often broadcastburned. Slash in shelterwood stands also may be broadcastburned, but it is often piled and burned to minimize overstory

damage. Broadcast-burning lowers the fire hazard, eliminates physical obstructions, eradicates mistletoe present on

advance regeneration, and creates favorable mineral-soil

seedbeds (16). Although this promotes a more diverse blend

of species in subsequent stands, repeated slash burning may

deplete the nutrient capital, destroy advanced conifer

regeneration, stimulate the germination or sprouting of some

brush species, and, at some sites, create microsites subject to

erosion and high soil surface temperatures.

Soil, climate, and topography are more important than

species composition in determining silvicultural practices in

southwestern Oregon; and no single silvicultural system is

applicable throughout the mixed conifer forests. Even-age

management seems necessary if the present species composition of most mixed conifer stands is to be maintained.

Uneven-age silviculture probably should be limited to situations where a mixture of tolerant species is desirable or to

open-grown stands on poor sites.

Clearcutting creates severe environments for conifer

seedlings on south and west aspects with shallow soils and on

flat or concave topography above 3,000 feet (914 m) in the

eastern Siskiyous, pumice plateau, southern Cascade, and

central valley-ridge subregions. Adequate site preparation,

high quality planting stock, proper planting techniques, and

careful timing are essential for prompt seedling establishment

on shallow soils in these subregions; frost-tolerant species are

often required on flat topography at high elevations. Clearcutting

should also be used with extreme care on any topography

above 4,500 feet (1372 m) in the western Siskiyous (19).

Elsewhere, clearcutting usually creates favorable environments for conifer regeneration when competing vegetation is

adequately controlled. Recommended control methods include the application of low volatile esters of 2,4-D for

shrubs and weed trees (6), late autumn atrazine treatments for

grass (2), and chemical desiccation followed by prescribed

burning for established brushfields (11). The edge effects

created by clearcutting are often beneficial for wildlife.

Seed-tree cutting is appropriate on some north slopes

where competing vegetation is not a problem, but natural

regeneration may be delayed until a seed crop occurs. The

seed trees do not provide adequate shade or frost protection

on severe sites in the Siskiyous, southern Cascades, pumice

plateau, and central valley-ridge subregions; and they provide little wildlife cover. Seed trees are often windthrown

in the Coast Ranges.

Shelterwood stands are damaged less than seed trees by

storm winds, but are sometimes windthrown on exposed

sites. They provide seedling protection on hot dry slopes and

in frost pockets. Although adequate natural regeneration

occurs if the soil is scarified in many shelterwood stands,

underplanting is necessary on some sites. Overstory requirements vary with slope, aspect, tree size, species, and crown

form. On severe sites, residual basal areas of up to 180

square feet per acre (41.32 m^/ha) may be required (18), but

40 to 100 square feet per acre (9.18 to 22.96 m^/ha) are often

24
adequate in the southern Cascade, pumice plateau, Calapooya,

and central valley-ridge subregions. Dense brush understories

usually make shelterwood cutting impractical in the Coast

Ranges and western Siskiyous. Steep slopes limit its use in

the eastern Siskiyous. Wherever shelterwood cutting is practiced,

details such as the timing and direction of felling for

overstory removal and road layout should be planned in

advance, before the shelterwood is established. Overstory

densities that exceed shelter requirements should be avoided

to minimize the seedling damage that occurs during felling

and yarding operations.

Group selection is often appropriate where mixed conifer stands must be maintained with minimal disruption, but it

should be avoided where frost is a problem—openings

created by group selection may trap cold air. The smaller

openings created by single-tree selection do not form frost

pockets, and single-tree selection provides an opportunity to

leave hardwood species desirable for wildlife. Shade-tolerant

species are favored, however, and single-tree selection may

eventually result in a change of forest type. Both selection

methods are best applied on gentle slopes with good logging

access and little brush competition—conditions most often

found in the southern Cascade and pumice plateau subregions.

Both methods should be avoided in mistletoe-infected stands

because they tend to perpetuate the infection.

Literature Cited

1. Atzet, Thomas. Description and classification of the forests of the upper

Illinois River drainage of southwestern Oregon. Corvallis: Oregon State

University; 1979. 211 p. Dissertation.

2. Crouch, Glenn L. Atrazine improves survival and growth of ponderosa

pine threatened by vegetative competition and pocket gophers. For. Sei.

25(1): 99-111; 1979.

3. Edgren, J. W. Field survival and growth of Douglas-fir by age and size

of nursery stock. Res. Pap. PNW-217. Portland, OR: U.S. Department ot Agriculture, Forest Service, Pacific Northwest Forest and

Range Experiment Station; 1977. 6 p.

4. Eyre, F H., ed. Forest cover types of the United States and Canada.

Washington, DC: Society of American Foresters; 1980. 148 p.

5. Fumiss, R. L.; Carolin, V. M. Western forest insects. Misc. Publ.

1339. V/ashington, DC: U.S. Department of Agriculture; 1977. 654 p.

6. Gratkov/ski, H. Herbicides for shrub and weed control in western

Oregon Gen. Tech. Rep. PNW-77. Portland, OR: U.S. Department

of Agriculture, Forest Service, Pacific Northwest Forest and Range

Experiment Station; 1978. 48 p.

7. Hamrick, J. L.; Libby, W. J. Variation and selection in western U.S.

montaine species. I. White fir. Silvae Genet. 21(1): 29-35; 1972.

8. Hayes, G. L. Forest and forest-land problems of southwestern Oregon.

Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific

Northwest Forest and Range Experiment Station; 1959. 54 p.

9. Hepting, George H. Diseases of forest and shade trees of the United

States. Agrie. Handb. 386. Washington, DC: U.S. Department of

Agriculture; 1971. 658 p.

10. Hobbs, S. D.; Byars, R. H.; Henneman, D. C; Frost, C. R. First year

performance of 1-0 containerized Douglas-fir seedlings on droughty

sites in southwestern Oregon. Res. Pap. 42. Corvallis, OR: Oregon

State University, Forest Research Laboratory; 1980. 15 p.

11. Hooven, Edward F.; Black, Hugh C. Prescribed burning aids reforestation of Oregon Coast Range brushlands. Res. Pap. 38. Corvallis, OR:

Oregon State University, Forest Research Laboratory; 1978. 15 p.

12. Irwin, William P.; Hotz, Preston E. The Klamath Mountains and Coast

Ranges of northern California and southern Oregon. In: Heilman, Paul

E.; Anderson, Harry W.; Baumgartner, David M., comps., eds. Forest

soils of the Douglas-fir region. Pullman, WA: Washington State

University Cooperative Extension Service; 1979: 7-10.

13. Kinloch, Bohun B., Jr.; Littlefield, Julia L. White pine blister rust:

hypersensitive resistance in sugar pine. Can. J. Bot. 55(9): 1148— 1155;

1977.

14. McKee, Bates. Cascadia. The geologic evolution of the Pacific Northwest.

New York: McGraw-Hill; 1972. 394 p.

15. Minore, Don. Comparative autecological characteristics of northwestem tree species; a literature review. Gen. Tech. Rep. PNW—87.

Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific

Northwest Forest and Range Experiment Station; 1979. 72 p.

16. Ruth, Robert H. Regeneration and growth of west-side mixed conifers.

In: Cramer, Owen P., ed. Environmental effects of forest residues

management in the Pacific Northwest. Gen. Tech. Rep. PNW-24.

Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific

Northwest Forest and Range Experiment Station; 1974: K1-K21.

17. U.S. Department of Commerce, National Oceanic and Atmospheric

Administration, Environmental Data and Information Service. Oregon

climatological data. Asheville, NC: National Climatic Center; June,

1973 through February, 1981.

18. Williamson, Richard L. Results of shelterwood harvesting of Douglasfir in the Cascades of western Oregon. Res. Pap. PNW—161. Portland,

OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest

Forest and Range Experiment Station; 1973. 13 p.

19. Wolfson, Alan W. Where should we clearcut next? A reforestation

status report. Cave Junction, OR: U.S. Department of Agriculture,

Forest Service, Siskiyou National Forest, Illinois Valley Ranger District;

undated. 26 p.

20. Zaerr, Joe B.; Lavender, Denis P. Size and survival of 2-0 Douglas-fir

seedlings. Res. Pap. 32. Corvallis, OR: Oregon State University, Forest

Research Laboratory; 1976. 6 p.

25
Red Alder

Dean S. DeBell

Pacific Northwest Forest and Range Experiment Station

Thomas C. Turpin

Pacific Northwest Region

Red alder (Alnus rubra Bong.) is the most widely

distributed hardwood type in the coastal Pacific Northwest,

occupying more than 3 million acres (1.2 million ha) of

commercial forest land in Oregon and Washington. This type

is identical to Society of American Foresters cover type 221

of the same name (4). The type is found from southern

California to southeastern Alaska, but stands seldom occur

east of the Cascade Range or the Sierra Nevadas. Red alder

stands grow on a wide range of soil and site conditions,

varying from well-drained gravels and sands to poorly

drained clays and organic soils (17). Because red alder can

tolerate poorly drained conditions and some flooding in the

growing season, it prevails on soils of restricted internal

drainage, along streams, and on swampy or marshy areas.

The most productive stands are usually found on deep,

well-drained loams or sandy loams derived from marine

sediments or alluvium; some very good stands also grow on

residual or colluvial soils of volcanic origin. Rapidly growing

red alder stands occur on hillsides as well as along streams at

elevations below 1,500 feet (460 m) in coastal areas of

northern Oregon, Washington, and British Columbia. At

mid-elevations in the Cascade Range, stands of commercial

dimensions are limited mainly to stream bottom sites.

Climate in the type's range is humid or superhumid,

with most precipitation occurring as rain during winter.

Summers are cool and dry, sometimes with considerable

morning fog. Annual precipitation and temperature extremes

are 16 to 220 inches (405 to 5590 mm) and -22° to 115° F

(—30.0° to 46.1° C), respectively. Most stands, however,

are found where annual precipitation exceeds 40 inches (1015

mm) and winter temperatures are relatively mild.

Red alder occurs in both pure and mixed stands.

Common tree associates include coast Douglas-fir {Pseudotsuga

menziesii (Mirb.) Franco var. menziesii), western hemlock

(Tsuga heterophylla (Raf.) Sarg.), western redcedar {Thuja

plicata Donn ex D. Don), Sitka spruce {Picea sitchensis

(Bong.) Carr.), black cottonwood {Populus trichocarpa Torr.

& Gray), bigleaf maple {Acer macrophyllum Pursh), and

willow {Salix spp).

Red alder regenerates most commonly by natural seeding.

It has also been established by direct seeding and planting in

several research and pilot-scale trials (17). Survival of both

bare-root and container seedlings has been excellent (3). Red

alder will sprout vigorously from the stump when young and

has been repeatedly coppiced on short cycles (6). Stumps of

pole- and sawlog-size trees may sprout, but sprouts rarely

persist.

Individual trees reach sexual maturity at 3 to 4 years,

and most dominant trees in a stand will begin to produce seed

at 6 to 8 years (11). Red alder is a prolific seeder, with

moderate seed crops produced almost annually. Bumper

crops occur at 3- to 5-year intervals, and seed crop failure is

unusual. Seed dispersal begins soon after ripening in late

summer, but most seeds are shed during fall and winter.

Dissemination is primarily by wind, and sufficient seed for

natural regeneration is usually present throughout the species'

range (17).

Germination and early growth is best on moist mineral

soil and in full sunlight. The species is a common pioneer on

landings, skidtrails, road cuts, and other areas where mineral

soil has been freshly exposed. Seeds will also germinate on

soil organic horizons and on rock-surfaced logging roads, but

the newly developing roots must quickly penetrate a moist,

nutritious substrate if the seedlings are to survive. Some early

mortality has been observed after girdling by meadow mice

or cutting by mountain beaver, but its extent is unknown.

Red alder is moderately intolerant of shade. Seedlings

will survive in partial shade for several years, but full

sunlight is required for normal development. Compared with

most of its associates, red alder is relatively tolerant of

flooding and salinity. Windthrow is not common except

along exposed cutting boundaries or where root systems have

been undermined by flooding or erosion. Mortality, stem

breakage, and other top damage have been observed in

natural stands after ice storms and unseasonable frosts (3,

17).

Red alder is the only commercial tree species native to

westem North America that fixes atmospheric nitrogen symbiotically in its root nodules; both content and availability of

nitrogen are increased in soils beneath red alder stands.

Accretion rates varying from about 40 to more than 300

pounds of nitrogen per acre (45 to 335 kg/ha) per year have

been reported for alder stands of 50 years and less (12, 13).

Soil organic matter is higher and bulk density is lower in red

alder stands than in conifer stands of comparable history

(12). Red alder has therefore been proposed for site improvement purposes, either by itself or in crop rotations and

mixtures with other species.

Young stands of red alder may be very dense, having

more than 100,000 stems per acre (247 100 stems/ha) at 1

and 2 years (2). Self-thinning or suppression-related mortality begins at an early age in such stands, but they remain too

dense for optimum growth without management. Spacing

control or thinning in previously unmanaged stands is effective in stimulating growth if done before age 15 to 20.

Thinning in overly dense, older stands can salvage mortality

but is of questionable value for increasing growth on selected

crop trees (10, 15).

Young alder trees grow rapidly. On favorable sites,

seedlings grow 3 feet (0.9 m) or more in the first year; they

may attain 30 feet (9.1 m) by age 5 and more than 80 feet

(24.4 m) by age 30 (16). Good growth rates are maintained

from establishment to at least age 25; during this period,

growth of red alder surpasses that of any conifer or other

hardwood species in the Pacific Northwest, with the exception of black cottonwood on its best sites. Growth thereafter

slows, and the decrease begins earlier and is greater on poor

than on good sites.

Growth and yield information is available for natural,

unmanaged stands of red alder (1, 2, 10, 13, 14, 16). On

26
well-stocked sites of the highest quality, mean annual increment (total stem) may approach 150 cubic feet per acre (10.5

m^/ha) for 20- to 40-year rotations; a comparable value for

sites of average quality is 120 cubic feet per acre (8.4 m^/ha).

Projections based on early performance of experimental

plantings, results of thinning trials, and gains obtained with

spacing control of other species suggest that yields of

managed red alder stands will be much higher than natural

stands (2). For example, coppice stands can be grown on

cutting cycles of 2 or more years, and pulpwood-size (6-inch

(15 cm) diameter at breast height (d.b.h.)) trees can be

produced in 10 to 15 years on good sites. Sawlog- and veneer

log-size trees (12-inch (30 cm) d.b.h.) can probably be

grown in 25 to 35 years on such sites. Annual total stem

yields are estimated at 170 to 210 cubic feet per acre (11.9 to

14.7 m^/ha). Rotations longer than 40 years are not recommended for timber production because of increased disease

problems and reduced growth of red alder at older ages (3,

13, 17).

Young, vigorous stands of red alder appear relatively

free from serious insect and disease problems, but such pests

could become more evident or serious as the species becomes

more widely managed (17). Insect damage observed in alder

stands include twig girdling by flatheaded borers, defoliation

by tent caterpillars and sawflies, and infestation by bark

beetles. Red alder is susceptible to several canker-causing

fungi and foliage and catkin diseases, but none have significant economic importance. A white heart rot is the major

cause of defect in older trees, and many other fungi species

have been identified on alder as secondary invaders of dead

or dying tissues. Red alder is resistant to laminated root rot

(Phellinus weirii (Murr.) Gilb.), and therefore is a suitable,

non-susceptible species for growing on sites severely infested

with the fungus (5).

Fire rarely damages red alder stands—in fact, the

species has been planted as a fire break (17). The low fire

hazard is due to scarcity of flammable understory and organic

debris in closed alder stands and because natural alder stands

commonly occur on wet sites. Fire may be an important site

preparation tool in red alder management. Dense understories

of shrub species develop in older, unmanaged red alder

stands with less than full stocking, particularly on the more

productive sites. Such shrub species may take over the site

following harvest and thereby prevent successful regeneration of alder or other commercial tree species, unless special

site preparation measures are taken. Tractor scarification is

rather expensive and is inappropriate on many red alder sites

because of steep terrain or excessive soil moisture. Broadcast

burning is usually difficult because of moist conditions,

green underbrush, and the non-resinous, light slash of such

stands (17). Coupled with preparatory applications of herbicides and/or desiccants, however, broadcast burning can be a

suitable method for ameliorating the brush encroachment

problem following harvest cuts on such sites (9).

Although natural stands of red alder occupy about 15

percent of commercial forest lands in western Oregon and

western Washington, foresters have had littíe experience in

managing the species. Historically, red alder has been

regarded primarily as a weed species limiting production of

more highly valued conifers. Stumpage values for red alder

are very low; available supplies far exceed present demand

(7). There is growing interest, however, in regeneration and

management of red alder because of its rapid juvenile growth

and ability to fix atmospheric nitrogen and improve other

chemical and physical properties of soils. Recent expansions

in use of the species in solid wood, paper, and other

reconstituted fiber products as well as recognition of its

potential contributions in multiple-use situations have also

aided the developing interest in red alder management.

Because of the dearth of operational experience with the

species, present management recommendations are based

primarily on extrapolation of results from limited research

trials as well as management experience with other species

having similar biological traits.

Silvical characteristics and regeneration requirements of

red alder mandate a silvicultural system adapted to even-aged

management, specifically, clearcutting, seedtree, orshelterwood.

Of the three, clearcutting provides the greatest flexibility in

use of site preparation techniques to control brush and to

expose mineral soil. Natural seeding from adjacent uncut

stands, direct seeding, and planting of container or bare-root

seedlings have all resulted in satisfactory establishment of

new alder stands in clearcut areas (3, 17). Stocking in

naturally established stands, however, is commonly either

clumpy with much unoccupied growing space or extremely

dense. Thus, planting may be preferable in situations where

red alder is managed primarily for wood production. In most

cases, clearcutting is probably the most effective silvicultural

system, followed, if necessary, by scarification or some other

form of site preparation. Clearcutting is also the appropriate

method to use in short-rotation management systems for fiber

and energy production (2, 6).

No attempts to reproduce red alder by the seedtree

method have been documented. Only in rare cases does seed

supply limit natural regeneration ofred alder after clearcutting;

seedbed condition is more likely to be the limiting factor.

Leaving a few seed trees per acre, however, might provide a

more uniform distribution of seedlings where cutting units

are exceptionally large or where there are few adjacent uncut

red alders.

The shelterwood system might also be used to regenerate red alder, but there is little documented information to

recommend it. Seed is usually produced every year, and

established seedlings grow best in full sunlight. Moreover,

juvenile growth rate of red alder is so rapid that, even in areas

of high esthetic value, the overstory would probably have to

be removed in less than 2 years; excessive damage to the

young reproduction would otherwise be expected.

Because red alder can become established naturally in

abundance, precommercial thinning will probably be an

essential feature of management programs—especially those

that entail natural regeneration. There are several reports of

enhanced growth of the species following early spacing

control (10, 15); such cutting also provides opportunities to

favor stems of superior form. Uniform spacing may also

reduce the sweep or lean characteristic of red alder in

unmanaged, irregularly spaced stands (2).

Maintenance of the red alder type is no problem; the

estimated acreage occupied by red alder in western Oregon

and western Washington has more than tripled in the past

quarter century. Recent emphasis on conversion of red alder

stands to conifers, however, has resulted in an unbalanced

distribution of age classes in some areas. Individual alder

stands begin to break up by age 60 to 70; intact stands more

than 80 years old are rare. Much evidence points to maximum rotation ages of 40 years or less if wood production is

the primary objective of management.

Mixed stands of red alder and other species are more

common than pure red alder stands in many parts of the

species range. These mixtures are both even- and unevenaged, and may include most of the previously listed associated tree species. There is no specific management experience and little research data for most of these mixtures; the

intention of most forest owners and managers is to convert

such stands to pure conifers after harvest of the existing

stands. There are some exceptions, however, and interest in

27
mixed-species management has increased substantially in the

last decade. For example, mixed stands of Douglas-fir and

red alder have been established on an experimental basis and

such mixtures are now being considered for limited operational use on some nitrogen-deficient soils. Interplanting

alder seedlings in a 4-year-old Douglas-fir plantation at a

ratio of nearly two alders to one Douglas-fir, increased soil

nitrogen and soil organic matter and lowered bulk density

(12); it also enhanced growth of Douglas-fir (8). Similar

benefits might be obtained with a lower ratio of red alder to

Douglas-fir. Mixed red alder-Douglas-fir stands are prescribed on the Siuslaw National Forest for soils that are low

in nitrogen but are otherwise productive (site index class II).

Current management plans for these sites call for leaving

some naturally established red alder when Douglas-fir plantations are precommercially thinned at about age 10 (14). The

red alder will be removed in a commercial thinning at about

age 40. It is assumed that nitrogen accumulated in the soil

during the period of alder's occupancy will enhance Douglasfir growth in the remaining years of the conifer rotation.

Red alder stands can be established and managed for

purposes other than, or in addition to, wood production.

Because of the species' tolerance of poor drainage and

flooding, alder is sometimes recommended for management

in riparian zones. It can be especially useful in the amelioration of coal mine spoils, landslides, and other eroded or low

fertility areas. Although red alder is not a preferred browse

species, its presence in pure stands, small clumps or stringers,

and mixed stands within extensive conifer forests provides

edges and adds structural diversity; it may therefore be used

to enhance the forest habitat for many wildlife species.

Esthetically, red alder stands provide variety in a landscape

covered mainly by stands of conifers, and its rapid juvenile

growth rate permits its use where rapidly established tree

cover is desired for protection or enhancement of visual

resources.

Literature Cited

1. Chambers, C. J. Empirical yield tables for predominantly alder stands in

western Washington. Report No. 31. Olympia, WA: State of Washington Department of Natural Resources; 1974. 70 p.

2. DeBell, D. S.; Strand, R. F.; Reukema, D. L. Short-rotation production

of red alder: Some options for future forest management. In: Briggs, D.

G.; DeBell, D. S.; Atkinson, W. A., comps. Utilization and management of alder. Gen. Tech. Rep. PNW-70. Portland, OR: U.S.

Department of Agriculture, Forest Service, Pacific Northwest Forest

and Range Experiment Station; 1978: 231-245.

3. DeBell, D. S.; Harrington, C. A. Mini-monograph on Alnus rubra. In:

Documents, Technical consultation on fast-growing plantation broadleaved

trees for Mediterranean and temperate zones; 1979 October 16-20;

Lisbon, Portugal. Volume 1. Invited Papers. Food and Agriculture

Organization of the United Nations; 1979: 169-186.

4. Eyre, F. H., ed. Forest cover types of the United States and Canada.

Washington, DC: Society of American Foresters; 1980. 148 p.

5. Hansen, E. M. Survival oí Phellinus weirii in Douglas-fir stumps after

logging. Can. J. For. Res. 9(4): 484-488; 1979.

6. Harrington, C. A.; DeBell, D. S.; Strand, R. F. An experiment in

biomass production: Results from three consecutive harvests of cottonwood and alder. In: Proceedings of Solar '79 Northwest, U.S. Seattle,

WA: U.S. Department of Energy and others; 1979: 363-366.

7. McGillivray, R. Alder survey. Pullman, WA: State of Washington

Department of Natural Resources; 1981. 24 p.

8. Miller, R. E.; Murray, M. D. The effects of red alder on growth of

Douglas-fir. In: Briggs, D. G.; DeBell, D. S.; Atkinson, W. A., comps.

Utilization and management of alder. Gen. Tech. Rep. PNW-70.

Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific

Northwest Forest and Range Experiment Station; 1978: 283-306.

9. Newton, M. Herbicides in alder management and control. In: Briggs,

D. G.; DeBell, D. S.; Atkinson, W. A., comps. Utilization and

management of alder. Gen. Tech. Rep. PNW-70. Portland, OR: U.S.

Department of Agriculture, Forest Service, Pacific Northwest Forest

and Range Experiment Station; 1978: 223-230.

10. Smith, J. H. G. Growth and yield of red alder: Effects of spacing and

thinning. In: Briggs, D. G.; DeBell, D. S.; Atkinson, W. A., comps.

Utilization and management of alder. Gen. Tech. Rep. PNW-70.

Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific

Northwest Forest and Range Experiment Station; 1978: 245-263.

11. Stettler, R. F. Biological aspects of red alder pertinent to potential

breeding programs. In: Briggs, D. G.; DeBell, D. S.; Atkinson, W. A.,

comps. Utilization and management of alder. Gen. Tech. Rep. PNW-70.

Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific

Northwest Forest and Range Experiment Station; 1978: 209-222.

12. Tarrant, R. F.; Miller, R. E. Accumulation of organic matter and soil

nitrogen beneath a plantation of red alder and Douglas-fir. Soil Sei. Soc.

Amer. Proc. 27(2): 231-234; 1963.

13. Trappe, J. M.; Franklin, J. F.; Tarrant, R. F.; Hansen, G. M., eds.

Biology of alder. Portland, OR: U.S. Department of Agriculture, Forest

Service, Pacific Northwest Forest and Range Experiment Station; 1968.

292 p.

14. Turpin, T. C. Managing red alder on the Siuslaw National Forest. In:

Proceedings, National Silviculture Workshop—Hardwood Management;

1981 June 1-5; Roanoke, VA. Washington, DC: U.S. Department of

Agriculture, Forest Service, Timber Management; 1981: 268-272.

15. Warrack, G. C. Thinning effects in red alder. Victoria, BC: British

Columbia Forest Service, Research Division; 1964. 7 p.

16. Worthington, N. P.; Johnson, F. A.; Staebler, G. R.; Lloyd, W. J.

Normal yield tables for red alder. Res. Pap. 36. Portland, OR: U.S.

Department of Agriculture, Forest Service, Pacific Northwest Forest

and Range Experiment Station; 1960. 29 p.

17. Worthington, N. P.; Ruth, R. H.; Matson, E. E. Red alder: its

management and utilization. Misc. Pub. 881. Washington, DC: U.S.

Department of Agriculture; 1962. 44 p.

28
Southwestern Oregon-Northern California Hardwoods

Philip M. McDonald

Pacific Southwest Forest and Range Experiment Station

Don Minore

Pacific Northwest Forest and Range Experiment Station

Tom Atzet

Pacific Northwest Region

Hardwoods are abundant or predominate from southern

Coos and Douglas Counties, Oreg., southward through the

Klamath Mountains and Coast Range to Monterey County,

Cahf. They extend even farther south in the Coast Range and

eastward into the southern Cascades and northern Sierra

Nevada, but become disjunct. Elements of the Society of

American Foresters Douglas-Fir-Tanoak-Pacific Madrone

(type 234), California Black Oak (type 246), Canyon Live

Oak (type 249), and Oregon White Oak (type 233) forest

cover types are included in this composite hardwood type.

The climate of southwestern Oregon and northern California seasonally ranges from cool and moist to hot and dry.

In the Coast Range of California and southwestern Oregon,

temperatures average 41° to 50° F (5.0° to 10.0° C) in January

and 57° to 73° F (13.9° to 22.8° C) in July. Average annual

precipitation varies between 34 and 83 inches (865 and 2110

mm). Fog sometimes is a moderating influence in the Coast

Range. Number of days free of killing frost ranges from 204

to 338 (4, 14).

In the interior mountains (interior Coast Range, Klamath

Mountains, southern Cascades and northern Sierra Nevada),

average January temperatures range from 33° to 41° F (0.6° to

5.0° C) and average July temperatures from 62° to 75° F

(16.6° to 23.9° C). Average annual precipitation varies

between 30 and 68 inches (760 and 1730 mm). Number of

frost-free days ranges from 116 to 240 (3, 15).

Geology of the region is complex with volcanic,

sedimentar/, and metamorphosed rocks. All aspects are

represented in topography that often is steep, rugged, and

dissected by streams. Hardwood species are especially prevalent on the warmer and drier south and west aspects, but often

are present on north and east aspects as well. They also are

abundant in the transition zone between the mountains and

the foothills, and frequently dominate the low rolling foothills as well. The elevational range of the mixed-hardwood

forest in the Coast Range is from 40 to 4,000 feet (10 to 1220

m). In the interior mountains, most of the hardwood species

can be found within the 580- to 4,700-foot (175- to 1430-m)

elevational range.

Soils within the region reflect the effects of a wide range

of local climate, geology, parent material, and topography

interacting over a long time. They range from deep, moist,

fertile alluvium to shallow skeletal soils characterized by

coarse texture, excessive drainage, and relative infertility.

Most hardwood species tend to inhabit well-drained or

droughty soils.

Tanoak {Lithocarpus densiflorus (Hook. & Am.) Rehd.)

and Pacific madrone {Arbutus menziesii Pursh) are the most

abundant hardwoods in the Coast Range and western Klamath

Mountains. Other hardwoods throughout southwestern Oregon and northern California are California black oak {Quercus

kelloggii Newb.), canyon live oak {Q. chrysolepis Liebm.),

Oregon white oak {Q. garryana Dougl. ex Hook.), bigleaf

maple {Acer macrophyllum Pursh), California-laurel {Umhellularia calif arnica (Hook. & Am.) Nutt.), and, to a lesser

extent, giant chinkapin {Castanopsis chrysophylla (Dougl.)

A. DC).

Douglas-fir {Pseudotsuga menziesii (Mirb.) Franco var.

menziesii) often is associated with these hardwood species

and may be abundant. Incense-cedar {Libocedrus decurrens

Torr.) and ponderosa pine {Pinus ponderosa Dougl. ex

Laws. var. ponderosa) also are common conifer associates

except on the westem slopes of the Coast Range. Redwood

{Sequoia sempervirens (D. Don) Endl.) and Port Orfordcedar {Chamaecyparis lawsoniana (A. Murr.) Pari.) are

locally abundant in the Coast Range. Califomia white fir

{Abies concolor var. lowiana (Gord.) Lemm.) and sugar pine

{P. lambertiana Dougl.) are less abundant associates in the

mixed-hardwood forests.

Not all of the hardwood species grow together at a given

location. Four or more species may be found in mixture, but

two or three species are more common. Pure stands of one

species occasionally clothe a hillside or occupy favorable

sites. Hardwoods may cover large areas of more than 100

acres (40 ha). They also can be found as single trees, but

more commonly as groups covering from 0.2 to 10 acres (0.1

to 4.0 ha). Old-growth conifer stands sometimes contain pure

Douglas-fir that forms a solid canopy. At other locations,

however, Douglas-fir is part of a ragged overstory with

intervening spaces occupied by hardwoods. Sometimes only

scattered remnants of Douglas-fir are present, and the remainder of the stand is comprised of hardwoods. Two-storied

stands are common in the Coast Range and west-facing

slopes of interior mountains, with Douglas-fir above tanoak,

or Pacific madrone, or both. Sometimes a dense brush layer

forms beneath the trees in more open stands (12).

Steep, rocky slopes may be covered with scattered

Douglas-firs and more numerous canyon live oaks. Canyon

live oak also forms pure stands, as it tends to become

concentrated in steep, rocky areas with low incidence of fire

(9). Pacific madrone, canyon live oak, Califomia black oak,

and Oregon white oak are abundant on drier areas. Oregon

white oak, in groups or as single trees, often forms a

scattered fringe between grassland and forest. Giant chinkapin and Califomia-laurel are common associates of tanoak in

more mesic locales. Califomia black oak, more so than other

hardwoods, grows on a wide range of forest soils, from those

that are deep and fertile to others that are shallow and

impoverished. Bigleaf maple generally is limited to moist

sites in Califomia, but grows in both moist and dry environments in the Klamath Mountains of Oregon (6).

Most of the hardwood species of southwestem Oregon

and northem Califomia have a scrubby variety. On poor

sites, this variety prevails. On slightly better sites, taller

poorly formed trees occupy a large but unknown percentage

of the total land area. The scmbby stands, although

noncommercial, are valuable for wildlife habitat and watershed protection.

Most hardwood stands are even aged but, occasionally,

two or three age classes may be present. The tendency to be

29
even aged is a consequence of the species' ability to sprout

after major disturbances. Almost all hardwood species of

southwestern Oregon and northern California depend primarily on fire, logging, blow-down, insect devastation, or mass

soil movement to eliminate or reduce greatly the taller

conifers, freeing the hardwoods to dominate.

Without exception, the hardwood species are vigorous,

prolific sprouters. They may produce 20 to 40, or occasionally even 60 sprouts per stump. In Humboldt and Trinity

Counties, Calif., 3-year-old sprouts of Pacific madrone

averaged 10.1 feet (3.1 m), Oregon white oak 9.2 feet (2.8

m), tanoak 6.8 feet (2.1 m), and bigleaf maple 12.8 feet (3.9

m) in height (10). Ten-year-old madrone sprouts averaged

22.2 feet (6.8 m), tanoak 19.0 feet (5.8 m), and California

black oak 19.7 feet (6.0 m) in the northern Sierra Nevada (1).

At this location, tanoak and madrone sprouts grew more than

5 feet (1.5 m) the first year. Sprouting is a valuable

regeneration mode for keeping a species in place, while

acorns and other seeds, carried far and wide by a host of

disseminators, are valuable for extending the species into

new areas.

Some seed may be available almost every year (4, 13),

but large crops are produced by most hardwoods every 2 to 3

years. Seed crop frequency may be slightly greater for

California-laurel and Pacific madrone, however, and bigleaf

maple produces large seed crops almost every year.

Seed crops can be large. Tanoak acorns from 18- to

24-inch (46- to 61-cm) diameter trees in Trinity County,

Calif., numbered 78,000 to more than 91,000 per acre

(193 000 to 225 000/ha) and were 49 percent sound (11).

A 15.7-inch (40-cm) diameter Pacific madrone in the

northern Sierra Nevada produced 2.15 million seed in a

light seed year (4). Most seeds produced, however,

quickly lose viability or are eaten by rodents, birds,

and deer. California black oak acorns, for example, had

severely withered cotyledons 9 days after falling on

ground exposed to bright sunlight; acorns exposed to

subfreezing temperatures had gravish cotyledons and were

not viable (3). Inability to find a single seed in the spring,

even after a bumper seed crop, is commonplace—all have

been consumed or carried off.

Acorns of the oaks and tanoak, the nuts of giant

chinkapin, nutlets of California-laurel, and fruits of madrone

are relatively large, heavy, colorful, and probably nutritious.

These attributes enhance collection and dissemination by

birds and animals. Without such dissemination, the seeds fall

mostly beneath tree crowns, often into inhospitable environments.

Loose, moist mineral soil or soil covered by sufficient

leaves and litter to keep the seeds moist, insulate them from

high and low temperatures, and hide them from consumers,

are the best seedbeds for acorn- and nut-producing species.

Califoria-laurel seeds need to be covered either by ground

disturbance or from silt deposited by high water (13).

Partially shaded mineral soil is the best seedbed for Pacific

madrone because damping-off fungi and invertebrates in

organic material decimate the population of tiny seedlings

(4).

Seeds of southwestern Oregon-northern California hardwoods germinate at extremely variable rates. Trials have

been few, however, and germination media and laboratory

environments have been significantly different (1, 13). In the

only documented trial, 94 percent of Pacific madrone seed

germinated. Rates for other hardwoods are as follows:

tanoak, 19 to 78 percent; California black oak, 63 to 95

percent; giant chinkapin, 14 to 53 percent; California-laurel,

20 to 82 percent; canyon live oak, 56 to 75 percent; Oregon

white oak, 77 to 100 percent; and bigleaf maple, 32 to 90

percent (13).

Hardwood seedling survival varies with species' tolerance and amount of shade. Survival of California black oak

seedlings (65 percent after 7 years) was better than tanoak

seedling survival (30 percent after 10 years) when both were

seeded in open northern Sierra Nevada plantations. In a

shady hardwood forest nearby, however, 10- to 15-year-old

tanoak seedlings and seedlingrsprouts numbered 10,280 per

acre (25 400/ha). Only a few small California black oak

seedlings were present, however, because the environment

was too shady for seeding establishment (1).

Pacific madrone seedlings become established and survive moderately well on partially shaded mineral soil in 3- to

4-year-old clearcuttings (4).

Only 2 percent of 829 Pacific madrone seedlings survived the first growing season in a central California coast

study (7). No quantitative survival data are available for other

hardwoods, but several observations suggest species differences.

Oregon white oak reproduces in its own shade and in open

stands, but cannot tolerate conifer overtopping (15). Giant

chinkapin may be limited to relatively open stand conditions

in moist environments, but seedlings become increasingly

competitive on dry, nutritionally poor sites (5). Canyon live

oak seedlings grow under overstories or on shaded overstory

fringes (17), but the seedlings of California-laurel (14) and

bigleaf maple (7) probably are the most shade tolerant.

Although their seedlings become established in shade,

the tolerance of most hardwoods is not well defined. Tanoak,

California-laurel, bigleaf maple, and giant chinkapin appear

to be more tolerant than Douglas-fir, and Douglas-fir seems

to be more tolerant than Oregon white oak or canyon live oak

(4, 15). Canyon live oak may be slightly more tolerant than

Pacific madrone. California black oak is relatively intolerant

(3).

High water tables are lethal to nearly all of these

hardwoods. Oregon white oak may be the exception (4).

California-laurel (14) and bigleaf maple (6) survive temporary flooding. All of the hardwoods are adapted to periods of

drought and the evergreen species, in particular, are able to

minimize drought effects. All are windfirm except possibly

California-laurel (14). Unusually heavy snow loads, however,

can cause local damage.

Artificial regeneration of most of these hardwood species has not been reported. Only two trials with California

black oak and one with tanoak are known. Direct seeding of

California black oak acorns can be successful if competing

vegetation and pocket gophers are controlled (3). In contrast,

direct seeding of tanoak in the northern Sierra Nevada

indicated little promise (1). Limited outplantings of tanoak

and California black oak plug-seedlings in the northern Sierra

Nevada showed no gain over direct seeding (1).

Hardwood seedlings grow slowly. A 5-year-old tree

may be only a few inches tall. Fertilizer (16-20-0) applied

each year significandy improves height of California black

oak and tanoak seedlings (3). Shoot growth does not accelerate until root capacity is extensive enough for the seedling to

obtain adequate moisture. Fertilizer probably promotes growth

of feeder roots that aid in gathering moisture.

Diameter growth rates of trees vary with species, stand

density, and quality of site. In typically dense natural stands,

dominant and codominant trees, 60 to 80 years old, usually

grow at 12 to 15 rings per inch (5 to 6 rings/cm). These data

hold for Pacific madrone, California-laurel, and giant chinkapin in northern California. More open-grown stands of

Oregon white oak and canyon live oak grow at about the

same rate—the effect of lower stand density probably being

30
offset by lower site quality. Tanoaks grow slightly faster,

averaging 8 to 13 rings per inch (3 to 5 rings/cm) (11).

Diameter growth of more open-grown trees is greater than

that of trees in closed stands, and thrifty California black

oaks may attain 3 rings per inch (1 ring/cm) (3). Height

growth rates are poorly documented but appear to be fairly

rapid in the sapling and pole stages, and slow after trees reach

maturity.

Rotation age presently is not known for the hardwoods

of southwestern Oregon and northern California. Presence of

heart rot could influence rotation age. Incidence of incipient

heart rot in California black oak increases rapidly after 110

years and could determine rotation age for wood products

(3), but not for acorn production, wildlife benefits, or other

uses.

Yields have not been determined for managed hardwood

stands; even unmanaged stand data are scarce. Natural stands

of mixed hardwoods in the northern Sierra Nevada consist of

many stems (659/acre or 1628/ha) greater than 2 inches (5

cm) in diameter at breast height (d.b.h.) and contain 4,090

cubic feet of solid wood per acre (286.3 m^/ha) (2). An

average 70-year-old black oak stand in northern California

contains slightly more than 5,845 cubic feet per acre (409.2

m^/ha) (1). Comparable information for southwestern Oregon

is not available.

Many insects feed on hardwood species, but few kill

healthy trees. Local infestations of the western oak looper

{Lambdinafiscellaria somniaria (Hülst)), California oakworm

(Phryganidia californica Packard), Pacific oak twig girdler

{Agrilus angelicus Horn), and fruittree leafroller {Archips

argyrospila (Walker)), are common. Damage is unsighdy,

but short-lived. Insects often destroy entire acorn crops of the

oaks and tanoak. The filbertworm {Melissopus latiferreanus

(Walsingham)) may affect chinkapin seed production (5), but

no serious damage to developing seed crops of Californialaurel (14) or bigleaf maple (6) has been reported. The extent

of damage to seed crops of Pacific madrone is unknown.

Few fungi kill the hardwoods, but tanoak, California

black oak, and several other species are susceptible to heart

rots, such as Laetiporus sulphureus (Bull, ex Fr.) Bond &

Sing., Inonotus dryadeus (Pers. ex Fr.) Murr., and /.

dryophilus (Berk.), Murr, and root rots, especially Armillariellia mellea (Vahl. ex Fr.) Karst. (3, 4, 11, 14, 15). A

bleeding canker (Phytophthora cactorum Leb. & Cohn

Sehr.) is a damaging pest of Pacific madrone (4).

One means for virtually eliminating heart rot in young

hardwood stands in Oregon and California is to leave a stump

less than 8 inches (20 cm) tall, a practice that promotes

sprouting from the root crown. Sprouts from root .crowns

have an extremely low incidence of rot bridging from stump

to pith of sprouts. Stool sprouts, which arise at or near the top

of higher stumps, almost always are rotten and, also, are

susceptible to breakage by wind and snow (1). Once a stand

has been clearcut, slash disposal by broadcast burning

promotes root crown sprouts by removing accumulations of

slash from around the root crowns and by killing aboveground portions of stumps.

Slash in partially cut hardwood stands should be lopped

and scattered or piled. Prescribed burning is not recommended.

The bark of most hardwood species provides little insulation

from fire. Cambium is killed easily by small amounts of

radiant heat, and long vertical bole wounds are common after

fire.

Uneven-aged management of hardwood stands is not

practical in open stands like those of Oregon white oak or

Pacific madrone in the foothills, or in closed forest stands

where a mixture of species with differing shade tolerances is

present. The primary reason is that in stands of species

having mixed tolerances, uneven-aged management usually

promotes eventual conversion to the most shade-tolerant

species. An additional reason, at least in present stands, is

that seldom are enough age classes present to qualify for this

form of management. Leaving a fairly dense shelterwood

(removal of 40 to 60 percent of original 207.3 square feet per

acre (47.6 m^/ha) of basal area) also appeared to be impractical in mixed California black oak—tanoak—Pacific madrone

stands in the northern Sierra Nevada (1). Form and growth of

10-year-old sprouts of these three species were markedly

poorer in the shelterwood cutting than in a clearcutting.

Because sprouts are a principal mode of hardwood reproduction,

and most hardwood stands today are even-aged, clearcut

harvesting and manipulation of the sprout stands are suggested for present and future operations. Also, the natural

mixture of hardwood species should be preserved. Some

evidence from northern Sierra Nevada stands suggests that

greater volume growth is obtainable from thinned stands of

several species than from stands of a single species.

Establishment of plantations in clearcuttings is possible

for California black oak (3), and probably for Oregon white

oak and canyon live oak. Whether California-laurel, bigleaf

maple, Pacific madrone, or giant chinkapin can be established in this manner is not presently known. Tanoak

probably cannot be consistentíy propagated from acorns in

clearcuttings, at least not in the northern Sierra Nevada,

without extensive artificial shading.

After establishment and development, managed stands

from seed where stocking is controlled may differ appreciably from the present sprout stands in their response to

manipulation. Straighter trees, faster growth rates, lower

incidence of heart rot, and a shorter rotation age are likely.

Management guidelines for the hardwood stands of

southwestern Oregon and northern California differ as the

environments affecting the species differ. Environments can

be described broadly as woodland, hardwood type, and

hardwood element within a conifer type. A similar grouping

with management guidelines for California black oak in the

Sierra Nevada is available (16).

Management of hardwoods in woodlands is influenced

by their location near cities and farms. Stands generally are

tucked away in comers of fields, along streams, or on steep

ground. Management for wood products, such as fenceposts

and fuelwood often is incidental to other values such as

esthetics, shade for livestock, and food and shelter for

wildlife. Increased management for fuel and fiber in the

future is likely. An intensive program of stand management

and utilization has the best chance of being applied successfully and should be developed where hardwoods are numerous and where wood volumes are high. Well-stocked stands

often are found at lower elevations, where they form part of

the winter range for wildlife species. The forest manager,

therefore, has an opportunity to manage for increased wildlife habitat as well as for wood production.

Hardwoods growing within a conifer forest give the

forest increased diversity and an improved yield of both

amenities and commodities. The hardwoods often grow in

aggregations, the size of which varies inversely to site

quality. Large stands of hardwoods on poorer sites should

remain natural at least until uses for them are well defined.

Management of hardwood aggregations is useful because

specific treatments can be applied to discrete parts of the

stand.

On high-quality sites, continued absence of disturbance

will allow conifers to overtop hardwoods. Stand manipulation will be necessary to maintain a constant proportion of

groups of well-developed hardwoods.

On medium-quality sites where young conifers and

31
hardwood sprouts intermingle, opportunities are available to

simultaneously manage both kinds of trees with the proper

spacing of hardwoods above, sheltering the younger conifers

below. The conifers, in turn, reduce epicormic branching by

shading the hardwood boles. Together they constitute a

habitat conducive to a large and varied population of wildlife.

Eventually, both contribute to the harvest of timber and other

wood products.

Stand management information is limited to the results

of a single study in the northern Sierra Nevada in which a

stand of California black oak, tanoak, and Pacific madrone

trees was thinned (2). Where 34 to 55 percent of original

basal area (198 ft^/acre or 45.5 m^/ha) remained, total

diameter growth was 0.6 to 1.6 inches (1.5 to 4.1 cm) per

tree after 8 years. Diameter growth was consistentíy best for

trees in the dominant crown class, decreased successively

through the codominant and intermediate classes, and was

poorest in the suppressed class on both thinned and unthinned

plots (2). Eight-year volume growth indicated that stands of

black oak, tanoak, and Pacific madrone thinned to 102 and

125 square feet per acre (23.4 and 28.7 m^/ha) yield about 85

cubic feet per acre (6.0 m^/ha) per year. California black oak

appears to grow better at stand densities below 125 square

feet per acre (28.7 m^/ha) and tanoak and Pacific madrone at

stand densities above 102 square feet per acre (23.4 m^/ha).

Relatively dense stocking, whether from natural sprout stands

or stands artificially established from seed, is recommended.

Such stands produce better formed stems, fewer forks, and

less epicormic branching.

Native Oregon and California hardwoods are valuable

for \yildlife, esthetics, recreation, wood products, and watershed protection (8, 9). In a world of seemingly insatiable

needs for fuel and fiber, hardwoods also have high potential

for increased use as wood products, pulp, and energy (9).

References

1. McDonald, Philip M. Silviculture-ecology of three native California

hardwoods on high sites in north central California. Corvallis: Oregon

State Univ.; 1978. 309 p. Dissertation.

2. McDonald, Philip M. Growth of thinned and unthinned hardwood

stands in the northern Sierra Nevada . . . preliminary findings. In:

Proceedings of the symposium on the ecology, management, and

utilization of California oaks; 1979 June 26-28; Claremont, CA. Gen.

Tech. Rep. PSW-44. Berkeley, CA: U.S. Department of Agriculture,

Forest Service, Pacific Southwest Forest and Range Experiment Station;

1980: 119-127.

McDonald, Philip M. California black oak. U.S. Department of

Agriculture, Forest Service, Pacific Southwest Forest and Range Experiment Station; 1981. Unpublished report.

McDonald, Philip M.; Olson, David F., Jr. Pacific madrone. U.S.

Department of Agriculture, Forest Service, Pacific Southwest Forest

and Range Experiment Station; 1981. Unpublished report.

McKee, Arthur. Giant chinkapin. Corvallis, OR: Oregon State University,

1981. Unpublished report.

Minore, Don. Bigleaf maple. U.S. Department of Agriculture, Forest

Service, Pacific Northwest Forest and Range Experiment Station; 1981.

Unpublished report.

Pelton, John. Factors influencing survival and growth of a seedling

population of Arbutus menziesii in California. Madrono 16: 237-276-

1972.

Plumb, Timothy R., tech. coord. Proceedings of the symposium on the

ecology, management, and utilization of California oaks; 1979 June

26-28; Claremont, CA. Gen. Tech. Rep. PSW-44. Berkeley, CA:

U.S. Department of Agriculture, Forest Service, Pacific Southwest

Forest and Range Experiment Station; 1980. 368 p.

Plumb, Timothy R.; McDonald, Philip M. Oak management in Califomia.

Gen. Tech. Rep. PSW-54. Berkeley, CA: U.S. Department of

Agriculture, Forest Service, Pacific Southwest Forest and Range Experiment Station; 1981. 11 p.

Roy, D. F. Hardwood sprout measurements in northwestern Califomia.

Forest Res. Note 95. Berkeley, CA: U.S. Department of Agriculture,

Forest Service, Califomia Forest and Range Experiment Station; 1955.

6 p.

Roy, Douglas F. Tan oak. U.S. Department of Agriculture, Forest

Service, Pacific Southwest Forest and Range Experiment Station; 1981.

Unpublished report.

Sawyer, John O., Jr. Douglas-fír-tanoak-Pacific madrone. In: Eyre,

F. H., ed. Forest cover types of the United States and Canada.

Washington, DC: Society of American Foresters; 1980: 111-112.

13. Schopmeyer, C. S., tech. coord. Seeds of woody plants in the United

States. Agrie. Handb. 450. Washington, DC: U.S. Department of

Agriculture; 1974. 883 p.

Stein, William I. Califomia-laurel. U.S. Department of Agriculture,

Forest Service, Pacific Northwest Forest and Range Experiment Station;

1981. Unpublished report.

Stein, William I. Oregon white oak. U.S. Department of Agriculture,

Forest Service, Pacific Northwest Forest and Range Experiment Station;

1981. Unpublished report.

16. Tappeiner, John; McDonald, Philip. Preliminary recommendations for

managing Califomia black oak in the Sierra Nevada. In: Proceedings of

the symposium on the ecology, management, and utilization of California oaks; 1979 June 26-28, Claremont, CA. Gen. Tech. Rep.

PSW-44. Berkeley, CA: U.S. Department of Agriculture, Forest

Service, Pacific Southwest Forest and Range Experiment Station; 1980:

107-111.

Thomburgh, Dale O. Canyon live oak. Arcata, CA: Humboldt State

University, 1981. Unpublished report.

10

11

12

14

15

17

32
Interior Alaska White Spruce -Hardwoods

John C. Zasada

Pacific Northwest Forest and Range Experiment Station

Dean Argyle

Alaska Region

The interior Alaska white spruce-hardwood forest

complex is the western extension of the boreal forest zone

which spans Canada. In Alaska, these forests, also referred to

as taiga, are composed of the following Society of American

Foresters forest cover types (1): White Spruce (type 201),

White Spruce-Aspen (type 251), White Spruce-Birch (type

202), Paper Birch (type 252), Aspen (type 217), and Balsam

Poplar (type 203). The Black Spruce-White Spruce (type

253) and Black Spruce-Paper Birch (type 254) types may

intergrade with the white spruce-hardwood complex on

some sites. This complex covers approximately 22.5 million

acres (9.1 million ha) of commercial forest land.

The northern extent of this forest complex is the Brooks

Range with the exception of isolated balsam poplar stands

farther north. These boreal forest types extend south to the

coast in the Kenai Peninsula-Cook Inlet region. East of Cook

Inlet, they extend to the Kenai-Chugach Mountains while the

western most forests occur on the Seward Peninsula and

lower Yukon River (9, 11). Forests in this region extend from

sea level to a maximum treeline elevation of 3,000 feet (915

m).

Soil parent materials vary greatly, including alluvial

deposits along the major rivers, loess deposits (mainly in the

unglaciated portions of the interior), various types of glacial

deposits, lacustrine deposits and various bedrock types.

Spodosols are common south of the Alaska Range, with

Inceptisols occurring north of the Range. Entisols predominate on floodplain sites. Although organic layer development

is a prominent feature of these northern forests, Histosols are

not common.

A unique feature ofthe soils is the presence of permafrost.

However, permafrost is not continuous in the region and is

absent from the most productive forest sites (e.g., southfacing

upland and floodplain sites in particular). The occurrence of

permafrost and depth of the active layer (i.e., annual depth of

thaw) may be closely related to organic layer development

(8).

Three broad climatic zones occur in the boreal forest

area. These are the Arctic, Continental, and Transitional.

Temperature extremes vary from -75° to 100° F (-59.4° to

37.8^ C.) The duration of the frost-free period is normally

90 to 110 days (5). The warmest summer temperatures

normally occur in the central to eastern interior region with

decreasing maxima to the south, north, and west. The reverse

is true in winter when the Transitional Zone has the mildest

temperatures.

Annual precipitation varies from 8 inches (205 mm) at

Fort Yukon to 32 inches (815 mm) on the Kenai Peninsula.

The probability of precipitation is generally greatest from

June through September. Annual snowfall varies from 50 to

100 inches (1270 to 2540 cm) (5).

Maximum day length (hours of sun at summer solstice)

during the growing season varies from 17 hours at 60° N. to

24 hours north of the Arctic Circle. There is a 24-hour light

period throughout most of this area, if twilight is considered.

Day length at winter solstice varies from 0 to 6 hours (5).

The major species in this forest complex include white

spruce {Picea glauca (Moench) Voss), paper birch (Betula

papyrifera Marsh.), trembling aspen (Populas tremuloides

Michx.), balsam poplar (Populus balsamifera L.), and black

cottonwood {Populus trichocarpa Torr. & Gray). Hybrids

between Sitka spruce {Picea sitchensis (Bong.) Carr.) and

white spruce, and between black cottonwood and balsam

poplar occur in the southern portion of the range in Alaska.

Thinleaf alder {Alnus tenuifolia Nutt.), feltleaf willow {Salix

alaxensis (Anderss.) Cov.), Scouler willow {Salix scoulerana

Barratt ex Hook.), and Bebb willow {Salix bebbiana Sarg.)

are species normally classified as shrubs, but they do attain

tree size and are common in the early stages of forest

development. Black spruce and tamarack {Larix laricina (Du

Roi) K. Koch) are associated on some sites (9, 10).

Natural regeneration has been relied upon to restock

bums and harvested areas. Planting has been conducted on a

trial basis in interior Alaska, but at present it does not

contribute significantly to reforestation.

Good to excellent seed crops occur at 1- to 3-year

intervals for the hardwood species (6, 16). Occurrence of

white spruce cone and seed crops is more erratic, good to

excellent crops can occur at 2-year intervals or they can be

separated by 10 to 12 years (14, 18). Cold summer temperatures at the time of seed formation can retard seed maturation

and result in seed crops of poor quality. This can occur in

years of excellent cone production and thus excellent cone

crops do not necessarily mean excellent seed years. Immature

seed may have most consequence at higher latitudes above

the Arctic Circle and higher elevations (1,950 ft or 595 m)

(15).

Wind is the primary seed dispersal agent for these boreal

forest species. Maximum dispersal distance is greatest for

Populus spp. followed by paper birch and white spruce.

Secondary dispersal is accomplished by water, animals, and

by gravity or wind movement over snow. This may be

important in redistribution of seeds. Populus spp. seeds are

dispersed in June and July and must germinate within several

weeks to a month or die (6). Birch and white spruce seeds are

dispersed in the fall and winter; germination can begin soon

after snow melt and be completed by late June if temperature

and moisture are adequate. If conditions are limiting, germination may be delayed until late summer or, in some cases,

until the following summer (6, 16, 18).

In harvested or burned forest areas, mineral soil seedbeds appear to provide the best conditions for germination

and early establishment. This is particularly true for the small

seeds of aspen, balsam poplar, and black cottonwood. White

spruce and birch, to a lesser degree, are able to germinate and

become established on shallow organic layers and mixed

mineral soil-organic matter seedbeds. In undisturbed natural

forests, rotted wood provides good conditions for spruce

germination and seedling establishment (6, 14).

Scarification also benefits seedling growth and survival.

The benefits, however, are not always as clear as they are for

germination. Examples of significant variation in response to

33
seedling growth on scarified surfaces have been observed

(14). In prescribing scarification, particular attention must be

given to extent of scarified areas, depth, soil type, and

overall site productivity. These variables can have a differential effect on stocking levels and growth rates of different

species.

All of the hardwood species have the capacity to

reproduce vigorously by vegetative means. Aspen stand

formation depends on the distribution of the root systems of

trees present prior to disturbance. These stands tend to have

relatively uniform distribution of individual stems (6). Birch

reproduces vegetatively by stump sprouting, and the stands

formed usually consist of groups of stems arising from

stumps of the previous trees. Birch begins to lose its ability to

sprout at age 60. Balsam poplar and black cottonwood

reproduce vegetatively by stump sprouting, root suckering,

or by rooting and growth of broken, buried stem or branch

segments (19). White spruce has the capacity to layer. This

process appears to be an important way of maintaining stands

near treeline but has little importance in recovery from

disturbances such as fire or logging.

The hardwoods are early successional species and have

the characteristics normally attributed to these species (e.g.,

rapid juvenile growth, relatively high light requirement, short

life span, and eventual replacement by more tolerant, longer

lived species). Aspen and birch are the most common upland

hardwoods. Birch frequently occupies cooler and moister

sites than aspen, although they occur in mixed stands.

Balsam poplar and black cottonwood form relatively large

stands adjacent to rivers and generally are of minor importance on uplands. These floodplain species tolerate flooding,

and their ability to regenerate from buried branch and stem

segments makes them well adapted to these sites.

White spruce is more tolerant than the hardwoods and

eventually replaces them, frequently at stand ages of 80 to

100 years if the spruce becomes established at the time of

stand formation. Replacement by spruce may require a much

longer period if invasion occurs gradually due to a lack of

adequate seed or seedbed conditions. White spruce tolerates

moderate levels of flooding and silt deposition. Trees suppressed for up to 150 years have shown the ability to grow

rapidly following release.

Rotation age will vary with species and the desired

product. In interior Alaska, 130 years is used by the Alaska

Department of Natural Resources in calculating the allowable

cut for sawlog production in unmanaged stands of white

spruce which have been regenerated naturally (13). Growth

and yield data for white spruce suggests that small-tomedium sized sawlogs can be produced in 70 to 90 years on

good sites with more intensive management (2). Alaska's

Department of Natural Resources has used 70 years for

calculating the allowable cut of hardwoods in the Fairbanks

District (13).

Mean annual increment of unmanaged white spruce

stands on moderate to good sites varies from 30 to 50 cubic

feet per acre (2,1 to 3.5 m^/ha). For aspen, mean annual

increment may be as high as 80 cubic feet per acre (5.6

m^/ha) on good sites, while birch on good sites is somewhat

less productive (48 ft^/acre or 3.4 m^/ha) (2, 3). Mean annual

increment of balsam poplar may attain 100 cubic feet per acre

(7.0 m^/ha). Average volumes being harvested on commercial forest land in the Fairbanks area are 15,000 to 19,000

fbm (Scribner Decimal C Log Rule) or 3,000 to 3,800 cubic

feet* per acre (210.0 to 266.0 m%a); volumes up to 30,000

' Cubic foot and metric conversions of measurements expressed in board

feet should be viewed as estimates because of the assumptions involved in

the conversion process.

board feet (fbm) or 6,000 cubic feet per acre (420.0 m^/ha)

have been measured.

The most serious insect pest is the spruce beetle

(Dendroctonus rufipennis (Kirby)). During the past decade,

this species has caused significant mortality over an area in

excess of 500,000 acres (202 340 ha) in the Kenai PeninsulaCook Inlet area. Other bark beetles are important causes of

mortality north of the Alaska Range. A key factor in keeping

these insects at acceptable population levels is good sanitation following harvesting (4).

The most noticeable insect pests of hardwoods are

defoliators. Epidemics ofthe large aspen tortrix {Choristoneura

conflictana (Walker)), whose host tree is aspen, and the

spearmarked black moth (Rheumaptera hastata (Linnaeus)),

whose host tree is paper birch, have occurred in the last 15

years in interior Alaska. These epidemics were controlled by

natural processes, and little tree mortality was observed (4).

Cone and seed insects significantly damage white spruce

seed crops during some years in local areas. Although they

may not have a significant impact on natural reproduction,

they can greatly reduce the quantity and quality of seed

available for collection (4).

The impact of diseases on forest growth and development is poorly known. Various species of heart and root

rotting fungi affect white spruce and the hardwoods; these are

particularly noticeable in the overmature hardwood stands.

Spruce needle rust (Chrysomyxa ledicola Lagh.) and spruce

cone rust (C. pirolata Wint. ex Rabh.) affect white spruce

over large areas with the latter making collection of highquality seed difficult in some years (4).

Large and small mammals can have an impact on

selected portions of the tree or, more significantly, on stand

composition and early growth. Red squirrels are capable of

harvesting the majority of cones produced in moderate-togood cone years. During periods of high population density,

the snowshoe hare significantly slows stand growth and

development by browsing at intensities approaching 100

percent (12).

Fire has played an important role in forest development.

Fire intervals are estimated to range from less than 50 to more

than 200 years. None of these species is resistant to fire; and

in most cases, trees are killed by fires of light-to-moderate

intensity. Pure spruce forests are more flammable than

hardwoods because of the greater accumulation of cured

fuels, and crown and foliage characteristics. Because of

varying species mixtures and site conditions there are generally significant unbumed areas within the perimeter of any

bum. Site conditions, species composition, proximity to a

seed source, fire intensity, and postfire residual organic layer

depths determine the rate of recovery following fire.

Fire has not been used as a management tool in Alaska.

It has been used successfully, however, in adjacent western

Canada. The main objectives in prescribing fire would be for

fuel reduction and site preparation following harvesting.

Forest management and silviculture are in a very early

stage of development in these subarctic forests, and little

Alaskan experience exists upon which to make recommendations. The trends to date appear to follow those which exist

for these species in other parts of their range. That is,

even-aged management will predominate. Under natural

conditions, however, white spruce may occur in multipleaged stands and land managers may desire to maintain this

condition.

Clearcutting is the only silvicultural practice currently

applied. The species managed under this system are able to

regenerate in the open conditions created by clearcutting.

Both an adequate seed source and a mineral soil seedbed

within 300 feet (91 m) of a source of seeds must be present to

34
attain acceptable levels of white spruce stocking. An adequate mineral soil seedbed is not usually created by harvesting and is normally accomplished by scarification. Because

the quality of the seedbed in terms of germination and

seedling survival deteriorates with time, seedbed preparation

should coincide with good to excellent seed crops, where

possible.

In aspen and birch stands, clearcutting is generally

followed by vigorous vegetative reproduction. Provided preharvest stand density is adequate, aspen vegetative reproduction produces high stocking levels within 2 years. Aspen

appears to respond most vigorously when the organic mat is

disturbed but not completely removed and the root systems

remain intact. Vegetative reproduction cannot be relied on,

however, for high levels of birch stocking. High levels of

birch stocking require attention to seed source proximity and

seedbed conditions (6). Mature to overmature balsam poplar

and black cottonwood stands do not always attain high

stocking levels as a result of vegetative reproduction (19).

Again, some degree of organic matter disturbance appears to

improve stocking levels for these species.

The shelterwood system has been applied only on an

experimental basis in white spruce. The results in terms of

stocking have been good. This system is a viable option to

clearcutting as a way of creating even-aged stands and

perhaps a superior method where esthetic considerations are

important. Hardwood regeneration has also been abundant

under the open stand conditions created in the shelterwood

(17).

Group selection appears to be an option for landowners

that wish to maintain a multiple-aged forest condition.

Abundant white spruce and birch regeneration has been

observed in small forest openings no larger than 0.75 acre

(0.3 ha) in size created by harvesting and seed bed preparation (15).

All species in this complex tend to have shallow root

systems and are vulnerable to logging damage and windthrow.

Silvicultural systems should attempt to minimize windthrow

and maintain an adequate seed supply during the regeneration

period. In addition, these species tend to have relatively thin

bark and are susceptible to mechanical damage during

harvesting. Limited application of the shelterwood system

on upland sites in the Fairbanks area has shown that loss

of residual trees can be minimal.

Management of sapling- and pole-sized stands has

received little attention. White spruce can respond immediately to cultural practices such as thinning and fertilization

(7). Thinning is currently being conducted on a limited

operational scale in white spruce and birch stands on upland

sites in the Tanana Valley.

The combined research and operational experience to

date suggests that the major concern in maintaining this

complex is achieving adequate stocking of white spruce.

Vegetative reproduction will generally maintain some level

of stocking of hardwoods; however, unless particular attention is given to proximity of seed source, site, and seedbed

conditions, white spruce importance will decline. If the land

manager wants to maintain a high level of white spruce

stocking and it is not possible to address these factors,

artificial regeneration must be used.

The white spruce-hardwood forests of Alaska provide

a multitude of products and amenities. Past fires have created

a mosaic of forest conditions that provide wildlife habitat,

recreational opportunity, and a diversity of commercial and

non-commercial forest products. Watershed values and stream

habitat are an important resource. Interior watersheds are

large with a majority of the area extending beyond the

forested zone. Silvicultural activities will probably have little

effect on the major river systems, such as the Tanana and

Yukon, but might affect tributaries where the majority offish

spawning takes place. Watershed studies are in their infancy

in this region.

Properly applied silvicultural practices and fire management can maintain the forest diversity needed to provide the

range of products and amenities available in the natural

forest. In populated areas, the recommended silvicultural

practices offer the best means of maintaining diversity.

Literature Cited

1. Eyre, F. H., ed. Forest cover types of the United States and Canada.

Washington, DC: Society of American Foresters; 1980. 148 p.

2. Farr, Wilbur A. Growth and yield of well-stocked white spruce stands in

Alaska. Res. Pap. PNW-52. Portland, OR: U.S. Department of

Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment Station; 1967. 30 p.

3. Gregory, Robert A.; Haack, Paul. Growth and yield of well-stocked

aspen and birch stands in Alaska. Res. Pap. NOR-2. Juneau, AK: U.S.

Department of Agriculture, Forest Service, Pacific Northwest Forest

and Range Experiment Station; 1965. 28 p.

4. Holsten, Edward H.; Werner, Richard A.; Laurent, Thomas H. Insects

and diseases of Alaskan Forests. Alaska Region Report No. 75. Juneau,

AK: U.S. Department of Agriculture, Forest Service, Alaska Region;

1980. 187 p.

5. Johnson, Philip R.; Hartman, Charles W. Environmental atlas of

Alaska. Fairbanks, AK: University of Alaska, Institute of Arctic

Environmental Engineering, Institute of Water Resources; 1969. 111 p.

6. U.S. Department of Agriculture. Forest Service. Silvics of forest trees

of the United States. Agrie. Handb. 271. Washington, DC: U.S.

Department of Agriculture; 1965. 762 p.

7. Van Cleve, Keith; Zasada, John C. Response of 70-year-old white

spruce to thinning and fertilization in interior Alaska. Can. J. For. Res.

6: 145-152; 1976.

8. Viereck, Leslie A. Forest succession and soil development adjacent to

the Chena River in interior Alaska. Arct. and Alpine Res. 2(1):

1-26; 1970.

9. Viereck, Leslie A.; Little, E. L., Jr. Alaska trees and shrubs. Agrie.

Handb. 410. Washington, DC: U.S. Department of Agriculture; 1972.

265 p.

10. Viereck, Leslie A. Forest ecology of the Alaska taiga. In: Proceedings

of the Circumpolar Conference on Northern Ecology; September 15-18.

Ottawa, ON. Ottawa, ON: National Resource Council of Canada; 1975:

11-122.

11. Viereck, Leslie A. Characteristics of treeline plant communities.

Holarctic Ecol. 2: 228-238; 1979.

12. Wolff, Jerry O. The role of habitat patchiness in the population

dynamics of snowshoe hares. Ecol. Monogr. 50(1): 111-130; 1980.

13. Wieczorak, Daniel H. Forest resources and allowable cut, Fairbanks

working circle. Fairbanks, AK: Alaska Department of Natural Resources,

Division of Forest, Land and Water Management; 1980. 98 p.

14. Zasada, John C. Some considerations in the natural regeneration of

white spruce in interior Alaska. Gen. Tech. Rep. PNW-107. Portland,

OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest

Forest and Range Experiment Station; 1980: 25-29.

15. Zasada, John C; Foote, M. Joan; Deneke, Frederick, J.; Parkerson,

Robert H. Case history of an excellent white spruce cone and seed crop

in interior Alaska. Gen. Tech. Rep. PNW-65. Portland, OR: U.S.

Department of Agriculture, Forest Service, Pacific Northwest Forest

and Range Experiment Station; 1978. 53 p.

16. Zasada, John C.; Gregory, Robert A. Paper birch seed production in the

Tanana Valley, Alaska. Res. Note PNW-177. Portland, OR: U.S.

Department of Agriculture, Forest Service, Pacific Northwest Forest

and Range Experiment Station; 1972. 7 p.

35
17. Zasada, John C; Grigal, David F. The effects of silvicultural system 18. Zasada, John C; Viereck, Leslie A. White spruce cone and seed

and seedbed preparation on natural regeneration of white spruce and production in interior Alaska 1957-68. Res. Note PNW-129. Portland,

associated species in interior Alaska. In: Proceedings Fifth North OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest

American Forest Biology Workshop; 1978 August; Gainesville, FL. Forest and Range Experiment Station; 1970. 11 p.

Asheville, NC: U.S. Department of Agriculture, Forest Service, South- 19. Zasada, J. C; Viereck, L. A.; Foote, M. J.; Parkerson, R. H. [and

eastern Forest Experiment Station; 1978: 213-220. others]. Natural regeneration of balsam poplar following harvesting in

the Susitna Valley, Alaska. For. Chron. 57(2): 57-65; 1981.

36
Redwood

David F. Olson, Jr.

Pacific Southwest Forest and Range Experiment Station

John N. Fiske

Pacific Southwest Region

The range of redwood (Sequoia sempervirens (D. Don)

Endl.) encompasses a narrow strip of land 450 miles (724

km) long and 5 to 35 miles (8 to 56 km) wide, along the

central and north coast of California and extending into

extreme southwestern Oregon (21).

Within this range, redwood trees now grow, or could

grow, on an estimated 1.6 million acres (647 500 ha). On

this land, 643,000 acres (260 210 ha) comprise the commercial redwood forest type. Society of American Foresters

Forest Cover type 232, which consists of more than 50

percent redwood stocking (10). The remainder of the area

contains parks, other forest types including redwood, and

recently logged redwood type (8). The old-growth redwood,

much of which is in State and National Parks, occupies less

than 200,000 acres (80 940 ha). The old growth in commercial forests will be harvested within the next few decades.

Climate in the redwood region is mild and humid, with

winter rains and summer fogs. Major associated conifers are

Douglas-fir {Pseudotsuga menziesii (Mirb.) Franco), Sitka

spruce {Picea sitchensis (Bong,) Carr.), grand fir (Abies

grandis (Dougl. ex D. Don) Lindl.), western hemlock (Tsuga

heterophylla (Raf.) Sarg.), and Port Orford-cedar (Chamaecyparis lawsoniana (A. Murr.) Pari.). Hardwood associates

include red alder (Alnus rubra Bong.), Pacific madrone

(Arbutus menziesii Pursh), and tanoak (Lithocarpus densiflorus

(Hook. & Am.) Rehd.). Redwood changes to Douglasfir-Tanoak-Pacific Madrone (type 234) along the eastern

fringes of its range and at higher elevations. The topography,

ranging from near sea level to an elevation of about 2,500

feet (760 m), is often broken and moderate to steep.

Redwood grows principally on loam and clay-loam soils

(13). A common characteristic is that these soils are deep and

have moderate to high moisture-storage capacity.

Various habitat classifications have been proposed for

redwood. One is based on soil moisture, soil nutrients, light,

and temperature (24). Another relies on herbaceous plants as

indicators (1). Easily recognized broad habitat differences

exist between the alluvial flat and slope redwoods. The

almost pure, world-renowned groves of large trees, most of

which are in State and National Parks, are mainly on alluvial

flats. Redwood on slopes seldom forms pure, extensive

stands.

The alluvial-flat stands develop in an environment that

includes periodic fires and floods. Such an environment

favors redwood because, unlike its associates, redwood can

maintain itself when subjected to low- or high-intensity fire

and severe flooding. The thick bark of redwood protects it

from low-intensity fires. After high-intensity fires, redwood

produces a new crown from the sprouting of dormant buds

along the bole and new individuals from root crown sprouts

around the stump. When redwood is buried beneath sediments carried by floods, its feeder roots turn negatively

geotropic and grow upwards into the sediments. Later, its

supporting roots are replaced by new ones developed adventitiously higher up the stem (22).

Although redwood seedlings sometimes become established under overstory canopies, they are scarce on undisturbed seedbeds in timber stands. This scarcity may be

because of destruction by root rot and damping-off fungi (9).

Juvenile growth is best in full sunlight, but redwood grows

satisfactorily in moderate shade and will persist in heavy

shade. New redwood seedlings require more moisture for

survival than do seedlings of most associated species (12).

Potential moisture stresses caused by low humidity, high air

temperatures, wind, or low soil water, therefore, deter

redwood establishment and growth.

Redwood has the capacity to sprout from stumps and

root crowns in any season of the year within 2 or 3 weeks

after harvesting. These sprouts originate from both dormant

and adventitious buds. Those that originate below the soil

surface are generally favored for tree crops because they are

more firmly rooted and durable. Sprouts originating from the

sides and top of stumps often are destroyed by strong wind.

Sprouting capacity is related to variables associated with tree

size or age. Stumps of small, young trees sprout more often

than those of large, old trees (19).

Seed production by redwood and associates is fairly

regular (3,5). Proportion of sound redwood seed is low (less

than 15 percent), but germination of sound seed is excellent.

Mineral soil is the best seedbed for establishment because

seeds germinate rapidly and losses from fungi are few.

Although many redwood stumps sprout, the spacing of

stumps is such that resulting tree reproduction is apt to be

poorly distributed, especially in old-growth stands where

stumps are widely spaced. Additional seedling regeneration,

therefore, is needed to complete a full stand. The associated

species, notably Douglas-fir, supplement the natural stocking

of redwood seedlings in proportion to the seed sources

available.

Prompt regeneration of conifers requires that other

vegetation not gain control of the site. In the northern part of

the redwood range, red alder and several shrub species may

dominate severely disturbed sites. Tanoak, Pacific madrone,

and blueblossom ceanothus (Ceanothus thyrsiflorus Eschsch.)

are potential threats if these species are present in significant

amounts before cutting. Blueblossom is especially aggressive

in the southern redwoods, and slash burning usually will

greatly increase the shrub cover by stimulating seed germination (4).

Controlling competing vegetation in newly established

stands of redwoods is simple on fairly level topography, but

difficult on steep lands because of inaccessibility and tight

constraints on aerial application of phenoxy herbicides or, in

some instances, the outright banning of their use by county

ordinance. Redwood shows great sensitivity to phenoxy

herbicides at all seasons of the year because of its indeterminate growth habit and lack of protective bud scales. In spite

of this sensitivity, successful release operations of sapling

redwood by aerial application of phenoxys have been made.

Redwood trees injured by the chemical recover in a year, and

the result is a net benefit from release.

37
Release of redwood has been done by other conventional techniques, including basal spray, frilling and herbicide application (hack and squirt), and manual release, with

and without applying herbicide to cut stumps. Manual release

is most effective when competing brush is nonsprouting or

only a weak sprouter, such as blueblossom and red alder.

Redwood sprouts have an advantage over other young

conifers in competing with hardwoods and brush. Height

growth often exceeds 4 feet (1.2 m) a year on stems that reach

5 inches (13 cm) diameter at breast height (d.b.h.) in 6 to 8

years. Seedlings ofredwood and associated conifers, however,

will die or become seriously suppressed by many competing

species if not released within a few years after establishment.

Redwood is extremely long lived (more than 2,(X)0

years), and the old-growth stands differ greatly from the

young-growth stands in their structure and management

needs. Management of these two stand types, therefore, is

discussed separately. Old growth is now almost exhausted on

commercial ownerships, and interest is greater in younggrowth management than in old-growth management. Because redwood reproduces by sprouting and seeding, can be

planted successfully on many sites, and grows well in full

light and partial shade, both even-aged and uneven-aged

silvicultural systems can be used to manage redwood stands.

In old-growth stands 600 to 1,200 years old, clearcutting,

seed-tree cutting, and shelterwood cutting resulted in evenaged stands as a result of sprout and seedling regeneration

(7). In clearcuttings that exceed 30 to 40 acres (12 to 16 ha),

even with those having surrounding seed sources, however,

some supplemental seeding or planting is needed in central

positions of the cut area where seed distribution may be

inadequate. Seeding or planting is needed 1 to 2 years after

harvesting, while the site is still favorable for seedling

establishment. Once seedlings are established, seed trees or

shelterwood trees are cut and this logging may reduce

stocking of small seedlings as much as 25 percent because of

logging damage. Sprouting of cut trees, however, will

replace some seedling losses.

Gradual harvesting of virgin old-growth redwood by the

selection system is practiced in some situations where a

continuous forest cover is desired and the landowner wishes

to promote an uneven-aged stand structure. It is generally

best, however, to first convert old-growth redwood to younggrowth stands by an even-aged silvicultural system, and then

to develop the desired uneven-aged stand structure by manipulation of the young-growth stands. This procedure is recommended because any silvicultural system that requires multiple harvest entries into stands of large, old-growth trees will

result in some destruction of young growing stock. Regeneration cuttings that minimize harvest entries, such as clearcutting,

seed-tree cuttings, or two-cut shelterwood cuttings, therefore,

should be favored over three-cut shelterwood cuttings or

selection cuttings (7).

Tall, old-growth conifers in virgin redwood stands are

particularly susceptible to windthrow after harvest by partial

cutting (2). The leeward edges of clearcuts also are highly

susceptible to windfall. Associated conifers are less windfirm

than redwood, but loss of valuable old-growth redwoods is

often serious. These large trees may have a value of $20,000

to $50,0(X) each on the stump. Any partial cutting or

exposure of a stand edge will upset the balance required for

windfirmness that uncut stands usually have. Storms that

cause windfall come mainly from the south and to a lesser

extent from the southwest and southeast during the winter

season. The necessary combination of wet soil and strong

wind makes time of occurrence unpredictable. Windfall

losses along the leeward edges of clearcuts can be lessened

by planning clearcuts with a minimum of edge exposed to

storm winds.

Fire has a moderate ecological role in old-growth

redwood forests under park management, principally in

altering conditions for major associated species (23). Light

ground fires favpr western hemlock regeneration, but eliminate older hemlock. Relatively hot fires appear essential for

the establishment of Douglas-fir trees in discrete age classes.

In no observed instance has a natural redwood stand been

decimated by fire on the coastal side of the redwood type, but

inland, as fire frequency and intensity increase and environmental conditions become harsher, redwood is replaced by

other species.

Many mixed old-growth-young-growth stands have

developed after partial cuttings by tractor logging since the

mid-1930's (11). Most of these were partial cuttings that

high-graded the stands. A mixture of stump sprouts, Douglasfir seedlings, and hardwoods dominated the understory. In

these stands the objective should be overstory removal with

minimum disturbance to the young growth, and control of

hardwoods. This technique will result in uneven-aged young

Stands, with two or more age classes.

After harvest, some areas may require seeding or

planting to supplement natural regeneration. Direct seeding

of Douglas-fir, with some redwood, spruce, and Port Orfordcedar, has been done successfully in redwood cut blocks, but

overiy dense young stands often develop after seeding.

Planting of either containerized or bareroot seedlings is the

preferred method of artificial regeneration. Both redwood

and Douglas-fir can be planted successfully if proper technique is used and animal damage is not severe. Douglas-fir is

more susceptible to browsing damage than redwood, and

sometimes needs to be protected from browsing animals.

Planting densities of 400 to 500 seedlings per acre (990 to

1240/ha) provide adequate stocking.

Young-growth redwood, comprised of well-stocked stands

up to 130 years old, are capable of yielding more than

200,000 fbm (International one-quarter-inch) or 40,000 cubic

feet^ per acre (2800 m%a) in 100 years on many sites. Yields

at 100 years are expected to range from 56,000 fbm (11,200

cubic feet) per acre (784 m^/ha) on low sites to 350,000 fbm

(70,000 cubic feet) per acre (4900 m^/ha) on high sites (18).

Although this yield provides valuable commercial products,

it is not as highly prized as old-growth yield.

Site curves and conversions from various Douglas-fir

site indices to young-growth redwood site indices have been

developed (14, 17, 25). Recently, a computerized stand

growth model was developed, based on projections of densitydependent tree growth for young-growth redwood and associated conifers in northwestern California (15). The model has

been available for less than 1 year. Validation and testing of

the model are not yet complete.

A combination of reliable sprout regeneration and heavy

seeding will provide an overabundance of young trees in

many redwood stands of average and above average quality.

In the absence of heavy seeding, young-growth redwood

develops into irregular stands, with dense clumps of sprouts

(more than 40/clump in many instances) separated by openings that are generally occupied by tanoak or other brush. It is

common to have five to eight sprouts in a clump develop into

good sawtimber trees, though they may be only 2 to 4 feet

(0.6 to 1.2 m) apart. It has been found that 5-year-old sprouts

from old-growth stumps more than double in diameter after 5

years when thinned to two sprouts per stump, and increase by

one-half when thinned to five sprouts per stump (6).

Eariy control of growing stock (age 10 to 20 years) in

overdense stands is necessary. The need differs somewhat for

' Cubic feet and metric conversions of measurements expressed in board

feet should be viewed as estimates because of the assumptions involved in

the conversion process.

38
Stands established after old-growth removal and those originating after young-growth harvests. Many more sprouting

stumps are found in harvested young-growth than in harvested old-growth.

Rapid initial height and diameter growth of redwood

sprouts and open-grown Douglas-fir make it vital that

precommercial thinning be done early in the stand's development if the objective is to optimize lumber and veneer

production. Many of these stands show remarkable cubic foot

growth in an unthinned condition because of the large

number of stems that become established. Unless thinning is

done early, however, much of this potential is expended on

trees that will not be marketable, or that will stagnate or die.

Precommercial thinning in redwood and associated conifers

must deal with a wide range of stand conditions because of

the extreme differences in early growth rate between trees of

sprout origin and trees of seedling origin.

We know of no published guidelines for precommercial

thinning of redwood and associated conifers. Guidelines for

use in Douglas-fir stands in the Pacific Northwest often are

adapted for use in the redwood region (20). Precommercial

thinning should be done when leave trees are 10 to 15 feet

(3.0 to 4.6 m) tall and about 15 years old. Because trees must

be of sawtimber size in most stands before commercial

thinnings can be made, only 200 to 290 trees per acre (490 to

720/ha) should be left. In some parts of the redwood region,

markets are developing for small diameter posts. With this

product in mind, stands can be thinned somewhat later than

age 15. When thinning redwood, it is not desirable to thin

sprout clumps to one stem; several sprouts in a clump can

grow into valuable crop trees. Conventional spacing guidelines can be used between clumps.

Many of the young-growth redwood stands established

after harvest of old growth will need commercial thinning

one or more times before they are ready for the regeneration

cut at age 50 to 90 years, if an even-aged silvicultural system

is used. These short rotations are economic rotations. Culmination of mean annual increment does not occur until after

age 100. Several of these stands, now well stocked, originated after eiirly clearcutting and were not given a precommercial

thinning. On recent thinnings that removed 25, 50, and 75

percent of the basal area in 40-year-old stands, most redwood

stumps sprouted (16). In the two heaviest thinnings, it

appears that sprouts will develop as a new age class. With

light thinning (25 percent removal), sprouts develop weakly,

and few of them will survive as future crop trees. Seedlings

of redwood and associated species germinate also on disturbed surfaces after heavy thinning. Moderate to severe

competition from other vegetation, especially in the more

northerly areas, often causes heavy mortality, but many

seedlings survive as advance reproduction.

Commercial thinning guidelines for redwood have not

been established through experimentation. Thinning must not

be heavy, or, because of sprouting, an uneven-aged stand

will result. Many commercial operations leave about 70

percent of the volume (50 percent of the trees). In terms of

basal area, residual stands will range from 160 to 220 square

feet per acre (36.7 to 50.5 m^/ha). Thinning is generally from

below, but some dominants and codominants must be cut to

provide release. As with precommercial thinning, sprout

clumps should not be thinned to one stem.

Individual tree selection and group selection, by coppice

regeneration, can be used in young-growth stands. Unevenaged stands can be maintained by removing selected redwood

and fostering the development of smaller sprouts and natural

seedlings. Careful logging is necessary to minimize destruction of advance regeneration. This method has yet to be

tested in controlled experiments, but is being used operationally in several stands in the redwood region.

Redwood is remarkably free of serious pests. Insect and

disease considerations do not dictate forest management

strategies. Bark stripping by the American black bear has

become a serious problem in some parts of the redwood

region. Trees 10 to 30 years old and 6 to 10 inches (15 to 25

cm) in diameter are damaged most, and many may be

girdled. Control is by hunting or live trapping and removing

animals. Wood rats often injure trees, from seedlings and

sprouts to mature trees. But they seldom do sufficient

damage to warrant control measures.

Literature Cited

1. Becking, Rudolf W. The ecology of the coastal redwood forest and the

impact of the 1964 floods upon redwood vegetation. Washington, DC:

Nati. Sei. Found.; 1967. 91 p.

2. Boe, Kenneth N. Windfall after experimental cuttings in old-growth

redwood. In: Proceedings, Society of American Foresters National

Meeting; 1965 October 24-28; Detroit, MI. Washington, DC: Society

of American Foresters; 1966: 59-63.

3. Boe, Kenneth N. Cone production, seed dispersal, germination in

old-growth redwood cut and uncut stands. Res. Note PSW-184.

Berkeley, CA: U.S. Department of Agriculture, Forest Service, Pacific

Southwest Forest and Range Experiment Station; 1968. 7 p.

4. Boe, Kenneth N. Redwood. In: Silvicultural systems for the major

forest types of the United States. Agrie. Handb. 445. Washington, DC:

U.S. Department of Agriculture; 1973: 23-26.

5. Boe, Kenneth N. Sequoia sempervirens (D. Don) Endl. Redwood. In:

Seeds of woody plants in the United States. Agrie. Handb. 450.

Washington, DC: U.S. Department of Agriculture; 1974: 764-766.

6. Boe, Kenneth N. Thinning promotes growth of sprouts on old-growth

redwood stumps. Res. Note PSW-290. Berkeley, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Forest and

Range Experiment Station; 1974. 5 p.

7. Boe, Kenneth N. Natural seedlings and sprouts after regeneration

cuttings in old-growth redwood. Res. Pap. PSW-111. Berkeley, CA:

U.S. Department of Agriculture, Forest Service, Pacific Southwest

Forest and Range Experiment Station; 1975. 17 p.

8. Bolsinger, Charles L. California forests: trends, problems, and opportunities.

Resour. Bull. PNW-89. Portland, OR: U.S. Department of Agriculture,

Forest Service, Pacific Northwest Forest and Range Experiment Station;

1980. 138 p.

9. Davidson, John G. N. Pathological problems in redwood regeneration

from seed. Berkeley: Univ. of California; 1971. 288 p. Thesis.

10. Eyre, F. H., ed. Forest cover types of the United States and Canada;

Washington, DC: Society of American Foresters; 1980. 148 p.

11. Fritz, Emanuel. Characteristics, utilization and management of secondgrowth redwood. San Francisco, CA: Found, for Am. Resour. Manage.;

1959. 34 p.

12. Fritz, Emanuel; Rydelius, James A. Redwood reforestation problems:

an experimental approach to their solution. San Francisco, CA: Found,

for Am. Resour. Manage.; 1966. 130 p.

13. Gardner, Robert A. Soil-vegetation associations in the redwood-Douglasfir zone of California. In: Proceedings of the North American Forest

Soils Conference; 1958 September 9; East Lansing, MI: Michigan State

University; 1958: 86-101.

14. Krumland, B.; Wensel, L. C. Procedures for estimating redwood and

Douglas-fir site indexes in the north coastal region of California. Coop.

Redwood Yield Res. Note 5. Berkeley, CA: Univ. of California, Dep.

of For. and Conserv.; 1977. 13 p.

15. Krumland, B.; Wensel, L. C. Illustrative yield tables for coastal

conifers in California. Coop. Redwood Yield Res. Note 18. Berkeley,

CA: Univ. of California, Dep. of For. and Conserv.; 1980. 25 p.

16. Lindquist, James L. Sprout regeneration of young-growth redwood:

sampling methods compared. Res. Note PSW-337. Berkeley, CA:

U.S. Department of Agriculture, Forest Service, Pacific Southwest

Forest and Range Experiment Station; 1979. 8 p.

17. Lindquist, J.; Palley, M. Site curves for young-growth coastal redwood.

California Forestry and Forest Products. Berkeley, CA: Univ. of

California, School of Forestry; 1961. 4 p.

18. Lindquist, James L.; Palley, Marshall N. Empirical yield tables for

young-growth redwood. Bull. 796. Berkeley, CA: California Agrie.

Exp. Stn.; 1963. 47 p.

39
19. Neal, Robert L., Jr. Sprouting of old-growth redwood stumps ... first

year after logging. Res. Note PSW-137. Berkeley, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Forest and

Range Experiment Station; 1967. 8 p.

20. Reukema, Donald L. Guidelines for precommercial thinning of Douglasfir. Gen. Tech. Rep. PNW-30. Portland, OR: U.S. Department of

Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment Station; 1975. 10 p.

21. Roy, Douglass F. Silvical characteristics of redwood {Sequoia sempervirens

(D. Don) Endl.). Res. Pap. PSW-28. Berkeley, CA: U.S. Department

of Agriculture, Forest Service, Pacific Southwest Forest and Range

Experiment Station; 1966. 20 p.

22. Stone, E. C; Vasey, R. B. Preservation of coast redwoods on alluvial

flats. Science 159(3811): 157-161; 1968.

23. Veirs, Stephen D., Jr. The role of Are in northern coast redwood forest

dynamics. In: Proceedings of the conference on scientific research in the

National Parks, Volume 10 (Fire Ecology); 1979 November 26-30;

San Francisco, CA. Washington, DC: U.S. Department of the Interior,

National Park Service; 1980: 190-209.

24. Waring, R. H.; Major, J. Some vegetation of the California coastal

redwood region in relation to gradients of moisture, nutrients, light, and

temperature. Ecol. Monogr. 34(2): 167-215; 1964.

25. Watson, K.; Krumland, B.; Wensel, L. C. Conversions for site index

systems used in the north coast of California. Coop. Redwood Yield

Res. Note 10. Berkeley, CA: Univ. of California, Dep. of For. and

Conserv.; 1979. 2 p.

40
Red Fir and White Fir

Robert J. Laacke

Pacific Southwest Forest and Range Experiment Station

John N. Fiske

Pacific Southwest Region

More than 4 million acres (1.6 million ha) of commercial forest land at the higher elevations in California and

southern Oregon are dominated by two forest types—Red

Fir, Society of American Foresters type 207, and White Fir,

type 211 (1, 7). On the basis of current environmental and

biological information, silvicultural practices for the two

types are generally the same. For this reason, they will be

discussed separately only when differences are silviculturally

significant.

California white fir (Abies concolor var. lowiana (Gord.)

Lemm.) forms extensive, pure, or nearly pure, stands in a

relatively narrow band above the Sierra Nevada Mixed

Conifer (type 243) and below the California red fir (Abies

magnifica A. Murr.) forests. Elevational ranges are from

4,590 to 5,900 feet (1400 to 1800 m) in the Siskiyou

Mountains and southern Cascades of Oregon (2), and from

4,500 to 5,500 feet (1370 to 1675 m) in the Klamath

Mountains and interior Coast Ranges of California, as far

south as Lake County. Minimum and maximum elevations

increase toward the south and the type lies between 6,000

feet (1830 m) and 7,000 feet (2135 m) in various mountain

ranges of southern California (11). Pure stands of limited

extent are found east of the Sierra Nevada, and in the Warner

Mountains. In the Sierra Nevada, white fir occupies thousands of acres that were logged and burned during the last

century (1).

California red fir, including its commonly recognized

variety Shasta red fir (A. magnifica var. shastensis Lemm.),

and lodgepole pine (Pinus contorta Dougl. ex Loud.) are the

dominant forest cover (types 207 and 218) at elevations

above the white fir forests. Lower elevational limits for red

fir begin at 5,300 feet (1615 m) in the Siskiyou Mountains of

Oregon, and increase southward through the Cascades, rising

to 7,000 feet (2135 m) in the southern Sierra Nevada of

CaUibmia (11). In California's Coast Ranges the red fir type

occurs from 4,600 to 6,000 feet (1400 to 1830 m) in elevation

(11). Red fir is not found in the Warner Mountains of

California or south of Lake County in the Coast Ranges.

Between the elevational levels where red fir and white

fir form nearly pure stands, the species are found in mixture,

with either one dominant. Throughout their ranges, except at

their northern limits in Oregon (1), these true firs form

climax forests (1, 2). Both species appear to merge with

similar but separate species at the northern end of their

ranges. White fir merges with grand fir (Abies grandis

(Dougl. ex D. Don) Lindl.) and red fir with noble fir (Abies

procera Rehd.) (6, 17).

The two firs grow on soils that have developed on a

variety of parent materials: volcanic and glacial deposits of

recent origin; unmetamorphosed granitic, basic igneous, and

sediments; and sedimentary, volcanic, and igneous material

of various compositions and degrees of metamorphism. Most

of the soils are young, have poorly developed profiles, and

are cold, with mean annual temperatures from 32° to 50° F

(0.0° to 10.0° C).'

Upland meadows are scattered throughout the true fir

forests and Sierra lodgepole pine (Pinus contorta var. murrayana

(Grev. & Balf.) Engelm.) is a common associate surrounding

these meadows.

Climate of the true fir zone is relatively mild for

high-elevation forests and can be classified as cool to cold

and moist, with daily extremes only occasionally exceeding

90° F (32.2° C) or falling below -20° F (-28.9° C) (7, 8).

Precipitation is between 30 and 70 inches (760 to 1780 mm)

per year with more than 80 percent as snow. Snowpacks can

exceed 13 feet (4.0 m) frequently and 20 feet (6.1 m)

occasionally in the Sierra Nevada and 7 feet (2.1 m) in

Oregon.^ Almost all precipitation falls between October and

May. Scattered thunderstorms between May and October

seldom deliver enough water to significantíy affect soil

moisture.

Winds are generally westerly to southwesterly, and vary

locally depending on terrain. Because true fir forests are

located at high elevations and on young, generally shallow

soils, they are susceptible to damage, especially on exposed

ridges. Windthrow and stem breakage are common in closed,

old-growth stands. These types of damage are related more to

heart and root rots than to wind alone (4). Dense young

stands often suffer top damage during winter storms.

In exceptional years, both firs can produce more than

570,000 seeds per acre (1.4 million/ha), but only 10 percent of

that number is produced in good years. Good to heavy seed

crops are borne every 1 to 4 years by red fir and every 3 to 9

years by white fir (5,13). Seeds are wind-disseminated as the

cones disintegrate between late September and mid-October.

Most seeds fall within 1 to 1.5 times tree height (5, 10).

Because fir seeds are borne only in the crown tops, any top

damage reduces seed production. The most prolific and

reliable seed bearers are healthy, mature dominants. Immature trees can produce heavy crops but are erratic. Proportions of sound seed are low, generally less than 50 percent

(13). Seed germination in the field can be as low as 5 percent.

Bare mineral soil is the best seedbed, although seeds of

both species will germinate and seedlings will grow in light

litter providing they are under partial shade. Early mortality

is lowest under shade, but growth is best in full sunlight (7).

Red fir is slightly less tolerant of shade and less sensitive

to frost than white fir. Both species are more tolerant of shade

and less tolerant of drought than lodgepole pine, Jeffrey pine

(Pinusjeffreyi Grev. & Balf.), sugar pine (Pinus lambertiana

Dougl.), western white pine (Pinus monticola Dougl. ex D.

Don), or incense-cedar (Libocedrus decurrens Torr.)—all

minor associates in the fir types (1, 9, 11). Unlike lodgepole

pine, the firs are sensitive to wet or poorly-drained soils (9).

Although both fir species can survive 40 years or more

of suppression, tree growth increases dramatically after

' Laacke, Robert J. California red fir {Abies magnifica A. Murr.), and

white fir {Abies concolor (Gord. & Glend.) Lindl. ex Hildebr.). 1981. Two

unpublished drafts supplied to the authors by Robert J. Laacke.

41
release. Diameter and height growth can triple, depending on

tree condition as evidenced by prerelease live-crown ratio,

and height and diameter growth (8). Both species grow

slowly for the first 3 to 4 years from seed and then accelerate

to 8 to 20 mches (20 to 51 cm) each year, if not suppressed

(1). Good quality seedlings, especially those of white fir, can

grow rapidly soon after planting. Both species can support

unusually heavy stand densities and impressive volumes. On

the best sites (site index 90 at 50 years), unmanaged stands of

white fir can carry 471 square feet of basal area per acre (108

m^/ha) and a volume of 23,100 cubic feet per acre (1617.0

m /ha) at age 150. Mean annual increment of unmanaged

stands culminates at 70 years (14). On sites of equivalent

quality, red fir can carry 573 square feet of basal area per acre

(131.6 m /ha) and a volume of 31,900 cubic feet per acre

(2233.0 m /ha) at 150 years. Mean annual increment of

unmanaged stands culminates at 140 years (15).

Management practices vary, but can be grouped generally into two categories on average quality sites: a short

rotation of 70 years and a long rotation of 125 years (16). On

the basis of data from normal yield tables for average sites

(14, 15), annual growth averages 128 and 102 cubic feet per

acre (9.0 and 7.1 m%a) for white fir having 70 and 125 year

rotations. On the same basis, red fir growth averages 81 and

129 cubic feet per acre (5.7 and 9.0 m^ha). In areas where the

types overlap and the two species grow together, red fir will

usually outgrow white fir in height and diameter.

Seed and cone insects that affect the two fir species are

not unusual, and insects significantly damage regeneration

only locally and periodically. White fir in the central and

southern Sierra Nevada is subject to infection by true

niistletoe (Phoradendron bolleanum (Seem.) Eich, subspecies/7ú!way7(?rMm (Torr.) Fosb.), which results in topkilling of

old trees and reduced seed production.

Three major threats to new seedlings are cutworms

(Noctuidae), drought, and heat, which account for 70 percent

of early mortality (3). Brush, including various species of

ceanothus {Ceanothus spp.), manzanita {Arctostaphylos spp.),

chinkapin {Castanopsis spp.), and others, rapidly invade

disturbed sites. In general, brush alone does not prevent

reforestation because both firs can survive and, within 30 to

50 years, overtop the brush to dominate the site. In forests

managed for timber production, however, neither this delay

nor the frequently haphazard stocking are acceptable.

Pocket gophers are neariy ubiquitous in both fir types

and can kill or cause substantial growth losses to seedlings

and saplings over large acreages (7). Damage to poles and

sawtimber has been observed. Enclosing seedlings in plastic

tubing and direct control of gophers by baiting can offer

effective protection, but are expensive. Chemical control of

preferred food, such as lupine and other herbaceous vegetation,

may be needed to help keep gopher populations to acceptable

levels and reduce costs of direct control. Browsing of

succulent growth by deer and elk can retard height growth for

years. Normally, trees are not killed and grow rapidly when

browsing pressure is removed. Once the sapling is about 4

feet (1.2 m) tall, browse damage is no longer a concern.

Annosus root disease fungus {Heterobasidium annosum

(Fr.) Bref.) is present in most fir stands. Direct damage from

the disease, although restricted primarily to heart rot of butt

and major roots, leads to windthrow and breakage. Root

damage also causes moisture stress and loss of vigor, which

predispose trees to insect attack. New infection centers begin

by aerial spread of spores and infection of basal wounds and

freshly-cut stumps. Once established, the fungus spreads

from tree to tree through root contacts. Two other heart rots

cause major volume losses. Yellow cap fungus {Pholiota

adiposa (Fr.) Kumm.) and Indian paint fungus (Echinodontium

tinctorium (E. & E.) E. & E.) infect basal wounds, old dwarf

mistletoe {Arceuthobium abietinum Engelm. ex Muntz f. sp.

concoloris Hawks, and Weins and A. abietinum Engelm. ex

Muntz. f. sp. magnificae Hawks, and Weins) bole cankers

and other wounds, and cause major volume losses. With

intensive management and multiple entries in young stands,

mechanical damage to the thin-barked fir will become a

serious consideration because these and other heart rots can

reduce final volume by as much as 1 percent for each year

until harvest.'2

Dwarf mistletoes infect about 30 percent of white fir and

40 percent of red fir stands (12). Heavily infected trees suffer

significant growth losses and are vulnerable to insect attack

and branch kill caused by cytospora canker {Cytospora

chrysosperma Pers. ex Fr.). Two varieties of dwarf mistletoe

are involved. The parasite can be controlled silviculturally by

even-aged management, because both varieties are hostspecific, spread slowly, and grow slowly (12).

Conditions that reduce tree vigor, including overstocking,

drought, fire, and disease, predispose trees and stands to

insect attack. The fir engraver (Scolytus ventralis LeConte) is

the major killer of true fir, although several other beetles

contribute to the volume loss each year.

With strictly controlled prescriptions, fire is a potential

management tool. Thin bark, long-lived crowns, retention of

branches, and heavy litter accumulations, however, make use

of fire hazardous in dense, immature stands.

Almost all land in the red and white fir types that is

currently managed for timber is under, or is being converted

to, even-aged management. The capacity of both species to

produce large volumes in dense, even-aged stands and the

opportunity to control dwarf mistletoe make even-aged management attractive. Artificial and natural regeneration are

both possible.

For natural regeneration under even-aged management,

shelterwood and seed-tree cuttings work well, but selection

of seed trees is critical. The trees chosen must be windfirm

and capable of reliably producing seed. Mature, healthy

dominants with sound tops, full crowns, and rot-free stems

and butts are the best choice (5). Down-wind dimensions of

clearcut openings should not exceed 1 to 1.5 times tree height

to ensure adequate seed coverage (4). The shelterwood or

seed trees should be removed as soon as regeneration is

achieved and before the young trees are 3 feet (0.9 m) tall, to

reduce logging damage and chances of dwarf mistletoe

infection from above (12).

Artificial regeneration is gaining in acceptance. Until

recently, lack of information concerning necessary growing

conditions and lifting schedules in the nursery and inadequate

care of stock resulted in many failures. With current practices,

survival rates vary from 40 to 80 percent (with red fir slightly

higher than white fir) (7) and these rates can be improved if

each step from seed collection to planting of seedlings in the

field is followed carefully. Timely access to planting sites at

high elevations can be a problem because of snow-blocked

roads.

Both natural and artificial regeneration are most reliable

after thorough site preparation. Site preparation methods vary

Aho, P. E.; Fiddler, G.; Srago, M. Logging damage in thinned second

growth true fir stands in California. 1981. Unpublished paper supplied to

authors by Paul Aho.

42
depending on local conditions including slope, soil, prelogging

stand condition, and expected vegetation response. Tractor

piling and subsequent burning of slash and brush is commonly used on slopes of up to 35 percent. Where terrain and

soil permit, double discing can be effective for controlling

grasses, forbs, and some brush. Discing is not recommended

for sprouting species. Broadcast burning is often used,

especially on slopes too steep for tractors. Control of competing vegetation is essential. Growth losses from competition

by lesser vegetation can be excessive even if survival is high.

Herbicides, applied aerially, by tractor, or by hand sprayer,

are usually the most cost-effective control. Machine cutting

or chipping of nonsprouting brush can be effective on

suitable slopes. Choice of equipment and operator skill are

critical. Ability of the operator to locate seedlings to be

released is vital to success. Hand weeding of brush seedlings

less than 4 years old may also be cost effective, particularly

on steep slopes in places where herbicides cannot be used.

True fir forests have come under intensive management

only recently and published data regarding growth response

to various stocking levels are lacking. Thinning prescriptions

developed for other types are being applied and modified on

the basis of experience. On National Forest lands, two

general approaches are used for commercial thinning. Young

stands (40 to 70 years old) are reduced to 55 or 60 percent of

the basal area indicated in normal yield tables for natural,

uncut stands. For less vigorous or older stands, the guideline

suggests thinning from below to leave those trees that

currently produce 80 percent of the cubic foot periodic annual

increment. Young (12 to 15 years old) stands can sometimes

be thinned profitably through sale of Christmas trees.

Uneven-aged management is possible. But with the

dense stand conditions normally encountered on good sites,

at least several trees must be removed in a group to allow

regeneration to take place. Site preparation of small spots is

expensive and seedling growth exceedingly slow. Infection

of young trees by dwarf mistletoe in the overstory is

impossible to prevent. In managed, all-aged stands, risk of

loss to fire may become unacceptably high, since slash

disposal in closed stands is difficult and may be undesirable

because of injury and subsequent infection by rot organisms.

The large amount of cull usually found in old trees would add

to the problem, at least during conversion to all-aged

management. For these reasons and others, single-tree selection is not a usable option for management.

Group selection is possible with openings as small as

0.4 acre (0.16 ha) (2). Many of the same disadvantages

mentioned earlier, such as poor growth and dwarf mistletoe

infection, apply, although their seriousness decreases as

opening size increases. With either approach to uneven-aged

management, maintenance of the required age-size class

distributions is a formidable task.

High elevation true fir forests provide much of the water

for California's more than 20 million people and habitat for

more than 123 bird, 60 mammal, and 14 amphibian species.

Seven bird and one mammal species are considered sensitive,

rare, or endangered. Recreation use is high at upper elevations where stands are open and vistas common. As a result,

visual and water resources management are a concern.

Livestock grazing in and around meadows is a consideration

primarily where true fir grades into open forests and ranges of

the eastern Sierra Nevada and Cascades.

Literature Cited

1. Eyre, F.H., ed. Forest cover types of the United States and Canada.

Washington, DC: Society of American Foresters; 1980. 148 p.

2. Franklin, Jerry F.; Dymess, C. T. Natural vegetation of Oregon and

Washington. Gen. Tech. Rep. PNW-8. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Forest and

Range Experiment Station; 1973. 417 p.

3. Gordon, Donald T. Natural regeneration of white and red fir ...

influence of several factors. Res. Pap. PSW-58. Berkeley, CA: U.S.

Department of Agriculture, Forest Service, Pacific Southwest Forest

and Range Experiment Station; 1970. 32 p.

4. Gordon, Donald T. Damage from wind and other causes in mixed white

fir-red fir stands adjacent to clearcuttings. Res. Pap. PSW-90.

Berkeley, CA: U.S. Department of Agriculture, Forest Service, Pacific

Southwest Forest and Range Experiment Station; 1973. 22 p.

5. Gordon, Donald T. White and red fir cone production in northeastern

California: report of a 16-year study. Res. Note PSW-330. Berkeley,

CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest

Forest and Range Experiment Station; 1978. 4 p.

6. Griffin, James R.; Critchfield, William B. The distribution of forest

trees in California, (reprinted with Supplement, 1976.) Res. Pap.

PSW-82. Berkeley, CA: U.S. Department of Agriculture, Forest

Service, Pacific Southwest Forest and Range Experiment Station; 1972.

118 p.

7. Helms, John A. The California Region. In: Barrett, J. W., ed. Regional

silviculture of the United States. New York: John Wiley; 1980: 391-446.

8. Helms, John A.; Standiford, R. B. Release of advance growth mixed

conifer species in California following overstory removal. Report of a

cooperative study. University of California-Berkeley and U.S. Forest

Service; San Francisco, CA: Pacific Southwest Region; undated. 28 p.

9. Minore, Donald. Comparative autecological characteristics of northwestem tree species ... a literature review. Gen. Tech. Rep. PNW-87.

Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific

Northwest Forest and Range Experiment Station; 1979. 72 p.

10. Oliver, William W. Seed maturity in white fir and red fir. Res. Pap.

PSW-99. Berkeley, CA: U.S. Department of Agriculture, Forest

Service, Pacific Southwest Forest and Range Experiment Station; 1974.

12 p.

11. Parker, I.; Matyas, W. CALVEG: A classification of Califomian

vegetation, 2d ed.; San Francisco, CA: U.S. Department of Agriculture,

Forest Service; 1980. 168 p.

12. Scharpf, Robert F. Control of dwarf mistletoe on true firs in the West.

In: Proceedings of the symposium on dwarf mistletoe control through

forest management; 1978 April 11-13; Berkeley, CA. Gen. Tech. Rep.

PSW-31. Berkeley, CA: U.S. Department of Agriculture, Forest

Service, Pacific Southwest Forest and Range Experiment Station; 1978:

117-123.

13. Schopmeyer, C. S., tech. coord. Seeds of woody plants in the United

States. Agrie. Handb. 450. Washington, DC: U.S. Department of

Agriculture; 1974. 883 p.

14. Schumacher, Francis X. Yield, stand and volume tables for white fir in

the California pine region. Bull. 407. Berkeley, CA: Univ. of California,

Agriculture Experiment Station; 1926. 26 p.

15. Schumacher, Francis X. Yield, stand and volume tables for red fir in

California. Bull. 456. Berkeley, CA: Univ. of California, Agriculture

Experiment Station; 1928. 29 p.

16. U.S. Department of Agriculture, United States Environmental Protection Agency 2,4,5-T Rebuttable Presumption Against Registration

Assessment Team, Timber Commodity Group. Economic impacts from

loss of 2,4,5-T in timber production. (Revised from: The biologic and

economic assessment of 2,4,5-T, Chapter 1, Part 2. Final draft report.)

Washington, DC: U.S. Department of Agriculture, Forest Service; 1981.

740 p.

17. Zavarin, E.; Critchfield, W. B.; Snajberk, K. Geographic differentiation of monoterpenes from Abies procera and Abies magnifica. Biochem.

Syst. and Ecol. 6: 267-278; 1978.

43
Sierra Nevada Mixed Conifers

Robert J. Laacke

Pacific Southwest Forest and Range Experiment Station

John N. Fiske

Pacific Southwest Region

Sierra Nevada Mixed Conifers, Society of American

Foresters Forest cover type 243, occupy between 4.5 and 7.8

million acres (1.8 and 3.2 million ha) of commercial forest

land in California and southern Oregon (2, 7, 15) and

dominates mid-elevations of the Sierra Nevada's western

slopes. The type covers extensive areas of the southern

Cascades, Klamath Mountains, and interior Coast Ranges as

far south as Lake County. Extensions of the type are found in

various mountain ranges as far south as San Diego County

and on eastern slopes of the Sierra Nevada in Plumas Countv

(6).

The type grows at elevations from 2,500 feet (760 m) to

4,600 feet (1400 m) in the north, 3,000 feet (915 m) to 6,000

feet (1830 m) in the central Sierra Nevada, and 4,000 feet

(1220 m) to 10,000 feet (3050 m) in the south. Below this

range of elevations are Pacific Ponderosa Pine-Douglas-fir,

Pacific Ponderosa Pine, or Interior Ponderosa Pine Types

(types 244, 245, 237); above are the White Fir and Red Fir

types (types 211 and 207) (6). Long, irregular parts of the

mixed-conifer forest type extend into adjacent cover types,

sometimes complicating stand delineation and management

(6).

In the Sierra Nevada, air temperatures decrease fairly

regularly as elevations increase. In summer, temperatures are

seldom above 96° F (35.6° C) or below 40° F (4.4° C).

Winter temperatures generally range from 60° to -10° F

(15.6 to -23.3° C) (26). Temperatures occasionally drop

below -25° F (-31.7° C) and rise above 100° F (37.8° C)

(19). Potential growing seasons vary with elevation and, in

the northern Sierra Nevada, are from 90 to 330 days, with 40

to 200 frost-free days. Potential growing seasons in the south

are from 180 to 365 days, with about 180 frost-free days

(15). Prevailing winds are westerly to southwesterly and may

cause problems on exposed ridges and in some canyons.

Precipitation is not as clearly related to elevation as is

temperature because of the effects of rugged, mountainous

terrain and major storm patterns (19). Total precipitation is

from 30 to 90 inches (760 to 2290 mm) per year. In general,

precipitation increases as elevation increases, as does the

proportion that falls as snow. Snow comprises almost 80

percent of the total precipitation at the upper limits of the type

(19), but as little as 20 percent at lower elevations. In

California's Mediterranean-like climate almost all precipitation arrives from October to May (19). Summer storms are

unusual and rarely deliver enough water to significantly

affect available soil moisture (15, 19). The lack of effective

summer precipitation emphasizes the importance of the

balance between water demand and soil-water storage capacity in determining site quality. Available soil moisture is

especially critical for regeneration. Access to water stored

below the soil in fractured or decomposed rock can affect site

quality significantly (1) and is dependent on local geologic

conditions.

The age, size, structure, and species composition of

many current stands were largely determined by timing and

kind of logging as accessibility, technology, market condition,

and landowners changed. When logging began 50 to 100

years ago, access was largely by railroad, and large, highquality pine was removed. Later entries took more pine and

large Douglas-fir. As trucks were developed, subsequent

entries were for salvage, sanitation, and removal of the

remaining high-value trees to pay for extending road access.

Tax laws strongly favored heavy cutting on most private

lands. Logging history, therefore, combined with biological

characteristics of the tree species and local variables of slope,

aspect, soils, elevation, geology, and fire history, produced

the current mosaic of small stands or groups. These stands or

groups, usually between 0.5 and 10 acres (0.2 and 4.0 ha) in

extent, are recognized as the basis for silvicultural prescriptions.

Differences in species composition and vertical mixing with

up to five species in the overstory and one to three species in

the understory are common (6).

Five conifer and one hardwood species define the type:

California white fir {Abies concolor var. lowiana (Gord.)

Lemm.), ponderosa pine (Pinus ponderosa Dougl. ex Laws,

var. ponderosa), coast Douglas-fir (Pseudotsuga menziesii

(Mirb.) Franco var. menziesii), sugar pine {Pinus lambertiana

Dougl.), incense-cedar {Libocedrus decurrens Torr.), and

California black oak (Quercus kelloggii Newb.). Douglas-fir

dominates the mix in the north, white fir at higher elevations

and on north slopes, ponderosa pine at lower elevations and

on south slopes. Douglas-fir is absent from the mixture south

of the Merced River. White fir and incense-cedar are the

niost common species, although incense-cedar, unlike white

fir, is seldom more than a minor component in the overstory

(6). Any of the major conifer species, however, can dominate

a specific stand.

Jeffrey pine {Pinus jejfreyi Grev. & Balf.) replaces

ponderosa pine at high elevations, on cold sites, and on soils

derived from serpentinaceous and ultramafic parent materials.

Giant sequoia {Sequoiadendron giganteum (Lindl.) Buchholz)

is found in groves scattered through the central and southern

Sierra Nevada. Red fir {Abies magnifica A. Murr.) is a minor

associate at the highest elevations (6).

Each of the species has a combination of silvical

characteristics that suits it to particular environments and

stages of succession.

White fir bears heavy seed crops on a 3- to 9-year cycle

and adequate to good crops every 2 to 5 years. The most

prolific seed producers are mature, healthy dominant trees 12

to 35 inches (30 to 89 cm) in diameter at breast height

(d.b.h.) (10, 13). Relatively small proportions (20 to 50

percent) of seeds are sound, but as many as 600,000 can fall

per acre (1.5 million/ha) where white fir is the dominant

species, and as many as 220,000 per acre (544 000/ha)

where white fir is a minor component (10, 14). Seeds are

wind disseminated and will travel as far as 2.5 times tree

height downwind into openings (14). Although seed germination and seedling establishment are best on bare mineral soil,

white fir seedlings survive and grow better in light litter than

seedlings of associated pines (21, 30). Eariy survival rates

are highest in partial shade, but subsequent growth is best in

44
full sunlight (8, 9). Seedling growth is inherently slow for the

first 3 to 5 years but then, if free from overstory competition,

accelerates rapidly (15).

Compared with its five associated species, white fir is

the most shade tolerant and the least tolerant of hot, dry sites.

It is least damaged by snow (23). All six species are easily

destroyed by fire when they are young and small, but white

fir remains vulnerable longer than the others (4) and is

moderately susceptible to fire damage when mature (23).

White fir can survive more than four decades of suppression

beneath closed canopies and dramatically increase height and

diameter growth when released (12).* In spite of its low

relative drought tolerance (23), white fir can survive the

presumably intense root competition of dense brush fields for

30 years or more until it grows above the brush canopy and

begins to dominate the site (4, 15).

On medium-to-poor quality sites, white fir will grow

faster than any of its associates in height and diameter (4).

Gross volumes increase as the proportion of white fir

increases in young, unmanaged, mixed-conifer stands (5).

Douglas-fir bears heavy seed crops irregularly with a

cycle of 2 to 11 years (27). Seeds are wind disseminated,

lighter, and travel farther than seeds of associated species

(23). Seeds will germinate on a wide variety of seedbeds

although bare mineral soil is best. Eariy survival of natural

Douglas-fir seedlings is strongly related to microclimate.

After the first summer, survival ranged from 3 percent in full

sunlight and 6 percent in heavy shade to 22 percent in partial

shade (32). Growth, however, is best in full sunlight (8).

Douglas-fir is moderate in relative shade tolerance. It is

more tolerant than ponderosa pine, about equal to sugar pine,

and less tolerant than white fir or incense-cedar. It does not

respond well to release after long suppression. Douglas-fir is

moderately susceptible to snow damage and is about average

in drought tolerance (23). Two-year-old Douglas-fir seedlings do not have tap roots as deep or lateral roots as long as

ponderosa pine, sugar pine, or incense-cedar (31). The

volume of soil tapped and, therefore, the amount of water

potentially available is less than that for the other three

species. Eariy growth from seed is slow but accelerates

rapidly.

Ponderosa pine bears large seed crops on a cycle of 2 to

5 years (27), but produces fewer seeds per acre than the

associated conifers. The largest trees bear the most seed (10).

Seeds are wind disseminated and are carried somewhat

farther than white fir seeds but not as far as Douglas-fir seeds

(29). Germination rate is about 70 percent (27). Bare mineral

soil and full sunlight favor ponderosa pine regeneration.

In mixed-conifer forests, ponderosa pine is the least

tolerant of suppression by an overstory and rapidly loses its

ability to respond to release. It is the most drought resistant of

the conifer seedlings because of its extensive root system

with deep tap roots, wide-reaching laterals, and many deep

sinker roots (8, 23, 31). It also is more tolerant of heat.

Growth is relatively slow at high elevations and snow

damage can be severe (23). Jeffrey pine replaces ponderosa

pine as temperature decreases and snow increases with

elevation. Initial growth rates in full sunlight are high and, on

all but the poorest sites, sufficient to achieve dominance over

brush if regeneration is established within 1 to 2 years after

logging or fire (30). i ^a. ^

Sugar pine bears heavy seed crops on a cycle ot 3 to ^

years (27) and, of the conifers, generally has the highest

proportion of sound seed. Cone production increases with

tree size and crown vigor (10) and most seeds are produced

by large, mature dominant trees (8). About 180,000 seeds per

acre (445 000/ha) are produced (10). Sugar pine seeds are

large and are carried no more than about 200 feet (61 m) even

in gale winds (10). The seeds germinate best in light litter and

full sunlight (30). Sugar pine is moderate in relative shade

tolerance. It is more tolerant than ponderosa pine, about the

same as Douglas-fir, and much less tolerant than white fir

(23). It responds well if released from overstory competition

within 30 to 40 years. Sugar pine seldom survives heavy

brush competition, unless it is established before the brush

can assert dominance (8).

Sugar pine grows slowly at first but then accelerates and

sustains high growth rates longer than the other conifer

species. It can exceed ponderosa pine by 20 percent in

volume and basal area in as few as 40 years, even on a hot,

dry site (24). Sugar pine ultimately will outgrow most other

species but cannot survive under a dense overstory of white

fir or Douglas-fir (4,8). Sugar pine is a common associate of

Jeffrey pine, Douglas-fir, and incense-cedar on serpentine or

ultramafic soils that are relatively infertile and have low

available soil moisture storage.

Incense-cedar seed production has no clear cycle and

can vary dramatically from tree to tree in any year (8). The

species can produce large numbers of seeds—up to 186,000

per acre (459 610/ha)—even though it rarely dominates the

stand (10). Seeds are wind disseminated. Seeds germinate

well on both bare soil and light litter and seedling survival is

best under partial shade (30). Field germination rates are

between 20 and 40 percent (9). Incense-cedar is rated as

tolerant to shade in California (8). Response to release is

good but growth is generally slower than that of the other

conifers (8). Up to a diameter of 24 inches (61 cm) and under

ideal conditions, however, young incense-cedar can outgrow

all associated species except white fir (4). It is relatively

drought tolerant and can grow on physically and chemically

undesirable serpentine-derived soils.

California black oak, although widespread, is rarely

more than a minor stand component and, in spite of its

potential for quality hardwood lumber, has insufficient economic value to warrant specific management except in

limited situations. Wildlife value of the tree, especially its

acorn crop, however, is high.^ Black oak produces heavy

seed crops every 2 to 3 years (27). Trees and seedlings sprout

vigorously. Most mature trees appear to have originated from

sprouts.^

Various cone and seed insects attack all of the species

and are periodically a serious local problem. Unless controlled,

rodents can consume most seeds from either natural seedfall

or sowing. Cutworms (Noctuidae) can destroy 30 percent or

more of seedlings in natural regeneration areas and are most

damaging to incense-cedar and white fir (11). Summer

drought alone can kill more than 20 percent of all natural

regeneration (11).

Annosus root disease {Heterobasidium annosum (Fr.)

Bref.) is a threat to conifers, killing pines directly, and white

fir and Douglas-fir indirectly, through heart rot of roots and

butt (3). A common root rot (Armillariella mellea (Vahl. ex

Fr.) Karst.) infects all trees in the mixed-conifer forest,

including black oak (3). In much of the Klamath Mountains

and certain areas of the northern Sierra Nevada, young sugar

pine rarely survives beyond the pole stage because of white

pine blister rust {Cronartium ribicola J. C. Fisch.) (3). Until

a rust-resistant strain is either identified or bred, and resistant

stock becomes available, sugar pine is not a realistic manage-

' Helms, John A.; Standiford, R. B. Release of advance growth mixed

conifer species in California following overstory removal. Unpublished

paper supplied to author by John A. Helms.

2 McDonald, Philip M. Quercus kelloggii Newb. California black oak.

1981. Unpublished draft supplied to author by Philip M. McDonald.

45
ment option for some areas. All of the conifers except

incense-cedar are infected by their own species-specific

dwarf mistletoes {Arceuthobium spp.), which predispose

their hosts to insect attack, cause varying degrees of damage

from growth reduction to topkill and, indirectly through entry

courts in open cankers, heart rots (26). True mistletoe species

(Phoradendron spp.) infect white fir from Lake Tahoe south

and incense-cedar throughout the mixed-conifer type. Damage to incense-cedar is minimal but can be important to

severe on large, old firs (3). All conifers except incensecedar are attacked by one or more species of bark beetles

{Scolytus, Dendroctonus, or Ips). Damage is widespread but

generally significant only locally and primarily in overstocked or diseased stands and occasionally near fresh slash

accumulation. Salvage cutting of trees that die because of

overmaturity and/or insect and disease attacks has been as

high as 180 million cubic feet (5.09 million m^) per year.

After a recent 2-year drought, mortality was estimated as 1.3

billion cubic feet (36.8 million m^) for 2.5 years (15). Pocket

dry rot (Tyromyces amarus Hedge. Lowe) enters through fire

scars (8) and causes major volume loss in old incense-cedar

but is not significant in trees less than 150 years old (3).

Fire is always a hazard during California's long, dry

summers and each year many thousands of acres are burned.

Massive efforts during the last half century have reduced

greatly the frequency of wildfires within a stand and enhanced the importance of the tolerant and relatively firesensitive white fir. Reintroduction of fire under carefully

controlled conditions may have potential as a silvicultural

tool for species and stocking control. Fire is used widely for

site preparation and slash treatment for fuels management.

The major threat to productivity, at least in the short

term, is a variety of aggressive woody shrub species that are

well adapted to take advantage of forest disturbance. Slightly

more than 2 million viable shrub seeds per acre (4.9

million/ha) have been found in the duff and soil of mature,

virgin forests (25). Under some conditions, various species

of woody brush {Ceanothus, Arctostaphylos, Chamaebatia),

and brush forms of tanoak {Lithocarpus spp.) and chinkapin

{Castanopsis spp.) can prevent successful conifer regeneration for decades. Where maximum tree growth is desired,

control of competing vegetation must be accomplished early

and maintained until the trees fully dominate the site.

Delayed or incomplete control can reduce growth from 2 to

14 percent, and total lack of control can reduce volume in

plantations as much as 67 percent (33).

Damage from vertebrate pests in the mixed-conifer type

is generally limited to regeneration and varies considerably

from place to place. Usually, pocket gophers are the most

damaging, followed by deer, porcupine, rabbits, and hares.

Pocket gophers can destroy seedlings over extensive acreage

and can prevent regeneration unless controlled.

Current management schemes vary depending on owners'

objectives, site quality, stand structure, stand condition, and

economic constraints. Uneven-aged management is theoretically possible, although group selection with relatively large

openings—greater than 90 feet (27.4 m) in diameter—is

necessary to prevent a species change because smaller

openings and partial cutting tend to eliminate the shademtolerant species (4, 11, 21). On the extensive acreage

where uneven-aged management is practiced, the objective is

not to regulate stand structure by controlling diameter class

distribution. Instead, existing irregular stand structures are

maintained or changed to a two- or three-aged stand through

a modified diameter-limit cutting, as described by Marquis

(20). On lands under group selection, regeneration cuttings

are from 0.5 to 1 acre (0.2 to 0.4 ha) in extent with the intent

to achieve complete regulation in 40 to 70 years. Single-tree

selection is used rarely where timber production is a major

objective. Limitations to single-tree selection are: slow growth

of young trees, extreme difficulty of maintaining a mix of

shade-tolerant and intolerant species, inability to control

dwarf mistletoes, diseconomy of scale for cultural treatments

(including site preparation), and the immense cost of inventorying and maintaining required age-class distribution.

Probably more than one-half of the mixed-conifer forest

is currently under, or being converted to, even-aged

management. Although individual management schemes differ,

they can be described as generally falling into two categories

on average quality sites—a short rotation (85 years) and a

long rotation (130 years). Rotation lengths differ considerably within these general classes. Growth under the short

rotation scheme averages 112 cubic feet per acre (7.8 m^/ha)

per year, and under the long rotation 90 cubic feet per acre

(6.3 m^/ha) per year (34). Intensively managed young stands

on better-than-average sites can be expected to produce from

150 to 200 cubic feet per acre (10.5 to 14.0 m%a) per year

(15). In the absence of sound, published data to indicate

stocking levels for maximum wood production in young,

managed, mixed-conifer stands, stocking decisions are based

mostly on experience and judgment. Commercial thinning is

generally from below, although some owners cut both large

and small trees to make thinning more profitable. Wellstocked, vigorous young stands (40 to 70 years old) are often

reduced in merchantable volume by 30 to 40 percent. A

common Forest Service practice is to reduce stocking to 55 to

66 percent of the basal area indicated in normal yield tables

for uncut, natural stands every 10 years. On poor sites or in

older stands, the residual basal area is increased. Another

approach is to thin from below and leave the trees that are

producing 80 percent of the periodic annual increment (cubic

volume). Intermediate cuts of all kinds are used currently and

provide an opportunity to adjust species composition as well

as stocking.

Artificial regeneration of all conifer species is feasible

now in most places if species and suitable seed sources are

chosen, dormant seedlings are properly stored and correctly

planted in spring, site preparation is adequate, and competing

vegetation is controlled. Direct seeding is costly, uncertain,

and rarely used, although it has been popular in the past (9,

28). Planting, after harvesting and site preparation, is the

normal procedure. California's long summer drought places a

premium on planting stock condition and treatment. Both a

lack of information concerning species requirements in the

nursery and often poor care and planting of nursery stock

have resulted in many failures, even for ponderosa and

Jeffrey pines. Nursery lifting and storage times that ensure

high survival potentials in planting stock are now known for

diverse seed sources of ponderosa pine, Jeffrey pine, white

fir, and Douglas-fir (16, 17, 18). Threshold soil temperatures

for root growth are known for the pines (16), Douglas-fir,

and true firs (17), and can be used to select planting times.

Natural regeneration usually can be achieved under

systems from single tree selection to clearcut, if site preparation and seed source are adequate. Control of competing

vegetation is critical and control of various rodents, including

pocket gophers, often is necessary. Regeneration cuts mus[t

be designed to suit stand conditions and the species desired.

Openings of at least 0.2 acre (0.1 ha) are required for initial

survival of the intolerant pines, however, long-term survival

and growth are questionable. Single-tree selection provides

adequate openings for the survival of the tolerant white fir

although growth of all species increases as overstory density

decreases (21, 22). Germination and growth of the generally

intolerant brush also is favored by heavier cutting (11, 21,

ZZ).

46
Stream protection and habitat requirements for nine

wildlife species (seven birds, one reptile, and one mammal)

listed as sensitive, rare, or endangered (35) are considerations in every timber sale on private or public lands.

Protection of esthetic values in high travel zones and in areas

receiving recreational use are additional management considerations on public land. Relatively little grazing is done

within the type.

The range and heterogeneity of natural environments

within the geographic area now occupied by the Sierra

Nevada Mixed-Conifer type will maintain a mixed-conifer

forest. Several variables, however, are changing species

composition. Removal of frequent wildfires from the environment through massive fire suppression efforts, a history (not

universal) of partial cutting, and limitations on brush control

measures are favoring the more tolerant species—especially

.white fir.

Literature Cited

1. Arkley, R. J. Soil moisture use by mixed conifer forest in a summer-dry

climate. Soil Sei. Soc. Am. J. 45: 423-427; 1981.

2. Barbour, Michael G.; Major, Jack. Introduction. In: Barbour, M. G.;

Major, J., eds. Terrestrial vegetation of California. New York: John

Wiley; 1977: l-ll.

3. Bega, Robert V., tech. coord. Diseases of Pacific Coast conifers. Agrie.

Handb. 521. Washington, DC: U.S. Department of Agriculture; 1978.

206 p.

4. Dunning, Duncan. Some results of cutting in the Sierra forests of

California. Dep. Bull. 1176. Washington, DC: U.S. Department of

Agriculture; 1923. 27 p.

5. Dunning, Duncan; Reineke, L. H. Preliminary yield tables for secondgrowth stands in California pine region. Tech. Bull. 354. Washington,

DC: U.S. Department of Agriculture; 1933. 24 p.

6. Eyre, F. H., ed. Forest cover types of the United States and Canada.

Washington, DC: Society of American Foresters; 1980. 148 p.

7. Forest Survey Staff. Forest statistics for California. Forest Survey

Release 25. Berkeley, CA: U.S. Department of Agriculture, Forest

Service, California Forest and Range Experiment Station; 1954. 66 p.

8. Fowells, H. A., comp. Silvics of forest trees of the United States.

Agrie. Handb. 271. Washington, DC: U.S. Department of Agriculture;

1965. 762 p.

9. Fowells, H. A.; Schubert, G. H. Recent direct seeding trials in the pine

region. Forest Res. Note 78. Berkeley, CA: U.S. Department of

Agriculture, Forest Service, California Forest and Range Experiment

Station; 1951. 9 p.

10. Fowells, H. A.; Schubert, G. H. Seed crops of forest trees in the pine

region of California. Tech. Bull. No. 1150. Washington, DC: U.S.

Department of Agriculture; 1956. 48 p.

11. Fowells, H. A.; Stark, N. B. Natural regeneration in relation to

environment in the mixed conifer forest type of California. Res. Pap.

PSW-24. Berkeley, CA: U.S. Department of Agriculture, Forest

Service, Pacific Southwest Forest and Range Experiment Station; 1965.

14 p.

12. Gordon, Donald T. Released advance reproduction of white and red

fir . . . growth, damage, mortality. Res. Pap. PSW-95. Berkeley, CA:

U.S. Department of Agriculture, Forest Service, Pacific Southwest

Forest and Range Experiment Station; 1973. 12 p.

13. Gordon, Donald T. White and red fir cone production in northeastern

California: report of a 16-year study. Res. Note PSW-330. Berkeley,

CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest

Forest and Range Experiment Station; 1978. 4 p.

14. Gordon, Donald T. Successful natural regeneration cuttings in California true firs. Res. Pap. PSW-140. Berkeley, CA: U.S. Department of

Agriculture, Forest Service, Pacific Southwest Forest and Range Experiment Station; 1979. 14 p.

15. Helms, John A. The California region. In: Barrett, J. W., ed. Regional

silviculture of the United States. New York: John Wiley; 1980: 391 -446.

16. Jenkinson, James L. Cold storage of bare-root planting stock. In:

Proceedings, Servicewide Conference on Planting Stock Production;

1975 September 16-18; Coeur d' Alene, ID. Washington, DC: U.S.

Department of Agriculture, Forest Service; 1975: 80-95.

17. Jenkinson, James L. Improving plantation establishment by optimizing

growth capacity and planting time of western yellow pines. Res. Pap.

PSW-154. Berkeley, CA: U.S. Department of Agriculture, Forest

Service, Pacific Southwest Forest and Range Experiment Station; 1980.

22 p.

18. Jenkinson, James L.; Nelson, J. A. Seed source lifting windows for

Douglas-fir in the Humboldt Nursery. In: Proceedings, Western Forest

Nursery Council and Intermountain Nuserymans Assoc. combined conf.

and seed processing workshop; 1978 August 7-11; Eureka, CA. San

Francisco, CA: U.S. Department of Agriculture, Forest Service, Pacific

Southwest Region; 1978: B77-95.

19. Major, Jack. California climate in relation to vegetation. In: Barbour,

M. G.; Major, J., eds. Terrestrial vegetation of California. New York:

John Wiley; 1977: 11-74.

20. Marquis, David A. Application of uneven-aged silviculture and management on public and private lands. In: Proceedings, 1976 Uneven-aged

Silviculture and Management in the Western United States workshop;

1976 October 19-21; Redding, CA. Washington, DC: U.S. Department

of Agriculture, Forest Service, Timber Management Research; 1976:

20-54.

21. McDonald, Philip M. Forest regeneration and seedling growth from five

major cutting methods in north-central California. Res. Pap. PSW-115.

Berkeley, CA: U.S. Department of Agriculture, Forest Service, Pacific

Southwest Forest and Range Experiment Station; 1976. 10 p.

22. McDonald, Philip M. Shelterwood cutting in a young-growth, mixedconifer stand in north-central California. Res. Pap. PSW-117. Berkeley,

CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest

Forest and Range Experiment Station; 1976. 16 p.

23. Minore, Donald. Comparative autecological characteristics of northwestem tree species ... a literature review. Gen. Tech. Rep. PNW-87.

Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific

Northwest Forest and Range Experiment Station; 1979. 72 p.

24. Oliver, William W. Sugar pine outperforms ponderosa pine on a hot,

dry site. Tree Planters' Notes 29(4): 14-17; 1978.

25. Quick, C. R. Viable seeds from the duff and soil of sugar pine forests.

Forest Sei. 2(1): 36-42; 1956.

26. Scharpf, Robert F.; Parmeter, John R., Jr., tech. coord. Proceedings of

the symposium on dwarf mistletoe control through forest management;

April 11-13,1978; Berkeley, CA. Gen. Tech. Rep. PSW-31. Berkeley,

CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest

Forest and Range Experiment Station; 1978. 190 p.

27. Schopmeyer, C. S., tech. coord. Seeds of woody plants of the United

States. Agrie. Handb. 450. Washington, DC: U.S. Department of

Agriculture; 1974. 883 p.

28. Schubert, Gilbert H.; Adams, Ronald S. Reforestation practices for

conifers in California. Sacramento, CA: Division of Forestry, Department of Conservation, State of California; 1971. 359 p.

29. Siggins, H. W. Distribution and rate of fall of conifer seeds. J. Agrie.

Res. 47: 119-128; 1933.

30. Stark, N. B. Natural regeneration of Sierra Nevada mixed conifers after

logging. J. For. 63(6): 456-457, 460-461; 1965.

31. Stein, William I. Naturally developed seedling roots of five western

conifers. In: Proceedings of the root form of planted trees symposium;

1978 May 16-19; Victoria, BC. Victoria, BC: British Columbia

Ministry of Forests and Canadian Forest Service; 1980: 28-35.

32. Tappeiner, J. C, II; Helms, J. A. Natural regeneration of Douglas-fir

and white fir on exposed sites in the Sierra Nevada of California. Amer.

Mid. Nat. 86(2): 358-370; 1971.

33. U.S. Department of Agriculture, United States Environmental Protection Agency 2,4,5-T Rebuttable Presumption Against Registration

Assessment Team. The biologic and economic assessment of 2,4,5-T.

Final draft report. Washington, DC: U.S. Department of Agriculture;

1979. 876 p.

34. U.S. Department of Agriculture, United States Environmental Protection Agency 2,4,5-T Rebuttable Presumption Against Registration

Assessment Team Timber Commodity Group. Economic impacts from

loss of 2,4,5-T in timber production. (Revised from: The biologic and

economic assessment of 2,4,5-T. Chapter 1, part 2. Final draft report.)

Washington, DC: U.S. Department of Agriculture; 1981. 740 p.

35. Vemer, Jared; Boss, Alan S., tech. coords. California wildlife and their

habitats: western Sierra Nevada. Gen. Tech. Rep. PSW-37. Berkeley,

CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest

Forest and Range Experiment Station; 1980. 439 p.

47
Pacific Ponderosa Pine

William W. Oliver and Robert F. Powers

Pacific Southwest Forest and Range Experiment Station

John N. Fiske

Pacific Southwest Region

The range of Pacific ponderosa pine {Pinus ponderosa

Dougl. ex Laws. var. ponderosa). Society of American

Foresters Cover type 245 (7), extends from latitude 43° N in

the Klamath Mountains of Oregon, south through the southem Cascades, interior Coast Range, western Sierra Nevada,

and Transverse Ranges, to its southern Hmit at latitude 33° N

in the Peninsular Ranges of southern California near San

Diego. Elevational limits of the Pacific ponderosa pine type

range from 1,000 to 2,000 feet (305 to 610 m) in the Klamath

Mountains, through 1,500 to 3,500 feet (455 to 1065 m) in

the northern Sierra Nevada, to 5,300 to 7,300 feet (1615 to

2225 m) in the south (9). In all, this type covers about 1.5

million acres (607 000 ha) (39).

Pacific ponderosa pine develops best on western slopes

of the southern Cascades and Sierra Nevada, forming a

virtually continuous band of moderate to high productivity

from Shasta County south through Eldorado County (40).

Highly productive stands, however, also are found in southem Siskiyou County and as far south as Fresno County.

Spanning a broad range of site qualities, the type is

found mainly on soils formed from extmsive and intmsive

igneous rocks, their metamorphosed equivalents, and metamorphosed sedimentaries. Pacific ponderosa pine tolerates a

broad span of soil pH with A-horizon reactions ranging at

least between 4.9 and 7.5. The most productive stands have

A-horizon pH's between 6.0 and 6.5, and B-horizon pH's

between 5.5 and 6.0 (49). Perhaps the poorest stands grow on

calcium-deficient soils formed from ultramafic rocks, where

survival is possible because the calcium requirement for

ponderosa pine is comparatively low and because the species

has a strong potential for uptake of this and other nutrients

(14, 35).

Growing seasons within the Pacific ponderosa pine type

are warm, dry, and mostly cloudless. Annual temperatures

average 42° to 50° F (5.5° to 10.0° C), with July and August

temperatures averaging 62° to 70° F (16.6° to 21.1° C).

Depending on elevation, consecutive frost-free days vary

from 110 to 250 in the Klamath Mountains, 115 to 250 in the

southem Cascades and northem Sierra Nevada, and 165 to

206 in the southem Sierra Nevada (27).

Most precipitation falls from November through April.

Snowfall is light in the Pacific ponderosa pine type, averaging less than 6 percent of total precipitation, and varying

between 0 and 15 percent (27). Snowfall increases rapidly

with elevation, however, and may cause breakage where

ponderosa pine is planted at higher elevations, or where

stocking densities in stands of pole-sized trees are too great

(37). December through February are the wettest months,

and June through September the driest. July and August

usually are rainless. Climatic records (27) show a narrow

range in precipitation for the type in the southem Sierra

Nevada, where annual averages vary from 30.0 to 37.5

inches (760 to 950 mm). In contrast, precipitation is greater

and more varied in the northern Sierra Nevada, where

productivity also is higher. There, precipitation varies from

39.8 inches (1010 mm) annually near Placerville, to 67.8

inches (1720 mm) at Challenge, where many of the most

productive sites are found.

Because of the long, frost-free period and the summerdry climate characterizing the Pacific ponderosa pine type,

growing seasons typically are long and limited mainly by soil

moisture availability. Radial growth periods last between 148

and 183 days in the 3,000 to 4,000 feet (915 to 1220 m)

elevational zone of the central Sierra Nevada (8), and at least

167 days at 2,590 feet (790 m) elevation in the north-central

Sierra Nevada (35). Although ponderosa pine is adapted to

hot, dry summers, growth is greater and continues longer on

deep, well-drained soils with moderate water-holding capacities.

In a plantation on contrasting soils at 3,200 feet (975 m)

elevation in the northem Sierra Nevada, height growth

continued 42 days longer and was twice as great on a

clay-loam soil formed from andésite as on a gravelly-loam

soil formed from schist.*

The Pacific ponderosa pine type typically forms almost

pure even-aged stands. Its characteristic stmcture and composition result largely from two natural conditions: low soil

rnoisture availability during the summer and recurring wildfires (40). Ponderosa pine also has been planted extensively

within other forest cover types (7), such as Douglasfir-Tanoak-Pacific Madrone (type 234) and Sierra Nevada

Mixed Conifer (type 243). Digger pine {P. sabiniana Dougl.)

or knobcone pine {P. attenuata Lemm.) mix with the type on

xeric soils at lower elevations and on lower- to midelevation ultramafic soils. Incense-cedar {Libocedrus decurrens

Torr.), coast Douglas-fir {Pseudotsuga menziesii (Mirb.)

Franco var. menziesii), and sugar pine (P. lambertiana

Dougl.) are common associates on zonal soils at upper

elevations, and Califomia white fir {Abies concolor var.

lowiana (Gord.) Lemm.) grows at the edge of the mixedconifer forest. Jeffrey pine (P. jejfreyi Grev. & Balf.) and

incense-cedar displace the type on upper-elevation soils from

ultramafic rocks. Califomia black oak {Quercus kelloggii

Newb.) is common throughout much of the Pacific ponderosa

pine type, and tanoak {Lithocarpus densiflorus (Hook. &

Am.) Rehd.) and Pacific madrone {Arbutus menziesii Pursh)

are associates in the northem Sierra Nevada and in parts of

the Coast Range. Fire helps maintain the type by excluding

relatively thinner barked species, such as Digger pine at

lower elevations, and Douglas-fir and white fir at higher

elevations.

Cones are produced fairly regularly on trees growing on

the westem slopes of the Cascades and Sierra Nevada, but

heavy cone crops over broad areas are rare. Although no

complete failures were noted in Califomia for the period

1956-66, cone production was rated medium or better only

once, and very light crops were recorded in 8 of 11 years

(42). Good cone crops, however, are more frequent at

specific locations. On the average, medium to better crops

appear every 1 to 3 years (10, 45).

^ Powers, Robert F. Unpublished data. 1980. U.S. Department of Agriculture,

Forest Service, Pacific Southwest Forest and Range Experiment Station.

48
More than a dozen insects have been identified as

causing seed losses (13). Insects can destroy as much as 95

percent of a cone crop, but losses ranging from 30 to 60

percent are more common. Usually the proportion of seed

lost to insects is highest when crops are small. Seeds also are

consumed by a great many birds and small mammals.

Even-aged silvicultural systems are well suited to the

Pacific ponderosa pine type where wood production or

maintaining the type are primary objectives. The species'

intolerance of shade favors even-aged groups or stands.

Regenerating stands by clearcutting with prompt site preparation and planting, or, in some instances seeding (28), is

recommended. At the Challenge Experimental Forest, in the

northern Sierra Nevada, California, seed-tree cuttings leaving 4 to 8 trees per acre (10 to 20/ha) and shelterwood

cuttings leaving about 12 trees per acre (30/ha) are other

systems that have regenerated ponderosa pine successfully

(21), with the shelterwood method favoring shade-tolerant

species as well (19).

Uneven-aged management systems are impractical for

the type. F*onderosa pine regenerates and grows poorly in the

presence of overstory competition (19). Other conifers and

hardwoods, especially, become more numerous and the type

may convert to the California black oak or the Sierra Nevada

mixed-conifer type. When more shade-tolerant species are

absent, group selection can maintain the Pacific ponderosa

pine type more effectively than single-tree selection, but

stocking and growth will be poor under both systems. In the

short run, however, the selection system can result in a forest

of visual variety, harmony, and beauty, and has been used in

areas where these values are paramount (23).

Most managed stands of Pacific ponderosa pine are

regenerated by planting (42), but natural seeding (19, 21)

may be successful if an adequate seed source exists and the

seedbed has been prepared properly. Natural seeding can be

effective if mineral soil is exposed and if openings are not too

large. At Challenge Experimental Forest (22) annual seedfall

in 2-acre (0.8-ha) circular clearcuts averaged 10,420 sound

seeds per acre (25 750/ha) for a 4-year period, compared

with 4,045 per acre (9995/ha) in 10-acre (4 ha) clearcuts.

Seedfall v/as twice as heavy within 100 feet (30.5 m) of the

timber edge as in the center of the larger clearcuts. Of the

sound seed cast into clearcuts, almost 90 percent falls within

a distance from the forest edge equal to 1.5 times the height

of dominant border trees (22). The stocking that results may

be poorly distributed—too little in some areas and too much

in others.

Seed-tree and shelterwood systems also provide adequate regeneration (19, 21) if harvests and site preparation

are timed to match adequate cone crops, and seed trees are

chosen with care. Selection criteria for trees left as seed

producers are that they should be good phenotypes from the

largest size classes (21, 45); show evidence of past cone

production, such as fallen cones at the base of each tree (45);

and be windfirm, as witnessed by full crowns and relatively

large growing space before logging. Large trees compete

strongly with seedlings for site resources, and will retard

height growth of seedlings to distances of at least 40 feet

(12.2m) (20). For this reason, seed trees should be removed

once regeneration stocking is satisfactory, allowing for an

average stocking reduction of 8 percent attributable to felling

and tractor skidding (18).

Natural seeding has an advantage of insuring that the

regeneration is adapted to the site; it has a disadvantage in

that harvest may not coincide with an adequate seed crop. As

time passes, seedbeds rapidly become less favorable because

of weed invasion and rodent buildup. Although expensive,

direct seeding offers an alternative.

Controlling predatory rodents and birds, preparing seedbeds properly, and applying seed in appropriate amounts are

the keys to effective direct seeding (28). Research at Challenge Experimental Forest shows that ponderosa pine seeded

at the rate of 1.0 pound per acre (1.1 kg/ha) produces at least

400 seedlings per acre (990/ha) after the first year.^ Because

the best results have been obtained with predator repellents

not currently registered for forestry use, direct seeding should

not be attempted unless predator control is certain.

Planting is practiced more widely than seeding (42), and

has several advantages. First, roots are placed deeply in the

soil—an advantage in a summer-dry climate. Also, losses

resulting from predators, pathogens, and high soil temperatures are reduced greatly or eliminated. Further, large seedlings compete more effectively with weeds, and are less

susceptible to losses from frost-heaving and animal browsing.

Finally, planting provides early stocking control, and offers a

chance at improving genetic traits beyond those characterizing natural stands.

Keys to successful planting include adequate site

preparation, appropriate stock, and proper lifting and planting procedures. Moisture is scarce in surface soil during the

summer in the Pacific ponderosa pine type. Consequently,

potentially competing vegetation must be removed before

planting. On clearcut sites, logging slash often must be

reduced to lower the risk of wildfire and insect buildup, and

to improve access for subsequent silvicultural treatments.

Because broadcast burning can stimulate germination of

dormant seeds of manzanita {Arctostaphylos spp.) or ceanothus

{Ceanothus spp.) species existing in the forest duff, logging

slash and duff usually are piled and burned. In brushfields,

many potential competitors sprout from root crowns even if

tops are killed, and tractors equipped with brush rakes can

uproot brush and push duff into windrows without excessive

soil displacement (42). Windrows should be spaced at least

50 feet (15.2 m) apart and burned when dry to eliminate fuel

hazards and to reduce competition from vegetation developing within them. When brush crowns are crushed or chipped,

follow-up treatments to control sprouts usually are required.

Mountain misery (Chamaebatia foliolosa Benth.) is a

particularly competitive shrub causing management problems

throughout much of the western Sierra Nevada. Because the

shrub forms a dense canopy and is a vigorous sprouter, single

applications of topkilling herbicides are ineffective in preventing its regrowth, although they may improve survival of

planted stock (1, 44). Usually, regrowth is swift and aggressive,

and may depress stand yields by as much as 75 percent at 50

years (44). Better control is provided by a combination of

treatments—late fall burning, herbicide spraying the next

summer through fall, and additional spraying as needed (1).

Contour terracing by tractor on slopes as steep as 45 percent

also has proved excellent for controlling mountain misery,

establishing ponderosa pine, and protecting watershed values

where maintenance of esthetic values is not paramount. The

effect of displacing fertile topsoil on terraces is unknown, but

may not be detrimental if soils are deep and lateral displacement is small.

Seed collections for reforesting properly prepared sites

should come from trees of medium or better phenotypes

growing within 1,000 feet (305 m) elevation and 100 miles

(160 km) north or south of the regeneration site. Seeds should

be collected from the same seed zone or, if this is not

^Neal, Robert L., Jr. A successful test of the Challenge direct seeding

prescription for ponderosa pine. 1981. Unpublished draft. U.S. Department

of Agriculture, Forest Service, Pacific Southwest Forest and Range Experiment Station.

49
possible, from the nearest adjacent zone of the same physiographic and climatic region (5).

Root-growth capacity of ponderosa pine peaks in fall to

winter, and seedlings should be lifted from nursery beds

between December and February (15). Seedlings may be

stored for up to 3 months without appreciable drop in

root-growth capacity or outplant survival, provided that

temperature is held near 33° F (0.6° C) and relative humidity

is at least 90 percent (42).

Fall or winter planting sometimes results in satisfactory

survival, but creates a heavy risk of losses from frost heaving

and desiccation. Spring planting is favored, but should not

begin until soil temperatures at the field site at 4 inches (10

cm) are warming above 41° F (5.0° C), and soon will exceed

50° F (10.0° C) (15). Seedlings planted too early in cold soils

cannot grow new roots, may undergo severe moisture stress,

and may exhaust stored energy reserves prematurely. Planting machines also may be used where slopes are not too

steep, provided that the same sound practices used in hand

planting are followed (42). Improper planting techniques

produce stunted ''J" and ''L" rooted seedlings. Stunting

effects may last for decades.

Compared with associated conifers, ponderosa pine

requires more sunlight but less soil moisture for survival and

satisfactory growth (26). Drought can be tolerated through

strong stomatal control of water loss (17). Ponderosa pine

also holds a competitive edge on infertile sites because of its

low nutrient requirement and its ability to store considerable

reserves in foliar biomass (35).

Because sites generally are productive within the Pacific

ponderosa pine type, tree growth is rapid, exceeding rates

found for ponderosa pine elsewhere within its native range.

Young ponderosa pine grows faster than associated conifers.

In a 6-year-old plantation at Challenge Experimental Forest,

ponderosa pine averaged 2.6 times greater in biomass than

the next largest species, sugar pine, and 41 percent taller than

incense-cedar, the next tallest species (35). Planted trees

reach breast height in 5 to 9 years depending upon site quality

(32). On average and better sites, diameter growth increases

lineariy with height growth, and the ratio does not change

until crowns nearly touch.^ In managed plantations, periodic

annual growth of pole-sized trees averages 0.2 to 0.4 inch

(0.5 to 1.0 cm) in diameter, 1.5 to 2.5 feet (0.46 to 0.76 m)

in height, 6 to 8 square feet per acre (1.38 to 1.84 m^/ha) in

basal area, and 150 to 250 cubic feet per acre (10.5 to 17.5

m^/ha) in total volume (31, 33). Height growth is rapid for at

least 80 years on medium to better sites, where heights reach

110 to 170 feet (34 to 52 m) (38). Growth rates slacken

thereafter (2), but even 200-year-old dominant trees can grow

0.4 feet (0.12 m) in height annually on the best sites (24).

Volume yields of well-stocked stands at 50 years range from

7,000 to 11,700 cubic feet per acre (490 to 819 m%a)

equivalent to 20,300 to 51,300 board feet (fbm)'* (Scribner)

per acre on the more productive sites (24, 33).

Rotation lengths vary depending upon criteria. Using

culmination of mean annual increment, cubic measure,

rotation ages of 50 to 80 years in unthinned stands or 100 to

120 years in thinned stands are anticipated. If financial

considerations are paramount, shorter rotations of 40 to 60

years have been recommended for productive sites (46).

Growth losses commonly result from competition with

woody shrubs and from high stand density. When numerous,

shrubs can reduce growth of pines, including trees of

sawtimber size.^ When stand density is high, trees may grow

little in diameter and, in extreme cases, little in height (29).

To maintain acceptable rates of growth, young stands may

require either release from competing brush (42), or a

precommercial thinning, or both. Brush control usually is

needed when manzanita or mountain misery are the competitors (1, 30, 36). Even a light cover of brush reduced the mean

height of dominant and codominant trees by 20 percent in one

19-year-old plantation.^ Tentative guidelines suggested by

two separate studies (4, 16) that may be used for evaluating

the need to control brush are 10,000 cubic feet per acre

(700 m^/ha) of total brush crown volume and 30 percent

total brush crown cover. Densities that exceed these values

will reduce growth of planted pine seedlings and saplings

significantly. Firm recommendations, yet to be formulated,

are expected to be site- and brush-species specific. Weeding

and thinning in the sapling stage (as soon as potential crop

trees can be identified) to 170 to 260 trees per acre (420 to

640/ha), depending on crop tree-size objectives, timing of

yields, and site quality, should allow the stand to grow

rapidly and to contain enough trees to support a thinning

when the stand reaches sawtimber size.

Thinning stands of commercial size can promote stand

health, transfer growth to the best crop trees, and provide an

eariy return on investment (31). Recommended post-thinning

stand densities depend upon the kinds of wood products

desired, how frequently commercial thinnings are planned,

and the density, vigor, and age of the stand before thinning.

For vigorous 30- to 60-year-old stands managed for lumber

production and thinned every 10 years, a post-thinning basal

area of about 55 percent of normal yield (24) has been

effective. For less vigorous or older stands with the same

management objective and entry frequency, more basal area

should be left after thinning. Another successful but conservative guideline for determining leave density for commercial

thinning from below in unmanaged stands is to leave trees

currently producing 80 percent of the periodic annual cubic

increment. After thinning or release, stands usually respond

rapidly even at advanced ages, provided that live crowns of

leave trees have lengths at least equal to 40 percent of tree

height (12).

Many ponderosa pine plantations are deficient in nitrogen—

particularly on sites where site preparation was heavy.^

There, nitrogen fertilization can increase height growth of

saplings by 25 to 80 percent, and volume growth of poles by

as much as 30 percent (34). Moisture supply on xeric sites,

however, must be improved first by weeding or thinning

before fertilization can be effective (36).

The most destructive insect pest threatening ponderosa

pine is the western pine beetle (Dendroctonus brevicomis

LeConte) which, when epidemic, kills vigorous trees 6

inches (15 cm) or more in diameter (11). Trees often are

attacked jointly with the California fivespined ips {Ips paraconfusus Lmicr) (11)—perhaps the second most destructive insect to ponderosa pine. Stands with basal areas that

exceed normal stocking for that height and age (24) are

especially susceptible. Thinning such stands usually will help

them withstand insect attack. But because Ips populations

build rapidly in slash, and can attack and kill standing trees as

large as 6 inches in diameter and the tops of larger trees,

thinning should be avoided in spring and early summer.

Western dwarf mistletoe {Arceuthobium campylopodum

Engelm.) is responsible for significant losses in growth (41).

^ Powers, Robert F., and Oliver, William W. Unpublished data. 1971.

"^ Cubic foot and metric conversions of measurements expressed in board

feet should be viewed as estimates because of the assumptions involved in

the conversion process.

^ Powers, Robert F. Unpublished data. 1971.

^ McDonald, Philip M. Unpublished data. 1980. U.S. Department of

Agriculture, Forest Service, Pacific Southwest Forest and Range Experiment

Station.

50
Three important root diseases attacking ponderosa pine are

Fomes root and butt rot {Heterobasidium annosum (Fr.)

Bref.), shoestring root rot (Armillariella mellea (Vahl. ex

Fr.) Karst.), and black stain root disease (Verticicladiella

wageneri Kend.) (43). Fomes root and butt rot kills trees of

all ages and usually results in groupwise mortality that is

sometimes mistaken for the work of bark beetles, which are

frequent secondary invaders. Borax sprinkled on freshly cut

stumps seems to retard spread of the disease in logged areas.

Shoestring root rot causes noticeable mortality in young

plantations and thinned stands where the disease spreads

from dead oak root systems.

Two needle diseases can, when injury is severe, resuh in

growth loss and predisposition of the tree to attack by other

agents. Pacific ponderosa pine is more susceptible to foliar

injury from ozone than associated mixed conifers (25).

Ozone injury presently is restricted to the southern California

mountains and the west slope of the southern Sierra Nevada.

A needle cast caused by Elytroderma deformans (Weir)

Dark., however, is found throughout the Pacific ponderosa

pine type (6).

Pocket gophers can kill many trees up to pole size, and

rodent baiting or seedling protection with plastic mesh tubing

may be needed (3, 42). Porcupines severely damage young

pines when local populations are high. Shooting is the control

method practiced widely.

Although fire helps perpetuate stands of ponderosa pine,

destructive fires, logging, and smog may convert many lower

elevation sites to the chaparral or California black oak types.

Along the upper elevational margin, many areas would

convert gradually to the Sierra Nevada mixed conifer type if

fires were excluded (40). Potentially, low-intensity fires can

reduce the hazard of destructive wildfires, but formulating

prescriptions is difficult because understory shrubs and accumulated debris often are abundant (48).

The Pacific ponderosa pine type provides many benefits

other than wood. Wildlife habitat can be enhanced if a

maximum amount of edge is furnished with stands of all age

classes, including those physiologically mature (47). Livestock find forage in young plantations and managed stands.

But grazing should be avoided for a few years after planting

because of damage from trampling and wrenching. Pacific

ponderosa pine forests are found at low elevations offering

year-round recreation, and they frequently border forest

roads where esthetic values are high. Few, if any, rare and

endangered plant species have been identified within this

type. If present, most are found on enclaves of harsh sites

caused by serpentinite rock that support a different forest

type.

Literature Cited

1. Adams, Ronald S. How to cure mountain misery. Sacramento, CA:

Calif. Div. For.; 1969. 23 p.

2. Arvanitis, L. G.; Lindquist, J.; Palley, M. Site index curves for

even-aged young-growth ponderosa pine of the west-side Sierra Nevada.

California Forestry and Forest Products 35. Berkeley, CA: Univ. of

California School of Forestry; 1964. 8 p.

3. Barrett, James W. Silviculture of ponderosa pine in the Pacific

Northwest: the state of our knowledge. Gen. Tech. Rep. PNW-97.

Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific

Northwest Forest and Range Experiment Station; 1979. 106 p.

4. Bentley, Jay R.; Carpenter, Stanley B.; Blakeman, David A. Early

brush control promotes growth of ponderosa pine planted on bulldozed

site. Res. Note PSW-238. Berkeley, CA: U.S. Department of Agriculture,

Forest Service, Pacific Southwest Forest and Range Experiment Station;

1971. 6 p.

5. Buck, John M.; Adams, Ronald S.; Cone, Jerrold; Conkle, M.

Thompson [and others]. California tree seed zones. San Francisco, CA:

U.S. Department of Agriculture, Forest Service, Calif. Region, and

Calif. Div. For.; 1970. 6 p.

6. Childs, T. W.; Shea, Keith R.; Stewart, James L. Elytroderma disease

of ponderosa pine. Forest Pest Leafl. 42. Washington, DC: U.S.

Department of Agriculture, Forest Service; 1971. 6 p.

7. Eyre, F. H., ed. Forest cover types of the United States and Canada.

Washington, DC: Society of American Foresters; 1980. 148 p.

8. Fowells, H.A. The period of seasonal growth of ponderosa pine and

associated species. J. For. 39(7): 601-608; 1941.

9. Fowells, H. A., comp. Ponderosa pine (Pinus ponderosa Laws.). In:

Silvics of forest trees of the United States. Agrie. Handb. 271.

Washington, DC: U.S. Department of Agriculture; 1965: 417-431.

10. Fowells, H. A.; Schubert, G. H. Seed crops of forest trees in the pine

region of California. Tech. Bull. 1150. Washington, DC: U.S. Department of Agriculture; 1956. 48 p.

11. Fumiss, R. L.; Carolin, V. M. Western forest insects. Misc. Publ.

1339. Washington, DC: U.S. Department of Agriculture; 1977. 654 p.

12. Hallin, William E. Pruning ponderosa and Jeffrey pine. Forest Res.

Note 115. U.S. Department of Agriculture, Forest Service. California

Forest and Range Experiment Station; 1956. 4 p.

13. Hedlin, Alan F.; Yates, Harry O., Ill; Cibrian Tovar, David; Ebel,

Bernard H. [and others]. Cone and seed insects of North American

conifers. Washington, DC: U.S. Department of Agriculture, Forest

Service; 1981. 122 p.

14. Jenkinson, James L. Ponderosa pine progenies: differential response to

ultramafic and granitic soils. Res. Pap. PSW-101. Berkeley, CA: U.S.

Department of Agriculture, Forest Service, Pacific Southwest Forest

and Range Experiment Station; 1974. 14 p.

15. Jenkinson, James L. Improving plantation establishment by optimizing

growth capacity and planting time of western yellow pines. Res. Pap.

PSW-154. Berkeley, CA: U.S. Department of Agriculture, Forest

Service, Pacific Southwest Forest and Range Experiment Station; 1980.

22 p.

16. Kirchner, W.; Bradley, B.; Griffin, S. The effect of brush competition

on conifer plantation growth on the Sequoia National Forest and

recommended release schedules. Porterville, CA: Sequoia National

Forest. 1978; 11 p.

17. Lopushinsky, W. Stomatal closure in conifer seedlings in response to

leaf moisture stress. Bot. Gaz. 130(4): 258-163; 1969.

18. McDonald, Philip M. Ponderosa pine seed-tree removal reduces stocking only slightly. J. For. 67(4): 226-228; 1969.

19. McDonald, Philip M. Forest regeneration and seedling growth from five

major cutting methods in north-central California. Res. Pap. PSW-115.

Berkeley, CA: U.S. Department of Agriculture, Forest Service, Pacific

Southwest Forest and Range Experiment Station; 1976. 10 p.

20. McDonald, Philip M. Inhibiting effect of ponderosa pine seed trees on

seedling growth. J. For. 74(4): 220-224; 1976.

21. McDonald, Philip M. Shelterwood cutting in a young-growth, mixedconifer stand in north central California. Res. Pap. PSW-117. Berkeley,

CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest

Forest and Range Experiment Station; 1976. 16 p.

22. McDonald, Philip M. Seed dissemination in small clearcuttings in

north-central California. Res. Pap. PSW-150. Berkeley, CA: U.S.

Department of Agriculture, Forest Service, Pacific Southwest Forest

and Range Experiment Station; 1980. 5 p.

23. McDonald, Philip M.; Whitley, Raymond V. Logging a roadside stand

to protect scenic values. J. For. 70(2): 80-83; 1972.

24. Meyer, Walter H. Yield of even-aged stands of ponderosa pine. Tech.

Bull. 630. Washington, DC: U.S. Department of Agriculture; 1938. 59

P25. Miller, Paul R. Abiotic diseases. In: Bega, Robert V., tech. coord.

Diseases of Pacific Coast conifers. Agrie. Handb. 521. Washington,

DC: U.S. Department of Agriculture; 1978: 5-41.

26. Minore, Don. Comparative autecological characteristics of northwestem tree species ... a literature review. Gen. Tech. Rep. PNW-87.

Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific

Northwest Forest and Range Experiment Station; 1979. 72 p.

27. National Oceanic and Atmospheric Administration. Climatological data

annual summary California. (10 volumes) Asheville, NC: U.S. Department of Commerce, National Climatic Center; 74(13): 469-493; 1970.

75(13): 471-495; 1971. 76(13): 465-489; 1972. 77(13): 1973. 30 p.

78(13): 1974. 30 p. 79(13): 1975. 30 p. 80(13): 1976. 30 p. 81(13):

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51
28.

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Neal, Robert L., Jr. Ponderosa pine seeding trials in west-side Sierra

Nevada clearcuts: some early results. Res. Note PSW-305. Berkeley,

CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest

Forest and Range Experiment Station; 1975. 8 p.

Oliver, William W. Ponderosa pine can stagnate on a good site. J. For

65(11): 814-816; 1967.

Oliver, William W. Early response of ponderosa pine to spacing and

brush: observations on a 12-year-old plantation. Res. Note PSW-341.

Berkeley, CA: U.S. Department of Agriculture, Forest Service, Pacific

Southwest Forest and Range Experiment Station; 1979. 7 p.

Oliver, William W. Growth of planted ponderosa pine thinned to

different stocking levels in northern California. Res. Pap. PSW-147.

Berkeley, CA: U.S. Department of Agriculture, Forest Service, Pacific

Southwest Forest and Range Experiment Station; 1979. 11 p.

Oliver, William W.; Powers, Robert F. Early height growth of

ponderosa pine forecasts dominance in plantations. Res. Note PSW-250.

Berkeley, CA: U.S. Department of Agriculture, Forest Service, Pacific

Southwest Forest and Range Experiment Station; 1971. 4 p.

Oliver, William W.; Powers, Robert F. Growth models for ponderosa

pine: I. Yield of unthinned plantations in northern California. Res. Pap.

PSW-133. Berkeley, CA: U.S. Department of Agriculture, Forest

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21 p.

Powers, Robert F. Mineralizable nitrogen as an index of nitrogen

availability to forest trees. Soil Sei. Soc. Amer. J. 44(6): 1314-1320;

1980.

Powers, Robert F. Nutritional ecology of ponderosa pine (Pinus

ponderosa Laws.) and associated species. Berkeley: University of

California; 1981. 234 p. Dissertation.

Powers, Robert F.; Jackson, Grant D. Ponderosa pine response to

fertilization: influence of brush removal and soil type. Res. Pap.

PSW-132. Berkeley, CA: U.S. Department of Agriculture, Forest

Service, Pacific Southwest Forest and Range Experiment Station; 1978.

9 p.

Powers, Robert F.; Oliver, William W. Snow breakage in a pole-sized

ponderosa pine plantation . . . more damage at high stand-densities.

Res. Note PSW-218. Berkeley, CA: U.S. Department of Agriculture,

Forest Service, Pacific Southwest Forest and Range Experiment Station;

1970. 3 p.

38. Powers, Robert F.; Oliver, William W. Site classification of ponderosa

pine stands under stocking control in California. Res. Pap. PSW-128.

Berkeley, CA: U.S. Department of Agriculture, Forest Service, Pacific

Southwest Forest and Range Experiment Station; 1978. 9 p.

39. Roy, Douglass F.; McDonald, Philip M. Pacific ponderosa pine. In:

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40. Rundel, Philip W.; Parsons, David J.; Gordon, Donald T. Montane and

subalpine vegetation of the Sierra Nevada and Cascade ranges. In:

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41. Scharpf, Robert F. Mistletoes. In: Bega, Robert V., tech. coord.

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DC: U.S. Department of Agriculture; 1978: 121-141.

42. Schubert, Gilbert H.; Adams, Ronald S. Reforestation practices for

conifers in California. Sacramento, CA: Calif. Div. For.; 1971. 359 p.

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44. Tappeiner, John C, II; Radosevich, Steven R. Effect of bearmat

{Chamaebatia foliolosa) on soil moisture and ponderosa pine {Pinus

ponderosa) growth. Weed Sei. 30(1): 98-101. 1982.

45. Sundahl, William E. Seedfall from young-growth ponderosa pine. J

For. 69(11): 790-792; 1971.

46. Teeguarden, Dennis E. Economics of replacing young-growth ponderosa

pine stands ... a case study. Res. Pap. PSW-47. Berkeley, CA: U.S.

Department of Agriculture, Forest Service, Pacific Southwest Forest

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47. Thomas, Jack Ward, tech. coord. Wildlife habitats in managed forests

in the Blue Mountains of Oregon and Washington. Agrie. Handb. 553.

Washington, DC: U.S. Department of Agriculture; 1979. 512 p.

48. Wright, Henry A, The effect of fire on vegetation in ponderosa pine

forests. A state-of-the-art review. Range and Wild. Inform. Series 2.

Lubbock, TX: Texas Tech. University; 1978. 21 p.

49. Zinke, Paul J. Site quality of Douglas-fir and ponderosa pine in

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Sei. Soc. Amer. Proc. 20(4): 167-171; 1959.

52
Ponderosa Pine and Rocky Mountain Douglas-fír

Russell A. Ryker

Intermountain Forest and Range Experiment Station

Jack Losensky

Northern Region

In the interior Northwest States of Montana, Idaho, and

eastern Washington, ponderosa pine {Pinus ponderosa Dougl.

ex Laws. var. ponderosa) and Rocky Mountain Douglas-fir

(Pseudotsuga menziesii var. glauca (Beissn.) Franco) forests

cover about 20 million acres (8 million ha). The two species

occur together over an elevation range of about 4,000 feet

(1220 m). Ponderosa pine is found from 1,000 to 6,000 feet

(305 to 1830 m), and Douglas-fir from 1,800 to 8,000 feet

(550 to 2440 m) (7). On the lower edge of its range,

ponderosa pine is the climax tree species in the first forest

zone above grasslands. Above this narrow zone, it is a

topographic climax on steep southerly slopes or is a serai

species on Douglas-fir and grand fir {Abies grandis (Dougl.

ex D. Don) Lindl.) sites (11). With increasing elevation and

precipitation, ponderosa pine gives way to Douglas-fir,

which in turn gives way to grand fir on mid-elevations in

northern Idaho and northwestern Montana and to subalpine

fir {Abies lasiocarpa (Hook.) Nutt.) on higher elevations

throughout the Northern Rocky Mountains.

These forests are represented by two Society of American Foresters forest cover types (5): Interior Ponderosa Pine

(type 237) and Interior Douglas-fir (type 210). They include

pure forests of ponderosa pine or Douglas-fir, or various

mixtures of these two species and their major associates

grand fir, western larch {Larix occidentalis Nutt.), and

lodgepole pine {Pinus contorta var. latifolia Engelm.). Timber productivity rates vary from 10 to more than 100 cubic feet

per acre (0.7 to 7.0 m-^/ha) per year, depending on site and

stand conditions (9, 11, 14).

The distribution of ponderosa pine and Douglas-fir is

strongly influenced by climate and available soil moisture.

Ponderosa pine is not found in north-central and northeast

Montana because of cold and windy conditions (1). Similarly,

its distribution is limited in southwest and south-central

Montana and central and eastern Idaho because of too little

precipitation during May and June, a critical time for the

survival of new seedlings (2). At higher elevations where

moisture is adequate, the temperatures are too low. Though

both species occur on a variety of soils, their distribution on

drier sites is related to supplies of available soil moisture that,

in turn, are related to soil texture and depth (7). Ponderosa

pine extends into drier areas on sandy soils and along

streams. Douglas-fir can be found on dry soils too, but only

on higher elevations where temperatures are lower. Douglasñr does not tolerate poorly drained soils or soils normally

subjected to flooding during part of the year.

Precipitation ranges from about 14 inches (355 mm) on

the lower ponderosa pine sites to 40 inches (1015 mm) on the

higher elevations (7), but throughout the type July to August

rainfall is deficient, often less than 1 inch (25 mm) (1, 5, 7).

During the establishment of a new stand, the scant summer

rainfall creates a need for protecting sites from the extremes

of temperature and moisture losses that occur on exposed

sites on southerly aspects.

Natural regeneration of ponderosa pine and Douglas-fir

is sporadic. On the drier sites successful natural regeneration

is thought to be the result of a chance combination of a good

seed crop and favorable weather during the next growing

season. Regeneration is enhanced by leaving enough trees to

ameliorate temperature and moisture extremes in the openings,

and to provide larger quantities of seed. On the driest sites,

where ponderosa pine is the climax and only tree species,

prompt natural regeneration is difficult to obtain no matter

what cutting method is used, because the combination of

good seed crops and moisture conditions favorable for

seedling survival is infrequent. On more moist sites, ponderosa

pine natural regeneration depends on timing the site preparation to coincide with a good seed crop. The number of

seedlings can be increased by protecting the cone crop from

tree squirrels and by reducing populations of seed-eating

rodents (13).

Seed production directly influences regeneration and the

cutting method that may be applied. Ponderosa pine is a poor

seed producer west, and a fair producer east, of the Continental Divide in Montana. Most seed falls to the ground within

130 feet (39.6 m) of the parent tree. Douglas-fir is somewhat

more prolific, and the effective dissemination distance is

about twice that of ponderosa pine (7).

Prescribed fire and scarification are the methods most

often used to create favorable conditions for regeneration. On

the dry sites, it is imperative to control vegetation competing

for the limited soil moisture. Seed germination and seedling

establishment are best on mineral soil seedbeds; however,

Douglas-fir can establish seedlings on litter if it is not more

than 2 inches (5 cm) deep. Both species do well on burned

seedbeds (6, 12, 15).

Planting of bareroot and container-grown trees has been

widely used to reestablish ponderosa pine and Douglas-fir.

Because of the low predictability of natural regeneration,

these species are planted whenever prompt regeneration is

needed. Successful planting requires good site preparation to

control competing vegetation, and vigorous seedlings capable of initiating root growth soon after planting. Survival

often depends on maintaining contact with the receding soil

moisture level during summer drought.

New growth on young Douglas-fir trees is occasionally

damaged by late-spring and late-summer frosts. Plantations

established on high elevations with trees grown from seed

collected at somewhat lower elevations are especially

susceptible. Damage also occurs in some lower elevation

valley bottoms that collect cold air when the protective cover

of trees is removed. Ponderosa pine is seldom damaged by

frost.

The potential of understory Douglas-fir to respond,

grow, and become a vigorous forest once the overstory trees

are cut, is most important in deciding on a cutting method.

Some stands contain healthy understory trees that have large,

vigorous crowns that enable them to grow rapidly once the

overstory is removed. However, other mature stands contain

small but old understory trees that have small crowns and do

not possess the vigor to grow when released from competition.

Many trees, though alive, are infected with dwarf mistletoe

53
or other diseases and are thus unsuitable for further management.

Ponderosa pine has excellent juvenile growth rates.

Growth rates are generally slower for Douglas-fir. Young

Douglas-fir trees appear to grow best with partial shade;

whereas ponderosa pine requires full sunlight (7, 10).

Insects and disease can play a major role in establishment and development of trees in this forest type. Outbreaks

of the western spruce budworm (Choristoneura occidentalis

Freeman) have caused serious defoliation and growth loss of

Douglas-fir. Heavy feeding by the budworm severely reduces

seed production by Douglas-fir and is apparently responsible

for regeneration failures in some areas (4). The Douglas-fir

beetle {Dendroctonus pseudotsugae Hopkins) can cause serious losses. Old, dense stands containing a high proportion of

Douglas-fir are most susceptible (8). The mountain pine

beetle {Dendroctonus ponderosae Hopkins) is a primary

killer of ponderosa pine trees. Group killing occurs in mature

forests and in young over-stocked stands. The dwarf mistletoes (Arceuthobium douglasii Engelm. and A. Campylopodum

Engelm.) are major enemies of Douglas-fir and of ponderosa

pine in some areas. They infect trees of all ages, and although

mortality is low, significant growth loss can occur along with

lower lumber quality.

On Douglas-fir sites, fire has played an important role in

the maintenance of serai stands of larch and pine (3). On the

drier Douglas-fir sites, pure ponderosa stands were maintained by fire. On the more mesic sites within the range of

western larch, the larch was favored as it is slightly more fire

resistant than ponderosa pine and is less affected by crown

scorch because it grows a new crop of needles each year.

Though older Douglas-fir trees are also fire resistant, burning

that destroys seedlings and saplings favors the aggressive

pioneer species, larch and pine. On cooler sites lodgepole

pine is the serai species maintained by fire. Although

lodgepole pine can withstand light ground fire, it is generally

considered susceptible to fire at all ages. It is, however,

aggressive in reestablishment following a stand-destroying

fire.

Depending on site and stand conditions, both even-aged

and uneven-aged management systems are feasible. On dry

climax ponderosa pine sites, prompt natural regeneration is

difficult to obtain because of the need for the combination of

good seed crops, good site preparation, and favorable weather

during the first two growing seasons. Single tree and group

selection cutting methods are usually prescribed. Site preparation in the openings should coincide with good seed crops.

Heavy infections of dwarf mistletoe in many stands in Idaho

and eastern Washington may limit the choice to clearcutting

and planting in order to prevent infection of the regenerated

stand. When ponderosa pine is managed in uneven-aged

stands, low stand densities are needed to maintain reasonable

individual-tree growth rates.

On moderate sites where Douglas-fir and ponderosa or

lodgepole pine occur in mixture, group selection and shelterwood

cutting methods are preferred, but the choice often depends

on the amount of dwarf mistletoe. If a merchantable stand of

ponderosa pine and Douglas-fir is vigorous and relatively

free of dwarf mistletoe, these methods may be used. In stands

where most of the Douglas-fir trees are badly infected with

dwarf mistletoe and little mistletoe-free understory is present,

a silviculturally satisfactory method is to clearcut the merchantable trees, dispose of remaining trees, prepare the site

with mechanical equipment or fire, and establish a new stand

by planting. In lightly infected stands, any partial cutting

should be accompanied by cutting or killing infected trees.

On moist sites, Douglas-fir and ponderosa pine may

occur in mixture with lodgepole pine, western larch, and

grand fir. The seed tree, shelterwood, and clearcutting

methods are appropriate depending on insect and disease

infestations and site and stand conditions. The shelterwood

method is increasingly used in mature even-aged stands, but

seed tree cutting is occasionally used, especially for regenerating western larch on northerly aspects. The clearcutting

method is frequently used in overmature stands. Clearcutting

is particularly useful in efforts to control insects and dwarf

mistletoe. It also facilitates slash disposal and site preparation.

On higher elevation dry sites, Douglas-fir occurs in pure

stands. The sites are severe, establishment of natural regeneration is slow, and juvenile growth rates are low. Often the

Douglas-fir is heavily infected with dwarf mistletoe, and

badly damaged by the western spruce budworm. If a merchantable stand is healthy and relatively free of dwarf

mistletoe, a shelterwood or selection method of cutting may

be used, but the regeneration period will be long. In stands

heavily infected with dwarf mistletoe or badly damaged by

the budworm, the only reasonable method is to clearcut if the

timber is to be salvaged. However, clearcuts on these sites

are difficult to regenerate even by planting.

The forests in this type are truly multiple-use forests.

Some of the most important forest range for livestock found

in the Northern Rocky Mountain region occurs in this forest

type. Timber harvest and prescribed fire can significantly

increase livestock and wildlife forage. Though this type is a

low to moderate water producer, excessive soil disturbance

can impact the many large streams flowing through the type,

adversely affecting fish populations and increasing sedimentation in reservoirs. The majority of the present deer and elk

winter range occurs in this type. Portions of the type are used

by the grizzly bear and wolf. Because this forest type is

located on lower elevations, esthetics and recreation must

also be important management considerations.

Literature Cited

1. Amo, Stephen F. Forest regions of Montana. Res. Pap. INT-218.

Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain

Forest and Range Experiment Station; 1979. 39 p.

2. Baker, F. S.; Korstian, Clarence F. Suitability of brush lands in the

Intermountain Region for the growth of natural or planted western

yellow pine forests. Tech. Bull. 256. Washington, DC: U.S. Department of Agriculture; 1931. 82 p.

3. Davis, Kathleen M.; Clayton, Bruce D.; Fisher, WiUiam C. Fire

ecology of Lolo National Forest habitat types. Gen. Tech. Rep.

INT-79. Ogden, UT: U.S. Department of Agriculture, Forest Service,

Intermountain Forest and Range Experiment Station; 1980. 77 p.

4. Dewey, Jerald E. Damage to Douglas-fir cones by Choristoneura

occidentalis. J. Econ. Entomology 63(6): 1804-1806; 1970.

5. Eyre, F. H., ed. Forest cover types of the United States and Canada.

Washington, DC: Society of American Foresters; 1980. 148 p.

6. Foiles, Marvin W.; Curtis, James D. Regeneration of ponderosa pine in

the Northern Rocky Mountain region. Res. Pap. INT-145. Ogden, UT:

U.S. Department of Agriculture, Forest Service, Intermountain Forest

and Range Experiment Station; 1973. 44 p.

7. Fowells, H. A., comp. Silvics of forest trees of the United States.

Agrie. Handb. 271. Washington, DC: U.S. Department of Agriculture;

1965. 762 p.

8. Fumiss, Malcolm M.; Livingston, R. Ladd; McGregor, Mark D.

Development of a stand susceptibility classification for Douglas-fir

beetle. In: Proceedings, Hazard-rating systems in forest insect pest

management symposium; 1980 July 31-August 1; Athens, GA. Gen.

Tech. Rep. WO-27. Washington, DC: U.S. Department of Agriculture,

Forest Service: 1981. 115-128.

9. Meyer, Walter H. Yield of evenaged stands of ponderosa pine. Agrie.

Handb. 630. Washington, DC: U.S. Department of Agriculture; 1938.

59 p.

10. Minore, Don. Comparative autecological characteristics of northwestern

tree species—a literature review. Gen. Tech. Rep. PNW-87. Portland,

OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest

Forest and Range Experiment Station; 1979. 72 p.

54
11.

12.

Pfister, Robert D.; Kovalchik, Bernard L.; Arno, Stephen F.; Presby,

Richard C. Forest habitat types of Montana. Gen Tech. Rep. INT-34.

Ogden, IJT: U.S. Department of Agriculture, Forest Service, Intermountain

Forest and Range Experiment Station; 1977. 174 p.

Ryker, Russell A. A survey of factors affecting regeneration of Rocky

Mountain Douglas-fir. Res. Pap. INT-174. Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Forest and Range

Experiment Station; 1975. 19 p.

Shearer, Raymond C; Schmidt, Wyman C. Natural regeneration in

ponderosa pine forests of western Montana. Res. Pap. INT—86. Ogden,

UT: U.S. Department of Agriculture, Forest Service, Intermountain*

Forest and Range Experiment Station; 1970. 19 p.

Steele, Robert; Pfister, Robert D.; Ryker, Russell A.; Kittams, Jay A.

Forest habitat types of central Idaho. Gen. Tech. Rep. INT—114. Ogden,

UT: U.S. Department of Agriculture, Forest Service, Intermountain

Forest and Range Experiment Station; 1981. 137 p.

U.S. Department of Agriculture, Forest Service. The scientific base for

silviculture and management decisions in the National Forest System:

Selected papers. Washington, DC: U.S. Department of Agriculture,

Forest Service; 1977. 59 p.

55
Western Larch

Wyman C. Schmidt and Raymond C. Shearer

Intermountain Forest and Range Experiment Station

John R. Naumann

Northern Region

Western larch (Larix occidentalis Nutt.) grows in the

upper Columbia River Basin, mostly in the Northern Rocky

Mountains west of the Continental Divide. As a Society of

American Foresters forest cover type (type 212) (3), it

comprises a plurality of the stocking on nearly 3 million acres

(1.2 million ha) and is an important stand component on

additional millions of acres in most other forest cover types in

northwestern Montana, northern and west-central Idaho,

central and northeastern Oregon, central and eastern Washington,

and southeastern British Columbia (8).

The western larch cover type usually occurs in mountain

environments at elevations from about 2,000 to 5,500 feet

(610 to 1675 m) in British Columbia— the northern part of its

range—and up to 7,000 feet (2135 m) in south-central

Idaho—the southern part of its range. It typically is found on

north and east facing slopes, valley bottoms, and benches.

However, in the mid-to-northem part of its range, particularly at higher elevations, larch can grow on all exposures.

The western larch type occurs on a wide variety of soils

including deep, well-drained soils developed from glacial till

of limestone, argillite, and quartzite bedrock of Precambrian

origin; alluvium from the recent Tertiary; and lake sediments

from the Pleistocene. Nearly all soils in the larch type have

been influenced by volcanic ash deposits. Inceptisols and

Alfisols comprise the bulk of the soils where this cover type

predominates, but Spodosols also support some of the cover

type at the cool-moist end of the type's environmental

gradient.

Larch forests grow in relatively moist, cool conditions,

with low growing-season temperatures limiting its upper

elevational range, and deficient moisture its lower range.

Mean annual temperature is about 44° F (6.7° C), with a

range from about 37° to 52° F (2.8° to 11.1° C). Temperature

extremes average as low as -35° F (-37.2° C) and as high

as 105° F (40.6° C). During the May to August growing

season temperatures average about 60° F (15.6° C) with July

the warmest month. The frost-free period varies from about

60 to 160 days (usually early June to early September), but

frosts may occur any month of the year.

Annual precipitation in the larch cover type ranges from

about 18 to 50 inches (46 to 127 cm) with an average of 28

inches (71 cm) in the north to 32 inches (81 cm) in the south.

About one-fifth of the moisture falls during the May to

August period, most in May and June. July and August are

characteristically hot and dry with low humidity and high

evapo-transpiration rates under clear, sunny skies. Coastal

maritime conditions influence this cover type even though

much of it is 500 miles (805 km) inland, resulting in cloud

cover much of the winter. Snow accounts for over one-half of

the total annual precipitation and blankets most of the type

from early November to late April (8).

Western larch is a long-lived serai species with a wide

ecological amplitude (7). It grows in mixture with several

other pioneer, subclimax, and climax species including

ponderosa pine (Pinus ponderosa Dougl. ex Laws.) and

Rocky Mountain Douglas-fir {Pseudotsuga menziesii var.

glauca (Beissn.) Franco) on the lower, warmer, and drier

sites; grand fir {Abies grandis (Dougl. ex D. Don) Lindl.),

western white pine {Pinus monticola Dougl. ex D. Don),

western redcedar {Thuja plicata Donn. ex D. Don), and

western hemlock {Tsuga heterophylla (Raf.) Sarg.) on moist

sites; and Engelmann spruce {Picea engelmannii Parry ex

Engelm.), subalpine fir {Abies lasiocarpa (Hook.) Nutt.),

and mountain hemlock {Tsuga mertensiana (Bong.) Carr.) on

cool, moist locations (8).

Western larch can be regenerated quite easily by both

natural and artificial methods. Good larch cone crops are

produced at about 5-year intervals, with a ratio of about one

good or fair crop produced for each poor crop (8). Occasionally,

two good or up to four poor seed crops may occur consecutively.

Dominant and codominant larch bear abundant cone crops

throughout their crowns from about 40 through 500 years of

age. The small seeds are usually dispersed by upslope

thermal winds in late summer and fall; some seeds can be

carried long distances (9). Most seeds fall near the edge of

openings and decrease rapidly away from the source (9, 11).

In years of good cone production, even the centers of

clearcuts as large as 60 acres (24 ha) (800 feet (240 m) from

the nearest seed source) receive seed for adequate stocking.

Good cone crops average about 40 to 50 percent viable seed,

but poor cone crops average less than 10 percent.

Burning or scarification is required to create favorable

seedbed conditions for regeneration (7). Both the vegetative

competition and duff layer must be reduced temporarily to

promote early establishment of larch seedlings; otherwise,

more shade tolerant species will dominate the new stand.

Prescribed burning is preferred for site preparation and fuel

reduction because little soil damage results (2), and larch

seedlings grow best on burned seedbeds (8). More seedlings

are established as the amount of soil exposed during site

preparation increases and as the number of viable seed

increases. Less bare soil is needed to achieve regeneration

goals near a timber edge bordering a clearcut than near its

center, or within shelterwood than with seed tree cuttings.

Western larch seeds germinate well when temperature

and moisture are favorable (8). Natural stratification of larch

seed during the winter prompts rapid and complete germination.

Germination begins at snowmelt in late April on exposed

low-elevation sites to mid-May or early June on sheltered

north slopes at higher elevations (8). Larch seed germinates

from a few days to 2 weeks before its associated tree species.

Spring-sown larch seed without stratification has slow and

incomplete germination, and some seeds germinate the next

spring.

Aspect greatly influences seedling survival (8). Northwest to north to nearly east aspects, and gentle or flat

topography provide the most favorable conditions for larch

seedling survival. Seedling mortality begins at or soon after

germination. Initially, fungi, rodents, and birds cause most

loss. When the soil surface dries, particularly on unshaded

south and west aspects, high temperatures at the soil-air

interface cause heat girdling of new seedlings. Later, insuffi56
cient soil water may cause heavy drought losses. Frost

heaving can kill young seedlings in the fall before snowfall

and the next spring after snowmelt. Seedling mortality

(usually caused by drought, frost heaving, and rodents)

decreases the second and each successive year.

The natural regeneration principles just described apply

equally to artificial regeneration, particularly direct seeding.

Both broadcast and spot-seeding can be successful on wellprepared seedbeds, but should be limited to north and east

exposures. Bare root and containerized seedlings can be

successfully planted on sites that are adequately prepared.

Planted larch survive best on well-drained soils and poorest

on heavy soils. At higher elevations and south and west

aspects, shade, such as that provided by logging debris, will

increase plantation survival. Because larch seedlings break

dormancy very early in the spring, and because survival is

much better for stock that has not broken dormancy, fall

lifting at the nursery, frozen winter storage, and cold field

storage in the spring during outplanting is recommended.

Because western larch is the least shade tolerant conifer

in the Northern Rockies (8), it requires nearly full sunlight

for best development. Only in its early seedling stage can it

tolerate any shade. In developing stands, it either dominates

or loses vigor when overtopped, and dies if not released. Its

widespread distribution has been attributed to frequent historic wildfire (13). Mature larch is well adapted to survive

fire because of its thick and low-resin bark, its high and open

branching habit, its low foliage flammability, and its low

duff volume. However, fire normally kills most of the

thin-barked seedlings and saplings. Scars on the survivors

provide an entry for rot. Larch develops a deep and

widespreading root system that makes it windfirm until root

rots weaken the trees in old age. Snow and ice seldom

damage larch because the needles are deciduous. However,

wet snow in early fall or late spring can fall on a full

complement of needles and cause severe bending in young

trees and broken branches in older trees.

Grovy/th patterns of the species that comprise the larch

cover type are related to their shade tolerance (8). Larch and

lodgepole pine are the least shade tolerant and, during the

juvenile years, grow substantially faster than Douglas-fir,

grand fir, and Engelmann spruce, their more tolerant associates.

These species' differences ameliorate as the stands grow

older, but larch normally retains the dominant position in the

stand. Cultural practices improve and prolong growth if done

before crown lengths and vigor are reduced. At age 100,

larch heights range from 130 feet (40 m) on good sites to 65

feet (20 m) on poor sites. Diameter growth of western larch

parallels height growth and is affected by many of the same

factors. Larch has the potential for rapid diameter growth,

but overstocking, insects, and dwarf mistletoe (Arceuthobium

laricis (Piper) St. Johns) often decrease the potential. In fully

stocked unmanaged stands basal area increases to about age

40, decelerates, and nearly levels off after age 100 when it

has about 300 square feet per acre (68.9 m^/ha) on highquality sites, and about 200 square feet per acre (45.9 m^/ha)

on low-quality sites. Volume growth follows the same trend

as basal area but peaks later. With full stocking, 7,765 cubic

feet per acre (543.6 m^a) is a reasonable objective in 100

years on medium-quality sites (8). Intensive management

using thinning and improvement cuttings should permit

sawtimber production in 60 to 80 years (1).

Insects, disease, and other biological factors substantially reduce the growth potential for trees and stands in the

larch cover type (8). The larch casebearer (Coleophora

laricella (Hubner)), a larch defoliator, can reduce growth and

cause occasional death, but weather factors and parasites

appear to be limiting its damage potential. Western spruce

budworm (Choristoneura occidentalis Freeman) damages

both shoots and cones, reducing height growth and seed

production of larch. Other insects causing less extensive

damage to larch are the larch sawfly {Pristiphora erichsonii

(Hartig)), twolined larch sawñy (Anoplonyx laricivorus (Rohwer

and Middleton)), larch budmoth {Zeiraphera improbana

(Walker)), a western subspecies ofthe larch looper {Semiothisa

sexmaculata incolorata (Dyar)), false hemlock looper (Nepytia

canosaria (Walker)), Douglas-fir beetle {Dendroctonus

pseudotsugae Hopkins), and the California fourspined ips {Ips

plastographus (LeConte)). A cone maggot {Hylemya spp.)

and a woolly adelgid {Adelges spp.) can cause high mortality

of cones and seeds. Heavy infections of dwarf mistletoe kill

treetops and reduce cone production, seed viability, wood

quality, and height and diameter growth. Other damaging

diseases are larch needle cast fungus (Hypodermella laricis,

Tub.), quinine fungus {Fomitopsis officinalis (Vill. & Fr.)

Bond & Sing.), and red ring rot (Phellinuspini (Thore) Pilat).

Girdling and stripping of cambium by bears and squirrels can

cause serious local problems.

The western larch cover type can easily be maintained

by silviculture practices that parallel the natural processes,

such as wildfire, which have perpetuated this cover type.

Developing and maintaining a plurality or majority of westem larch in a stand is effectively achieved by even-aged

management systems. These systems, using shelterwood,

seed tree, or clearcut cutting methods, best meet the regeneration requirements of this intolerant species. Western larch is

difficult to maintain as a cover type with uneven-aged

management systems. However, some larch can be regenerated with uneven-aged management systems if the growing

stock levels of reserve stands are kept low and the site is

prepared. Of the two uneven-aged systems, the group selection cutting method comes closest to satisfying the regeneration needs of western larch, but may not provide enough of

this species in a stand over time to constitute a plurality of

larch. The single tree selection cutting method provides the

least favorable conditions for the establishment and development of western larch and tends to convert the cover type to

the more shade-tolerant species. Also, dwarf mistletoe can

become a significant problem using uneven-aged management methods but can be largely eliminated by using evenaged management methods.

The shelterwood cutting method is most effectively used

on south and west aspects where some protection is needed

for survival of new seedlings (8). Seeding or planting may be

required in poor seed years to take advantage of mineral soil

exposed by site preparation efforts. If associated species are

retained with western larch in the overstory, the shelterwood

cutting method increases species diversity in regenerated

stands. Once regeneration is established, the overstory must

be removed promptly to maintain environmental conditions

that will retain western larch as a viable component in the

new stand and prevent infection from possible sources of

dwarf mistletoe from the overwood. Early removal of the

reserve trees also results in the least amount of damage to the

young stand. Shelterwood cutting may not be wise if overstory

western larch are heavily infected with dwarf mistletoe or if

adequate site preparation is seriously hampered by the

residual trees retained for seed and shelter. While shelterwood

cutting may sometimes be used primarily to meet multipleresource needs, overwood densities must be lighter on less

severe north and east aspects. The longer the overwood is

retained for resource needs other than timber production, the

less chance there is to perpetuate western larch as a cover

type because the more tolerant trees will dominate.

Seed tree and clearcut harvest cutting methods generally

utilize the same silvicultural principles and produce the same

57
results. The seed tree method provides a more uniform seed

distribution and allows the retention of some mature trees for

cavity-nesting birds and animals. Clearcutting offers the

greatest choice and ease of site preparation and provides a

favorable environment for the establishment of regeneration

on all but hot and dry exposures. Here shelterwood cuttings

might be more appropriate, but, if clearcutting is the only

option, larch may have to be planted to maintain this species

as a stand component.

Immature stands in the larch cover type respond rapidly

and substantially to cultural practices, and there are nearly

always enough conifer species present to mold a diversified

stand. Early thinning should be the rule in this cover type. It

prevents height suppression found in heavily overstocked

stands, effectively concentrates diameter growth on the

featured trees, and retains crowns on the shade-intolerant

larch. Furthermore, thinning reduces overall water consumption,

increases understory vegetation, and keeps the stand in a

vigorous condition so that it is better able to recuperate after

insect attacks (6).

Thinning stands 40- to 50-years old and older in the

larch cover type is less effective than early thinning. At this

age, the more tolerant Douglas-fir, Engelmann spruce, and

grand fir are better able to capitalize on the increased growing

space than are larch or lodgepole pine. Because larch crowns

are so intolerant of shade, they are substantially shortened in

heavily overstocked stands, and they respond more slowly

than their associates that retain fuller crowns. As a result,

moderately overstocked stands respond more rapidly than

heavily overstocked stands.

Selection of species to feature in stand culture should be

based on knowledge of the productivity of species within the

different ecological habitat types that make up the larch cover

type. On nearly all habitat types larch should be one of the

featured species. Species diversity can be maintained by

thinning and other intermediate cuttings. This capitalizes on

the rapid juvenile growth of larch, retains those species that

reach their greatest potential at a later age, and provides some

insurance against host-specific insect and disease attacks.

The western larch type occupies lands that produce a

wide variety of forest resources. Western larch is a premier

species for the production of plywood, lumber, and wood

fiber for pulp and paper products.

Even-aged management methods generally give forest

managers the flexibility they need to enhance or maintain

forage production for wildlife and livestock, water quality

and yield, wood production, and esthetics (10). Forage

production for big game, such as elk, moose, and deer, is

high with even-aged silviculture systems, but excessive size

openings can reduce visual and thermal cover and discourage

use by these animals. Uneven-aged management is sometimes used to maintain specific habitat conditions for certain

timber, wildlife, water quality, and esthetic situations. Special management considerations are often needed; for example,

cavity-nesting animals and birds prefer old, broken-topped

larch, and some should be retained in harvested areas to

provide that habitat (4, 12).

Several rare and endangered species that live in this

cover type include grizzly bear, grey wolves, bald eagles,

and peregrine falcons. For grizzly bear habitat, size of

openings and retention of forbs and berry-producing plants

are important considerations. Grey wolf habitat is benefitted

by practices that favor deer and elk—the wolfs food source.

Habitat for eagles and falcons is influenced by site-specific

considerations rather than broad management strategies applied to favor the larch cover type.

Water quality is seldom affected by careful harvest

cutting, site preparation, or stand culture. However, care

must be taken in the design, construction, and maintenance

of access roads because they are the greatest potential source

of soil movement. Water yields are moderate in this cover

type in relation to other cover types in the Northern Rockies.

XVater yields are increased by harvest cutting and thinning in

direct relation to the amount of forest removed. However,

rapid tree and understory vegetation development soon ameliorates these increases (5).

Fall and spring coloration of larch, a deciduous conifer,

adds unique esthetic diversity to areas where it is perpetuated

in this cover type. The effect of silviculture systems on the

visual resource depends upon the objectives established for

an area. Viewing requirements can be satisfied if harvest

cuttings are carefully shaped, residues properly managed,

and tolerant understories retained in some foreground views.

Literature Cited

1. Adams, David L. The Northern Rocky Mountain Region. In: Barret,

John W., ed. Regional silvicuhure of the United States. New YorkJohn Wiley; 1980: 341-389.

2. DeByle, Norbert V. Clearcutting and fire in the larch/Douglas-fir forests

of western Montana—a multifaceted research summary. Gen. Tech.

Rep. INT-99. Ogden, UT: U.S. Department of Agriculture, Forest

Service, Intermountain Forest and Range Experiment Station; 1981

73 p.

3. Eyre, F. H., ed. Forest cover types of the United States and Canada.

Washington, DC: Society of American Foresters; 1980. 148 p.

4. McClelland, B. R.; Frissell, S. S.; Fischer, W. L.; Halvorson, C. H.

Habitat management for hole-nesting birds in forests of western larch

and Douglas-fir. J. For. 77(8): 480-483; 1979.

5. Newman, Howard C; Schmidt, Wyman C. Silviculture and residue

treatments affect water used by a larch/fir forest. In: Proceedings,

Symposium on environmental consequences of timber harvesting in

Rocky Mountain coniferous forests. Gen. Tech. Rep. INT-90. Ogden,

UT: U.S. Department of Agriculture, Forest Service, Intermountain

Forest and Range Experiment Station; 1980: 75-110.

6. Schmidt, Wyman C. Some biological and physical responses to forest

density. In: Proceedings, Eighth World Forestry Congress; 1978 October 16-28; Jakarta. Forestry for Quality of Life 25(2): 1-11; 1978.

7. Schmidt, Wyman C; Shearer, Raymond C. Western larch. In: Silvicultural systems for the major forest types of the United States. Agrie.

Handb. 445. Washington, DC: U.S. Department of Agriculture- 1973-

37-38.

8. Schmidt, Wyman C; Shearer, Raymond C; Roe, Arthur L. Ecology

and silviculture of western larch forests. Tech. Bull. 1520. Washington,

DC: U.S. Department of Agriculture; 1976. 96 p.

9. Shearer, Raymond C. Regeneration establishment in response to harvesting and residue management in western larch-Douglas-fir forest. In:

Environmental consequences of timber harvesting in Rocky Mountain

coniferous forests. Gen. Tech. Rep. INT-90. Ogden, UT: U.S.

Department of Agriculture, Forest Service, Intermountain Forest and

Range Experiment Station; 1980: 249-269.

10. Shearer, Raymond C. Silvicultural systems in western larch forests J

For. 69(10): 732-735; 1971.

11. Shearer, Raymond C. Silviculture. In: DeByle, Norbert V., ed. Clearcutting

and fire in the larch/Douglas-fir forests of western Montana—a multifaceted research summary. Gen. Tech. Rep. INT-99. Ogden, UT: U.S.

Department of Agriculture, Forest Service, Intermountain Forest and

Range Experiment Station; 1981: 27-31.

12. Thomas, Jack Ward; Miller, Rodney J.; Black, Hugh; Rodiek, Jon E.;

[and others]. Guidelines for maintaining and enhancing wildlife habitat

in forest management in the Blue Mountains of Oregon and Washington.

Trans. North Am. Wildl. Nat. Resource. Conf. 41: 452-476; 1976.

13. Wellner, Charles A. Fire history in the Northern Rocky Mountains. In:

The role of fire in the Intermountain West, Symposium; 1970 October

27-29, Missoula, MT. Missoula, MT: University of Montana,

Intermountain Fire Research Council; 1970: 42-64.

58
Engelmann Spruce - Subalpine Fir

Robert R. Alexander

Rocky Mountain Forest and Range Experiment Station

Orviile Engelby

Intermountain Region

The Engelmann spruce-subalpine fir type, Society of

American Foresters forest cover type 206, occupies about 10

million acres (4 million ha) in the western United States.

These forests grow on areas of moderate to high timber

production potential. They are also important water yielding

areas, and they provide habitat for a wide variety of wildlife,

forage for livestock, and recreational opportunities and scenic beauty. Much land now covered by serai tree species such

as lodgepole pine (Pinus contorta Dougl. ex Loud.) and other

vegetation also has the potential to grow spruce and fir (4,7).

Spruce-fir forests are widely distributed. In the Pacific

Northwest, the type is found along the crest and east slope of

the Cascade Mountains of Washington and Oregon to Mt.

Shasta in California. In the Rocky Mountains, it ranges from

Idaho and Montana and adjacent mountains of eastern Washington and Oregon; then south through the high mountains of

Utah, Wyoming, Colorado, New Mexico, and northern

Arizona (1, 2, 7).

Engelmann spruce (Picea engelmannii Parry ex Engelm.)

and subalpine fir {Abies lasiocarpa (Hook.) Nutt.) are the

only tree species common throughout the type, but their

proportions and site preferences vary. In the Rocky Mountains of Idaho and Montana and associated ranges, and in the

Pacific Northwest, the spruce element of the type usually

occupies moist sites at lower elevations (2,000 to 6,000 ft

(610 to 1830 m)), stream bottoms, and basins characterized

by slow drainage and accumulation of cold air. The subalpine

fir element extends above the spruce-fir zone, and at

timberline (8,000 to 11,000 ft (244Ö to 3350 m)) may form

pure stands that are either serai or climax. More often,

subalpine fir is found at timberline in association with

subalpine larch {Larix lyallii Pari.), whitebark pine {Pinus

albicaulis Engelm.), and mountain hemlock {Tsuga mertensiana

(Bong.) Carr.) where it may be replaced by the mountain

hemlock type. South of Montana and Idaho in the Rocky

Mountains and associated ranges, the spruce-fir type makes

up the timberline forests (9,500 to 12,000 ft (2895 to 3655

m)). In Colorado, Wyoming, and Utah, both spruce and fir

are characteristically present, but subalpine fir rarely predominates at timberline. In the Rocky Mountains of Arizona and

New Mexico, spruce extends above subalpine and cork-bark

fir {Abies lasiocarpa var. arizonica (Merriam) Lemm.),

forming nearly pure stands at timberline (7).

The spruce-fir type grows in a humid climate with

long, cold winters and short, cool summers. It occupies the

highest, coldest, and wettest forested continental climate in

the western United States, characterized by heavy snowfall

(150 to 400+ inches (3810 to 10 160 mm)), and temperature

extremes of more than -50° F (-45.6° C) to above 90° F

(32.2° C). The range of mean annual temperatures is narrow

considering the wide distribution of the type. Average annual

temperatures are near freezing (30° to 35° F (-1.1° to 1.7°

O), and frost can occur any month of the year. Average

precipitation exceeds 24 inches (610 mm) annually, with

little or no seasonal moisture deficiencies. Summer is the

driest season in the Cascades and in the Rocky Mountains

west of the Continental Divide to southern Colorado. The

northern Rocky Mountains east of the divide, and the

mountains in southwestern Colorado, in southern Utah, and

in New Mexico and northern Arizona receive considerable

summer rainfall (1, 2).

Engelmann spruce, which is the most valuable timber

species of the type, is frequently difficult to regenerate either

naturally or artificially, particularly in openings at high

elevations, lower latitudes, and on southerly aspects. While

spruce is restricted to cold, humid habitats, solar radiation is

high at elevations where spruce grows in the Rocky Mountains.

Newly germinated and planted seedlings are not resistant to

drought or heat girdling; in the central and southern Rocky

Mountains, spruces planted in the open are also frequently

killed by solarization (light injury). Mountain pocket gophers

periodically cause heavy mortality to natural and planted

spruces, and trampling damage can be severe if livestock are

not excluded from newly regenerated areas (3, 10).

Spruce reproduces best in partial shade and on protected

sites, and many old-growth forests have an understory of

advanced reproduction, some of which is spruce. If logging

damage to established regeneration is controlled, these stands

may be managed by removing the overstory and releasing the

advanced growth (3, 4, 9). Where serai species are part of the

original overstory, and a seed source and suitable seedbed

conditions exist, they may regenerate after the overstory is

removed, thus providing an opportunity for mixed species

management in the replacement stand.

In stands without advanced growth, spruce regenerates

from seed provided there is a dependable seed supply, at least

40 percent of the seedbeds are exposed mineral soil, and

environmental conditions are favorable (3, 11). Shade and

other forms of site protection are especially important to early

survival and growth because they lower temperatures, thereby

reducing moisture losses from soil and seedlings.

Engelmann spruce is a moderate seed producer, with

good crops occurring about every 2 to 5 years. The amount of

seed produced is in direct proportion to the basal area of

dominant and codominant spruces of the seed source. Spruce

seed is light and dispersed by wind or gravity, but usually

less than 10 percent of the seedfall is dispersed beyond 3(X)

feet (91 m) from the windward source, except in years of

bumper seed crops when about 5 to 10 percent of the seedfall

may be dispersed as far as 600 feet (183 m) (1, 11). In the

Rocky Mountains, the maximum size opening likely to

restock naturally on shaded mineral soil seedbeds on north

slopes, is 400 to 500 feet (122 to 152 m) wide, and it will

require at least 20,000 sound seeds per acre (49 420/ha) to

produce 1,000 first-year seedlings per acre (2470/ha). On

south slopes, the maximum size opening is only 100 to 200

feet (30.5 to 61.0 m) wide, and it will require at least

100,000 sound seeds per acre (247 100/ha) to produce

1,000 first-year seedlings per acre (2470/ha). Moreover,

adequate stocking will usually require more than one good

seed year. On unshaded and unprepared seedbeds, openings

50 to 100 feet (15.2 to 30.5 m) wide will restock on north

59
slopes, but will require a number of good seed years. On

south slopes under similar conditions, few seedlings survive

in openings. If openings larger than these are cut, the area

beyond effective seeding distance must be planted (3, 10,

11).

Partial cutting is more likely to result in evenly distributed natural reproduction than clearcutting, but it may favor

fir and other more tolerant associates over spruce. While

spruce can be sucessfully regenerated artificially, planting

has been used primarily to fill in gaps where natural regeneration has failed, or to regenerate bums or large areas clearcut

to control insects (4).

At high elevations, the early growth of naturally established spruce and fir is very slow. Trees typically reach 4 to 5

feet (1.2 to 1.5 m) in height in the open or under a light

overstory in about 20 years, and under a moderate overstory

shade in about 40 years. Severe suppression of seedling

growth does occur at low light levels. Trees may be 80 to 100

years old and only 3 to 5 feet (0.9 to 1.5 m) tall under a very

dense overstory. At lower elevations growth is considerably

faster. For example, planted trees in the northern Rocky

Mountain and Intermountain Regions may reach 4 to 5 feet

(1.2 to 1.5 m) in the open in 10 years or less. Once trees

reach this size with sufficient space to grow, their growth rate

will equal or exceed that of their common associates, even

after long periods of suppression (9). Spruce is long-lived

and has the capacity to make good growth at advanced ages.

If given sufficient space, it will continue to grow steadily in

diameter for 300 years, long after the growth of most

common associates slows down. Subalpine firs older than

250 years are rare (1, 2).

Where Engelmann spruce and subalpine fir form the

spruce-fir type, and mountain hemlock and other true firs

are limited in number or absent, spruce is rated shade tolerant

and subalpine fir as very shade tolerant. They are definitely

more shade tolerant than such common associates as Rocky

Mountain Douglas-fir {Pseudotsuga menziesii var. glauca

(Biessn.) Franco), western larch {Larix occidentalis Nutt.),

lodgepole pine, and quaking aspen (Populas tremuloides

Michx.) (7).

The type forms either climax or long-lived serai forest

vegetation throughout much of its range. In the Rocky

Mountains south of Montana and Idaho, spruce and fir are

considered climax species and occur as codominants or in

nearly pure stands of one or the other. In the Rocky

Mountains of Montana and Idaho, and in Utah, eastern

Oregon, and Washington, subalpine fir is the major climax

species. Spruce may occur as a climax, but more often it is a

persistent long-lived serai species. Pure stands of either

species may be found, however (7).

Although spruce-fir forests form climax or near climax

vegetation associations, they differ from most climax forests

in that stands are not generally all-aged. Differences in stand

characteristics complicate the selection of silvicultural systems and cutting methods needed to convert old-growth

forests to managed stands. Some stands are clearly single- or

two-storied, indicating that spruce-fir forests can be successfully grown under even-aged management. Other stands are

three- to multi-storied, indicating that these forests can also

be successfully grown under uneven-aged management (3,5,

8).

Where the type is the climax forest, it is not easily

displaced by other vegetation, but fire, logging, and insects

have played an important part in the sucessional status and

composition of spruce-fir forests. Complete removal of the

stand results in such drastic environmental changes that

spruce and fir are usually replaced by lodgepole pine (the

most ubiquitous and conspicuous of the several serai coniferous species that initially replace spruce-fir), aspen, or

shrub-forb-grass communities unless sites are prepared

and planted to spruce (7, 11). The harshness of the site,

severity of disturbance, and the kind of vegetation initially

occupying the site usually determines the length of time

required to return to a spruce-fir forest. It may vary from a

few decades on cutover, protected sites initially occupied by

lodgepole pine or aspen, to as many as 300 years or more on

high altitude bums where grass is the replacement community (1, 2). Another feature of the spmce-fir forests is the

imbalance in age-class distribution. More stands are in

old-growth sawtimber than in pole or seedling and sapling

stands (3).

Windfall is a common cause of mortality after any kind

of initial cutting in old-growth spmce-fir forests, but partial

cutting increases the risk because the entire stand is opened

up. Windfall is usually less around clearcut openings because

only the boundaries between cut and leave units are exposed,

but losses can be substantial if no special effort is made to

locate windfirm cutting unit boundaries. While the tendency

of spmce and fir to windthrow is usually attributed to a

shallow root system, the development of the roots varies with

soil and stand conditions. Regardless of the kind or intensity

of cutting, or soil and stand conditions, windthrow is greater

on ridgetops, saddles in ridges and upper slopes, and on

upwind aspects than on other topographic exposures (3).

Spmce beetle (Dendroctonus rufipennis (Kirby)) is the

most serious insect pest attacking old-growth Engelmann

spmce (12). Outbreaks have been largely associated with

extensive windthrow. They have also started in cull material

left after logging, and high beetle populations have built up in

scattered trees windthrown after heavy partial cutting where a

cool shaded situation is maintained (3, 12). Subalpine fir is

attacked by several insect pests including bark beetles and

westem spmce budworm in the Rocky Mountains, but the

most destmctive insect is the balsam woolly adelgid (Adelges

piceae (Ratzeburg)), introduced from Europe, which has

virtually eliminated subalpine fir from some stands in the

Pacific Northwest. Wood rot is common in subalpine fir,

especially in residual trees damaged in partial cutting or older

than 100 years (2).

Both even- and uneven-aged silvicultural systems can be

used in spmce-fir forests, but not all cutting methods under

each system are applicable in every stand nor will every

cutting method meet specific management objectives.

Spmce-fir forests are harvested by clearcutting, shelterwood,

and selection cutting. Because of susceptibility to windthrow,

the seed-tree method is not suitable as a regeneration method.

Shelterwood can be standard, modified, or simulated. Modified shelterwood delays the final harvest until the replacement stand is tall enough to provide a forested aspect (at least

4 to 6 ft (1.2 to 1.8 m)). Simulated shelterwood removes the

overstory from a naturally established manageable stand of

advanced reproduction. Selection cutting removes trees singly,

in groups of a fraction of an acre up to 2.0 acres (0.8 ha), or

in a combination of individual tree and group removal (4).

In old-growth spmce-fir forests, if the harvest is

primarily for timber production including the salvage of

decadent stands, and the risks of windfall and/or spmce

beetle attack are high, there is little choice but to clearcut the

area and start a new stand. If management considerations

preclude clearcutting, these stands must usually be left uncut,

mnning the risk of the loss of most of the merchantable sized

trees (3).

If windfall and spmce beetle problems are not limiting,

and management objectives include maintenance of high

forests or the combination of openings and high forests, a

shelterwood method can be used in single- , two- , and even

60
three-storied stands, and a selection system in multi-storied

stands if trees are uniformly spaced. Group selection with

openings of a fraction of an acre up to 2 acres (0.8 ha), or

clearcutting in small (3 to 5 acre (12 to 2.0 ha)) patches

should be used in stands where trees are clumpy, groupy, or

patchy to take advantage of the natural arrangement of trees

(3). The initial entry into any old-growth stand under any

partial cutting method should be light to minimize windfall

losses.

In uncut old-growth spruce-fir forests, current average

annual increment will vary from a net loss due to mortality up

to 200 board feet (fbm) (Scribner Decimal C Log Rule) (40

ft^)* per acre (2.8 m^/ha), depending upon the age and vigor

of the stand. All harvest cutting methods will salvage

mortality, but none of the partial cutting methods are likely to

significantly increase increment on residual trees. However,

few old-growth stands will be managed solely for their tiniber

resource. Manipulation of vegetation for esthetics, recreation,

wildlife habitat and forage, and water production will require

a combination of cutting methods within constraints imposed

by stand conditions, silvical characteristics, windfall risk,

and spruce beetle populations (1, 3). While no spruce-fir

stands have been under management for a long period of

time, the probable growth responses to different stand parameters can be estimated by using the Rocky Mountain Yield

simulation program (RMYLD) (6). In managed even-aged

stands, simulations indicate that with prompt restocking to

600 to 800 stems per acre (1480 to 1975 trees/ha), followed

by periodic thinnings beginning at age 30 years to maintain

proper growing stock levels (GSL), growth and yield and tree

sizes can be substantially increased compared with unmanaged

stands, and time required to produce high volumes and large

sizes reduced. Stands managed at growing stock levels

considered optimum for timber production appear to be most

productive with a 140- to 160-year rotation. For example, at

GSLs 140 to 180, gross mean annual increment is estimated

to vary from 40 cubic feet per acre (2.8 m^/ha) on site index

50 lands (base age 100 years) to 140 cubic feet per acre (9.8

m%a) on site index 100 lands (6). In mixed stands, early

thinning should favor spruce, Douglas-fir, and lodgepole

pine over subalpine fir. Intermediate thinnings should favor

spruce and Douglas-fir over lodgepole pine. These potential

timber yields can be realized by either a clearcut or two-cutshelterwood option, but total yields are likely to be less under

a three-cut or modified shelterwood. Any increases in yields

resulting from reduction in rotation length under a simulated

shelterwood are likely to be offset by the higher proportion of

fir in the replacement stand. Comparable growth rates and

yields should be possible under either individual tree or group

selection alternatives, but some reduction in total yield may

also occur under individual-tree selection if the proportion of

fir is high (4).

In spruce-fir forests, where 90 to 95 percent of annual

streamflow (12 to 15 inches (305 to 380 mm)) results from

melting snow, water production may be increased by clearcutting

openings in the canopy. Size and arrangement of openings is

critical. Largest increases in streamflow (2.0+ inches (51

mm)) result when 30 to 40 percent of a drainage is harvested

in small patches (3 to 5 acres (1.2 to 2.0 ha)) dispersed over

the entire watershed (13). With this pattern, more snow

accumulates in the openings than in adjacent uncut stands.

Cutting openings larger than 5 acres (2.0 ha) may be less

efficient in increasing streamflow because, as opening size

' Cubic foot and metric conversions of measurements expressed in board

feet should be viewed as estimates because of the assumptions involved in

the conversion process.

increases, wind can scour deposited snow causing it to

evaporate into the air or blow into adjacent uncut stands

where consumptive use and recharge requirements are higher.

Group selection cutting can be nearly as favorable for water

production as clearcutting in small patches, but only if

openings are near the maximum size of 2 acres (0.8 ha).

Increase in water available for streamflow under individual

tree selection will be small because consumptive use and

recharge requirements will still be high, and the snow

deposition pattern will be about the same as in an uncut

stand. Standard and modified shelterwood cutting results in

increases similar to individual tree selection as long as the

overstory remains. After final harvest under any shelterwood

alternative, water yield will increase to the level obtained

under patch clearcutting, but the interval of increased water

yield will be less (4). In managed stands, if water production

is the primary goal from stand initiation to final harvest,

spruce-fir stands must be maintained at low GSLs (40 or

less), where timber production will be only about half of the

maximum potential (6).

Spruce-fir forests are summer habitat for big game

animals. Clearcutting and group selection result in the largest

increases in quantity and quality of forage, but game animal

use may be limited by the amount of cover available.

Openings 2 to 20 acres (0.8 to 8.1 ha) are used more by big

game animals in the Rocky Mountains than larger or smaller

openings. Small openings provide little difference in stand

structure, and large openings (more than 40 acres (16 ha))

can cause radical alteration of the microenvironment, often

making tree regeneration difficult. As trees grow into seedling and sapling size (about 20 years), forage production in

openings diminishes but cover increases. Shelterwood cutting provides less forage for big game than cutting methods

that create openings and less cover than the uncut forest.

These reductions vary with the density of the overstory and

length of time it is retained. Individual tree selection provides

forage and cover comparable to uncut forests, thus maintaining one kind of habitat at the expense of creating differences

in stand structure (4). In managed stands, a combination of

cutting methods, growing stock levels, and age classes are

needed to create cover and forage necessary to maintain game

animal populations, but may result in a reduction in timber

production.

The relationship of cutting methods in spruce-fir forests to specific nongame animal habitat requirements is

largely unexplored, but it is possible to estimate some of the

probable effects. Group selection and clearcuts that create

small, dispersed openings in old-growth forests provide a

wide range of habitats for birds and small mammals by

increasing the area supporting nontree vegetation and length

of edge between dissimilar vegetation types while at the same

time providing cover. Shelterwood cutting provides a variety

of habitats attractive to species that forage in stands with

widely spaced trees, but not to those that require closed

forests or fully open plant communities. Under this cutting

method, trees are still available for nesting, denning, and

feeding until final harvest, when plans should require retention of some snags and live trees with cavities. Enthusiasm

for increasing animal diversity by providing habitat diversity

within a treatment area should be tempered with caution.

Managers should maintain some old-growth timber for species that nest or den in large snags or live trees, feed largely

on tree seeds, or require large acreages of continuous mature

forest cover. Because most species have a minimum habitat

size below which they cannot exist, providing small patches

of all ages and stand structures can result in reduction of the

number of species present in a given treatment area. Individual tree selection provides the least difference in horizontal

61
stand structure, and favors species associated with uncut

forests and those that require stands with multi-storied

structure. However, snags and live trees with cavities can be

retained under any cutting method (2).

Much grazing land lies adjacent to or intermingled with

high elevation spruce-fir forests. Under a mature canopy,

forage production for livestock is low and may not be readily

accessible. The quantity and quality of forage increases in

proportion to the amount of canopy removed. Utilization of

available forage is usually greater in large clearcut areas

(more than 40 acres (16 ha)) because forage is more accessible to livestock. Forage production in managed stands can be

maintained only by frequent thinnings and intermediate cuts

that maintain low growing stock levels (GSL 40 to 60) (4,6).

Spruce-fir forests provide a variety of recreation

opportunities. Clearcutting has the greatest visual impact,

and individual tree selection the least. However, variety

typical of forests at the highest elevations—whose texture is

broken by natural opening—is preferred to the monotony of

vast, unbroken forest landscapes at middle and lower elevations.

To enhance amenity values, openings cut for timber and

water production and wildlife habitat improvement should be

a repetition of natural shapes, visually tied together to create

a balanced and unified pattern that will complement the

landscape. This is especially important for openings in the

middleground and background seen from a distance. Modified shelterwood or individual tree selection can be used to

retain a landscape in foregrounds, or small clearcut openings

can be used to create variety. Individual tree selection, group

selection, and modified shelterwood cutting are appropriate

in high-use recreation areas, travel influence zones, scenicview areas, and lands adjacent to ski runs—and also near

support facilities and subdivision developments where permanent forest cover is desired (4).

Literature Cited

1. Alexander, Robert R. Silvical characteristics of Engelmann spruce. Stn.

Pap. 31. Fort Collins, CO: U.S. Department of Agriculture, Forest

Service, Rocky Mountain Forest and Range Experiment Station; 1958

20 p.

2. Alexander, Robert R. Silvical characteristics of subalpine fir. Stn. Pap.

32. Fort Collins, CO: U.S. Department of Agriculture, Forest Service,

Rocky Mountain Forest and Range Experiment Station; 1958. 15 p.

3. Alexander, Robert R. Silviculture of subalpine forests in the central and

southern Rocky Mountains: The status of our knowledge. Res. Pap.

RM-121. Fort Collins, CO: U.S. Department of Agriculture, Forest

Service, Rocky Mountain Forest and Range Experiment Station; 1974

88 p.

4. Alexander, Robert R. Cutting methods in relation to resource use in

central Rocky Mountain spruce-fir forests. J. For. 75(7): 395-400;

1977.

5. Alexander, Robert R.; Edminster, Carieton B. Uneven-aged management of old-growth spruce-fir forests: Cutting methods and stand

structure goals for the initial entry. Res. Pap. RM-186. Fort Collins,

CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain

Forest and Range Experiment Station; 1977. 12 p.

6. Alexander, Robert R.; Edminster, Carleton B. Management ofspruce-fir

in even-aged stands in the central Rocky Mountains. Res. Pap.

RM-217. Fort Collins, CO: U.S. Department of Agriculture, Forest

Service, Rocky Mountain Forest and Range Experiment Station; 1980

14 p.

7. Eyre, F. H., ed. Forest cover types of the United States and Canada.

Washington, DC: Society of American Foresters; 1980. 148 p.

8. Hanley, Donald P.; Schmidt, Wyman C; Blake, George M. Stand

structure and successional status of two spruce-fir forests in southern

Utah. Res. Pap. INT-76. Ogden, UT: U.S. Department of Agriculture,

Forest Service, Intermountain Forest and Range Experiment Station;

1975. 16 p.

9. McCaughey, Ward W.; Schmidt, Wyman C. Understory tree release

following harvest cutting in spruce-fir forests in the Intermountain

west. Res. Pap. INT-285. Ogden, UT: U.S. Department of Agriculture,

Forest Service, Intermountain Forest and Range Experiment Station1982. 19 p.

Noble, Daniel L.; Alexander, Robert R. Environmental factors affecting

natural regeneration of Engelmann spruce in the central Rocky Mountains

For. Sei. 23(4): 420-429; 1977.

Roe, Arthur L.; Alexander, Robert R.; Andrews, Milton D. Engelmann

spruce regeneration practices in the Rocky Mountains. Prod. Res. Rep.

115. Washington, DC: U.S. Department of Agriculture; 1970. 32 p.

Schmid, J. M.; Frye, R. H. Spruce beetle in the Rockies. Gen. Tech.

Rep. RM-49. Fort Collins, CO: U.S. Department of Agriculture,

Forest Service, Rocky Mountain Forest and Range Experiment Station1977. 38 p.

13. Troendle, Charles A.; Leaf, Charies F. Effects of timber harvesting in

the snow zone on volume and timing of water yield. In: David A.

Baumgartner, ed. and comp. Proceedings, Interior West Watershed

Symposium; 1980 April 8-10; Spokane, WA. Pullman, WA: Cooperative Extension, Washington State University; 1981: 231-243.

10

11

12

62
Lodgepole Pine

Robert R. Alexander

Rocky Mountain Forest and Range Experiment Station

James E. Lotan

¡ntermountain Forest and Range Experiment Station

Milo J. Larson

Rocky Mountain Region

Leonard A. VoUand

Pacific Northwest Region

Lodgepole pine, Society of American Foresters forest

cover type 218, occupies about 13 million acres (5.3 million

ha) in the Rocky Mountain and Pacific Coast regions. It

commonly is found in pure or nearly pure stands, but in

mixed stands lodgepole pine may comprise only a plurality of

stocking (6). The timber potential ranges from extremely

poor to very good. These forests also provide watershed

protection, streamflow, forage and cover for wildlife and

livestock, recreational opportunities, and scenic beauty. Many

of the areas occupied by long-lived serai lodgepole pine

stands have the potential for growing other species (1, 6).

Lodgepole pine {Pinus contorta Dougl. ex Loud.) is one

of the most widespread species in the western United States.

It has a remarkable ecological amplitude, growing in many

different environments. In the Rocky Mountains, extensive

stands occur from Montana, Idaho, adjacent eastern Washington and Oregon, south through Utah and Wyoming to

southern Colorado. In the Pacific Coast region, lodgepole

pine grows throughout the Cascades of Washington and

Oregon, south to the mountains of northern California, and

extensively in the Sierra Nevada Mountains (6, 8, 10).

East of the Continental Divide in Montana, and in

Wyoming and Colorado, it grows at elevations between

6,000 and 11,500 feet (1830 to 3500 m). Its most common

associates are Engelmann spruce {Picea engelmannii Parry

ex Engelm.), subalpine fir {Abies lasiocarpa (Hook.) Nutt.),

and interior Douglas-fir {Pseudotsuga menziesii var. glauca

(Biessn.) Franco). West of the divide in the Rocky Mountains,

and in the Pacific Coast region, the inland form occurs from

1,500 to above 9,000 feet elevation (460 to 2740 m), where it

may be either serai to other indigenous tree species or a

topo-edaphic climax in some situations (6, 10).

Because of its wide distribution, lodgepole pine grows

in a variety of climatic situations. In general, the climate can

be characterized by heavy winter snowfall (120 to 250 inches

(3050 to 6350 mm)) at higher elevations and temperature

extremes of -50° F (-45.6° C) at high elevations to above

100° F (37.8° C) at lower elevations in the interior West.

Average annual temperatures are near freezing (32° to 35° F

(0° to 1.7° C)), and frost can occur any month of the year at

high elevations. Average precipitation usually exceeds 18

inches (455 mm) annually but may be as low as 12 inches

(305 mm) in low elevation interior forests. Total precipitation

decreases from west to east, and it is likely to be deficient for

short periods during the growing season west ofthe Continental

Divide. Summer is the driest season west of the divide, while

east of the divide, the Rocky Mountains from Montana to

Colorado receive more summer precipitation (1, 8, 10).

Lodgepole pine is usually not difficult to regenerate

either naturally or artificially. It reproduces naturally from

seed, and initial establishment is usually very good providing

that seedbeds and soil and environmental conditions are

favorable. Although germination is best on bare mineral soil

in full sunlight, first-year seedlings are not always resistant to

drought and heat girdling on hot, dry sites, or to radiation

frost damage or frost heaving in many other situations. On

south slopes and at low elevations in the interior West, and in

many situations in the Pacific Northwest, light overstory

shade benefits initial establishment by reducing daytime

temperatures and conserving moisture loss from soil and

seedlings. Shade also reduces losses from radiation frost, but

overhead shade has little beneficial effect on frost heaving.

Moreover, prolonged overstory shade reduces the growth and

vigor of lodgepole pine seedlings (1, 8, 10).

Lodgepole pine is a prolific seed producer; good crops

are borne every 1 to 3 years with light crops intervening.

Occasional failures do occur, however, so that seed supply

cannot be taken for granted. Lodgepole pine varies greatly in

its cone habit. Nonserotinous (open) cones are common in

Pacific Coast populations. Although the serotinous (closed)

cone habit is widespread in the Rocky Mountains, there are

many stands, particularly in the northern Rocky Mountains,

where less than half of the trees bear serotinous cones. It

cannot be assumed that the cone habit is open or closed; each

stand must be examined.

The cone habit of lodgepole pine has considerable

ecological and silvicultural significance. Large quantities of

seed are stored in closed cones for long periods of time and

are available for regenerating a new stand. This characteristic

is responsible for the ability of lodgepole pine to regenerate

after fire or cutting. These stands are often so dense that most

common associates are at least initially excluded (8, 10).

In stands with largely nonserotinous habit, cones open

when mature and the light seed is shed from standing trees.

Dispersal is by wind and gravity, but only about 10 to 30

percent of the seedfall at timber edge is dispersed into

openings as far as 66 feet (20.1 m), and sufficient seed to

restock cutovers is usually not dispersed more than 150 to

220 feet (45.7 to 67.1 m). The maximum size opening likely

to restock is about 300 to 400 feet (91.4 to 121.9 m) wide,

and it will require at least 50,000 to 100,000 sound seeds per

acre (123 500 to 247 100/ha) to produce 1,000 first-year

seedlings per acre (2470/ ha) on mineral soil seedbeds with

favorable environmental conditions (1). If larger openings

are cut, the area beyond effective seeding distance usually

will have to be planted. There are some exceptions to the size

of opening likely to restock naturally, however; for example,

in the intermountain region, much larger openings cut for

mountain pine beetle control have restocked, but this circumstance is not the normal occurrence in stands with nonserotinous

cones. Seedfall from nonserotinous cones is also important as

a means of restocking lodgepole pine along road cuts and

other rights-of-way as well as maintaining lodgepole pine in

mixed stands (1, 8, 10).

In stands with a large proportion of serotinous cones,

seed dispersal is from cones attached to the logging slash and

cones knocked from the slash and scattered on the forest

floor. Maximum seed release usually takes place the first

year as soon as temperatures are high enough to open the

cones. Successful natural regeneration is generally a one-shot

opportunity. How the slash is handled in seedbed preparation

and/or disposal is important because the seed supply is in the

63
slash-borne cones. There is considerable choice in the size

and shape of openings that will restock in these stands (1,8,

10).

The early growth of lodgepole pine is related to stand

density, overstory shade, and competing vegetation. In

fully-stocked stands in the absence of overstory shade and

competing understory vegetation, lodgepole pine will initially outgrow most of its common associates. It will reach 4

to 5 feet (1.2 to 1.5 m) in height in about 5 to 15 years and 15

to 25 feet (4.6 to 7.6 m) in 20 to 25 years. In severely

overstocked stands, under a dense overstory or in the

presence of severe vegetative competition, both diameter and

height growth are severely suppressed. Lodgepole pine is not

as long lived as some common associates. At low elevations

in northern Idaho and in the Pacific Northwest, stands begin

to deteriorate in about 100 years, and elsewhere in the Rocky

Mountains in 200 to 300 years. However, in the Sierra

Nevada Mountains, some stands may persist for 400 years (8,

10).

Lodgepole pine is very shade intolerant, more so than

any common associate except western larch (Larix occidentalis

Nutt.). In spite of this shade intolerance, it does not thin itself

well when established in overly dense stands as commonly

occurs. Thus, too many trees persist for long periods of time

(up to 100 years), and artificial thinning is required if these

stands are to produce usable wood products (1, 8, 10).

Throughout much of its range lodgepole pine is an

aggressive pioneer onto sites disturbed by fire, logging, or

overgrazing. It plays a minor serai role when a component of

stands with a mixed overstory composition, and it is usually

replaced by more tolerant associates in 50 to 100 years. It is

dominant serai when it is the principal overstory component

of stands with a vigorous understory of more tolerant

associates that will ultimately replace lodgepole pine in 100

to 200 years (7, 10). Where lodgepole pine stands are the

result of catastrophic fires, it is persistent serai because there

is no seed source for the normal replacement species. Where

lodgepole pine is the only available species capable of

growing in a particular environment, it is a self perpetuating

climax (1, 10).

The lodgepole pine type is generally considered to be a

pure, even-aged, single-storied, overly dense forest, varying

in age from place to place but uniform in age within any

given stand. This is true only where favorable fire, seed, and

climatic conditions once combined to produce a large number

of seedlings at one time. However, lodgepole pine may occur

in virtually any age or stand configuration as a result of

meadow invasion, past silvicultural treatments, scattered

trees that produced seed for subsequent stand development,

or the gradual deterioration of even-aged, old-growth stands

(1).

In mixed stands at higher elevations, the overstory can

be pure lodgepole pine, or lodgepole pine. Engelmann

spruce, subalpine fir, whitebark pine {Pinus albicaulis Engelm.),

or mountain hemlock (Tsuga mertensiana (Bong.) Carr.),

and at low elevations, lodgepole pine, western white pine

{Pinus montícola Dougl. ex D. Don), ponderosa pine (Pinus

ponderosa Dougl. ex Laws.), western larch, Douglas-fir,

grand fir (Abies grandis (Dougl. ex D. Don) Lindl.), or

western redcedar (Thuja plicata Donn ex. D. Don). The

climax or more tolerant species are generally in the understory.

Advanced reproduction of associated species will respond to

release when the overstory is removed (1, 6).

Lodgepole pine is susceptible to windthrow after cutting.

Partial cutting increases the risk because the entire stand is

opened up, whereas only the boundaries between cut and

leave units are vulnerable after clearcutting. Losses can be

substantial after clearcutting, however, if no special effort is

made to locate windfirm boundaries. While the tendency to

windthrow is frequently attributed to a shallow root system,

the development of the root system varies with soil and stand

conditions. Regardless of how stands are cut or the soil and

stand conditions, the risk of blowdown is greater on some

topographic exposures than others (1).

Mountain pine beetle (Dendroctonus ponderosae Hopkins)

is the most serious insect pest of lodgepole pine. In the Rocky

Mountains, stands most susceptible are over 80 years of age,

on good sites, with a low enough density that a substantial

number of trees are 12 inches (30 cm) in diameter at breast

height (d.b.h.) and larger, with phloem thickness of at least

0.1 inches (2.5 mm), at elevations where temperatures are

high enough for brood development. Generally Rocky

Mountain stands with trees less than 14 inches (36 cm) d.b.h.

will not support an attack, and trees smaller than 6 inches (15

cm) d.b.h. are not usually killed (4, 5). However, these

limits change with elevation and latitude. For example, at

low elevations on good sites mountain pine beetle is able to

maintain epidemic populations in trees smaller than 14 inches

(36 cm) d.b.h. The pine engraver (Ips pini (Say.)) is a

potentially dangerous pest; populations build up in logging

slash or fire-scorched trees and emerge to attack and weaken

or kill trees (10). The lodgepole needleminer (Coleotechnites

milleri (Busck)) is a serious pest in the Sierra Nevada

mountains (9).

Dwarf mistletoe (Arceuthobium americanum Nutt. ex

Engelm.) is the most serious disease affecting lodgepole

pine, with over 50 percent of the stands in the Rocky

Mountains infected to some degree. The disease reduces

diameter and height growth, seed production, and vigor. The

mortality rate depends largely on the age of the host when

attacked. Dwarf mistletoe is most damaging in stands partially opened up by cutting, bark beetles, or windthrow, and

of least consequence on regenerated bums following catastrophic fires (1, 8, 10). Stem cankers caused by rust fungi

also attack lodgepole pine. Comandra rust (Cronartium

commadrae Pk.) and western gall rust (Peridermium harknessii

J. P. Moore) are the most serious in terms of growth and

mortality losses (1, 8, 10).

Although an even-aged silvicultural system is preferred

for lodgepole pine, both even-aged and uneven-aged systems

can be used to regenerate lodgepole pine. But, not all cutting

methods under each system are applicable in every stand.

Moreover, some cutting methods cannot be used in lodgepole

pine forests under most circumstances. The only unevenaged method of cutting that can be used is group selection,

and then only where management objectives include the

combination of small openings and high forests, and mountain pine beetle and dwarf mistletoe problems are minimal

(2). Individual tree selection should not be used to perpetuate

lodgepole pine. The even-aged methods include clearcutting

and shelterwood cutting. Seed-tree cutting is usually not

applicable as a regeneration method because of susceptibility

of residual trees to windthrow. Shelterwood cutting can be

standard, modified, or simulated. Modified shelterwood

delays the final harvest until the understory is large enough

(at least 4 to 6 feet (1.2 to 1.8 m)) to provide a forested

appearance, and is applicable only in areas where timber

production is not the primary concern and dwarf mistletoe

infection is low. Simulated shelterwood removes a pine

overstory from an established and manageable stand of

advanced reproduction of more tolerant associates (1, 7, 8).

In overmature old-growth stands of lodgepole pine

heavily infected with dwarf mistletoe and where the risks of

windthrow and mountain pine beetle attacks are high, there is

little choice but to clearcut the area and start a new stand.

Where dwarf mistletoe control is a primary consideration,

64
there is no advantage to cutting openings larger than 20 to 40

acres (8.1 to 16.2 ha) to reduce the proportion of perimeter to

opening. Small patch clearcuts can be used to create a mosaic

of different size and age classes where the probability of

mountain pine beetle attack is high. Openings larger than 40

acres (16.2 ha) may have to be cut in stands actually

sustaining a beetle attack. If management considerations

preclude clearcutting, the alternatives are limited. Stands can

be left uncut, running the risk of the loss of the merchantable

stand to bark beetles and dwarf mistletoe. Partial cutting that

removes the trees 10 inches (25 cm) and larger at d.b.h. will

help in regulating losses to mountain pine beetle in stands

with a good stocking of trees in the small diameter classes,

but may leave a dwarf mistletoe infected stand or a stand with

limited future economic options (1, 4, 5).

When management considerations include the combination of high forests and openings, and/or when sites are

difficult to regenerate, a mix ofstandard two-step shelterwood,

simulated shelterwood, and group selection methods can be

used so long as windfall, mountain pine beetle, and dwarf

mistletoe problems are not limiting.

In unmanaged, overmature stands, current average annual growth will vary from a net loss due to mortality up to

40 board feet (fbm) (Scribner Decimal C Log Rule) (8.0

cubic feet)^ per acre (0.6 m%a) to yields of about 2,400 to

3,200 cubic feet per acre (168.0 to 224.0 m^a). Partial

cutting may prevent mortality in these stands, but it is not

likely to increase growth of residual trees. In unmanaged,

thrifty stands less than 150 years old, average annual increment may be as high as 150 fbm (30 cubic feet) per acre (2.1

m^/ha), and the potential for maintaining this growth is high

under a two-cut shelterwood (1, 7, 10).

Many second-growth stands of lodgepole pine, originated after fires or cutting, are overly dense and in need of

thinning before stagnation occurs. Age and level of thinning

depends upon density, site quality, and management objectives.

Stands older than 60 to 70 years with 2,000 to 3,000 stems

per acre (4940 to 7410/ha) are not likely to respond sufficiently to produce usable products in a reasonable amount of

time. Stands with more than 4,000 stems per acre (9880/ha)

should be thinned no later than age 30 years (1, 3, 8).

While no lodgepole pine stands have been under management for a long period of time, the probable growth responses

to different stand parameters can be estimated by using the

Rocky Mountain Yield Simulation program (RMYLD) (3).

In managed stands, simulations indicate that with prompt

restocking to 800 to 1,200 stems per acre (1980 to 2970/ha)

followed by periodic thinnings beginning at age 30 years to

maintain proper growing stock levels (GSL), growth and

yield and tree sizes can be substantially increased, while

reducing the time required to produce high volumes and large

sizes. Stands managed at growing stock levels considered

optimum for timber production in the Rocky Mountains are

most productive with 80- to 120-year rotations. For example,

at GSLs 140 to 160, gross mean annual increment is

estimated to vary from about 45 cubic feet per acre (3.2.

m-^/ha) on site index 50 lands (base age 100 years) to 105

cubic feet per acre (7.4 m-^/ha) on site index 80 lands (3). In

some Pacific Northwest environments, maximum timber

production occurs at lower stem densities. Mean annual

increment will vary from less than 20 cubic feet per acre (1.4

m^/ha) on site index 50 lands to 80 cubic feet per acre (5.6

m-^/ha) on site index 85 to 90 lands.

' Cubic foot and metric conversions of measurements expressed in board

feet should be viewed as estimates because of the assumptions involved in

the conversion process.

Highest potential timber yields can be realized under a

clearcutting or a two-cut shelterwood option, providing that

the final harvest with a shelterwood is made within 5 years

after regeneration is established. Comparable growth rates

can be achieved with group selection only if the openings are

near the maximum size (2 acres (0.8 ha)). Total yields will be

less under a modified or three-cut shelterwood. Under

simulated shelterwood, yield increases resulting from reduction in rotation length will be offset by the slower growth of

tolerant species in the replacement stand. Yields will be

considerably less under group selection in situations where

lodgepole pine is difficult to maintain and very small openings are cut.

In high elevation lodgepole pine forests, the proportion

of water yielded to precipitation is high because of the cold

climate, short growing season, and accumulation of overwinter snowpack. Approximately 90 to 95 percent of the water

available for streamflow comes from snowmelt. The most

efficient timber harvest pattern for increasing water yield

(2.0+ inches (50.8-1- mm)) in old-growth forests is to clearcut

about 30 to 40 percent of a drainage in small irregular-shaped

patches about 5 to 8 times tree height in diameter (3 to 5 acres

(1.2 to 2.0 ha)) interspersed with uncut patches of about the

same size. With this pattern, more snow accumulates in the

opening than in adjacent uncut stands. Openings larger than 8

tree heights wide may be less efficient in increasing streamflow

because, as size of opening increases, wind can scour

deposited snow causing it to evaporate into the air or blow it

into adjacent stands where autumn recharge requirements and

évapotranspiration during the growing season are greater.

Group selection cutting can be nearly as favorable for water

production as patch clearcutting, but only if openings are

near the maximum size. Standard and modified shelterwood

result in small increases as long as the overstory remains.

After final harvest under any shelterwood alternative, water

yield will increase to the level obtained under patch clearcutting,

but the interval of increased water yield will be less. If water

production is the primary goal in stands managed from

initiation to final harvest, lodgepole pine stands must be

maintained at low GSL (40 or less). At these growing stock

levels, timber production may be only about half of the

maximum potential (3, 11).

Understory vegetation in lodgepole pine forests is potentially important as forage for big game and livestock, but

production varies widely. In dense stands, there is little or no

understory vegetation. As the overstory decreases, forage

production increases, reaching maximum in recently clearcut

openings or bums. Forage production, changes in species

composition, and palatability vary considerably, depending

upon the plant community and successsional stage. The

increase in forage production in openings usually persists for

about 10 to 20 years before competition from tree reproduction begins to reduce understory vigor and composition. It

can be maintained only by frequent thinnings and intermediate cuts that keep growing stock levels low (3, 8).

Biotic diversity is generally low in old-growth lodgepole

pine stands, but these forests provide habitat for a variety of

game and nongame animals. Openings created by clearcutting

and group selection can greatly benefit big game if a balance

between forage and cover is maintained. Dispersed openings

2 to 20 acres (0.8 to 8.1 ha) are used more by big game than

are larger or smaller openings. Small openings provide little

difference in stand structure or forage, and large openings

(more than 40 acres (16 ha)) can cause radical alteration in

habitat, especially if coupled with extensive site preparation

and tree planting. As trees grow to seedling and sapling size,

forage production in openings decreases, but cover increases

until it reaches maximum in immature to mature stands.

65
depending upon location (3). Shelterwood cutting provides

less forage for big game than cutting methods that create

openings, and less cover than the uncut forest. In managed

stands, a combination of cutting methods, growing stock

levels, and age classes provide forage openings and hiding

cover necessary to maintain game animal populations (2).

Clearcutting and group selection create small dispersed

openings (2 to 5 acres (0.8 to 2.0 ha)) and provide a wide

range of habitats for birds and small mammals. The area

supporting nontree vegetation and length of edge between

dissimilar stand conditions are increased while at the same

time providing cover. Shelterwood cutting provides a variety

of habitats attractive to nongame species that forage in stands

of widely spaced trees, but not those that require closed

forests or fully open plant communities. Under this cutting

method, trees are still available for nesting, denning, and

feeding until final harvest, when consideration should be

given to leaving some of the snags and trees with cavities.

Attempts to increase animal diversity through stand structure

modification should be tempered with caution. Managers

should maintain areas of old-growth for species that nest,

den, or feed in snags or large live trees or require large areas

of mature forest cover. Most nongame species have a

minimum habitat size below which they cannot exist. Small

patches of varying ages and structures and all-aged stands

may reduce the number of species.

Lodgepole pine forests provide a variety of recreational

opportunities. Clearcutting has the greatest visual impact,

and partial cutting methods the least. However, the variety

typical of forests at high elevations—whose texture is broken

by natural openings—is preferred to the monotony of vast,

unbroken forest landscapes common to lodgepole pine forests.

To enhance q^menity values, harvested openings should

emulate natural shapes. These openings should be visually

blended to create a balanced and unified pattern that will

complement the landscape. This is especially important for

openings in the middleground and background seen from a

distance. Modified shelterwood can be used to retain a

landscape in foregrounds, or small clearcut openings can be

used to create variety. Group selection and modified shelterwood

cutting are appropriate in high-use recreation areas, travel

influence zones, scenic-view areas, lands adjacent to ski run

support facilities, and subdivision developments where permanent forest cover is desired (2, 3).

Literature Cited

1. Alexander, Robert R. Silviculture of subalpine forests in the central and

southern Rocky Mountains: The status of our knowledge. Res. Pap.

RM-121. Fort Collins, CO: U.S. Department of Agriculture, Forest

Service, Rocky Mountain Forest and Range Experiment Station; 1974.

88 p.

2. Alexander, Robert R. Partial cutting in old-growth lodgepole pine. Res.

Pap. RM-136. Fort Collins, CO: U.S. Department of Agriculture,

Forest Service, Rocky Mountain Forest and Range Experiment Station;

1975. 17 p.

3. Alexander, Robert R.; Edminster, Carleton B. Management of lodgepole

pine in even-aged stands in the central Rocky Mountains. Res. Pap.

RM-229. Fort Collins, CO: U.S. Department of Agriculture, Forest

Service, Rocky Mountain Forest and Range Experiment Station; 1981.

lip.

4. Amman, Gene D.; McGregor, Mark D.; Cahill, Donn B.; Klein,

William H. Guidelines for reducing losses of lodgepole pine to the

mountain pine beetle in unmanaged stands in the Rocky Mountains.

Gen. Tech. Rep. INT-36. Ogden, UT: U.S. Department of Agriculture,

Forest Service, Intermountain Forest and Range Experiment Station;

1977. 19 p.

5. Cole, Walter E.; Amman, Gene D. Mountain pine beetle dynamics in

lodgepole pine forests Part I: Course of an infestation. Gen. Tech. Rep.

INT-89. Ogden, UT: U.S. Department of Agriculture, Forest Service,

Intermountain Forest and Range Experiment Station; 1980. 56 p.

6. Eyre, F. H., ed. Forest cover types of the United States and Canada.

Washington, DC: Society of American Foresters; 1980. 148 p.

7. Lotan, James E.; Cochran, P. E.; Frykman, Joel L. Lodgepole pine. In:

Choices in silviculture for American Forests. Washington, DC: Society

of American Foresters; 1981: 46-53.

8. Lotan, James E.; Perry, David A. Ecology and regeneration of

lodgepole pine. Agrie. Handb. 606. Washington, DC: U.S. Department

of Agriculture; 1983. In press.

9. Struble, George R. Biology, ecology and control of the lodgepole

needle miner. Tech. Bull. No. 1458. Washington, DC: U.S. Department of Agriculture; 1972. 38 p.

10. Tackle, David. Silvics of lodgepole pine. Misc. Pub. No. 19. Ogden,

UT: U.S. Department of Agriculture, Forest Service, Intermountain

Forest and Range Experiment Station; 1961. 24 p.

11. Troendle, Charies A.; Leaf, Charles F. Effects of timber harvesting in

the snow zone on volume and timing of water yield. In: Baumgartner,

David A., ed., comp. Proceedings, Interior West Watershed Symposium;

1980 April 8-10; Spokane, WA. Pullman, WA: Cooperative Extension,

Washington State University; 1981: 231-243.

66
Mixed Conifers, Western White Pine, and Western Redcedar

Russell T. Graham and Charles A. Wellner (retired)

Intermountain Forest and Range Experiment Station

Roger Ward

Northern Region

The mixed conifer, western white pine, and western

redcedar forest cover types Hsted by the Society of American

Foresters (2), types 215 and 228, occupy about 5 milUon

acres (2.0 million ha) in the Northern Rocky Mountains. The

type is found in western Montana, northern Idaho, eastern

Washington, northeastern Oregon, and adjacent parts of

British Columbia. Topography is characterized by massive

mountains with deep V- and round-bottomed valleys. Elevations vary from 1,500 feet (460 m) to 6,000 feet (1830 m).

Stream erosion in addition to mountain and continental

glaciation has shaped the landscape of the area. Soil depths

range from 4 inches (10 cm) to 90 inches (229 cm) and have

developed from a variety of base rocks; including granite,

basalt, and sedimentary. Soils of the region are Inceptisols

capped with a layer of loess; soils are frequently covered by

layers of volcanic ash.

The climate is characterized by dry summers with the

majority of the precipitation falling during the fall, winter,

and spring (6). Precipitation averages between 28 inches (710

mm) and 60 inches (1525 mm). Snowfall averages 103 inches

(2600 mm) with totals up to 244 inches (6200 mm) recorded

at higher elevations. Temperatures average between 40° and

50° F (4.4° to 10.0° C) with lows of -40° F (-40° C) and

highs of 107° F (41.7° C) recorded. Below-freezing temperatures may occur in any month. Because of local topographic

features, frost pockets are common. Although frost damage

is usually limited to young trees, sudden drops in temperature

occasionally cause damage to mature trees. Wind velocities

are generally low, but occasional high winds can cause

extensive windthrow. The dry summers frequently result in

drought damage to both natural and artificial regeneration.

The mixed conifer, western white pine, and western

redcedar cover types include those areas where western white

pine (Pinus montícola Dougl. ex D. Don) is a major serai

species. Numerous cover types recognized by the Society of

American Foresters are included (2). The more important

species that occur include grand fir (Abies grandis (Dougl. ex

D. Don) Lindl.), subalpine fir (A. lasiocarpa (Hook. Nutt.),

western white pine, lodgepole pine (Pinus contorta Dougl.

ex Loud.), ponderosa pine (P. ponderosa Dougl. ex Laws,

var. ponderosa), western larch (Larix occidentalis Nutt.),

western redcedar (Thuja plicata Donn ex D. Don), western

hemlock (Tsuga heterophylla (Raf.) Sarg.), Douglas-fir

(Pseudotsuga menziesii (Mirb.) Franco), and Engelmann

spruce (Picea engelmannii Parry ex Engelm.). The type

includes the Tsuga heterophylla and Thuja plicata habitat

type series, and those portions of the Abies grandis, Abies

lasiocarpa, and Tsuga mertensiana series where western

white pine grows (1). The tree species occurring in the type

have a wide range of shade tolerance (6) and vary in drought

tolerance and frost resistance (8).

Species in the type vary widely in seed production and

dissemination. Western redcedar and western hemlock produce larger and more frequent seed crops than most of their

associated species (6). The interval between good seed crops

in western larch is highly variable and is often greater than 10

years. The remaining tree species usually produce good seed

crops at intervals less than 5 years. Wind plays a major role

in seed dissemination. Only lodgepole pine exhibits cone

serotiny, and it is variable within the type. Seedling germination,

survival, and initial growth also vary by species. Bare

mineral soil and burned-over mineral soil tend to favor

germination of the tree species. Western hemlock and westem redcedar usually have high germination rates; Douglasfir, ponderosa pine, western white pine, and lodgepole pine

have intermediate rates; and western larch and grand fir have

low rates. Western hemlock, mountain hemlock, western

redcedar and subalpine fir occasionally reproduce vegetatively.

This regeneration is as important as reproduction from seed

in high-density western redcedar stands (8).

For species in the type, response to release after periods

of crowding or suppression is directly related to the length

and vigor of the crown. Generally, shade-tolerant species

respond well to release after suppression and intolerant

species respond poorly. Lodgepole pine, which often regenerates prolifically, is prone to stagnation early in its development,

making later release cuttings ineffective.

Much of the type has higher-than-average potentials for

timber production compared to other types in the Rocky

Mountains. In fully stocked, even-aged stands at culmination,

mean annual increment can reach 150 cubic feet per acre (10.5

m^/ha) per year with an average potential of 80 cubic feet per

acre (5.6 m^/ha) per year (5). Actual growth falls below the

potential because of losses due to diseases, insects, and

weather. Depending on site quality, stand density, species

composition, and objectives of management, rotation lengths

range from 50 to over 150 years. On an excellent site at age

50 years, 4,830 cubic feet per acre (338.1 m^/ha) is the

expected yield in fully stocked normal stands and at age 150

the expected yield is 18,100 cubic feet per acre (1267.0 m^^/ha)

(5).

Forest insects are a major factor in management (4).

Western hemlock and western redcedar are the most resistant

to insect attack. All sizes of grand fir and subalpine fir are

subject to damage by the Douglas-fir tussock moth (Orgyia

pseudotsugata (McDunnough)) and western spruce budworm

(Choristoneura occidentalis Freeman). Subalpine fir is often

killed by Dryocoetes spp. throughout the type. The spruce

budworm also affects cone production of Douglas-fir, grand

fir, and western larch. Grand fir is often damaged by the fir

engravers (Scolytus spp.). The introduced pest, larch casebearer

(Coleophora laricella (Hubner)), defoliates western larch

trees causing growth reduction; this affects their rapid growth

advantage over slower growing competitors. It may partially

account for poor seed production. Most often mature lodgepole,

ponderosa, and western white pine, are often heavily damaged by the mountain pine beetle (Dendroctonus pseudotsugae

Hopkins).

A number of diseases cause serious damage (7). The

most devastating is white pine blister rust (Cronartium

ribicola Fisch.), which has caused extensive mortality in all

sizes and ages of western white pine. Because tree-breeding

67
programs have developed western white pine resistant to

blister rust, and because the level of natural resistance in

young stands is steadily increasing, western white pine is

manageable. The dwarf mistletoes (Arceuthobium spp.) occur on lodgepole pine, ponderosa pine, western larch, and

Douglas-fir, causing considerable growth loss. Other than

heart rots, western hemlock, western redcedar, and grand fir

have minimal disease problems. Root diseases, especially

Armillariella mellea (Vahl. ex Fr.) Karst., Phellinus weirii

(Murr.) Gilb., and Heterobasidium annosum (Fr.) Bref.,

attack all tree species in the type and are most damaging to

Douglas-fir and grand fir on drier sites. The pines and

western larch show some tolerance to root diseases; conversion to these species is a preferred alternative in stands with

root disease problems. Diseases cause growth reduction and

mortality, interfere with cone production, and cause infected

trees to be more susceptible to attack by other damaging

agents. When young, all species of the type are easily killed

by fire. However, mature and overmature trees exhibit

differences in fire resistance by species (8). Western larch,

ponderosa pine, and Douglas-fir, are the most fire resistant

species. Grand fir, lodgepole pine, western white pine, and

western redcedar are intermediate in tolerance to fire damage,

and the remaining species are very susceptible. Historically,

serai species such as western white pine, lodgepole pine, and

western larch have regenerated as a result of fire. Fire is a

useful tool for slash disposal and site preparation.

Management of the type has become more responsive to

nontimber uses and values. Silvicultural treatments give

consideration to watershed conditions, wildlife habitat, forage for livestock, esthetic values, and rare animals and

plants, as well as timber production. Providing for nontimber

uses and values usually requires a reduction in timber

production.

Choice of a silvicultural system in the type depends on

objectives of management, stand conditions, species requirements (3), and other forest uses. Although even- and unevenaged silvicultural systems are used, even-aged systems have

the widest application. Even-aged management is more

applicable when regeneration of the shade-intolerant species

is desired. Uneven-aged management is applicable where a

continuous forest cover is desired (9) and the preferred

species are shade tolerant.

Single tree selection, though little used to date, could be

a useful method in certain situations in the type. This

regeneration method will create stands with high proportions

of shade-tolerant species. Individual tree selection is applicable in stands that may require continuous forest cover such as

along stream courses or in sensitive viewing areas. Individual

tree selection is best applied in stands that already have

several age classes, resulting from past natural or cultural

activities. The group selection method has advantages for

certain situations. It provides conditions for incorporation of

intermediate and shade-intolerant species in selection stands.

Slash disposal can be accomplished by broadcast burning,

hand work, or mechanical means. The smaller the opening,

the larger the proportion of regeneration from tolerant species.

Planting of the site with improved stock is possible, if

desired. The method can be used to favor elk and deer use or

where snowmelt needs to be carefully controlled. Group

selection can, to some extent, reduce disease problems by

species conversion. Although site preparation and slash

disposal can be achieved using group selection, the costs are

greater, and the risks of using fire are much greater, than with

the clearcut system.

Both individual and group selection methods are difficult to apply in forests which have resulted from fire and tend

to be more even-aged than all-aged. The methods do not

necessarily preclude the need for stocking control in the

smaller diameter classes to meet the desired stand structure.

Both the individual and group selection methods require

more planning, are silviculturally difficult to apply, are more

expensive, and are more difficult to regulate than even-aged

methods.

The shelterwood regeneration method is applicable on

all aspects and slopes, but is especially suited to the steep,

dry slopes in the type. Overwood densities used in the

method range from 15 to 40 trees per acre (37 to 90/ha).

Cool, moist slopes need less shelter to achieve regeneration.

The greater the number of trees left in the overwood, the

greater will be the proportion and number of tolerant species

regenerated. Because of the wide range of fire resistance of

the species present, slash disposal and site preparation may

be difficult and expensive. Vigorous trees should be left in

the overwood to withstand the shock of release and act as

good seed producers. When an adequate amount of regeneration is achieved, the overstory should be removed promptly.

The shelterwood method offers a gradual regeneration period

in areas sensitive because of recreation or esthetic values.

Stocking control is frequently needed to maintain desired

number of trees and the desired species composition. As with

all even-aged methods, stocking control should be delayed

until dominance is well expressed and the young stand is tall

enough to minimize ingrowth of tolerant species.

The seed-tree method can be applied on all slopes and

aspects, but best results are achieved on northerly aspects. As

in the shelterwood method vigorous, wind-firm trees should

be left as seed trees. Four to six trees per acre (10 to 15/ha) are

adequate for seed production for the species in the type. If

possible, site preparation should coincide with a seed crop in

the overstory. The seed trees should be removed as soon as

possible after regeneration. Again, stocking control is usually

needed to maintain the desired number and species composition in the regenerated stand. The seed-tree method is better

than shelterwood for increasing forage for livestock, and for

grazing and browsing by big game.

The clearcut regeneration method is the easiest to apply

in the type and is often the most applicable. It is well suited

for species conversion when required because of disease or

insect problems. Also, planting of improved stock from

breeding programs is facilitated by the clearcut method.

Disposal of fuels and site preparation can be accomplished by

broadcast burning or by mechanical means on suitable

slopes. Even without an overstory seed source, small, patch

clearcut units on flats and northerly aspects can be regenerated by seed from surrounding uncut stands. Thinning or

release treatments may be needed as the stand develops.

Clearcutting is used on all slopes and aspects, but southerly

slopes, especially steep slopes, are usually difficult to regenerate either artificially or naturally. These slopes are prone to

heavy brush development and animal damage to regeneration.

In addition, surface temperature and available soil moisture

tend to be more critical. These factors make other regeneration methods preferred. If clearcutting is used on such slopes

cutting unit should be small (2 to 5 acres or 0.8 to 2.0 ha) to

provide as much protection as possible for regeneration. If

progressive clear-strip cuttings are used, they should be

limited to no wider than one tree height and oriented to

provide maximum protection from the elements. Clearcutting

provides the most latitude for watershed manipulation and for

forage production for both livestock and big game, but has

disadvantages, especially in terms of esthetics.

Intermediate cuttings are being used more often as part

of the even-aged system. Commercial thinnings are used

frequently, and salvage cutting can utilize trees that are

seriously damaged. Liberation cuttings are often used to

68
release advance regeneration of shade-tolerant species. Intermediate cutting should be planned carefully so they are not

dysgenic nor develop stands dominated by undesirable trees.

The western white pine and associated species cover

type has a wide range of commercial species that offer much

latitude in the silvicultural system used. The serai species

offer fast growth for quality lumber and fiber production,

while the tolerant species offer opportunities for timber

management where other uses require a continuous forest

cover. All recognized silvicultural systems and methods have

applicability in the type, but the local management objectives,

site factors, and feasibility of the treatment must be considered for each stand.

Literature Cited

1. Daubenmire, R.; Daubenmire, Jean B. Forest vegetation of eastern

Washington and northern Idaho. Tech. Bull. 60. Pullman, WA:

Washington State University Agricultural Experiment Station; 1968.

104 p.

2. Eyre, F. H., ed. Forest cover types of the United States and Canada.

Washington, DC: Society of American Foresters; 1980. 148 p.

3. Fowells, H. A., comp. Silvics of forest trees of the United States.

Agrie. Handb. 271. Washington, DC: U.S. Department of Agriculture;

1965. 762 p.

4. Fumiss, R. L.; Carolin, V. M. Western forest insects. Misc. Pub. 1339.

Washington, DC: U.S. Department of Agriculture; 1977. 654 p.

5. Haig, Irvine T. Second-growth yield, stand, and volume tables for the

western white pine type. Tech. Bull. 323. Washington, DC: U.S.

Department of Agriculture; 1932. 68 p.

6. Haig, Irvine T.; Davis, Kenneth P.; Weidman, Robert H. Natural

regeneration in the western white pine type. Tech. Bull. 767. Washington,

DC: U.S. Department of Agriculture; 1941. 99 p.

7. Hepting, George H. Diseases of forest and shade trees of the United

States. Agrie. Handb. 386. Washington, DC: U.S. Department of

Agriculture; 1971. 658 p.

8. Minore, Don. Comparative autecological characteristics of northwestem tree species—a literature review. Gen. Tech. Rep. PNW-87.

Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific

Northwest Forest and Range Experiment Station; 1979. 72 p.

9. U.S. Department of Agriculture, Forest Service. Uneven-aged silviculture and management in the United States: A combined proceedings of

two In Service Workshops; 1975 July; Morgantown, WV; 1976 October;

Redding, CA. Washington, DC: U.S. Department of Agriculture,

Forest Service; 1978. 234 p.

69
Southwestern Ponderosa Pine

Frank Ronco, Jr.

Rocky Mountain Forest and Range Experiment Station

Kenneth L. Ready

Southwestern Region

Rocky Mountain ponderosa pine {Pinus ponderosa var.

scopulorum Engelm.) occupies nearly 11 million acres (4.5

million ha) in New Mexico, Arizona, Utah, and Colorado

(19). The variety, which is recognized as type 237 by the

Society of American Foresters (5), grows in the Rocky

Mountains and on canyons, plateaus, breaks, and discontinuous mountain ranges of the plains at elevations up to 10,000

feet (3050 m) in the southern Rocky Mountains (4, 19).

Mostly, however, ponderosa pine in the Southwest lies

between 6,000 and 8,500 feet (1830 and 2590 m) in

elevation, reaching its best development between 7,000 and

7,800 feet (2135 and 2375 m) (19).

Soils on which ponderosa pine may be found are derived

from igneous, metamorphic, and sedimentary materials, and

range in texture from gravels to clay loams (4). About half of

the soils in the Southwest are derived from basalt, while

limestone, sandstone, and shale are common in many localities.

In addition, sizable areas on the Colorado Plateau in Arizona

are covered by cinders up to 5 feet (1.5 m) deep (19).

The climate of ponderosa pine forests in the Southwest

is cool and mostly subhumid (4). Pinyon-juniper or oak

woodlands generally are found in the warm-dry zone below

ponderosa pine, while above, the more mesic mixed conifer,

Douglas-fir, or lodgepole pine forests are situated (5, 19).

Mean annual precipitation varies from about 15 to 25 inches

(380 to 635 mm), depending on location; seasonal distribution also varies. In northeastern New Mexico and along the

east slope of the Rocky Mountains, rainfall is well distributed

throughout the growing season; elsewhere, scant precipitation is received in May and June. Early fall is also dry, but to

a much lesser extent. Low rainfall coupled with low humidities,

clear skies, increasing temperatures, and consistent winds

create severe drought conditions during May and June. In

contrast, July and August are wet. Precipitation at one

northern Arizona station during these months, for example,

was about 80 percent of the May through August total of 7.75

inches (195 mm). Average annual snowfall varies from a low

of 12 inches (305 mm) in the southern portion of the species

range to 94 inches (2390 mm) on the Colorado Plateau. Mean

annual temperatures over the entire southwestern ponderosa

pine type are relatively narrow, ranging from 44° to 52° F

(6.7° to ll.r C), and mean July temperatures are equally

narrow, varying from 64° to 71° F (17.8° to 21.7° C). The

frost-free period is about 135 days, but it varies widely within

the type (19).

Ponderosa pine typically grows in pure stands at elevations where it is climax (5, 18). At higher and lower

elevations, ponderosa pine may be replaced, respectively, by

more mesic or xeric species that have a competitive advantage.

Common associates of ponderosa pine at higher elevations

throughout its southwestern range are Rocky Mountain Douglasfir {Pseudotsuga menziesii var. glauca (Beissn.) Franco),

blue spruce {Picea pungens Engelm.), and quaking aspen

{Populus tremuloides Michx.). In Utah and Colorado, ponderosa

pine grows with lodgepole pine {Pinus contorta var. latifolia

Engelm.) and limber pine {P.flexilis James), while at higher

elevations in New Mexico and Arizona, ponderosa pine is

found with southwestern white pine {P. strobiformis Engelm.),

white fir {Abies concolor var. concolor (Gord. & Glend.)

Lindl. ex Hildebr.), corkbark fir {A. lasiocarpa var. arizonica

(Merriam) Lemm.), and Engelmann spruce {P. engelmannii

Parry ex Engelm.) (5, 10).

In the ecotone with lower woodland or grassland types,

associates of ponderosa pine include Rocky Mountain juniper

{Juniperus scopulorum Sarg.), alligator juniper {J. deppeana

Steud.), Utah juniper {J. osteosperma (Torr.) Little), pinyon

pine {Pinus edulis Engelm.), and Gambel oak {Quercus

gambelii Nutt.) (5).

Cone crops are not produced regularly anyplace over the

entire range of ponderosa pine but, in general, good crops

can be expected every 3 to 4 years in the Southwest (4, 19).

Seedfall varies somewhat, but in Arizona it begins about the

middle of October and is 65 percent complete by the first

week in December (13).

A number of cone and seed insects are harmful, but not

all of them cause serious damage. Ponderosa pine seedworm

{Laspeyresia piperana (Kearf.), ponderosa pine cone beetle

{Conophthorus ponderosae Hopk.), and ponderosa pine

coneworm {Dioryctria auranticella (Grote)) are among the

most important (19).

In some years over 50 percent, and in localized areas

nearly all, of the seed crop may be destroyed by insects (15,

17). The extent of depredation by rodents and birds is not

known, but Abert's squirrels reduced the cone crop in one

study about 21 percent over a 10-year period by clipping

twigs bearing flowers or conelets (13). Seed viability may

also be reduced a similar amount by the impact of southwestem dwarf mistletoe {Arceuthobium vaginatum (Willd.) Presl.

subsp. cryptopodum (Engelm.) Hawks, and Wiens) (19).

Seeds are wind disseminated, but they are relatively

heavy and are not borne far—about 75 percent falls within

120 feet (36.6 m) of the source (2). Spring germination may

be the rule where rain falls in the spring, as on the east side of

the Rocky Mountains in Colorado. Elsewhere, however,

ponderosa pine seeds germinate during the summer rainy

season, or even into August or early September if precipitation is delayed (19). Seedlings resulting from late seed

germination are subject to greater mortality from frost heaving,

fall drought, and an inability to harden-off before winter. The

best seedbed is loose, mineral soil, which tends to cover

seeds lightly as it settles, thus enhancing germination (15,

19).

Optimum seedbed conditions alone, however, will not

insure natural ponderosa pine regeneration, which historically is sporadic in the Southwest. Site preparation to loosen

and expose mineral soil and eliminate grass competition must

coincide with a good supply of seed and adequate moisture

for germination and initial seedling establishment. Protection

from livestock and rodents is also necessary (19). On coarser

textured sedimentary soils in the Southwest, large areas have

been successfully regenerated by meeting all these conditions

(9). Where fine-textured, basaltic soils with a high silt

70
content exist, however, natural regeneration is more difficult

to establish because of the greater probability of frost

heaving.

Once established, ponderosa pine has the ability to

withstand drought (4). It has a vigorous taproot, while lateral

roots also elongate rapidly. Within a few months after seed

germination, taproots can penetrate to 23 inches (58 cm) in

loosened and watered soil, and about half that under natural

conditions (11, 12). Lateral roots can more than double in

length during the second growing season following seed

germination. Furthermore, root growth of planted seedlings

can be appreciable even in relatively dry soil if lifting at the

nursery is timed to insure high root-regenerating potential of

the seedlings (20). The deep-rooting habit of ponderosa pine

imparts a relatively high degree of windfirmness*, except

where shallow soils or high water tables restrict root-system

development (19).

Regardless of root growth capabilities, planted ponderosa

pine seedlings cannot cope with competing vegetation, particularly grasses, during the spring and early summer drought

following spring planting. Grasses that grow best in the cool

season, such as Arizona fescue (Festuca arizonica Vasey),

are especially competitive for moisture during spring and

early summer (15, 19). Some grasses are also phytotoxic to

ponderosa pine seeds and seedlings (16). Therefore, adequate

site preparation by mechanical or chemical means is imperative if planting is to be successful.

Ponderosa pine is classed as shade-intolerant (4). As a

consequence of its need for adequate light, it tends to grow

and is usually managed under even-aged conditions. While

ponderosa pine forests in the Southwest most commonly

appear to be irregular, uneven-aged stands, they essentially

consist of a mosaic of even-aged groups varying in size from

a few trees to several acres (19). Other stands, however, are

essentially even-aged following regeneration of past clearcuttings, bums, and other open areas (18). Although ponderosa

pine seeds germinate best under partial shade, continued

growth and survival are reduced when overhead sunlight is

less than about 50 percent (15, 19). Stagnation is a serious

problem in densely stocked stands and, although growth is

slow, southwestern ponderosa pine remains physiologically

young and will respond to release up to 200 years of age (15).

The four major causes of mortality in southwestern

ponderosa pine are, in decreasing order of importance,

diseases, insects, fire, and windthrow (19). Losses from

lightning, however, may equal those of windthrow in some

areas (15). Under some conditions, windthrow can cause

major losses, as when strong winds, preceded by heavy rains

in areas with shallow soils, blow from the opposite direction

of prevailing winds. While a number of diseases—such as

Atropellis canker (Atropellis piniphila (Weir) Lohm. and

Cash), shoestring root rot (Armillariella mellea (Vahl. ex

Fr.) Karst.), Annosus root rot {Heterobasidium annosum

(Fr.) Bref.), and western root rot {Dichomitus squalens

(Karst.) Reid)—damage or kill trees, the most prevalent and

devastating is southwestern dwarf mistletoe. About one-third

of all commercial forests in the Southwest are infected with

dwarf mistletoe (17, 19).

Many insects also attack ponderosa pine, but the most

destructive is the mountain pine beetle (Dendroctonus

ponderosae Hopkins). At times, engraver beetles, especially

Arizona fivespined ips {Ips lecontei Swaine), and pandora

moth {Coloradla pandora Blake) also can be serious pests

(17, 19). Many insect and disease problems can be lessened

by applying intermediate cuttings, which improve growth

and eliminate susceptible trees (14, 19). Common intermediate cuttings in the Southwest include improvement, sanitation,

salvage, and thinning (19). Improvement and sanitation

cuttings effectively maintain or increase net growth, but their

repeated use could result in understocking or a reduction in

potential snags of value to wildlife.

Older ponderosa pines are resistant to fire because of

thick bark, but younger trees are easily killed (4, 19). Other

damaging agents to seedlings and saplings include southwestem pine tip moth (Rhyacionia neomexicana (Dyar)), rabbits,

hares, pocket gophers and other rodents, and browsing

animals; among the abiotic factors are winter kill, frost

heaving, and snow breakage or bending in dense stands,

especially after thinning operations (19).

Site quality and stand density are major factors controlling growth. Studies have shown that diameter growth in

young stands thinned to growing stock levels of 30 and 150

was 4.6 and 2.2 times greater, respectively, than the prethinning

rate (19).' Average net annual increment on understocked

experimental plots of old-growth timber in central Arizona

ranged from 25 to 93 board feet (fbm) (Scribner Decimal C

Log Rule) (5 to 19 cubic feet)^ per acre (0.4 to 1.3 m-^/ha)

(15). Under intensive even-aged management, in contrast,

estimated annual net growth can be increased to 300 fbm (60

cubic feet) per acre (4.2 m^/ha) or more (1).

Since ponderosa pine forests in the Southwest are

composed of both even-aged and uneven-aged stands, a

combination of even-aged and uneven-aged management is

best suited to maintain present stand stmctures (18, 19).

Furthermore, some uneven-aged stands can be converted to

even-aged, depending on the age or size class distribution of

individual groups. However, a long period may be needed to

convert most stands—perhaps through the remainder of the

present rotation. Conversion, if elected, should be affected

with the least disturbance to growing stock levels (19).

Because of the need to protect seedlings from the harsh

environmental conditions of the Southwest, the most effective means for regenerating even-aged stands is a two-cut

shelterwood, consisting of a seed cut and an overstory

removal cut (18, 19). Some fully stocked stands, however,

may require one or more preparatory cuts to enhance seed

production through crown development, and to develop

windfirmness. Preparatory cuts should remove about 20 to 30

percent of the volume, whereas the seed cut should leave 20

to 40 square feet (4.6 to 9.2 m^/ha) of basal area per acre,

depending on the harshness of the site and the subsequent

need for protection. Seed trees should be good producers,

preferably 20 to 24 inches (51 to 61 cm) d.b.h. The overstory

usually is removed in one cut when seedlings are 1 to 2 feet

(0.3 to 0.6 m) tall to reduce seedling damage during harvest

(19), and to minimize growth retardation (6, 15).

Historically, regeneration success in clearcuttings has

been mixed (15, 19). While some clearcuttings logged during

a good seed year have regenerated successfully, others

generally were converted to grass or bmsh. Because of this

uncertainty, and because better results have been obtained

under the shelterwood system, clearcutting has been little

used in recent years. Similarly, the seed-tree system—successful

in 1913, but with no subsequent reported successes—is not

particularly suitable for ponderosa pine forests (19). However,

where management goals are to increase water yields or other

multiple-use values, clearcutting and planting could be appropriate (3).

' Growing stock level, a numerical index, is defined as the residual square

feet of basal area per acre when average stand diameter is 10 inches d.b.h. or

more. Basal area retained in a stand with an average diameter of less than 10

inches is less than the designated level (1).

^ Cubic foot and metric conversions of measurements expressed in board

feet should be viewed as estimates because of the assumptions involved in

the conversion process.

71
Patch clearcutting is an effective means to control dwarf

mistletoe (7) and such insects as the mountain pine beetle

(14). Clearcuttings larger than a few acres should be planted

immediately after harvesting following established planting

techniques (8, 19). Regeneration by artificial seeding, whether

by drilling, broadcasting, or seed spotting, is less reliable

than planting. Although all have been successful in some

instances, planting is still the preferred method of artificial

regeneration in the Southwest (19).

The selection system can be applied to some stands in

the Southwest to accomplish uneven-aged management objectives (18, 19). Since ponderosa pine is shade-intolerant,

however, individual tree selection is not recommended.

Stands harvested in such a manner most likely would not

regenerate to pine, or would be converted to the more tolerant

component species if any were present. Also, this method

tends to accelerate the spread of dwarf mistletoe in infected

stands (7).

Group selection, in contrast, is an appropriate way to

regenerate stands having a suitable age-size class structure

(18, 19). Under this system, the size of harvested groups

should range from 0.5 to 2 acres (0.2 to 0.8 ha). Slash

treatment in groups of this size, however, will be more

difficult than under even-aged management. Furthermore,

growth of regeneration along the edge of openings will tend

to be reduced because of competition from adjacent groups

(6).

Group selection, and even-aged cutting methods as

well, will increase forage yields where livestock and big

game management is desired (3). Herbage production increases with decreasing stand density from a maximum of

600 pounds per acre (672 kg/ha) in clearings to a minimum of

50 pounds per acre (56 kg/ha) or less under stands with basal

areas between 60 and 100 square feet per acre (13.8 to 23.0

m^/ha) (19).

Abert's squirrels, Kaibab squirrels, bald eagles, and

Merriam's turkeys are important elements of forest wildlife,

and their habitats must be considered when applying any

silvicultural method. Large, mature trees or snags suitable for

squirrel nests, eagle perches and nests, or turkey roosts must

be left in sufficient numbers to provide for these, as well as

other species of wildlife, such as cavity nesters. Similarly,

cover and opening requirements for mule deer, white-tailed

deer, and Rocky Mountain elk are also important considerations in the management of ponderosa pine. Special silvicultural provisions to meet these wildlife needs are probably not

necessary, however, since suitable habitats can be created by

modifying standard cutting methods.

Literature Cited

1. Alexander, Robert R.; Edminster, Carleton B. Management of ponderosa

pine in even-aged stands in the Southwest. Res. Pap. RM-225. Fort

Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky

Mountain Forest and Range Experiment Station; 1980. 11 p.

2. Barrett, James W. Silviculture of ponderosa pine in the Pacific

Northwest: the state of our knowledge. Gen. Tech. Rep. PNW-97.

Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific

Northwest Forest and Range Experiment Station; 1979. 106 p.

3. Brown, Harry E.; Baker, Malchus B., Jr.; Rogers, James J.; Clary,

Warren P. land others]. Opportunities for increasing water yields and

other multiple-use values on ponderosa pine forest lands. Res. Pap.

RM-129. Fort Collins, CO: U.S. Department of Agriculture, Forest

Service, Rocky Mountain Forest and Range Experiment Station; 1974.

36 p.

4. Curtis, James D.; Lynch, Donald W. Ponderosa pine (Pinus ponderosa

Laws.). In: Fowells, H. A., comp. Silvics of forest trees of the United

States. Agrie. Handb. 271. Washington, DC: U.S. Department of

Agriculture; 1965: 417-431.

5. Eyre, F. H., ed. Forest cover types of the United States and Canada.

Washington, DC: Society of American Foresters; 1980. 148 p.

6. Harrington, Michael G.; Kelsey, Rick G. Influence of some environmental factors on initial establishment and growth of ponderosa pine

seedlings. Res. Pap. INT-230. Ogden, UT: U.S. Department of

Agriculture, Forest Service, Intermountain Forest and Range Experiment Station; 1979. 26 p.

7. Heidmann, L. J. Silvicultural control of dwarf mistletoe in heavily

infected stands of ponderosa pine in the Southwest. Res. Pap. RM-36.

Fort Collins, CO: U.S. Department of Agriculture, Forest Service,

Rocky Mountain Forest and Range Experiment Station; 1968. 11 p.

8. Heidmann, L. J.; Larson, Frederic R.; Rietveld, W. J. Evaluation of

ponderosa pine reforestation techniques in central Arizona. Res. Pap.

RM-190. Fort Collins, CO: U.S. Department of Agriculture, Forest

Service, Rocky Mountain Forest and Range Experiment Station; 1977.

10 p.

9. Heidmann, L. J.; Johnsen, Thomas N., Jr.; Cole, Quinten W.; Cullum,

George. Establishing natural regeneration on the Apache-Sitgreaves

National Forest in central Arizona. J. For. 80(2): 77-79; 1982.

10. Jones, John R. Silviculture of southwestern conifers: the status of our

knowledge. Res. Pap. RM-122. Fort Collins, CO: U.S. Department of

Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station; 1974. 44 p.

11. Larson, M. M. Initial root development of ponderosa pine seedlings as

related to germination date and size of seed. For. Sei. 9(4): 456-460;

1963.

12. Larson, M. M.; Schubert, Gilbert H. Root competition between

ponderosa pine seedlings and grass. Res. Pap. RM-54. Fort Collins,

CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain

Forest and Range Experiment Station; 1969. 12 p.

13. Larson, M. M.; Schubert, Gilbert H. Cone crops of ponderosa pine in

central Arizona, including the influence of Abert squirrels. Res. Pap.

RM-58. Fort Collins, CO: U.S. Department of Agriculture, Forest

Service, Rocky Mountain Forest and Range Experiment Station; 1970.

15 p.

14. McCambridge, William F.; Amman, Gene D.; Trostle, Galen C.

Mountain pine beetle. Forest Insect and Disease Leaflet 2. Washington,

DC: U.S. Department of Agriculture; 1979. 7 p.

15. Pearson, G. A. Management of ponderosa pine in the Southwest. Agrie.

Monogr. 6. Washington, DC: U.S. Department of Agriculture; 1950.

218 p.

16. Rietveld, W. J. Phytotoxic grass residues reduce germination and initial

root growth of ponderosa pine. Res. Pap. RM-153. Fort Collins, CO:

U.S. Department of Agriculture, Forest Service, Rocky Mountain

Forest and Range Experiment Station; 1975. 15 p.

17. Rogers, T. J., comp. Forest insect and disease conditions in the

Southwest—1980. Forest Pest Management Report No. R-3 81-6.

Albuquerque, NM: U.S. Department of Agriculture, Forest Service;

1981. 27 p.

18. Schubert, Gilbert H. Southwestern ponderosa pine. In: Silvicultural

systems for the major forest types of the United States. Agrie. Handb.

445. Washington, DC: U.S. Department of Agriculture; 1973: 45-46.

19. Schubert, Gilbert H. Silviculture of southwestern ponderosa pine: the

status of our knowledge. Res. Pap. RM-123. Fort Collins, CO: U.S.

Department of Agriculture, Forest Service, Rocky Mountain Forest and

Range Experiment Station; 1974. 71 p.

20. Stone, Edward C; Jenkinson, James L. Influence of soil water on root

growth capacity of ponderosa pine transplants. For. Sei. 16(2): 230-239;

1970.

72
Southwestern Mixed Conifers

Frank Ronco, Jr., and Gerald J. Gottfried

Rocky Mountain Forest and Range Experiment Station

Richard Shaffer

Southwestern Region

The area covered by southwestern mixed conifer forests

is about 2.0 milHon acres (0.8 million ha) of highlands and

mountains in Arizona, New Mexico, and southwestern Colorado (11). Mixed conifer inclusions are also scattered within

the Interior Ponderosa Pine, Society of American Foresters

forest cover type (type 237) (7), where higher elevations or

topography provide moister sites (12). Most mixed conifer

stands are found between 8,000 feet (2440 m) and 10,000

feet (3050 m), but they may extend below 6,000 feet (1830

m) on north-facing slopes or in canyon bottoms and draws.

A mixed conifer forest in the Southwest may constitute

one of the more complex plant associations known, exhibiting great variation in species composition. While some

stands may consist of only two species, others can be

comprised of as many as eight associates. Overstory species

in these forests include Rocky Mountain Douglas-fir

(Pseudotsuga menziesii var. glauca (Beissn.) Franco), Rocky

Mountain ponderosa pine (Pinus ponderosa var. scopulorum

Engelm.), white fir {Abies concolor var. concolor (Gord. &

Glend.) Lindl. ex Hildebr.), Engelmann spruce {Picea

engelmannii Parry ex Engelm.), quaking aspen {Populus

tremuloides Michx.), southwestern white pine {Pinus

strobiformis Engelm.), blue spruce {Picea pungens Engelm.),

and corkbark fir {Abies lasiocarpa var. arizonica (Merriam)

Lemm.) (12). Subalpine fir (A. lasiocarpa (Hook.) Nutt. var.

lasiocarpa) may replace corkbark fir in Colorado and northem parts of Arizona and New Mexico (2, 12).

Mixed conifer forests grow on nearly every kind of

parent material. While soil types, textures, and species

preferences are highly variable, best growth is on moderately

deep to deep loamy soils where drainage is good (1, 6, 17,

22).

Mixed conifer forests are generally found in cool,

subhumid to humid climatic zones, typically with short

growing seasons, long winters, and moderate to heavy

snowpacks (1, 17). Average annual temperatures vary from

near freezing to more than 43° F (6.1° C), depending on

location (1,2, 18). The frost-free period usually ranges from

about 30 to 120 days, but frost may occur during any month.

Average annual precipitation varies from about 25 to more

than 30 inches (635 to 760 mm), while snowfall may vary

from about 70 to more than 200 inches (1780 to 5080 mm)

(1,5, 18). Spring, early summer, and fall are dry periods in

the Southwest, but the resulting drought conditions are much

less severe in the fall than earlier (12). In contrast, July and

August are wet, with as much as 45 percent of the annual

precipitation falling during this period (21).

Natural reproduction of species in mixed conifer stands

is nearly entirely by seed except for aspen, which reproduces

almost always by root sprouts (1,2, 12). Blue spruce is the

best seed producer, bearing moderate to heavy cone crops

every 1 to 3 years (12, 20), whereas corkbark fir is considered the poorest, with infrequent crops of low yield. Good to

large seed crops are produced by Engelmann spruce every 2

to 5 years and by white fir every 2 to 4 years, although the

latter may be more sporadic (1, 12, 17, 20). Production of

Douglas-fir seed is slightly less than that of Engelmann

spruce (5, 12). Ponderosa pine seed crops are lighter and less

frequent at higher than at lower elevations where good crops

are produced every 3 to 4 years (12, 21). Large crops of

southwestern white pine seed are produced every 3 to 4 years

(15).

Seeds of all the conifers other than southwestern white

pine are wind disseminated (15). Engelmann spruce seeds

cover the greatest distances, as much as 600 feet (182.9 m),

but most of the seed normally falls within 100 feet (30.5 m)

to leeward of the seed source (3). The distance heavier true

fir and Douglas-fir seeds are disseminated is probably even

less, while that of ponderosa pine is the shortest (17). In one

study of a ponderosa pine clearcut, only 22 percent as much

seed was found 120 feet (36.6 m) into the opening as at the

edge of the uncut stand (4). Southwestern white pine seeds,

which are mostly wingless or sometimes vestigially winged,

are disseminated primarily by rodents and birds (12, 15).

Several species of jays and Clark's nutcracker are important

dispersal agents for limber pine {Pinus flexilis James) and,

presumably, for southwestern white pine as well (16).

Except for white fir, corkbark fir, and some southwestem white pine seed that germinates in the spring, germination

of all other species is delayed until the summer rainy season

because of the drought conditions that exist in late spring and

early summer (12). Germination percentages under natural

conditions in the Southwest are not available for mixed

conifer species.

Seedlings of all species are exposed to many hazards

that reduce survival, including voles, pocket gophers, rabbits,

hares, big game, domestic livestock, snowmold {Neopeckia

coulteri (Pk.) Sacc. and Herpotrichia nigra Hartig), and

drought (3, 12). New growth of white fir, corkbark fir, and

Engelmann spmce trees, regardless of age, is killed by

growing-season frosts (3, 17, 19). Furthermore, seedlings of

white fir, Douglas-fir, Engelmann spmce, and especially

corkbark fir are killed or injured by solarization when grown

in full sunlight, but ponderosa pine, southwestem white pine,

blue spmce, and aspen are adapted to full sunlight (11, 12,

19).

The sensitivity of certain species to intense solar radiation is related to their shade tolerance, with the more tolerant

trees being most susceptible to injury. For southwestem

trees, tolerance ratings range from the very tolerant corkbark

fir to the very intolerant aspen (2, 22). Engelmann spmce and

white fir are tolerant, while southwestem white pine and

ponderosa pine are intolerant; blue spmce and Douglas-fir are

rated intermediate (1, 12). Reaction to competition is also a

function of tolerance—suppressed Engelmann spmce, white

fir, and presumably corkbark fir respond to release after

being suppressed for long periods (1, 2, 17). Except for

seedlings and saplings that have been severely suppressed,

Douglas-fir also responds to release, especially in the older

age classes (14). Ponderosa pine tends to stagnate easily in

dense stands (6), but responds well to release. In fact,

diameter growth in a 43-year-old stand of slow-growing trees

73
in Arizona increased up to 4.6 times following thinning (21).

In the Southwest, ponderosa pine remains physiologically

young and will respond to release even up to 200 years of age

(21). Similarly, southwestern white pine can maintain itself

equally well in the presence of other conifers (8), since it

appears to be somewhat more tolerant of shade than ponderosa

pine (12).

Although growth and yield data are available for pure or

nearly pure stands of the individual species comprising mixed

conifer forests, little is known about stands with a mixture of

species. In the Sacramento Mountains of New Mexico, an

old-growth stand of Douglas-fir (61 percent) and associated

species averaged 13,000 board feet (fbm) (Scribner Decimal

C Log Rule) (2,600 cubic feet)^ per acre (182.0 m%a), with

a range of 2,681 to 22,407 fbm (536 to 4,481 cubic feet) per

acre (37.5 to 313.7 m^/ha) (14). Another stand in eastern

Arizona with a total basal area of 178 square feet per acre

(40.9 m^/ha), representing all eight mixed conifer species,

yielded a gross annual basal area increment of 3.07 square

feet per acre (0.7 m^/ha) with a net annual volume growth of

356 fbm (71.2 cubic feet) per acre (5.0 m^/ha) (8). In

general, diameter growth of component species in mixed

conifer stands may be relatively slow because of overstocking;

for example, 12-inch (30-cm) diameter at breast height

(d.b.h.) Douglas-fir trees in one stand averaged 130 years of

age (14).

Because of the number of different species found in

mixed conifer stands, the number of potentially destructive

pests is formidable. Among the most damaging insects are

bark beetles, such as the spruce beetie {Dendroctonus rufipennis

(Kirby)), Douglas-fir beetle {Dendroctonus pseudotsugae

Hopkins), fir engraver {Scolytus ventralis LeConte), Arizona

fivespined engraver {Ips lecontei Swaine), and mountain pine

beetle {Dendroctonus ponderosae Hopkins) (1, 6, 12, 21).

Major defoliators are the western spruce budworm {Choristoneura occidentalis Freeman) on Douglas-fir, Engelmann

spruce, corkbark fir, and white fir (1, 2, 5, 17); Douglas-fir

tussock moth {Orgyia pseudotsugata McDunnough) on corkbark

fir, white fir, and Douglas-fir (12, 17); and the western tent

caterpillar {Malacosoma californicum (Packard)) on aspen

(12, 22). Many other foliage, cone, and seed insects present

in mixed conifer stands cause varying amounts of damage.

Dwarf mistletoes pose the most difficult disease problem in mixed conifer forests; especially serious are Douglasfir dwarf mistletoe {Arceuthobium douglasii Engelm.) and

southwestern dwarf mistletoe (A. vaginatum (Willd.) Presl.

subsp. cryptopodum (Engelm.) Hawks, and Wiens) (9, 12).

All coniferous species in mixed conifer stands are infected by

dwarf mistletoes, but the amount of damage caused by the

disease, while generally limited, may be locally severe.

Other major diseases are fungal trunk and root rots, which

affect all tree species.

Aside from direct damage, rots also contribute substantially to windthrow by weakening roots and stems. Most

wind losses, however, are primarily a function of rooting

habits and soil and topographical features; certain soil conditions decrease root-system depths, while topography influences wind behavior (12). Trees with deep tap roots, such as

ponderosa pine, Douglas-fir, and southwestern white pine,

are generally windfírm (6), whereas white fir, corkbark fir,

and Engelmann spruce are susceptible to windthrow because

of their shallow, lateral root systems (1,2, 17). Blue spruce

and aspen appear to be intermediate in tolerance to wind.

'Cubic foot and metric conversions of measurements expressed in board

feet should be viewed as estimates because of the assumptions involved in

the conversion process.

Fire appears to have had a major role in establishing

rnost mixed conifer stands, and in maintaining the composition and structure of others, primarily because the different

species vary in their susceptibility to fire (11, 12). Seedlings

of all species are readily damaged or killed by fire, while

rnature trees show greater variation. For example, ponderosa

pine and Douglas-fir are tolerant to fire (6); in contrast,

Engelmann spruce, blue spruce, corkbark fir, and aspen are

sensitive (1, 2, 12, 22). Southwestern white pine and white

fir are intermediate (12). Differences in young trees are not as

apparent, but spruces and true firs with thin bark and

typically persistent lower branches are damaged easily.

Uneven- and even-aged forms of management are applicable for mixed conifer stands because of the different

silvical characteristics exhibited by the component species

(11, 12). The form selected depends on stand structure and

composition and on management objectives, including species preference. Regardless of the form of management

selected, consideration must be given to all resources, within

the constraints imposed by the silvical characteristics of the

species and the physical nature of the site. A critical

ecological consideration for all mixed conifer stands is

susceptibility to windthrow as related to specific tree and

stand characteristics, with dense single-storied stands being

the most subject to wind damage and multi-storied stands the

least. These stands, in turn, are further classified by wind risk

according to the topographical position they occupy.

Consequently, basal area volumes removed in harvest cuts

may vary from light to heavy (10 percent to 30 percent or

more) in order to control wind loss. Under some circumstances,

the only alternatives may be clearcutting or leaving the stand

intact.

Individual tree and group selection systems are particularly suited to regenerating the shade-tolerant species found

in mixed conifer stands (3, 17). These systems are especially

applicable to well-stocked, uneven-aged stands where the

objective is to maintain a balanced age-class distribution by

harvesting at frequent, regular intervals. However, it may be

difficult to achieve fully regulated conditions in practice

because oflogging, administrative, and recordkeeping problems.

Maintenance of age diversity, which is characteristic of

climax or near-climax forests, is possible only because some

species comprising these successional stages exhibit the

ability to grow in shade. In stands characterized by uniform

spacing, individual tree selection is preferred, while clumpy

stands are appropriately harvested by group selection which

utilizes and maintains a mosaic age-class structure. In the

latter instance, individual groups may be treated by a variety

of silvicultural systems, ranging from shelterwood and its

modifications to clearcutting. Since selection systems leave a

continuous forest cover, they are suitable for harvesting in

areas where the immediate foreground is visible to travelers

and in other high-use recreational zones. They can also be

applied in riparian zones where multi-storied stands are

required by various mammals and where shading is necessary

to maintain favorable stream temperatures for fish (23). In

the Southwest, such habitats may be especially important to

the threatened Arizona trout and the endangered Gila trout.

Harvesting in mixed conifer forests under either selection system is directed towards removing excess trees in all

diameter-age classes. Initial cutting, however, may be aimed

at removing the most defective and overmature trees, which

can be abundant in some decadent old-growth stands (12).

Regardless of the silvicultural system selected, windfall risk

must be considered (12). For example, in stands consisting of

nonwindfirm species where the windfall risk from soil and

topographic features is below average, up to 30 percent of the

overstory basal area can be removed in the first entry either as

74
individual trees or groups oftrees, depending on tree distribution.

However, a few defective trees may have to be retained in

some instances to prevent excessive openness in the canopy,

which may lead to unfavorable wind movement and subsequent blowdown. Where the residual stand consists of

windfirm species, more basal area can be harvested and,

conversely, less basal area where the windfall risk is greater.

Even-aged management provides the means to regenerate intermediate and intolerant mixed conifer species to meet

timber and other resource needs (4, 5). Clearcutting in

patches, blocks, or strips may be desirable to improve water

yields from these forests, which produce relatively large

quantities of high-quality water (18). Forage for domestic

livestock or wildlife also can be increased. Furthermore,

wildlife can benefit through habitat improvement resulting

from the spatial arrangement, size, shape, and timing of

silvicultural treatments (10, 11). Large clearcuts are not

recommended in mixed conifer forests because they are

difficult to regenerate with coniferous species (11). However,

if aspen is an important component of the stand and continued maintenance is desired for esthetics or wildlife, regeneration by root sprouts will be greatest following clearcutting

and light burning (22).

The shelterwood system and its modifications also are

applicable in mixed conifer forests. Many stands in the

Southwest are two- or three-storied, with well-stocked

understories ranging from seedlings and saplings to polesized trees. Removal of the overstory is equivalent to the

final removal cut of the shelterwood system, but is accomplished over 10 to 20 years by two or more cuts, depending

on the existing wind risk or the need to protect advanced

regeneration (12). Generally, understory trees 4 inches (10

cm) or larger in diameter in these stands appear especially

susceptible to windthrow. The shelterwood method has been

practiced in Douglas-fir and ponderosa pine stands in the

Southwest and elsewhere (4, 5, 21) and in stands of more

tolerant species in other regions (3). However, when it is

applied to regenerate stands with overstories consisting of

species with different degrees of tolerance, subsequent regeneration of the more tolerant species will tend to be increasingly favored by additional increments in residual stand

densities resulting from regeneration cuts (1, 2, 17). Many

resource benefits other than timber may be derived from the

application of shelterwood systems, but to varying degrees

depending on the intensity and timing of cutting.

Regeneration under any silvicultural system can be

obtained by natural seeding, planting, or by protecting

advanced regeneration. Artificial seeding has not been successful in the Southwest. Site scarification to expose mineral

soil, generally the best seedbed (3,4, 14), should be timed to

coincide with a good seed crop. However, if natural regeneration has not become established, clearcuts should be planted

within 2 years to avoid competition from invading grass (11).

Planted seedlings of those species injured by intense sunlight

or frost must be protected by artificial or natural shade, which

often can be provided most easily by intentionally leaving

some cull logs during slash-disposal operations (12, 19).

Observation suggests that even the more resistant seedlings

also will benefit from shade, presumably because of better

moisture regimes. The species selected for planting should be

adapted to the particular site (12, 13). In general, intolerant

species should be planted on exposed sites at elevations

below 9,000 feet (2745 m) on northerly slopes, and 9,500

feet (2895 m) on southerly slopes. Tolerant species should be

planted under artificial or natural shade at elevations above

9,000 feet (2745 m) on southerly exposures, and 8,500 feet

(2590 m) on northerly exposures. Species of intermediate

tolerance appear suited to moderate shade at elevations

between 8,000 and 10,000 feet (2440 and 3050 m) on

southerly aspects, and somewhat lower on northerly aspects.

Intermediate cutting in mixed conifers is not yet a

common practice. Although information on growth is not yet

available, thinning operations were recently begun to favor

individuals with the best potential of becoming crop trees

(12). Annual mortality in mixed conifers is high—estimated

at 50 million fbm (Scribner Decimal C Log Rule) (10 million

cubic feet or 283 000 m^) in Arizona alone—^but merchantable volumes are salvaged wherever economic conditions

permit. Some sanitation cutting, combined with intensive

slash disposal, is conducted in areas infested with spruce

beetles. Salvage and sanitation are also considered in marking regeneration cuts.

Although dwarf mistletoes are a problem in many

stands, their host specificity and the large number of conifer

species provide control options that do not necessarily result

in large openings or excessive windthrow (9). Infected

overstory trees can be harvested over a short period, and the

understory can be treated with sanitation cuts as needed. If

the overstory cannot be removed in a short time, understory

trees of nonhost species can be encouraged naturally or

established by planting.

Similarly, excessive damage by the western spruce

budworm might be alleviated in mixed conifer stands through

appropriate silvicultural practices utilizing tolerance traits of

different species (24). For example, cuttings that discriminate against the more vulnerable true firs, yet favor establishment of nonhost species or the less susceptible Douglas-fir

and spruces, would tend to reduce high population levels of

budworms. Cultural treatments that maintain a thrifty, rapidly growing stand also would diminish the impact of insect

attacks.

Literature Cited

1. Alexander, R. R. Engelmann spruce (Picea engelmannii Parry). In:

Powells, H. A., comp. Silvios of forest trees of the United States.

Agrie. Handb. 271. Washington, DC: U.S. Department of Agriculture;

1965: 299-304.

2. Alexander, R. R. Subalpine fir {Abies lasiocarpa (Hook.) Nutt.). In:

Powells, H. A., comp. Silvics of forest trees of the United States.

Agrie. Handb. 271. Washington, DC: U.S. Department of Agriculture;

1965: 36-41.

3. Alexander, Robert R. Silviculture of subalpine forests in the central and

southern Rocky Mountains: the status of our knowledge. Res. Pap.

RM-121. Port Collins, CO: U.S. Department of Agriculture, Porest

Service, Rocky Mountain Porest and Range Experiment Station; 1974.

88 p.

4. Barrett, James W. Silviculture of ponderosa pine in the Pacific

Northwest: the state of our knowledge. Gen. Tech. Rep. PNW-97.

Portland, OR: U.S. Department of Agriculture, Porest Service, Pacific

Northwest Porest and Range Experiment Station; 1979. 106 p.

5. Buell, Jesse. Rocky Mountain Douglas-fir {Pseudotsuga menziesii var.

glauca (Beissn.) Pranco). In: Powells, H. A., comp. Silvics of forest

trees of the United States. Agrie. Handb. 271. Washington, DC: U.S.

Department of Agriculture; 1965: 554-556.

6. Curtis, James D.; Lynch, Donald W. Ponderosa pine {Pinus ponderosa

Laws.). In: Powells, H. A., comp. Silvics of forest trees of the United

States. Agrie. Handb. 271. Washington, DC: U.S. Department of

Agriculture; 1965: 417-431.

7. Eyre, P. H., ed. Porest cover types of the United States and Canada.

Washington, D.C.: Society of American Poresters; 1980. 148 p.

8. Gottfried, Gerald J. Pive-year growth and development in a virgin

Arizona mixed conifer stand. Res. Pap. RM-203. Port Collins, CO:

U.S. Department of Agriculture, Porest Service, Rocky Mountain

Porest and Range Experiment Station; 1978. 22 p.

9. Gottfried, Gerald J.; Embry, Robert S. Distribution of Douglas-fir and

ponderosa pine dwarf mistletoes in a virgin Arizona mixed conifer

stand. Res. Pap. RM-192. Port Collins, CO: U.S. Department of

Agriculture, Porest Service, Rocky Mountain Porest and Range Experiment Station; 1977. 16 p.

75
10. Hall, Frederick C; Thomas, Jack Ward. Silvicultural options. In:

Thomas, Jack Ward, tech. ed. Wildlife habitats in managed forests—the

Blue Mountains of Oregon and Washington. Agrie. Handb. 553.

Washington, DC: U.S. Department of Agriculture, 1979: 128-147.

11. Jones, John R, Southwestern mixed conifers. In: Silvicultural systems

for the major forest types of the United States. Agrie. Handb. 445.

Washington, DC: U.S. Department of Agriculture; 1973: 47-49.

12. Jones, John R. Silviculture of southwestern mixed conifers and aspen:

the status of our knowledge. Res. Pap. RM-122. Fort Collins, CO:

U.S. Department of Agriculture, Forest Service, Rocky Mountain

Forest and Range Experiment Station; 1974. 44 p.

13. Jones, John R. A southwestern mixed conifer plantation—case history

and observations. Res. Pap. RM-148. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range

Experiment Station; 1975. 8 p.

14. Krauch, Hermann. Management of Douglas-fir timberland in the

Southwest. Stn. Pap. No. 21. Fort Collins, CO: U.S. Department of

Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station; 1956. 59 p.

15. Krugman, Stanley L.; Jenkinson, James L. Pinus L. Pine. In: Schopmeyer,

C. S., tech. coord. Seeds of woody plants in the United States. Agrie.

Handb. 450. Washington, DC: U.S. Department of Agriculture; 1974:

598-638.

16. Lanner, Ronald M.; Vander Wall, Stephen B. Dispersal of limber pine

seed by Clark's nutcracker. J. For. 78(10): 637-639; 1980.

17. Maul, David C. White fir (Abies concolor (Gord. and Glend.) Lindl.).

In: Fowells, H. A., comp. Silvics of forest trees of the United States.

Agrie. Handb. 271. Washington, DC: U.S. Department of Agriculture;

1965: 42-49.

18. Rich, Lowell R.; Thompson, J. R. Watershed management in Arizona's

mixed conifer forests: the status of our knowledge. Res. Pap. RM-130.

Fort Collins, CO: U.S. Department of Agriculture, Forest Service,

Rocky Mountain Forest and Range Experiment Station; 1974. 15 p.

19. Ronco, Frank. Influence of high light intensity on survival of planted

Engelmann spruce. For. Sei. 16(3): 331-339; 1970.

20. Safford, L. O. Picea A. Dietr. Spruce. In: Schopmeyer, C. S., tech.

coord. Seeds of woody plants in the United States. Agrie. Handb. 450.

Washington, DC: U.S. Department of Agriculture; 1974: 587-597.

21. Schubert, Gilbert H. Silviculture of southwestern ponderosa pine: the

status of our knowledge. Res. Pap. RM-123. Fort Collins, CO: U.S.

Department of Agriculture, Forest Service, Rocky Mountain Forest and

Range Experiment Station; 1974. 71 p.

22. Strothmann, R. O.; Zasada, Z. A. Quaking aspen {Populus tremuloides

Michx.). In: Fowells, H. A., comp. Silvics of forest trees of the United

States. Agrie. Handb. 271. Washington, DC: U.S. Department of

Agriculture; 1965: 523-534.

23.

24.

Thomas, Jack Ward; Maser, Chris; Rodiek, Jon E. Riparian zones. In:

Thomas, Jack Ward, tech. ed. Wildlife habitats in managed forests—the

Blue Mountains of Oregon and Washington. Agrie. Handb. 553.

Washington, DC: U.S. Department of Agriculture; 1979: 40-59.

Williams, Carroll B., Jr.; Shea, Patrick J.; Walton, Gerald S. Population density of western spruce budworm as related to stand characteristics in the Bitterroot National Forest. Res. Pap. PSW-72. Berkeley,

CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest

Forest and Range Experiment Station; 1971. 8 p.

76
Rocky Mountain Aspen

Wayne D. Shepperd

Rocky Mountain Forest and Range Experiment Station

Orville Engelby

Intermountain Region

The Rocky Mountain aspen forest cover type occupies

about 4 million acres (1.6 million ha) of commercial forest

land in eight Rocky Mountain States (7). Colorado and Utah,

which contain 2.3 and 1.1 million acres (0.9 and 0.4 million

ha), respectively, account for the majority of this acreage.

These lands comprise 25 percent of the total commercial

forest land in Colorado and 31 percent in Utah.

Aspen {Populus tremuloides Michx.) is a very important

multiple-use species in the Rocky Mountains, providing

wood, water, forage, wildlife, and recreation. Although the

Rocky Mountain States have more aspen sawlog volume than

the Lake States (25), the species is currently not being

utilized to a great extent as a wood source. Most management

of aspen in the Rocky Mountains is keyed towards recreation,

forage production, wildlife, and esthetics.

Typical Rocky Mountain aspen stands yield from 10 to

12 inches (25 to 30 cm) of water, up to 2,500 pounds per acre

(2800 kg/ha) of forage, and about 50 cubic feet net growth

per acre (3.5 m^/ha) per year averaged over a rotation (4).

Aspen typically grows on all aspects and slope positions

in the Rocky Mountains and is associated with montane and

subalpine vegetation along an elevational gradient from

7,000 to 11,500 feet (2135 to 3505 m) (25).

Productivity and development of aspen in the Rockies is

largely dependent upon available water, which in turn is

related to weather patterns, elevation, physiographic position,

and edaphic characteristics. For example, stands on the west

slope of the Continental Divide occupy large areas on all

physiographic positions, whereas stands on the drier east

slope are restricted to bottoms, draws, and other areas where

sufficient soil water is available (21).

Soil characteristics further delineate the development of

Rocky Mountain aspen. While aspen can be found on all soil

types from loamy sands to heavy clays, rockiness greatly

limits stand development. Most productive stands are found

on deep, well-developed soils with abundant soil water (1).

Aspen soils have higher organic matter content, waterholding capacity, and pH than soils under adjacent vegetation

(11, 24). The nutrient content of leaf litter under aspen stands

is higher than coniferous litter (3); and it decomposes rapidly

(2), thus recycling these nutrients to the soil.

Climatic conditions under which Rocky Mountain aspen

grows vary widely. In addition to the microclimatic differences caused by topography, differences in precipitation

patterns also occur. Aspen grows in the Rocky Mountains on

sites that receive from 16 to 40 inches (405 to 1015 mm) of

precipitation per year, but most stands receive from 20 to 30

inches (510 to 760 mm) (4, 12, 25) per year, mostly from

snow. These conditions, along with low dew points, high

evaporative rates during the growing season, and cool spring

temperatures (26), may account for the greater longevity and

generally slower growth of Rocky Mountain aspen compared

with aspen in other regions.

Aspen is an associate of many western tree species. It is

recognized as a major component of Society of American

Foresters forest cover types 217 and 251 and a minor

component of sixteen others (5). It is a serai species and an

aggressive invader following fire or other major disturbance

to coniferous stands, even those containing only a few aspen

stems (4). If a coniferous seed source is lacking, aspen can

occupy a site for hundreds or perhaps even thousands of years

(15).

Rocky Mountain aspen reproduces almost exclusively

by suckering, whereby a number of stems are produced

asexually by adventitious sprouting from a single parent root

system to form a clone. Although stems within a clone are

indistinguishable, clones can often be recognized from their

neighbors by leaf shape and size, bark character, branching

habit, stem form, suckering ability, time of flushing, and

autumn leaf color (17). Such characteristics have important

management implications. For instance, cutting a clone with

an inherently poor stem form will only produce another stand

with the same characteristics. Natural seedlings do occasionally occur in the West, and they may be responsible for

genetic diversity and the colonization of new clones (16). A

mature aspen tree can produce up to 1.6 million seeds in a

single year (16, 22). Aspen begins bearing seed between 10

and 20 years of age and produces a large crop every 4 to 5

years (22). The small, light seeds are wind disseminated and

usually mature in late June or early July in the Rocky

Mountains (17). Seed can be stored under refrigeration for

well over a year (17, 22), but loses viability under natural

conditions 8 weeks or less after seedfall (16). Seed is not

dormant and usually germinates well under a wide temperature range, but requires bare mineral soil, a continuous

supply of abundant moisture, and relatively cool temperatures for survival (16). Such requirements preclude practical

regeneration of aspen by seed under natural conditions, but

make possible nursery or greenhouse production of landscape

planting stock.

Aspen is more intolerant of shade than many other tree

species. It demonstrates dominance well and restricts development of understory stems, which in turn contributes to its

ability to naturally thin itself (4, 12). However, understory

stems are capable of recovering from suppression where the

competitive overstory has been removed.

Early growth of Rocky Mountain aspen suckers can be

as rapid as those in the Lake States, with heights of 40 feet

(12.1m) reached in 20 years (12). Young stands can produce

well over 150 cubic feet per acre (10.5 m^/ha) per year (11),

but most good quality mature stands produce about 50 cubic

feet per acre (3.5 m^/ha) per year (1, 21). Depending upon

their location, most Rocky Mountain aspen stands will

achieve an average height of 50 to 85 feet (15.2 to 25.9 m) at

maturity. Individual stems 110 feet (33.5 m) tall at age 80

have been measured on extremely good sites (21).

Mature sawlog stands average about 95 years of age in

Colorado and southern Wyoming (21). Sound stands over

110 years are not uncommon, and some as old as 200 years

exist (4, 21). Stands younger than 50 years are rare in many

areas of the Rocky Mountains because of long-term fire

protection and the relative lack of utilization. The somewhat

77
slower growth rates of Rocky Mountain aspen may allow

longer rotations, as long as 120 years in some areas (1, 4).

Potential yield of managed aspen in the Rocky Mountains is not currently known. Young natural stands in Arizona

have produced nearly 200 cubic feet per acre annually (14.0

m^/ha) (12). Little precommercial thinning is currently practiced in the West.

Rocky Mountain aspen is host to numerous insects and

diseases; however, only a few result in substantial damage.

The western tent caterpillar (Malacosoma californicum

(Packard)) is the most catastrophic insect pest, defoliating

large acreages of aspen for several consecutive years, with

considerable mortality occurring in heavily infested areas.

Biologic control of outbreaks is possible by use of a watersuspension, bacteria spray. Several species of boring insects

cause direct damage to the wood product value of aspen and

serve as infectious agents for cankers and other diseases (4).

Although black leaf spot {Marssonia populi (Lib.)

Magn.) is the most common disease of Rocky Mountain

aspen, trunk cankers are the most serious. Sooty-bark

{Cenangium singulare (Rehm.) Davids. & Cash), Hypoxylon

{Hypoxylon mammatum (Wahl.) Mill.), Cryptosphaeria

{Cryptosphaeria populina (Pers.) Sacc), Cytospora (Cytospora

chrysosperma Pers. ex Fr.), and black cankers {Ceratocystis

fimbriata Ell. and Halst.) commonly infect wounds and can

cause considerable mortality and trunk deformity (4, 9).

Decay is the most serious cause of volume loss in Rocky

Mountain aspen. Although over 250 species of decay fungi

occur on aspen, Phellinus tremulae (Bond.) Bond. & Boris.,

is most destructive (4, 10). Some rot is present in most

stands. The infection rate appears to be related to age, and it

usually becomes serious in stems older than 100 years.

However, Rocky Mountain aspen does not appear to be as

rot-prone as its eastern counterpart (4, 10).

Fire plays an important role in the ecology of Rocky

Mountain aspen and is probably responsible for most evenage stands that exist in the West (4). In the absence of fire,

many aspen stands are being replaced by other vegetation, or

are evolving to an uneven-age mode. Protection of Rocky

Mountain aspen from fire is largely unnecessary. Even a few

aspen in a coniferous stand maintain root systems sufficient

to restock the area after a serious fire (4), and pure aspen

stands will not readily bum (6). However, basal wounds

caused by light groundfires can serve as entry points for

canker and decay infections (4). Light fuel loadings and

normally high moisture content of succulent understory

vegetation make prescribed burning of pure aspen stands

difficult. Such burning can normally be successful only under

extremely dry conditions (4), which occasionally exist after

leaf fall during a warm dry autumn when understory vegetation has cured.

The intolerance ofshade, ability to reproduce by suckering,

and natural thinning tendencies of Rocky Mountain aspen

ideally suit it to even-aged management by clearcutting,

especially where the intent is to produce wood fiber. It is

important that all stems, including nonmerchantable trees and

understory saplings, be cut—not only to promote the best

suckering (19), but to prevent poor-quality residual stems

from being released and dominating subsequent regeneration.

Past partial cuts and "logger's choice" clearcuts in Rocky

Mountain aspen have resulted in either uneven-aged, inadequately stocked, or pathologically unsound stands that are not

growing at optimum rates.

The occurrence of natural uneven-aged aspen stands in

the Rocky Mountains (4, 21) indicates that some form of

uneven-aged management may be possible where management objectives require vertical canopy diversity or the

continual retention of a high forest, and where maximum

fiber production is of little importance. In such cases, either

individual tree or group selection cutting methods might be

used to perpetuate or create uneven-aged stands. Individual

tree selection should only be applied in stands that have an

existing sucker understory and have demonstrated an ability

to sucker under an existing overstory. Extreme care must be

taken to avoid damage to residual stems when stands are

selectively logged. Even so, wounding and stem breakage

from falling and skidding operations could result in substantial insect and disease losses.

Deteriorating clones are of particular concern to western

land managers. In healthy clones, the abundant production of

suckers following clearcutting, fire, or other major disturbance that quickly kills most of the stems is apparently

caused by a hormonal imbalance in the root system that

promotes suckering (20). In deteriorating clones, the overstory

has died slowly, and concurrent root system deterioration has

maintained the hormonal balance and thus inhibited suckering (20). Cutting such clones is likely to result in sparse

suckering, which may require additional protective or cultural measures to regenerate the stand adequately.

Other methods attempted to regenerate noncommercial

aspen in the Rocky Mountains include bulldozing, herbicide

application, and girdling. Most, except girdling, have met

with varying success and, although evaluations of these

techniques are underway, no recommendations can be made

concerning their applicability as regeneration methods.

Many aspen stands grow in watersheds that supply

municipal and agricultural water throughout the West. Compared to conifers, aspen stands intercept less precipitation,

accumulate greater snowpacks (which melt faster and earlier),

use less soil moisture, and yield more water of better quality

with less erosion (4). As a broadleaf deciduous species, the

leaf water vapor conductance of aspen is generally higher

than corresponding subalpine coniferous species (13). However,

any increased water use by aspen may be offset by its having

a lower leaf area per unit area of sapwood water conducting

tissue (14) and a shorter transpiration season than associated

conifers.

Aspen stands typically yield more understory herbaceous biomass than adjoining coniferous types (25) and

provide habitat for numerous wildlife species. Browsing of

new sprouts by domestic and wild animals can prevent

successful regeneration, and protective measures may be

required for some stands to regenerate (18, 23). Clearcutting

in large scattered units may be a silvicultural means of

dealing with this problem where animals cannot be rigidly

controlled (18). In some cases, fencing or manipulation of

slash to discourage animal use may be necessary.

Human use can also be detrimental to aspen stands.

Although highly desirable as a place for concentrated recreation activities. Rocky Mountain aspen stands are not suitable for such sites because of the high disease mortality of

trees wounded by people using such areas (9). Relocation of

the facilities is the only effective means of dealing with this

problem.

Literature Cited

1. Baker, Frederick S. Aspen in the central Rocky Mountain region.

Department Bull. 1291. Washington, DC: U.S. Department of Agriculture;

1925. 47 p.

2. Bartos, Dale L.; DeByle, Norbert V. Quality, decomposition, and

nutrient dynamics of aspen litterfall in Utah. For. Sei. 27(2): 381 -390;

1981.

3. Daubenmire, R. Nutrient content of leaf litter of trees in the northern

Rocky Mountains. Ecol. 34: 786-793; 1953.

78
10.

12.

13.

14.

15.

DeByle, Norbert V.; Winokur, Robert P., eds. Ecology and management of aspen in the western United States. Gen. Tech. Rep. Fort

Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky

Mountain Forest and Range Experiment Station; 1982. In preparation.

Eyre, F. H., ed. Forest cover types of the United States and Canada.

Washington, DC: Society of American Foresters; 1980. 148 p.

Fechner, Gilbert H.; Barrows, Jack S. Aspen stands as wildfire fuel

breaks. Eisenhower Consortium Bull. 4. Fort Collins, CO: U.S.

Department of Agriculture, Forest Service, Rocky Mountain Forest and

Range Experiment Station; 1976. 26 p.

Green, Alan W.; Setzer, Theodore S. The Rocky Mountain timber

situation, 1970. Res. Bull. INT-10. Ogden, UT: U.S. Department of

Agriculture, Forest Service, Intermountain Forest and Range Experiment Station; 1974. 78 p.

Gruell, George E. Fire's influence on wildlife habitat on the BridgerTeton National Forest, Wyoming. Volume II—Changes and causes,

management implications. Res. Pap. INT-252. Ogden, UT: U.S.

Department of Agriculture, Forest Service, Intermountain Forest and

Range Experiment Station; 1980. 35 p.

Hinds, T. E. Aspen mortality in Rocky Mountain campgrounds. Res.

Pap. RM-164. Fort Collins, CO: U.S. Department of Agriculture,

Forest Service, Rocky Mountain Forest and Range Experiment Station;

1976. 20 p.

Hinds, Thomas E.; Wengert, Eugene M. Growth and decay losses in

Colorado aspen. Res. Pap. RM-193. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range

Experiment Station; 1977. 10 p.

Hoff, C. C. A comparison of soils, climate, and biota of conifer and

aspen communities in the central Rocky Mountains. Am. Mid. Nat. 58:

115-140; 1957.

Jones, John R.; Trujillo, David P. Development of some aspen stands in

Arizona. Res. Pap. RM-151. Fort Collins, CO: U.S. Department of

Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station; 1975. 11 p.

Kaufmann, M. R. Leaf conductance as a function of photosynthetic

photon flux density and absolute humidity difference from leaf to air.

Plant Physiol. 69: 1018-1022. 1982.

Kaufmann, Merrill R.; Troendle, Charles A. The relationship of leaf

area and foliage biomass to sapwood conducting area in four subalpine

forest tree species. For. Sei. 27(3): 477-482; 1981.

Kemperman, Terry A.; Barnes, Burton V. Clone size in American

aspens. Can. J. Bot. 54: 2603-2607; 1976.

16. McDonough, W. T. Quaking aspen—seed germination and early

seedling growth. Res. Pap. INT-234. Ogden, UT: U.S. Department of

Agriculture, Forest Service, Intermountain Forest and Range Experiment Station; 1979. 13 p.

17. Morgan, M. D. Ecology of aspen in Gunnison County, Colorado. Am.

Mid. Nat. 82(1): 204-228; 1969.

18. Mueggler, W. F.; Bartos, D. L. Grindstone Rat and Big Flat exclosures—a

41-year record of changes in clearcut aspen communities. Res. Pap.

INT-195, Ogden, UT: U.S. Department of Agriculture, Forest Service,

Intermountain Forest and Range Experiment Station; 1977. 16 p.

19. Schier, George A.; Smith, Arthur D. Sucker regeneration in a Utah

aspen clone after clearcutting, partial cutting, scarification, and girdling.

Res. Note INT-253. Ogden, UT: U.S. Department of Agriculture,

Forest Service, Intermountain Forest and Range Experiment Station;

1979. 6 p.

20. Schier, George A. Deterioration of aspen clones in the middle Rocky

Mountains. Res. Pap. INT-170. Ogden, UT: U.S. Department of

Agriculture, Forest Service, Intermountain Forest and Range Experiment Station; 1975. 14 p.

21. Shepperd, Wayne D. Stand characteristics of Rocky Mountain aspen.

In: DeByle, N. V., ed. Proceedings, Situation management of two

intermountain species: aspen and coyotes, a symposium. Part I. Aspen;

1981 April 23-24; Logan, UT: Utah State University; 1982: 22-30.

22. Schopmeyer, C. S., tech. coord. Seeds of woody plants in the United

States. Agrie. Handb. 450. Washington, DC: U.S. Department of

Agriculture; 1974. 883 p.

23. Smith, Arthur D.; Lucas, Paul A.; Baker, Calvin O.; Scotter, George

W. The effects of deer and domestic livestock on aspen regeneration in

Utah. Publ. No. 72-1. Logan, UT: Utah Division of Wildlife Resources;

1972. 31 p.

24. Tew, Ronald K. Properties of soil under aspen and herb-shrub cover.

Res. Note INT-78. Ogden, UT: U.S. Department of Agriculture,

Forest Service, Intermountain Forest and Range Experiment Station;

1968. 4 p.

25. U.S. Department of Agriculture, Forest Service. Utilization and marketing as tools for aspen management in the Rocky Mountains: Proceedings

of the Symposium. Gen. Tech. Rep. RM-29. Fort Collins, CO: U.S.

Department of Agriculture, Forest Service, Rocky Mountain Forest and

Range Experiment Station; 1976. 120 p.

26. U.S. Department of Interior. The National Atlas of the United States of

America. Washington, DC: U.S. Department of Interior, Geologic

Survey; 1970. 414 p.

79
Interior Ponderosa Pine in the Black Hills

Charles E. Boldt and Robert R. Alexander

Rocky Mountain Forest and Range Experiment Station

Milo J. Larson

Rocky Mountain Region

The gross area of the Black Hills of South Dakota and

associated Bear Lodge Mountains of eastern Wyoming is

about 3.5 million acres (1.4 million ha). Roughly half the

area supports forest or woodland cover. Essentially pure

stands of climax Rocky Mountain ponderosa pine {Pinus

ponderosa var. scopulorum Engelm.) predominate on about

1.5 milHon acres (0.6 million ha). Scattered, smaller aggregations of similar ponderosa pine stands occupy about 250,000

acres (101 170 ha) of butte-top and scarp sites to the north

and south of the Black Hills in Nebraska, Wyoming, and

Montana (3,8, 19).

In addition to being isolated from the rest of the interior

ponderosa pine forest cover type (Society of American

Foresters forest cover type 237) by wide expanses of nonforested

land, the ponderosa pine forests of the Black Hills are

sufficiently distinctive in their silvical characteristics to

warrant separate description and specialized silvicultural

treatment (2, 4, 5).

The Black Hills are the weathered remains of a domal

uplift of late Cretaceous/early Tertiary origin. A deep mantle

of diverse sedimentary deposits, which overlaid the dome as

originally uplifted, has been eroded almost entirely from its

central portions. Rock types exposed in the core area are a

complex of ancient and recent igneous intrusives and associated metasediments (10). Encircling this core of crystalline

rock types are irregular, concentric bands of residual sedimentary rock strata. Several of the most recent of these sedimentary layers, steeply uptilted, form a hogback ridge that

surrounds the hills like a rampart and boldly marks the

prairie/ forest ecotone.

Truncated by erosion, the uplift now rises to only a

fraction of its original height. The tallest peak, Hamey, of

durable Precambrian granite, reaches only 7,240 feet (2205

m) above mean sea level and a modest 4,000 feet (1220 m)

above the surrounding plains. Although the topography is

locally steep and rugged, the overall relief is gentle for

mountainous terrain. It is easily roaded, and the bulk of the

productive sites are accessible.

Soils show considerable variability attributable to parent

materials and elevation/climate zones; yet, the influences of

those factors on soil genesis and morphology evidently have

been modified by coniferous forest cover. Most soils show

morphological characteristics approximating those of the

Eutroboralfs Group (Gray-Wooded Soils). Even within major

grassland inclusions, where mixed prairie vegetation has

prevailed for long periods, soils usually show some physical

and chemical indications of previous occupancy by conifers.

Thus, most sites, irrespective of parent material or existing

vegetation, probably have the capability ofsupporting ponderosa

pine stands (16, 22).

Soils may be characterized as medium- to fine-textured,

moderately deep, and rocky. The upper horizon textural

range generally runs from sandy loam through clay loam. A

profile with an overall depth of 60 inches (152 cm) would be

considered deep; a 24-inch (61-cm) profile is about average.

Most residual soil profiles contain moderate volumes of

weathered, fragmented parent material. Except where parent

materials are of recent igneous origin, soils are usually

underlain by deep zones of fractured bedrock. Joints and

fissures in this rock admit and store gravitational soil water,

and they are often penetrated deeply by roots—particularly

those of ponderosa pine (2, 16, 22).

The climate of the Black Hills is similar, qualitatively,

to that of the associated High Plains; i.e., typically continental and rigorous, with virtually all climatic elements showing

unusual variability, both short- and long-term. Quantitatively,

the climate of the Black Hills is sufficiently different from

that of the surrounding steppe to favor forest cover over

grass. The critical differences—increased precipitation and

decreased temperature—are orographie effects (2, 14).

Compared to climates elsewhere in the type, the distinctive feature of the Black Hills climate is the relative abundance of precipitation early in the growing season (15). May

and June are normally the wettest months; April and July are

only slightly less so. Precipitation for these 4 months

amounts to about one-half of the expected annual total of 30

inches (760 mm) (14). This prolonged moist period in late

spring and early summer in most years is ideal for germination and establishment of ponderosa pine seedlings. The wet

snows and cool rains of April and early May provide ample

moisture for imbibition by pine seeds deposited the previous

autumn. When germination occurs late in May, an additional

2 months of periodic rains can be expected to keep the duff

moist while seedling roots grow toward the more dependable

moisture supplies of the mineral soil. First-season growth of

vertical roots of Black Hills pine seedlings averaged 6 inches

(15 cm) in limestone soils and 7 inches (18 cm) in metamorphic soils by the first of July (20).

Recurrent, severe droughts also exert a potent influence

on the vegetation of the High Plains and Black Hills. A tree

ring study of drought in nearby western Nebraska indicated

occurrence of 21 major droughts (5 years or longer in

duration) during the 748 years between 1220 and 1952 A.D.

Average duration was nearly 13 years; the most prolonged

lasted an estimated 38 years. The average interval between

droughts was about 24 years. The most recent severe drought

in the plains—which produced the infamous dust bowl

conditions of the 1930's—was, by comparison, well below

average in duration (21).

These droughts not only kill vegetation outright but also

increase its flammability. Drought and wildfires are the

principal reasons why extensive stands of very old ponderosa

pine were scarce even in the presettlement, virgin forests (7).

Grassland fires, especially frequent during droughts, also

tended to inhibit encroachment of ponderosa pine into the

interior and surrounding prairies (6). Recently, pine invasion

into pastures has become a range management problem,

presumably a consequence of human interference with the

natural wildfire regime, enhanced by recent absence of

drought.

The Black Hills are a veritable melting pot, with tree

species representing origins as diverse as the northern boreal.

80
the eastern deciduous, the western subalpine and montane

forests, and the pygmy conifer woodlands (2). Of the many

indigenous tree species other than ponderosa pine, only three

occur extensively enough to influence ponderosa pine

silviculture.

White spruce {Picea glauca (Moench) Voss) forms

pure, mostly even-aged stands on cool, moist sites where it is

considered the climax forest type. Ponderosa pine is serai on

these sites. Only about 2 percent of the commercial forest

land is currently dominated by white spruce, but it is

gradually replacing serai pine stands as a result of fire

control, pine-killing insects and diseases, and silvicultural

practices. On more xeric sites, spruce may mix with but is

eventually replaced by pine.

Stands of quaking aspen (Populus tremuloides Michx.)

occupy about twice as many acres as white spruce but, for the

most part, less permanently. Most stands are serai, replacing

pine or spruce only temporarily following disturbance. Stands

of bur oak {Quercus macrocarpa Michx.) of tree form are

mostly confined to low elevation bottoms on the eastern and

northern margins of the Black Hills. However, a scrub form

of oak also mixes with pine on some upland sites in the

northern Black Hills and Bear Lodge Mountains. On these

sites, loss of the dominant pine cover, through cutting or fire,

can lead to capture of the site by oak brush. Natural recapture

by pine is a very slow process; artificial restoration is difficult

and expensive.

For managers of multi-purpose lands, the main problem

with the associated forest types is their restricted occurrence.

The predominance of ponderosa pine seriously limits diversity of forest vegetation and complicates management efforts

to maintain or increase it (18).

Ponderosa pine is a dependable seed producer in the

Black Hills. Seed crops are normally good to excellent every

2 to 5 years; the longtime average interval between good

crops is 3 years. This characteristic, coupled with the

favorable spring and summer moisture regime, makes natural

reproduction readily and abundantly available. Ordinarily,

deforested sites within 120 feet (37 m) of an adequate pine

seed source restock promptly. Adverse seed bed conditions

seldom prevent pine regeneration, but rank stands of grass or

brush or heavy slash may delay it (2).

Extremely high stand densities are common in pine

regrowth. Established seedling stands often contain more

than one tree per square foot (11 trees/m^). Natural thinning

proceeds very slowly; initially overstocked stands are apt to

remain crowded from youth to biological maturity. The usual

result is early and persistent stagnation of growth. However,

many trees in overstocked, even stagnant stands, retain a

capacity to respond favorably to release. Satisfactory improvements of growth (especially in stem diameter) are

usually attainable by thinning stands less than 100 years old

(2).

Ponderosa pine site index is the only means available for

rating the productivity of Black Hills sites, whether they

support pine, other vegetation, or none at all. Various plant

community and habitat types have been identified and described,

but type-productivity relationships have not been quantified.

Conventional site index curves, developed during the 1930's

and based on dominant/codominant tree heights at age 100,

are still in use (9). These have been augmented by a

vegetation-independent system that derives estimates of index values from soil and topographic parameters (2). The

range of site index values is narrow, from 20 feet (6.1 m) to

100 feet (30.5 m). Sites with indexes at or near the maximum

are rare, and account for only a small fraction of the forest

land area. The modal site index class, 50 to 60 feet (15.2 to

18.3 m), lies between Meyer's classes V and VI (2, 9, 11).

Research on growth and yield of ponderosa pine has a

long history in the Black Hills but, from the start, the effort

has focused mainly on cutover and regrowth stands; only

limited information is available on biological growth potentials of natural stands (2, 9, 12). Unpublished data from old

plots indicates that gross mean annual increments will consistently range from 25 to 35 cubic feet per acre (1.8 to 2.5

m%a) at age of culmination (130 to 150 years) in fully

stocked, unmanaged stands on average sites. If harvested at

age 150 years, such stands could be expected to yield about

3,000 merchantable cubic feet per acre (210.0 m^/ha) or

14,000 board feet (fbm)' per acre, in trees 9 to 11 inches (23

to 28 cm) d.b.h. For comparison, forest survey estimates 32

cubic feet per acre (2.2 m^/ha) average annual net growth on

commercial forest lands of all ownerships and condition

classes. Similarly, Black Hills National Forest growth and

mortality plots indicate an average net growth of 33 cubic

feet per acre (2.3 m^/ha) in existing stands, including

volumes harvested between remeasurements (8, 18).

While no Black Hills pine stands have been under

management long enough to demonstrate the gains in growth

and yields attainable through continuous, reasonably intensive management, conservative estimates, based on research

and experience, indicate that: trees, 14 to 18 inches (36 to 46

cm) in diameter at breast height (d.b.h.), can be grown on

rotations as short as 100 years; and gross mean annual

increments can be increased by roughly 50 percent above

current levels to 50 cubic feet per acre (3.5 m^/ha) on average

sites or across large forest tracts (18). Best case estimates,

derived by using the Rocky Mountain Yield Simulation

program (RMYLD) indicate that, with prompt restocking

followed by periodic thinnings to maintain proper stocking

levels, gross mean annual increment in stands managed at

growing stock levels considered optimum for timber production on a 120-year rotation can vary from about 40 cubic feet

per acre (2.8 m^/ha) on site index 50 lands to about 90 cubic

feet per acre (6.3 m^/ha) on site index 80 lands (1). However,

these simulations may not fully account for all the diverse

social, economic, biological, and physical constraints that

limit productivity.

A distinctive pathological characteristic of Black Hills

ponderosa pine forests is the absence of dwarf mistletoe

{Arceuthobium spp.). This permits silviculturists to consider

a wide range of harvest/regeneration options, free of the

threat of mistletoe transmission from old to new stands.

There is some incidence of most other disease problems

common to the type (4); shoestring rot {Armillariella mellea

(Wahl, ex Fr.) Karst.), western gall rust {Peridermium

harknessii J. P. Moore), and red rot {Dichomitus squalens

(Karst.) Reid) are prominent and chronically troublesome

(2). However, none of these is serious enough to require

major modifications of silvicultural practices forestwide.

The most damaging insect pest is the mountain pine

beetle {Dendroctonusponderosae Hopkins). Periodic epidemics kill millions of trees, typically in patchwise fashion in

uniform, heavily stocked, large pole and small sawtimber

stands. The most widely applied control practice is timely

harvest and utilization, or burning, of infested trees. Subjective evidence suggests that the beetle problem will be

mitigated as intensified intermediate cutting programs reduce

the prevalence of overstocked stands and increase diversity of

size and age classes (1, 2, 17). Pine engravers {Ips spp.)

occasionally produce tree-killing populations in heavy thinning slash; the red turpentine beetle {Dendroctonus valens

' Cubic foot and metric conversions of measurements expressed in board

feet should be viewed as estimates because of the assumptions involved in

the conversion process.

81
LeConte) sometimes makes a primary attack on healthy trees;

and pine terminal borers often impede height growth of

juvenile trees (2).

Because it has posed so few problems, little research has

been done on natural regeneration of Black Hills ponderosa

pine. Most of what is known about silvicultural systems and

harvesting methods has been learned by experience. Fortunately,

the experience has been abundant, varied, and instructive.

During the more than a century of timber harvesting in the

Black Hills, the silvicultural systems applied on Federal

lands have covered the spectrum from clearcutting (1876 to

1896), to seed-tree cutting (1897 to 1907), to shelterwood

cutting (1908 to 1925), to individual tree selection (1926 to

1955), and then returned to shelterwood cutting (since 1956).

Virtually every operable acre has been cutover at least once;

the majority have received repeated partial cuts of one kind or

another (2, 13).

Several important lessons have been gained from these

diverse harvesting experiences: even-aged silviculture is

eminently suited to Black Hills ponderosa pine; within the

even-aged system, any one of the three standard regeneration

methods may be a valid option under appropriate circumstances;

the shelterwood method offers more advantages and entails

fewer disadvantages than either the seed-tree or clearcut

methods; and uneven-aged silviculture is not a desirable

option for timber production in Black Hills ponderosa pine,

but the selection method is a valid option in special situations.

The shelterwood method capitalizes on the species'

natural tendency to form even-aged stands. Furthermore, it

combines the advantages of continuous vegetative protection

of the site; absence of obvious openings; assurance of an

adequate, well-dispersed seed supply; fair control over development of competitive ground cover; good control over

accumulations of hazardous and unsightly logging residue;

and an esthetically acceptable appearance, provided the

harvest job is skillfully planned and executed (2). An

important disadvantage is that the parent overwood will

hamper development of the replacement stand if it is too

dense or left in place too long. Another disadvantage is that

even a light shelterwood is likely to supply more seed than is

needed, thus aggravating the problem of excess reproduction.

The grass-forb serai stage which is desirable for wildlife and

livestock forage does not develop fully nor persist for long

under a shelterwood (2).

A uniform, two-cut shelterwood appears to be the most

efficient and silviculturally acceptable variant of the method.

The seed cut should be heavy enough to interrupt the

competitive continuity of the mature stand and leave only 12

to 18 good parent trees per acre (30 to 44/ha); the removal cut

should be completed soon after regeneration is established. A

three-cut variant is an acceptable option in situations where

two cuts pose unusual problems of visual impact, residue

buildup, risk of windthrow, or logging damage to reproduction (2).

The other even-aged methods—seed-tree or clearcutting—

are acceptable alternatives to the shelterwood under some

conditions. Each, however, lacks one or more of the advantages of the shelterwood method. The seed-tree cutting

method entails the highest risk of loss of seed source,

especially from blowdown. Also, the widely spaced seed

trees offer little competition to invading ground cover in the

unlikely event of delayed pine regeneration. If it is surrounded by well-stocked stands, a seed-tree area has nearly

the same visual impact as a cleared opening. In well-stocked

stands, a seed-tree cut results in heavy accumulations of

logging residue on the first entry. These disadvantages may

be partially offset by reduced seed supply, less damage to

reproduction during seed stand removal, and higher production of herbage (2).

The clearcutting method creates conspicuous stand

openings. The size of opening should normally be restricted

to about twice the 250 feet (76.2 m) dispersal distance of

ponderosa pine seed if there is a seed-producing stand all

around the perimeter. In well-stocked stands, clearcuts generate maximum amounts of logging residues which may require

costly abatement. After the slash dissipates, pine regeneration is likely to develop vigorously, free of overhead

competition. Lack of timely pine regeneration may lead to

site capture by other vegetation for relatively long periods of

time. The clearcut method is most likely to produce significant increases in forage and water yields (2).

For regeneration, the uneven-aged system is out of place

in the naturally even-aged pine forests of the Black Hills.

Light selection cuts, which remove only a few individual

trees or small groups, ordinarily do not lead to satisfactory

establishment and development of replacement growing stock.

Stands of uneven- or all-aged structure can only be produced

and maintained at spacings wide enough to make all stand

components essentially free growing. For purposes other than

regeneration, individual tree selection can be a very useful

harvest practice. It is particularly applicable in the management of remnant old-growth stands being perpetuated for

esthetic reasons; for manipulation of stands on or adjacent to

riparian zones or other sensitive sites; and for management of

unusually large trees for high-quality wood, specialized

habitats, or visual appeal. The selection method is difficult to

prescribe and costly to apply, however (2).

Thinning is an appropriate and generally necessary

intermediate cutting method. In typically crowded regeneration stands, precommercial thinning should begin early,

before stagnation occurs, while trees are large seedling or

small sapling size. One moderately heavy, precommercial

thinning is more cost-effective than no precommercial thinning.

Commercial thinnings should be made at regular intervals

(usually 20 years) throughout the rotation to upgrade the

quality and productivity of the growing stock, to reduce

susceptibility to mountain pine beetle attack, and to promote

development of understory vegetation. Thinning to stocking

levels below the optimum for wood production results in

significant increases in forage for livestock and wildlife. Low

levels of growing stock also favor water yields; fully stocked

pine stands are capable of utilizing most of the moisture

which infiltrates the soil mantle in years of normal or

deficient precipitation (I).

Prescribed burning is an effective, efficient way to

eliminate unwanted pine reproduction invading grasslands

adjacent to forest; it may be an equally good way to control

advance reproduction in lightly stocked, immature pine

stands (6). Burning, either in piles or broadcast, is useful for

fuel and hazard reduction following harvest cuttings or

commercial thinnings; burning may or may not benefit

ground cover vegetation. Prescribed burning of precommercial

thinning slash is risky in that it is likely to kill small, thinbarked trees.

Intensive management should provide for improving the

genetic quality of the forest growing stock. Selection for

desirable traits should be routine in the choice of leave trees

in intermediate and harvest cuts. Seed used for artificial

regeneration should be from recognized, local collection

zones or seed production areas. When bona fide improved

strains of adapted ponderosa pine become available, their use

should be considered for reforestation of at least the most

productive sites.

82
Literature Cited 11

1. Alexander, Robert R.; Edminster, Carleton B. Management of ponderosa

pine in even-aged stands in the Black Hills. Res. Pap. RM-228. Fort

Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky

Mountain Forest and Range Experiment Station; 1981. 10 p.

2. Boldt, Charles E.; Van Deusen, James L. Silviculture of ponderosa pine

in the Black Hills: The status of our knowledge. Res. Pap. RM-124.

Fort Collins, CO: U.S. Department of Agriculture, Forest Service,

Rocky Mountain Forest and Range Experiment Station; 1974. 45 p.

3. Choate, Grover A. The forests of Wyoming. Resource Bull. INT-2.

Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain

Forest and Range Experiment Station; 1963. 47 p.

4. Curtis, James D.; Lynch Donald W. Silvics of ponderosa pine. Misc.

Pub. No. 12. Ogden, UT: U.S. Department of Agriculture, Forest

Service, Intermountain Forest and Range Experiment Station: 1957.

37 p.

5. Eyre, F. H., ed. Forest cover types of the United States and Canada.

Washington, DC: Society of American Foresters; 1980. 148 p.

6. Gartner, F. Robert; Thompson, Wesley W. Fire in the Black Hills

forest-grass ecotone. In: Proceedings, Annual Tall Timbers Fire Ecology Conference; 1972 June 8-9; Tallahassee, FL. Tallahassee, FL:

Tall Timbers Research Station; 1972: 37-38.

7. Graves, Henry S. The Black Hills Forest Reserve. In: 19th Annual

Report of the Survey, Part V; 1897-1898. Washington, DC: U.S.

Department of the Interior, Geological Survey; 1899: 79-149.

8. Green, Alan W. Timber resources of western South Dakota. Resource

Bull. INT-12. Ogden, UT: U.S. Department of Agriculture, Forest

Service, Intermountain Forest abd Range Experiment Station; 1978.

56 p.

9. Homibrook, E. M. Preliminary yield tables for selectively cut stands of

ponderosa pine in the Black Hills. J. For. 37(10): 807-812; 1939.

10. Kirchner, James G. Evidence of late Tertiary volcanic activity in the

northern Black Hills, South Dakota. Science 196: 977; 1977.

12

14

15.

16

Meyer, Walter H. Yield of even-aged stands of ponderosa pine. Tech.

Bull. 630. Washington, DC: U.S. Department of Agriculture; 1938

(Revised 1961). 59 p.

Meyers, Clifford A. Yield tables for managed stands with special

reference to the Black Hills. Res. Pap. RM-21. Fort Collins, CO: U.S.

Department of Agriculture, Forest Service, Rocky Mountain Forest and

Range Experiment Station; 1966. 20 p.

13. Newport, Cari A. A history of Black Hills forestry. Pierre, SD:

Department of Game, Fish and Parks; 1956. 112 p.

Orr, Howard K. Watershed management in the Black Hills: The status

of our knowledge. Res. Pap. RM-141. Fort Collins, CO: U.S.

Department of Agriculture, Forest Service, Rocky Mountain Forest and

Range Experiment Station; 1975. 12 p.

Pearson, G. A. A comparison of the climate in four ponderosa pine

regions. J. For. 49(4): 256-258; 1951.

Radeke, R. E.; Westin, Fred C. Gray wooded soils of the Black Hills of

South Dakota. Soil Sei. Soc. Amer. Proc. 27: 573-576; 1963.

17. Stevens, Robert E.; McCambridge, William F.; Edminster, Carieton B.

Risk rating guide for mountain pine beetle in the Black Hills. Res. Note

RM-385. Fort Collins, CO: U.S. Department of Agriculture, Forest

Service, Rocky Mountain Forest and Range Experiment Station; 1980.

2 p.

U.S. Department of Agriculture, Forest Service. Final environmental

statement, timber management plan for the Black Hills National Forest.

Denver, CO: Rocky Mountain Region; 1977. 218 p.

U.S. Department of Agriculture and U.S. Department of the Interior.

Black Hills area resources study. Washington, DC: 1967. 225 p.

Van Haverbeke, David F. Root development of ponderosa pine seedlings in the Black Hills. Ecology 44(1): 161-165; 1963.

Weakly, Harry E. History of drought in Nebraska. J. Soil and Water

Conserv. 1962 (Nov.-Dec): 271-275.

White, E. M.; Johnson, J. R.; Nichols, J. T. Prairie-forest transition

soils of the South Dakota Black Hills. Soil Sei. Soc. Amer. Proc. 33:

932-936; 1969.

18

19

20.

21

22

83
Pinyon-Juniper

Richard O. Meeuwig

Intermountain Forest and Range Experiment Station

Richard L. Bassett

Southwestern Region

Pinyon-juniper woodlands (Society of American Foresters forest cover type 239) occupy about 48 million acres

(19.4 million ha) in the western United States (2), primarily in

Nevada, Utah, Arizona, New Mexico, and Colorado. Extensive stands also occur in California and Texas, and a few

stands are in southern Idaho, southern Wyoming, and the

western tip of Oklahoma. The woodlands are on piedmont

slopes, foothills, mountain slopes, mesas, and plateaus at

elevations generally ranging from 4,500 to 8,000 feet (1370

to 2440 m). The lower elevational limit is above valley floors

of the high desert in the Great Basin and above low plains in

other parts of its range. Soils are derived from a wide variety

of parent materials and are typically well drained. Soil orders

include Mollisols, Alfisols, Entisols, Inceptisols, and Aridisols.

The pinyon-juniper type is one of the most xeric forest

cover types in the United States, and consequently, one of the

least productive. In the western portion particularly, cloudy

days are rare and relative humidity is extremely low during

the growing season, resulting in very high potential

évapotranspiration. Since the type covers a wide geographical area and has broad elevational limits, it apparently

tolerates a wide range of temperature extremes. The mean

minimum temperature in January, the coldest month, can be

as low as 14° F (-10.0° C); and the mean maximum

temperature in July, the hottest month, can be as high as 95°

F (35.0° C). Mean annual temperature varies from 40° to 60°

F (4.4° to 15.5° C). Average annual precipitation varies from

10 to 20 inches (255 to 510 mm), but can be as low as 8

inches (205 mm) on some alluvial fans and piedmont slopes

where surface and subsurface flow contributes to the soil

moisture supply. In the western portion of the type, most

precipitation occurs during the winter months (December

through April), usually as snow. In the eastern portion, most

of the precipitation occurs in summer (July through September).

In the central portion, precipitation is more evenly divided

between summer and winter, but spring and fall are usually

dry.

The pinyon—juniper type is composed of several different associations of pinyon and juniper species and includes

pure stands of pinyon or juniper. The most important species

in this type are pinyon (Pinus edulis Engelm.), singleleaf

pinyon {P. monophylla Torr, and Frém.), Utah juniper

{Juniperus osteosperma (Torr.) Little), oneseed juniper (7.

monosperma (Engelm.) Sarg.), and alligator juniper {J.

deppeana Steud.). Other species of local importance are

Rocky Mountain juniper (7. scopulorum Sarg.), Mexican

pinyon {Pinus cembroides Zuce), Parry pinyon {P. quadrifolia

Pari, ex Sudw.), and California juniper {Juniperus californica

Carr.). The singleleaf pinyon-Utah juniper association occurs throughout the type in Nevada and in parts of California,

Utah, and Arizona. The pinyon-Utah juniper association is

also widespread, occupying most of the type in Utah, western

Colorado, and northern Arizona. The pinyon-oneseed juniper association occurs in New Mexico, eastern Arizona, and

south-central Colorado. Alligator juniper is also a common

component at higher elevations of the type in Arizona and

New Mexico. Rocky Mountain juniper is a component at

higher elevations in Colorado, New Mexico, Arizona, Utah,

and eastern Nevada. Mexican pinyon occurs in a few

localities in southeast Arizona, southwest New Mexico, and

southwest Texas. California juniper is a component in parts

of southern California and western Arizona. Parry pinyon is a

minor species in southern California.

Juniper species produce abundant berry crops nearly

every year. Birds and mammals eat juniper berries and

excrete viable scarified juniper seeds over extensive areas.

Pinyon species produce good cone crops at irregular intervals,

usually varying between 3 and 7 years. But good crops in any

particular year vary from locality to locality. The heavy

wingless seeds are disseminated by birds and rodents. Rodents usually do not carry pinyon seeds far, but birds may

transport seeds considerable distances. Clark's nutcracker

has been reported to carry pinyon seeds nearly 14 miles (22

km) (13). Both birds and rodents cache pinyon seeds in the

ground, often at depths favorable for germination. They

consume most of these caches during the winter, but some

caches and individual seeds are overlooked and left to

germinate. Fresh pinyon seeds have high viability and

germinate readily with little or no stratification. Pinyon seeds

lose viability rapidly after one year, but juniper seeds

probably remain viable for several years. Seeds usually

germinate in early spring if the soil is moist. In the eastern

portion of the type, germination may be delayed until the

summer rainy season.

Few seedlings survive without some degree of shade

until they reach a height of about 12 inches (30 cm).

Surviving seedlings are generally found under shrubs or tree

crowns. Those growing under shrubs have the best chance for

survival because the tree seedlings can often overtop the

shrubs. Those beneath tree crowns usually die eventually,

unless the overstory is removed. When a tree is cut, seedlings

under it may die because of the sudden exposure to solar

radiation, unless they are shaded by the tree stump or by

slash. When a pinyon-juniper stand is cut, reestablishment

of the stand can be hastened by avoiding damage to the

residual stand of small trees and seedlings and by providing a

shading cover of slash over small seedlings exposed to full

sunlight.

Although pinyon and juniper are not shade tolerant,

water rather than light is the limiting factor in survival and

growth. Because of low precipitation and high potential

évapotranspiration, overstory foliage is rarely dense enough

to reduce light intensities below tolerance levels. Complete

crown closure is rare, but soils under well-developed

pinyon-juniper stands are completely occupied by tree

roots, resulting in suppression of understory vegetation. The

intense competition for moisture often results in suppression

of smaller trees. Young trees can be killed by severe moisture

stress. Older trees usually survive, though at greatly reduced

growth rates. Limited studies indicate that suppressed pinyon

and juniper trees gradually resume normal growth when

released from severe competition (9).

84
Growth rates of pinyon and juniper are highly variable

but generally quite low. Height growth of dominant pinyon

and juniper trees is usually 2 to 4 inches (5 to 10 cm) per year.

Average annual diameter growth of dominant trees generally

varies from 0.04 to 0.2 inches (1 to 5 mm). Diameter growth

rates are governed primarily by moisture availability and do

not necessarily decrease with tree age (9). A typical dominant

tree takes about 150 years to reach a height of 28 feet (8.5 m)

and a diameter of 12 inches (30 cm) at stump height, which is.

6 inches (15 cm). Since pinyon and juniper grow so slowly,

rotations for wood production are quite long. Even on the

best sites, rotations should be at least 1(K) years. Rotations

should be about 2(X) years on average sites and as much as

300 years on poor sites. Rotations for Christmas trees vary

from 20 to 50 years.

Volume increments and yields vary greatly depending

on stand density, age, and site quality. Gross annual increment averaged 9.5 cubic feet per acre (0.7 m^/ha) on sample

plots in northern Arizona and New Mexico (6). Annual

increment of cordwood on fully stocked plots in the Great

Basin ranged from 6 to 30 cubic feet per acre (0.4 to 2.1

m-^/ha) and averaged 17 cubic feet per acre (1.2 m^/ha) (10).

Cordwood volumes up to 1,440 cubic feet per acre (100.8

m^/ha) and cordwood increments up to 45.6 cubic feet per

acre (3.2 m^/ha) per year have been reported for overmature

stands of dense pinyon in western Nevada (11).

Mistletoe is the most important pathogen in the

pinyon-juniper type. Juniper mistletoe {Phoradendron

juniperinum Engelm. Subsp. juniperinum Wiens) is specific

to juniper species, and pinyon dwarf mistletoe {Arceuthobium

divaricatum Engelm.) is specific to pinyon species (5). Both

cause reduced vigor and occasional dieback but rarely cause

mortality. The most important insect pest is pinyon ips {Ips

confusas (LeConte)), which breeds primarily in pinyon and is

endemic throughout the range of pinyon (4). Minor epidemics can occur in areas where uprooted trees or slash accumulation permit the population to build up and successfully attack

healthy trees. Removal or burning of all pinyon slash larger

than 3 inches (8 cm) diameter during harvest will usually

prevent pinyon ips populations from reaching epidemic

proportions.

Pinyon and juniper species are rarely used for sawn

products because of their small size and poor growth form (1),

but pinyon-juniper woodlands provide a variety of other

products. Pinyon nuts were a major source of food for

Indians for many centuries and are still a major product (7).

The woodlands supplied most of the charcoal and fuelwood

to the booming mining industry in the Great Basin during the

latter half of the 19th century (14). Throughout the Southwest,

pinyon—juniper woodlands have been major sources of

fuelwood, fenceposts, and Christmas trees. As demands

increase and technology improves, the woodlands may become important sources of other products (1).

Pinyon-juniper woodlands provide food and shelter for

deer, elk, antelope, wild horses, turkeys, and many other

species of mammals and birds (3, 12). Mule deer depend on

pinyon-juniper woodlands for cover and travel corridors in

many parts of the West, and also for food and shelter during

severe winters (3).

The woodlands have been extensively grazed by livestock for more than a century and some parts have been

grazed for as long as four centuries. All too often, grazing

was continuous and excessive, resulting in deteriorated range

conditions. Grazing on most of the pinyon-juniper ranges

has been brought under management in the past 70 years, but

recovery of the range has been slow. In the past 35 years,

extensive areas of pinyon-juniper have been clearcut, cabled,

chained, crushed, or burned and then seeded to grass to

increase forage production for livestock. Some of these

conversion projects were successful, resulting in greatly

increased carrying capacity for livestock, but many others

failed to increase carrying capacity for more than a few years,

and the treated areas have been reoccupied by juniper and

pinyon.

With few exceptions, the woodlands have been used

with little regard for good forestry practices. Vast areas

around mining towns and other settlements were clearcut

during the 19th century for firewood, charcoal, and other

wood products. Throughout the rest of the woodlands, most

stands have been high-graded, leaving residual stands of

poorly formed trees and inferior species. The few remaining

virgin stands are confined to remote areas and to poor sites.

No silvicultural methods have been tested in pinyon-juniper woodlands. The following recommendations are based

on limited knowledge of the silvical characteristics of pinyon

and juniper. No single silvicultural method is best for all

situations. The appropriate method depends on management

objectives and stand characteristics. Management considerations include wildlife and esthetics as well as production of

fuelwood, juniper posts, Christmas trees, pine nuts, and

forage.

Where wood production is the primary objective, individual tree selection appears to be the best method because it

provides the best conditions for regeneration and continuously maintains adequate growing stock. Cutting cycles

should be long, usually 50 to 100 years, to avoid excessive

administration and harvesting costs. Each harvest cut should

reduce stand basal area (measured at stump height) to about

40 square feet per acre (9.2 m^/ha) to provide adequate

growing space until the next harvest without reducing current

annual increment excessively. Studies in Nevada indicate

that pinyon-juniper stands achieve full site dominance at

about 40 square feet per acre (9.2 m%a) basal area (10). To

meet immediate demands for wood, basal area could be

reduced to as low as 20 square feet per acre (4.6 m^/ha),

particularly if there is a good stand of advanced reproduction.

However, annual increment and future yield would be

reduced accordingly.

The harvest cut should remove all merchantable trees

that have poor growth form, that are infested by mistletoe, or

that would not be expected to survive until the next harvest.

Where pinyon and juniper occur together, pinyon should be

favored by selective removal of juniper except in localities

where juniper is at least as desirable as pinyon for firewood

or where there is existing or potential demand for other

juniper products. If the best nut producing pinyons are left

uncut, the immediate adverse impacts of tree cutting on nut

production would usually be small, and the long-term yields

of nuts would be increased in many cases (8).

Harvesting operations should be carefully managed to

minimize damage to residual vegetation, including advanced

reproduction and shrubs. Slash burning should be limited to

that needed to reduce fire hazard to acceptable levels. Slash

burning damages residual vegetation and results in loss of

nitrogen and other nutrients. Lopped and scattered slash

provides partial shade for seedlings, reduces soil erosion, and

gradually returns nutrients to the soil.

While Christmas trees can be harvested in woodlands

that are managed by the selection method, such harvesting

should be closely supervised to avoid cutting trees that should

be left to produce wood. As much as possible, Christmas tree

cutting should be confined to younger stands that have

reoccupied old bums and other cleared areas. The seed tree

method should be applied to those areas where Christmas tree

production is the primary management objective. About 10

seed trees per acre (25 per ha) are needed for an adequate

85
seed source to maintain a continuous supply of Christmas

trees, and a good shrub understory is necessary for survival

of new seedlings.

Forage production would usually increase in stands

harvested by the individual tree selection method, but the

increases would be small and of short duration because roots

of the residual stand reoccupy the soil mass previously

utilized by the harvested trees. In those localities where

substantial increases in forage production are required, patch

cutting should be used. The patches should be no larger than

5 acres (2 ha) and should be irregularly shaped to reduce

visual impact and to increase edge effect. Clearcutting of

larger areas is not appropriate in pinyon-juniper woodlands

unless the management objective is type conversion to

livestock range.

Literature Cited

1. Barger, R. L.; Ffolliott, P. F. Physical characteristics and utilization of

major woodland tree species in Arizona. Res. Pap. RM-83. Fort

Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky

Mountain Forest and Range Experiment Station; 1972. 80 p.

2. Eyre, F. H., ed. Forest cover types of the United States and Canada.

Washington, DC: Society of American Foresters; 1980. 148 p.

3. Frischknecht, N. C. Native faunal relationships within the pinyon-juniper

ecosystems. In: The pinyon-juniper ecosystem: a symposium; 1975

May; Logan, UT. Logan, UT: Utah State University; 1975: 55-65.

10.

12.

13,

14.

Fumiss, R. L.; Cardin, V. M. Western forest insects. Misc. Publ. 1339.

Washington, DC: U.S. Department of Agriculture; 1977. 654 p.

Hawksworth, F. G.; Wiens, D. Biology and classification of dwarf

mistletoes Arceuthobium. Agrie. Handb. 401. Washington, DC: U.S.

Department of Agriculture; 1974. 838 p.

Howell, J., Jr. Pinyon and juniper—a preliminary study of volume,

growth, and yield. Reg. Bull. 71. Albuquerque, NM: U.S. Department

of Agriculture, Soil Conservation Service, Region 8; 1940. 90 p.

Lanner, R. M. The piñón pine: a natural and cultural history. Reno,

NY: University of Nevada Press; 1981. 208 p.

Little, E. L., Jr. Suggestions for selection cutting of piñón trees. Res.

Note 90. Tucson, AZ: U.S. Department of Agriculture, Forest Service,

Southwestern Forest and Range Experiment Station; 1940. 3 p.

Meeuwig, R. O. Growth characteristics of pinyon—juniper stands in the

western Great Basin. Res. Pap. INT-238. Ogden, UT: U.S. Department

of Agriculture, Forest Service, Intermountain Forest and Range Experiment Station; 1979. 22 p.

Meeuwig, Richard O.; Cooper, Stephen V. Site quality and growth of

pinyon-juniper stands in Nevada. For. Sei. 27(3): 593-601; 1981.

Reveal, J. L. Single-leaf pinon and Utah juniper woodlands of western

Nevada. J. For. 42(4): 276-278; 1944.

Springfield, H. W. Characteristics and management of southwestern

pinyon—juniper ranges: the status of our knowledge. Res. Pap. RM—160.

Fort Collins, CO: U.S. Department of Agriculture; 1976. 32 p.

Vander Wall, S. B.; Balda, R. P. Coadaptations of the Clark's

nutcracker and the piñón pine for efficient seed harvest and dispersal.

Ecol. Monogr. 47(1): 89-111; 1977.

Young, J. A.; Budy, J. D. Historical use of Nevada's pinyon-juniper

woodlands. J. For. Hist. 23(3): 112-121; 1979.

86
Eastern Forest Cover Types

87

Red Pine

John W. Benzie

North Central Forest Experiment Station

James E. McCumber

Eastern Region

Red pine {Pinus resinosa Ait.) is native in the Lake

States, New England, New York, and Pennsylvania but

planted stands now comprise a major portion of the type over

its entire range. Red pine plantations have also been established somewhat south of the species' natural range. The area

of the Society of American Foresters red pine forest cover

type 15, totals more than 1.5 million acres (0.6 million ha)

with about two-thirds of it in the Lake States (3).

Red pine is most common on level to gently rolling sand

plains with soils classified as Entisols, Spodosols, or Alfisols.

In the East it grows on mountain slopes and hilltops in

addition to outwash plains. Although red pine stands are

found from sea level to more than 2,000 feet (610 m)

elevation, it is most common between 700 and 1,400 feet

(215 to 425 m).

Climatic conditions within the red pine range are generally from cool to warm summers, cold winters, and from low

to moderate rainfall. Average annual maximum temperatures

reach 95° F (35.0° C) and average annual minimum temperatures -40° F (-40.0° C) in some areas of the type in the

United States. Frost-free periods average from 80 to 160 days

and July temperatures from 60° to 70° F (15.5° to 21.1° C).

Summer droughts are common, particularly in the western

part of the range. Average growing season precipitation is 15

to 25 inches (380 to 635 mm) and average annual precipitation reaches more than 50 inches (1270 mm) in the eastern

part of the range (5).

Red pine occurs in pure stands or comprises a majority

of the stocking in mixture with eastern white pine {Pinas

strobus L.), jack pine {Pinus banksiana Lamb.), or both. In

addition to white pine, associates on fine sands to loamy

sands include red maple {Acer rubrum L.), northern red oak

{Quercus rubra L.), white spruce {Picea glauca (Moench)

Voss), and balsam fir {Abies balsamea (L.) Mill.). Associates on coarser, drier soils are jack pine, quaking aspen

{Populus tremuloides Michx.), bigtooth aspen {P. grandidentata

Michx.), paper birch {Betula papyrifera Marsh.), and northem pin oak {Quercus ellipsoidalis E. J. Hill). Composition in

planted stands is similar to that in natural stands because

common associates invade or because red pine is planted in

mixture with white pine or jack pine (3).

Red pine may be a coordinate species in mixture with

white pine, especially on dry, sandy loam soils. On the better

sites the rate of succession to white pine is much more rapid

than on the poorer sites. On the most fertile sites the pines

may be replaced by northern hardwood or spruce-fir types,

but on some sandy sites the succession may stop with red

pine as a persistent subclimax type. In the Lake States, red

pine may be established as a subordinate species with jack

pine or aspen in a mixed type. As these shorter-lived species

drop out, red pine predominates. The most common undergrowth in red pine stands includes American and beaked

hazel {Corylus americana Walt, and C cornuta Marsh.),

blueberry {Vaccinium spp.), raspberry {Rubus idaeus L.),

sweetfem {Comptonia peregrina (L.) Coult.), prairie willow

{Salix humilus Marsh.), dwarf bush-honeysuckle {Diervilla

lonicera Mill.), trailing arbutus {Epigaea repens L.), and

spiraea {Spiraea spp.) (3).

Most old-growth stands became established following

fire when a few scattered surviving trees had good seed crops

that coincided with favorable weather (1). Although red pine

seeds can germinate on the organic forest floor, few seedlings

survive because of the shade and rapid drying of the litter.

Exposed mineral soils or disturbed seedbeds increase the

chances for seedling success. Shrub competition may limit

seedling establishment especially on the better sites. Natural

regeneration requires a combination of good seed production,

seedbed preparation, and favorable precipitation during germination and seedling establishment. Because all these requirements are difficult to meet, more reliance is currently

placed on artificial regeneration, especially planting (I).

Seed production normally begins at about 25 years in

open-grown trees and at 50 years in closed stands. The

average number of seeds in a medium to good seed year

ranges from 75,000 to 110,000 per acre (185 330 to 271

810/ha) and in an excellent seed year exceeds 1 million

(2 471 00/ha). Excellent red pine seed crops occur at irregular

and infrequent intervals of from 10 to 12 years or more.

Medium to good seed crops are produced every 3 to 7 years

(5). Several pests reduce red pine seed crops including the

red pine cone beetle {Conophthorus resinosae Hopk.) and

several other insects that prevent normal cone development.

Red squirrels often cut cones and cone-bearing branch tips.

They may completely destroy the current and succeeding

year's cone crop but damage is usually less in closed stands

than in open-grown trees. White-footed mice, redbacked

voles, chipmunks, and birds also eat large quantities of seed

(5).

Seeds are wind-disseminated up to 900 feet (274 m) but

the effective range, as measured by established seedlings,

averages about 40 feet (12 m). Germination and survival are

best on mineral soils, averaging five times as many seedlings

as on undisturbed surfaces (5). Successful seedling establishment has been noted in years with more than 4 inches (100

mm) of rainfall in May, June, and July. But if rainfall is

deficient, some germination may be delayed up to 3 years.

Little germination occurs at temperatures below 60° F (15.5°

C) and is best at 70° F (21.1° C) or higher (5).

Direct seeding has only had limited success and is not

widely used at present. The best success has been on mineral

soil with the seed planted at a depth of 0.25 inch (6 mm) but

most seed is broadcast on the surface following site preparation.

Seed should be coated with bird and rodent repellents and

sown in the spring at the rate of 15,000 viable seeds per acre

(37 070/ha) (I). Red pine seed is normally not dormant and

germinates promptly after spring sowing.

The most common method used to establish red pine

stands is planting 400 to 1,200 trees per acre (990 to

2970/ha). Planting 800 trees per acre (1980/ha) will allow

them to reach merchantable size for posts or pulpwood by the

time the first thinning is needed, at about 25 years of age on

the most productive sites and 35 years on the less productive

89
ones, and will provide enough trees for periodic thinnings

throughout the rotation. Planting bare-root stock should be

done in the spring before growth begins, setting the trees the

same depth or slightly deeper than they grew in the nursery

(1). Container-grown seedlings can be planted any time

during the growing season although fall planting is not

recommended, especially on fine-textured soils where frost

heaving may kill the seedlings. Sites with competing vegetation that may overtop the planted seedlings should be planted

with large, vigorous seedlings. It is important to use seedlings with a well-developed root system and a favorable

top-root ratio. Site preparation to reduce the competing

vegetation will greatly improve survival.

Natural stands with less than 2,000 seedlings or saplings

per acre (4940/ha) will thin themselves through mortality, but

denser stands may stagnate. Dense stands respond well to

thinning and red pines overtopped by oak and red maple for

as long as 40 years have responded to release (5). Red pine is

relatively resistant to damage from herbicides commonly

used to release it from competing vegetation.

Red pine is less tolerant of shade than its common

associates except the aspens, paper birch, and jack pine. It

grows slowly at first but after 4 or 5 years height growth

increases and seedlings usually reach breast height by 8 years

of age. Some shade increases seedling survival on dry sites

but it may seriously inhibit growth. A light overstory of only

30 square feet of basal area per acre (6.9 m^/ha) will reduce

volume growth by 70 percent (1).

Red pine is a long-lived tree and can grow in stands up

to age 200 or more but commercial rotation age may be as

low as 60 years in some managed stands. In stands managed

at 100 square feet or more of basal area per acre (23.0 m^/ha),

mean annual board foot growth culminates around age 120

(1). The total net yield of 100-year-old, well-stocked, managed stands on site index 50 feet (15.2 m) averages about

40,000 board feet (fbm) (8000 cubic feet)' of sawtimber and

approximately 2,000 cubic feet of pulpwood per acre (700

mVha) and on site index 60 feet (18.3 m) about 55,000 fbm

(11,000 cubic feet) of sawtimber and approximately 3,000

cubic feet of pulpwood per acre (980 m-Vha) (2). More than

half of the total yield is removed in periodic thinnings,

beginning when the stand is approximately 30 years old. The

initial planting density, timing of thinnings, and stand density

left after thinning gready affect tree diameter growth (6).

Generally, recommendations based on obtaining maximum

timber yields favor a higher initial stand density than those

based on economic considerations.

Red pine is generally believed to have fewer natural

enemies than most other trees commonly associated with it.

However, trees may be injured or killed by disease, insects,

animals, fire, or weather.

Diseases that have caused problems in red pine plantations include Scleroderris canker {Gremmeniella abietina

(Lagerb.) Morelet) especially the European strain in the

Northeast, Sirococcus tip blight {Sirococcus strobilinus Preuss.),

and root rots {Heterobasidium annosum (Fr.) Bref, and

Armillariella mellea (Vahl. ex Fr.) Karst.). Insects that

sometimes damage red pine include the redheaded pine

sawfly {Neodiprion lecontei (Fitch)), European pine shoot

moth {Rhyacionia buoliana (Schiffermuller)), Sarotoga spittlebug (Aphrophora saratogensis (Fitch)), pine root collar

weevil (Hylobius radicis Buchanan), pales weevil {Hylobius

pales (Herbst)), and white grubs (Phyllophaga spp.) (5).

' Cubic foot and metric conversions of measurements expressed in board

feet should be viewed as estimates because of the assumptions involved in

the conversion process.

The leaders and shoots of red pine seedlings are sometimes nipped by white-tailed deer or snowshoe hare. During

periods of peak populations, the snowshoe or varying hare

may be very destructive. Mice occasionally damage planted

trees in local areas by girdling them under the snow, and

porcupines may girdle some larger trees by feeding on the

bark.

Young red pine stands are susceptible to fire injury, but

prescribed fires can be used in pole-size and larger timber to

control understory development and help reduce the risk of

wildfires. Mature trees are resistant to fire injury because of

their thick bark but sometimes hot fires cause fire scars that

can weaken trees and increase the risk of wind breakage. Red

pine has a wide, spreading root system and is relatively wind

firm, but occasionally suffers losses from wind, especially in

old even-aged stands on exposed sites, such as along lakeshores (5).

Summer droughts and high surface temperatures frequently kill or injure young seedlings. Drought resistance

varies with the condition of the trees but red pine is one of the

most drought resistant conifers. Frost damage is more severe

on dry than wet soils but red pine is generally frost hardy and

only rarely is the succulent growth killed by frost. However,

ice storms may cause breakage in dense sapling stands (5).

Even-age silvicultural systems are best for growing red

pine because it is intolerant. The clearcutting, seed-tree, and

shelterwood regeneration methods have occasionally been

used successfully to naturally regenerate stands following a

good seed crop or when advance regeneration was already

established. Natural regeneration, however, is not very

dependable so the most reliable silvicultural system to

regenerate red pine is clearcutting the mature trees and

planting a new stand (1). Planted stands range from only a

few acres to more than 100 (40 ha) but a large proportion of

them are about 40 acres (16 ha).

The seed-tree system, leaving about 6 trees per acre (15

trees/ha), received extensive trials in Minnesota as one of the

first large-scale efforts to regenerate red pine (4). It had very

limited success. New stands were established only where

seeding, seedbed, and weather conditions were favorable so

this system is not currently recommended for regenerating

red pine (1).

The shelterwood system is recommended where esthetic

or other multiple-use needs require the mature stand to

overlap establishment of the seedling stand. Managed stands

are periodically thinned beginning soon after the trees reach

merchantable size. As stands near rotation age, advance

regeneration can be encouraged by a heavier thinning or

shelterwood cutting (4). If established seedlings are not

adequate for a fully stocked stand at rotation age, planting or

direct seeding will be needed. A shelterwood strip harvesting

system that leaves about 16-foot (4.9 m) wide strips of

mature trees between 50-foot (15.2 m) wide cleared strips

can be used to keep large trees on the area until the seedling

stand is well enough established to dominate the landscape.

Removing the narrow shelterwood strips will provide access

to the seedling stand for protection and cultural operations

such as cleaning, releasing, thinning, and pruning (1). The

shelterwood system should not be used in stands infected

with Sirococcus tip blight because the disease may spread

from the overstory trees to the seedlings.

Although red pine is not well suited to uneven-age

silvicultural systems, it is sometimes desirable to keep

continuous forest cover on special areas. Uneven-aged red

pine stands require careful cutting of mature trees and

frequent release of seedlings, saplings, and pole-size trees to

maintain several age classes in small groups (1). The group

selection system may also be appropriate for a more even

90
flow of products and uses from small areas where it is not

possible to have enough age classes for even-age management.

Growing trees to 100 years would require 50 acres (20 ha) to

sustain cutting a one-half acre (0.2 ha) group every year or 10

acres (4.0 ha) to cut one group every 5 years.

The red pine type is dependent on planting not only to

maintain its present area but to restore it on some of the

several million acres where it once grew. Site preparation to

remove excessive slash, to control shrubs and unmerchant-,

able trees, and to prepare the soil for planting should be

prescribed for each specific site. Planting stock, especially

bare-root, requires careful handling to ensure successful

establishment of high quality, vigorous seedlings.

Seedling stands need to be kept free from overtopping

shrubs and trees to maintain favorable growth. One or more

release cuttings or the use of selective herbicides will be

needed on many areas. Commercial thinnings are recommended for merchantable stands with more than 140 square feet

of basal area per acre (32.1 m^/ha). Periodic thinnings should

remove the smaller, slower-growing intermediate trees to

favor the larger crop trees. High risk, poor quality, and

damaged red pines should also be removed along with

undesirable species at the periodic thinnings. Rotation ages in

stands managed for recreation or visual quality may be

extended beyond those recommended for timber production.

On the other hand, stands managed for wildlife habitat may

have much shorter rotations so that a larger proportion of the

area is regenerated more frequently.

Red pine stands in general are not considered prime

habitat for game birds and mammals, such as ruffed grouse

and white-tailed deer. However, even-aged seedling stands

provide a relatively open area for about a decade with a large

variety of pioneer plant species favorable for edge wildlife.

And dense sapling stands provide cover for many species of

wildlife. Old-growth stands provide favorable habitats for

some wildlife species such as the red squirrel, pine martin,

and pileated woodpecker (5). As already noted, mice, voles,

and chipmunks use red pine seed for food. The American

bald eagle builds nests in large old-growth trees and several

songbirds are associated with pine forests including the

red-breasted nuthatch, blackbumian warbler, pine warbler,

and chipping sparrow. Red pine stands managed near the

minimum recommended stocking level for timber production

will favor a greater variety of understory plants and increase

the supply of wildlife food. Carefully planned landings for

the periodic thinnings can also serve as wildlife openings and

provide some of the desirable food plants for wildlife (1).

Although grazing domestic livestock in red pine stands

is not a generally accepted practice, there is growing interest

in utilizing this potential range resource. In trials underway in

Minnesota, cattle are used to control growth of vegetation

and prepare planting sites. Grazing has also been utilized in

young red pine plantations as a means of reducing fire fuels.

The snow pack water content and the spring snowmelt

runoff is higher in young red pine stands than in unplanted

areas or those with deciduous trees (5). But watersheds with

closed pine stands have more interception and less streamflow

than those with aspen stands. Net precipitation under a

mature red pine stand with 100 square feet of basal area per

acre (23.0 m^/ha) averaged 75 percent of gross precipitation

compared to 84 percent under a comparable aspen stand (7).

Red pine stands managed near the minimum recommended

stocking level for timber production will yield more water

than denser stands.

Stream temperature and water quality are influenced by

tree species, stocking, and harvesting methods. Stands near

lakes and warm water streams are desirable for shade and

esthetics. In areas sensitive to erosion, harvesting operations

need to be carefully planned to prevent soil and logging

debris from getting into the water. Location of landings and

skid trails may be critical and on some areas the erosion

hazard may be severe enough to warrant harvesting only

when the soil is frozen.

Stands of majestic red pine trees have a natural appeal to

hikers, campers, and other forest visitors. In mature red pine

stands used for camping or picnicking, undergrowth may be

desirable for screening, but along traveled routes such as

forest highways or trails, an open, parklike appearance is

preferred. Heavy shade and a needle ground cover enhance

the scenic effects. Red pine stands in and adjoining recreation

areas should be managed to create or maintain a higher

proportion of the forest in large trees with a general appearance of an old-growth stand.

Literature Cited

1. Benzie, John W. Manager's handbook for red pine in the North Central

States. Gen. Tech. Rep. NC-33. St. Paul, MN: U.S. Department of

Agriculture, Forest Service, North Central Forest Experiment Station;

1977. 22 p.

2. Buckman, Robert E. Growth and yield of red pine in Minnesota. Tech.

Bull. 1272. Washington, DC: U.S. Department of Agriculture; 1962.

50 p.

3. Eyre, F. H., ed. Forest cover types of the United States and Canada.

Washington, DC: Society of American Foresters; 1980. 148 p.

4. Eyre, F. H.; Zehngraff, Paul J. Red pine management in Minnesota.

Circular 778. Washington, DC: U.S. Department of Agriculture, Forest

Service; 1948. 70 p.

5. Fowells, H. A., comp. Silvics of forest trees of the United States. Agrie.

Handb. 271. Washington, DC: U.S. Department of Agriculture; 1965.

762 p.

6. Lundgren, A. L. The effect of initial number of trees per acre and

thinning densities on timber yields from red pine plantations in the Lake

States. Res. Pap. NC-193. St. Paul, MN: U.S. Department of

Agriculture, Forest Service, North Central Forest Experiment Station;

1981. 25 p.

7. Verry, Elon S. Estimating water yield differences between hardwood

and pine forests: an application of net precipitation data. Res. Pap.

NC-128. St. Paul, MN: U.S. Department of Agriculture, Forest

Service, North Central Forest Experiment Station; 1976. 12 p.

91
Jack Pine

Thomas D. Rudolph

North Central Forest Experiment Station

Jack pine {Pinus banksiana Lamb.) occurs in the northem forests of the United States and Canada. The range of the

species extends latitudinally from 4r4r N to 64°40' N and

longitudinally from 60° W to 127° W (15, 27, 28). The major

portion of the species range is in Canada. In the United States

it is found in Maine, northern New York, and the northern

Lake States. Isolated stands occur in southeastern Minnesota,

northern Illinois, northern Indiana, and New Hampshire. The

range has been artificially extended by planting on stripmined areas in the central and northeastern States and on the

sand hills of Nebraska (8, 25, 29).

Although jack pine grows best on well-drained loamy

sands, it is usually found on dry sandy or gravelly soils and it

also occurs on loamy soils, thin soils over granites, and peats

(12, 25, 29). The most extensive stands are found on level to

gently rolling sand plains, usually of glacial outwash, fluvial,

or lacustrine origin. It occurs less commonly on eskers, sand

dunes, rock outcrops, and bald rock ridges (25).

In the Lake States jack pine is found chiefly at elevations between 1,000 and 1,500 feet (305 to 455 m). In the

northeastern United States it grows on a variety of sandy sites

from near sea level to about 2,000 feet (610 m) and an outlier

in New Hampshire occurs at 2,500 feet (760 m)(25).

Except in the eastern part of its range where it grows in a

maritime climate, jack pine is found primarily in diverse

continental climates with short, warm to cool summers, cold

winters, and low rainfall. The average January temperatures

range from -20° to 25° F (-28.8° to -3.9° C) and the

average July temperatures range from 55° to 72° F (12.7° to

22.2° C). Mean annual temperatures are between 23° and 49°

F (-5.0° to 9.4° C) (28).

The frost-free period over much of the range is between

80 and 120 days. Generally, temperatures, frost-free period,

and rainfall increase from the northwestern toward the

southeastern part of the range so the averages from these

factors may be higher in many areas in the Lake States and

the northeast than the averages for the entire range (25).

Average annual precipitation ranges from 10 to 55

inches (255 to 1400 mm) but 15 to 30 inches (380 to 760 mm)

are most common. The average warm season precipitation—

April through September—ranges from 6 to 25 inches ( 150 to

635 mm). Summer droughts commonly occur in the Lake

States (25).

Jack pine, a small- to medium-sized tree, is short-lived,

intolerant, and a pioneer in succession. When a source of

seed is available, jack pine establishes itself on areas where

mineral soil has been exposed by disturbances such as fires.

As a result, it is most often found in extensive pure even-aged

stands of Society of American Foresters forest cover type 1

(17, 25). However, it also occurs in mixed stands and is a

component of other forest types: black spruce (type 12);

paper birch (type 18); aspen (type 16); red pine (type 15); and

northern pin oak (type 14).

Associated tree species ranked from dry to mesic sites

include northern pin oak {Quercus ellipsoidalis E. J. Hill),

bur oak {Quercus macrocarpa Michx.), red pine {Pinus

resinosa Ait.), quaking aspen {Populus tremuloides Michx.),

bigtooth aspen {Populus grandidentata Michx.), paper birch

{Betula papyrifera Marsh, var. papyrifera), northern red oak

{Quercus rubra L.), eastern white pine {Pinus strobus L.),

red maple {Acer rubrum L.), balsam fir {Abies balsamea (L.)

Mill.), white spruce {Picea glauca (Moench) Voss), black

spruce {Picea mariana (Mill.) B.S.P.), tamarack {Larix

laricina (Du Roi) K. Koch), and balsam poplar {Populus

balsamifera L.) (17, 25).

Jack pine is less shade tolerant than any of its principal

associates except the aspens and paper birch. Thus, unless

natural succession is interrupted by a major disturbance such

as fire, jack pine is a temporary type that, at least on the

better sites, is replaced by the more tolerant species (6, 7).

On dry, sandy, low fertility sites, where associated species can

scarcely survive, jack pine may form an epaphic climax (7).

After regeneration cuts, establishment and survival of

jack pine from natural seeding is best on sites where mineral

soil has been exposed, competition from other vegetation is

not severe, some early but temporary partial shade is available,

and the water table is within 5 to 6 feet (1.5 to 1.8 m) of the

soil surface (12, 25). If conditions for germination and early

seedling survival are not favorable, direct seeding following

site preparation or planting will be required to establish a new

stand. Seed for direct seeding should be coated with a bird

and rodent repellent and sown at a rate of 20,000 viable seeds

per acre (49 420/ha) (less if seeding is on prepared scalped

spots only) early in the spring, or on snow in the winter to

take advantage of snowmelt waters for germination (7).

If precipitation is lacking during germination and early

seedling establishment, direct seeding will likely fail. If the

first direct seeding fails, the site can be reseeded the

following spring but some additional treatments to control

competing vegetation and potential leaf smother may be

necessary. When competing vegetation is to be controlled by

phenoxy herbicides, timing and dosage must be carefully

controlled to avoid injury to the jack pine seedlings. On sites

where direct seeding cannot be successfully accomplished

and on deep, dry, sandy soils planting will be necessary.

Planting should be done in the spring when nursery-grown

bare root stock is used, but container-grown stock can be

planted throughout the growing season. Spacing should be

about 6 to 8 feet (1.8 to 2.4 m) (7).

Under good early growing conditions in the greenhouse

and/or nursery, female flowering may be initiated on a small

percentage of seedlings before they are planted in the field

(26). Jack pine begins to produce significant amounts of seed

at 5 to 10 years in open stands but not until later in dense,

closed stands (25, 27). The cones are serotinous and persistent so viable seeds can be retained on the trees for many

years (25). These seeds are not released until the cones are

opened by heat. Therefore, when stands are destroyed by

fire, a new stand can be regenerated from the stored seed on

the trees. Once cone production in jack pine begins, some

92
seed is usually produced every year and total crop failures are

rare (18, 25).

In southern parts of the jack pine range, cones on some

trees are nonserotinous and begin releasing seed soon after

they mature, so seed may be disseminated during any season.

The effective range of seed dissemination is about two tree

heights, but is low beyond one tree height (25).

Germination is best on exposed, moist mineral soil

seedbeds and poorest on undisturbed litter and humus where

the surface is apt to dry out rapidly (12, 25). Thus, fires that

consume most of the litter and humus result in suitable seed

beds. Mechanical equipment may also be used to bare the

mineral soil (7, 31).

Jack pine seed occasionally exhibits some dormancy but

under favorable conditions usually germinates to capacity

within 15 to 60 days (25). However, some seeds have

delayed germination (27) so substantial increases in stocking

may be noted up to 3 years after direct seeding (24). Most

germination occurs the first or second growing season following fire but mortality is also highest between the first and

second growing seasons. Heat and drought are important

factors causing seedling mortality. The partial shading and

reduced évapotranspiration provided by slash and snags on

cut-over or burned-over areas can contribute substantially to

good gennination and early survival (12, 22, 25). Once

established, seedlings grow best in full sunlight (21). In

natural stands, jack pine seedlings are usually not found

under crown cover greater than 60 percent (25).

In well-stocked stands, jack pine develops into a short to

medium tall, slender tree, with a narrow crown. In dense

stands, it develops spindly stems that are susceptible to

breakage by wind, ice, and snow. During the first 20 years,

jack pine in its native range is the fastest growing conifer

other than tamarack. In the Lake States, a 20-year-old stand

on a site index 70 site will average 32 feet (9.8 m) tall and 4

inches (10 cm) in d.b.h. (7). Height growth slows in later

years and by age 80 may be less than 6 inches (15 cm) per

year. Mature trees are usually about 55 to 65 feet (16.8 to

19.8 m) tall and 8 to 10 inches (20 to 25 cm) in d.b.h.

although trees 100 feet (30.5 m) tall and 25 inches (64 cm) in

d.b.h. have been noted (7, 27).

Jack pine rotation ages of from 40 to 50 years are

recommended for pulpwood production and from 60 to 70

years are recommended for poles and sawtimber (7). Total

volume yields from well-stocked stands at 40 years will range

from 950 cubic feet per acre (66.5 m^/ha) on site index 40

sites to 2,500 cubic feet per acre (175.0 m^/ha) on site index

60 sites. At age 60 yields on the same sites will be 1,630

cubic feet per acre (114.1 m^/ha) and 3,800 cubic feet per

acre (266.0 m^/ha) respectively (7). Much shorter rotations

may be used when growing jack pine biomass for fiber and/or

energy on good sites, particularly when genetically improved

stock is grown (27, 32).

Jack pine is subject to numerous agents that can cause

damage or mortality at various stages of reproduction and

growth. Cone and seed crops may be reduced by rainy

weather at time of pollination and by red squirrels and other

rodents that destroy cones and eat seeds (14, 25, 27). Cone

and seed insects causing serious losses include the jack pine

budworm {Choristoneura pinus Freeman), a mirid {Platylygus

luridus Reuter), a cone borer {Eucosma monitorana Heinrich),

the webbing coneworm (Dioryctria disclusa Heinrich), the

red pine cone beetle (Conophthorus resinosae Hopk.), and

various cone midges (Lestodiplosis grassator ¥y\es, Resseliella

silvana (Felt), and Asynapta hopkinsi Felt) (23). Many other

insects usually cause lesser direct damage to conelets, cones

and seed or damage to potential cone-bearing shoots (19, 23).

Ovulate and cone abortion, due to unknown causes, can also

reduce seed crops (13).

Survival and growth of jack pine seedlings can be

affected by many insects including root borers (Hylobius

spp.); shoot and stem borers (Pissodes spp.); leaf feeders

such as sawflies (Neodiprion spp.) and the introduced pine

sawfly {Diprion similis (Hartig)), the jack pine budworm, the

pine chafer (Anómala oblivia Horn), the pine webworm

(Tetralopha robusteHa Zeil.), and a tip moth (Tortrixpallorana

(Rob.)); lodgepole needletier (Argyrotaenia tabulana

Freeman), pine needleminer (Exoteleiapinifoliella (Chamb.)),

pine needle sheathminer (Zelleria haimbachi Busck); root

feeders including primarily white grubs (Phyllophaga spp.);

and numerous sucking insects (30).

Many of the same insects that attack young trees are also

active in sapling- and pole-sized stands but at least two

destructive species, the pine root tip weevil (Hylobius

rhizophagus M.B. & W.) and a pine tussock moth (Parorgyia

plagiata Walker), prefer sapling- and pole-sized jack pine

(25, 30).

Numerous diseases attack young jack pines reducing

survival and growth' (25). Most serious are a needle rust

fungus (Coleosporium asterum (Diet.) Syd.), Diplodia blight

(Diplodia pinea (Desm.) Kickx.), Sirococcus shoot blight

(Sirococcus strobilinus Preuss.), scleroderris canker (Gremmeniella abietina (Lagerb.) Morelet), sweetfem blister rust

(Cronartium comptoniae Arth.), pine-oak (eastern) gall rust

(Cronartium quercuum (Berk.) Miy. ex Shirai), pine to pine

(western) gall rust (Endocronartium harknessii (J.P. Moore)

Y. Hirat.), stalactiform rust (Cronartium coleosporioides

(Diet. & Holw.) Arth.), mistletoe broom (Arceuthobium

americanum Nutt. ex Engelm.), and root rot caused by

Armillariella mellea (Vahl. ex Fr.) Karst.

Sapling- and pole-size jack pine suffer from Diplodia

blight, the European strain of scleroderris canker, rust fungi,

root rot fungi including annosum root rot caused by

Heterobasidium annosum (Fr.) Bref., and major decay organisms including Phellinus pini (Thore ex Fr.) A. Ames,

Phaeolus schweinitzii (Fr.) Pat., and Fomitopsis pinícola

(Swartz ex Fr.) Karst. Sapling- and pole-size trees frequently

show growth loss but rarely are killed by needlecast disease

(Davisomycelia ampia (Davids.) Dark.) (25).

Severe droughts may kill established jack pine seedlings,

particularly on coarse textured soils; saplings are more

drought tolerant. Several mammals, including the whitetailed deer, snowshoe hare, and meadow vole can severely

damage or kill young trees by feeding on them (25).

Fire is an important factor in the jack pine type. Most

older stands were established following wildfires (25). Surface wildfires kill seedlings and saplings and hot fires can kill

pole-size stands (7). But fire can also be used to obtain

natural regeneration following cutting or to prepare sites for

direct seeding or planting (1, 4, 5, 11). It can be used to

reduce slash following cutting to reduce the hindrance to

regeneration, to control shrubs and other vegetative competition,

to reduce humus and litter and expose mineral soil seedbeds,

and to open cones on remaining trees and on slash so seeds

can be released. However, the use of fire in jack pine requires

intensive, experienced supervision and even then the outcome is frequently unpredictable (5, 22).

Because of jack pine's intolerance, especially to shade,

even-age management using the clearcutting, shelterwood, or

seed-tree silvicultural system is the only practical method to

maintain the forest type (6, 7).

The clearcutting method is recommended for harvesting

mostjack pine stands (6, 7). Regeneration can be obtained by

direct seeding, by planting genetically improved seedlings of

' Skilling, D. D. Personal communication. October 15, 1981. U.S.

Department of Agriculture, Forest Service, North Central Forest Experiment

Station, St. Paul, Minn.

93
an adapted seed source, or by scattering serotinous cones

from high quality trees (6, 7). Whichever regeneration

method is used, some additional site preparation will usually

be necessary to reduce slash, expose mineral soil seedbeds,

and control competing vegetation.

Some existing stands may have originated by seeding

from cull trees left in the previous harvest and some plantations established during the 1930's and 1940's and now being

harvested were planted with nonadapted provenances or with

stock from seed of poor quality open-grown trees (27).

Catastrophic wood yield losses result from planting nonadapted

provenances (20). Such stands are not a suitable source of

seed for regeneration, so prescribed burning under conditions

that will consume the slash and kill the seeds it contains

should be considered, followed by planting or direct seeding

with an adapted, desirable seed source.

If tree quality in a stand to be harvested is good and the

cones are serotinous, a new stand can be established by

scattering cone-bearing slash within 12 inches (30 cm) above

prepared bare mineral soil seedbeds. The heat near the

ground surface will open the serotinous cones and release the

seed. The scattered slash will provide partial shade that is

beneficial during germination and early seedling establishment,

but care is needed to avoid accumulations of slash that might

interfere with subsequent seedling development, provide

habitat for high rodent populations, or present a fire hazard

during the most vulnerable seedling stage. These problems

are minimized if the slash is brought down close to the

ground where the seed will be released quickly and the slash

deteriorates rapidly.

The seed-tree system is an alternative silvicultural system for high quality stands with serotinous cones (6, 7).

During the harvest, at least 10 well distributed, high quality

seed trees should be left per acre (25 trees/ha). Prescribed

burning is recommended to consume the slash, kill the

vegetative competition, expose mineral soil, and open the

cones on the seed trees. This method has the advantage of

maintaining stand quality and of producing some genetic gain

from generation to generation because the best can be

selected as seed trees. For such potential gain to be realized,

the prescribed burn must kill the seed in the slash to assure

that regeneration is only from the selected trees. The slash

should be burned as soon after harvest as it is dry enough, to

minimize the time for windthrow-loss of seed trees before

cones are opened by the fire and seeds dispersed. Early

spring fires result in seeding at the most favorable time but

late fall fires with the released seed overwintering for early

spring germination may also be effective if rodent populations are low. If weather conditions following seed dispersal

are unfavorable for seedling establishment, direct seeding or

planting will be required because the seed trees will have

been killed by the hot prescribed bum (7).

The shelterwood silvicultural regeneration system can

be successful in vigorous, well-stocked jack pine stands in

which trees with nonserotinous cones form at least 8 square

feet of basal area per acre (1.8 m^/ha) (7, 10).^ The initial or

regeneration cut should leave 30 to 40 square feet of basal

area per acre (6.9 to 9.2 m^/ha), favoring trees with open

cones (10).

The removal cut should be made when milacre (4.0 m"^)

stocking reaches 60 percent, usually from 7 to 10 years after

the regeneration cut. Removal of the shelterwood overstory

as soon as possible after adequate regeneration is established

Schantz-Hansen, R. Personal communication. January 21, 1982. Potlatch Corporation, Cloquet, Minn.

will reduce volume losses due to mortality in the shelterwood

trees, seedling losses due to suppression and logging damage,

and the risk of jack pine budworm buildup in the overstory

and subsequent defoliation of the newly established seedlings

(10).

There are several disadvantages of the shelterwood

system for jack pine: first, regeneration of a fully stocked

new stand may take longer than in the clearcut or seed-tree

systems; second, control over stocking and density is lacking;

and, third, stands containing a mixture of associated species

may convert to other, more tolerant species so it may not be

possible to maintain the jack pine type (10).

Intermediate cutting methods will depend on the initial

stand density, economic feasibility, and whether the final

crop is to be pulpwood, or poles and sawtimber. Precommercial

and intermediate cuts in overly dense stands may not increase

total volume yields but the growth will be concentrated on the

better trees. Stands containing more than 2,000 sapling-size

trees per acre (4940 trees/ha) should be precommercially

thinned to about 1,000 trees per acre (2470 trees/ha) to

improve growth and development of the potential crop trees

(7). In denser young stands, mechanical methods that clear

strips about 8 feet (2.4 m) wide and leave strips of trees about

2 feet (0.6 m) wide, for example, may be more efficient than

leaving uniformly spaced trees. The mechanical equipment,

however, frequently damages the crop trees and growth

responses to precommercial thinning are not always favorable and may not justify the cost (2, 3, 9, 16).

For production of poles and small sawlogs, jack pine

stands on site index 60- or-better sites respond well to

commercial thinnings that can begin in stands at about age 30

(7). Stands can be thinned to 80 square feet of basal area per

acre (18.4 m^/ha) but no more than 30 percent of the basal

area should be removed per thinning to minimize postlogging

mortality. Row thinnings in plantations or other systematic

methods are recommended only when economics or high

stand densities prevent marking individual trees for removal.

Thinning should remove the smaller, slower growing, and

damaged or poor quality trees to improve overall stand

quality (7).

Harvesting, site preparation, and regeneration practices

in the jack pine type should be based on multiple-use

objectives. Harvesting and site preparation on slopes and

near lakes and streams must be carefully managed to protect

the watershed and to prevent soil erosion and debris from

entering the water. Harvesting when soils are frozen will

reduce erosion hazards on some areas (7).

Many wildlife species find food or shelter in jack pine

forests including major game species such as the snowshoe

hare and the white-tailed deer (7). Clumpy stands ofjack pine

in the Lower Peninsula of Michigan between 5 and 20 feet

(1.5 to 6.1 m) tall, provide nesting sites for the endangered

Kirtland's Warbler. Management for this bird requires application of silvicultural systems that will periodically regenerate stands covering large areas of 80 acres (32 ha) or more to

keep enough area in young stands where branches reach the

ground to provide nesting sites (7).

Before applying silvicultural systems that make major

changes in the appearance of an area, managers must also

consider recreation and esthetic values of the jack pine type.

Where it can be practically applied, the shelterwood system

may be esthetically more pleasing than the clearcut or

seed-tree system because a new stand is already established

before the mature one is completely removed (10).

Jack pine has been planted on strip-mine areas, mine

tailings, and pond levees; as windbreaks; and as protection

for dunes and sand-blows (8, 25, 29).

94
Literature Cited

1. Ahlgren, C. E. Some effects of prescribed burning on jack pine

reproduction in Northeastern Minnesota. Misc. Rep. 94. Forestry Series

5. St. Paul, MN: University of Minnesota Agricultural Experiment

Station; 1970. 14 p.

2. Aim, A. A.; Pflager, S. M.; Schantz-Hansen, R. Mechanized stripthinning in jack pine reproduction. Can. J. For. Res. 9: 470—473; 1979.

3. Aim, A. A.; Schantz-Hansen, R. Mechanized thinning of dense

post-fire jack pine regeneration. For. Res. Note 220. St. Paul, MN:

University of Minnesota; 1970. 4 p.

4. Beaufait, W. R. Influences of shade level and site treatment including

fire on germination and early survival of Pinus banksiana. Lansing, MI:

Michigan Department of Conservation, Forestry Division: 1960. 79 p.

5. Beaufait, W. R. Procedures in prescribed burning in jack pine. Tech.

Bull. 9. Houghton, MI: Michigan College of Mining and Technology;

1962. 39 p.

6. Benzie, J. W. Jack pine. In: Silvicultural systems for the major forest

types of the United States. Agrie. Handb. 445. Washington, DC: U.S.

Department of Agriculture; 1973: 60—62.

7. Benzie, J. W. Manager's handbook for jack pine in the north central

states. Gen. Tech. Rep. NC-32. St. Paul, MN: U.S. Department of

Agriculture, Forest Service, North Central Forest Experiment Station;

1977. 18 p.

8. Boldt, C. E. Jack pine plantations in Nebraska sandhills. J. For. 67(2):

96-100; 1969.

9. Buckman, R. E. Twenty-two-year results of a precommercial thinning

experiment in jack pine. Res. Note LS—46. St. Paul, MN: U.S.

Department of Agriculture, Forest Service, Lake States Forest Experiment Station; 1964. 2 p.

Caveney, E. W.; Rudolph, V. J. Reproducing jack pine by the

shelterwood method. Res. Rep. 110. East Lansing, MI: Michigan State

University Agricultural Experiment Station; 1970. 11 p.

Cayford. J. H. The role of fire in the ecology and silviculture of jack

pine. In Proceedings Tall Timbers Fire Ecology Conference; 1970;

Fredricton, NB. Tallahassee, FL: Tall Timbers Research Station; 1971:

221-244.

12. Cayford, J. H.; Chrosciewicz, Z.; Sims, H. P. A review of silvicultural

research in jack pine. For. Branch Publ. 1173. Ottawa, ON: Canadian

Department of Forestry and Rural Development; 1967. 209 p.

13. Cecich, R. A. Ovulate development and abortion in Pinus banksiana.

In: Proceedings lUFRO Symposium on flowering and seed development

in forest trees; 1978 May 15-18; Starkville, MS. Starkville, MS:

USDA Forest Service, Southern Forest Experiment Station and Mississippi State University; 1979: 33-40.

14. Cecich, R. A.; Rudolph, T. D. Time ofjack pine seed maturity in Lake

States provenances. Can. J. For. Res. 12: 368-373.

15. Critchfield, W. B.; Little, E. L. Geographic distribution of the pines in

the world. Misc. Publ. 991. Washington, DC: U.S. Department of

Agriculture; 1966. 97 p.

16. Dosen, R. C; Stoeckeler, J. H.; Kilp, F. G. Mechanized thinning in

jack pine saplings. J. For. 55(3): 201-204; 1957.

17. Eyre, F. H. ed. Forest cover types of the United States and Canada.

Washington, DC: Society of American Foresters; 1980. 148 p.

10

11

18. Godman, R. M.; Mattson, G. A. Seed crops and regeneration problems

of 19 species in northeastern Wisconsin. Res. Pap. NC—123. St. Paul,

MN: U.S. Department of Agriculture, Forest Service, North Central

Forest Experiment Station; 1976. 5 p.

19. Hedlin, A. F.; Yates, H. O. Ill; Tovar, D.C.; Ebel, B. H. [and others].

Cone and seed insects of North American conifers. Ottawa, ON:

Canadian Forestry Service; Washington, DC: U.S. Department of

Agriculture, Forest Service; Chapingo, Mexico: Secretaria de Agricultura

y Recursos Hidráulicos, 1980. 122 p.

20. Jeffers, R. M.; Jensen, R. A. Twenty-year results of the Lake States

jack pine seed source study. Res. Pap. NC-181. St. Paul, MN: U.S.

Department of Agriculture, Forest Service, North Central Forest Experiment Station; 1980. 20 p.

21. Logan, K. T. Growth of tree seedlings as affected by light intensity. II.

Red pine, white pine, jack pine, and eastern larch. Publ. 1160. Ottawa,

ON: Canadian Department of Forestry; 1966. 19 p.

22. Miller, E. L.; Schneider, G. First year growth response of direct seeded

jack pine. Res. Rep. 130. East Lansing, MI: Michigan State University

Agricultural Experiment Station; 1971. 8 p.

23. Rauf, A.; Cecich, R. A.; Benjamin, D. M. Life table evaluation of cone

and conelet mortality for jack pine, Pinus banksiana Lamb, in Wisconsin.

In: Proceedings Second North Central Tree Improvement Conference;

Madison, WI: North Central Tree Improvement Association; 1981:

166-175.

24. Riley, L. F. The effect of seeding rate and seedbed availability on jack

pine stocking and density in Northeastern Ontario. Info. Rep. O—X—318.

Sault Ste. Marie, ON: Canadian Forestry Service, Great Lakes Forest

Research Center; 1980. 36 p. plus append.

25. Rudolf, P. O. Jack pine {Pinus banksiana Lamb.). In: Powells, H. A.,

comp. Silvics of forest trees of the United States. Agrie. Handb. 271.

Washington, DC: U.S. Department of Agriculture; 1965: 338-354.

26. Rudolph, T. D. Female strobili on 12-month-old jack pine. Tree Plant.

Notes 30: 24-26; 1979.

27. Rudolph, T. D.; Yeatman, C. W. Genetics of jack pine. Res. Pap.

WO-38. Washington, DC: U.S. Department of Agriculture, Forest

Service; 1982. 60 p.

28. Schoenike, R. E. Geographic variation in jack pine. Tech. Bull. 304.

St. Paul, MN: University of Minnesota Agricultural Experiment Station;

1976. 47 p.

29. Sprackling, J. A.; Read, R. A. Jack pine provenance study in eastern

Nebraska. Res. Pap. RM-143. Fort Collins, CO: U.S. Department of

Agriculture, Forest Service, Rocky Mountain Forest Experiment Station;

1975. 8 p.

30. Wilson, L. F. A guide to insect injury of conifers in the Lake States.

Agrie. Handb. 501. Washington, DC: U.S. Department of Agriculture;

1977. 218 p.

31. Zasada, Z. A.; Aim, A. A. Effect of mechanized tree harvesting on jack

pine regeneration requirements. Misc. Rep. 97. Forestry Series 8. St.

Paul, MN: University of Minnesota Agricultural Experiment Station;

1970. 18 p.

32. Zavitkovski, J.; Jeffers, R. M.; Nienstaedt, H.; Strong, T. F. Biomass

production of several jack pine provenances at three Lake States

locations. Can. J. For. Res. 11: 441-447; 1981.

95
Black Spruce

William F. Johnston

North Central Forest Experiment Station

Thomas M. Smith

Eastern Region

Black spruce {Picea mariana (Mill.) B.S.P.) occurs

mainly in pure stands and makes up a majority of the stocking

in the black spruce forest cover type, Society of American

Foresters type 12 (1). Although primarily a Canadian type, it

occupies 1.7 million acres (0.7 million ha) of commercial

forest land in the northern Lake States (more than 1 million

acres (0.4 million ha) in Minnesota), and approximately

300,000 acres (121 400 ha) in the Northeastern States

(chiefly in northern Maine and New York).

In the Lake States the black spruce type grows mainly

on glacial lake beds and lake-swamp-moraine plains at

elevations averaging about 1,000 feet (305 m). In the

Northeast most of the type is found in the Adirondack-New

England highlands from elevations of about 1,000 feet (305

m) to more than 2,000 feet (610 m).

The black spruce type in the United States is found

mainly on peatland sites where the organic soil or peat is

more than 12 inches (30 cm) thick. The type also commonly

occurs on transitional sites between peatlands and uplands, as

well as on upland sites.

Most peatland sites are extensive areas on gently sloping

lake beds or smaller filled lakes. In both cases site quality and

associated vegetation differ greatly depending on water

sources and movement (1). The most productive peatland

sites occur where the soil water is continuous with the

regional ground water system and thus contains nutrients

from mineral soil areas. These sites have moderately well

decomposed peat that includes much partially decayed wood

and is dark brown to blackish. The poorest sites have thick

deposits of poorly decomposed, yellowish brown sphagnum

peat (7).

Transitional sites with shallow organic to wet mineral

soils are among the most productive black spruce sites. In the

Lake States the black spruce type is common on upland or

mineral soil sites mainly on the Laurentian Shield in northeastern Minnesota and in a few isolated areas of Michigan's

Upper Peninsula. On the Shield, black spruce grows on

gravelly and bouldery loam and on shallow soil over bedrock,

usually mixed with other species and occasionally as a pure

type. Growth is best where the slope is gentle and moisture is

plentiful, either from a shallow water table or seepage. South

of the Shield, black spruce is sometimes found on sandy soil

with a high water table (7).

The climate in which the black spruce type grows in the

Lake States and Northeast is generally humid, with short,

cool summers and long, somewhat severe winters. Average

annual precipitation ranges from about 20 inches (510 mm) in

northwestern Minnesota to 48 inches (1220 mm) or more in

the Adirondack-New England highlands; most of the precipitation comes in the summer. Average annual snowfall ranges

from about 40 inches (1015 mm) to more than 150 inches

(3810 mm). Average July temperatures range from about 65°

to 70° F (18.3° to 21. r C); January temperatures range from

0° to 20° F (-17.8° to -6.7° C). The average frost-free

period ranges from about 90 to 150 days.

Because of its exceedingly broad distribution (especially

in Canada) and various ecological attributes, the black spruce

type has been divided into six subtypes (1). Most of the

type's commercial forest area in the Lake States and Northeast,

however, is occupied by the following four subtypes: black

spruce-feather moss, black spruce-sphagnum, black

spruce-speckled alder, and black spruce-dwarf shrub.

These subtypes occur mainly on peatland sites. Tamarack

{Larix laricina (Du Roi) K. Koch) is the most common tree

associate. Other common associates, especially on the better

sites where the black spruce—speckled alder subtype is

characteristic, include northern white-cedar {Thuja occidentalis

L.), balsam fir {Abies balsamea (L.) Mill.), white spruce

{Picea glauca (Moench) Voss), quaking aspen {Populus

tremuloides Michx.), paper birch {Betula papyrifera Marsh.),

black ash {Fraxinus nigra Marsh.), and red maple {Acer

rubrum L.). Jack pine {Pinus banksiana Lamb.) is the most

common associate on the drier sandy and rocky sites. Red

spruce {Picea rubens Sarg.) is sometimes associated with

black spruce and hybridizes with it in northern New England

and New York (1).

Natural seeding is still the most important mode of

reproduction in the black spruce type, although artificial

(direct) seeding is being used extensively on large, peatland

harvest areas in Minnesota. Vegetative reproduction by

layering—where branches become buried in moss and develop adventitious roots—is common on poor sites, particularly in the black spruce-sphagnum subtype (1). Planting is

often used on upland and transitional sites where associated

trees are very competitive because it results in faster establishment and thus better control of composition. However,

planting black spruce to reforest productive, brushy peatlands

has met with little success despite many past attempts.

Black spruce stands 40 or more years old have a nearly

continuous seed supply because the persistent cones shed

seed for at least 4 years after ripening (7). Some new seed is

produced almost every year; heavy crops occur at intervals of

2 to 6 years. Natural seeding is effective up to about 260 feet

(79.2 m) from the windward edge of a mature stand and up to

half that distance from the leeward edge (7).

Seedling establishment is generally successful on peatland sites if the surface organic layer is removed by fire or

machine, compacted (as in a skid road), or composed of

living sphagnum moss {Sphagnum spp.). Most types of

sphagnum moss make good seedbeds, although some types

outgrow black spruce seedlings and smother them. Other

mosses—particularly the feather mosses Pleurozium schreberi

(Brid.) Mitt., Hylocomium splendens (Hedw.) BSG, and

Ptilium crista-castrensis (Hedw.) De Not.—dry up and die

when a stand is opened and make extremely poor seedbeds.

Thus seedbed conditions are usually much improved by

removing or compacting such mosses (7), especially in the

black spruce-feather moss subtype where they dominate the

moss carpet.

96
On both peatland and upland sites fires that completely

remove the surface organic layer usually prepare good

seedbeds for black spruce. On upland sites, however, scarification that incorporates this layer into the mineral soil is

probably a safer and more effective and economical way to

prepare seedbeds. Moist mineral soils usually provide good

seedbeds for black spruce (6), but exposed mineral soil may

be too waterlogged or subject to frost heaving in some

low-lying areas (12).

Except in poorly stocked stands, harvesting can produce

a heavy cover of slash that buries good seedbeds (such as

sphagnum moss) or suitable advance growth. Thus slash

disposal by broadcast burning, full-tree skidding, or piling

and burning usually favors black spruce reproduction.

Black spruce is shade-tolerant, but survival and growth

of seedlings (and apparently layers) are much better in the

open (3). Trees in older stands are generally susceptible to

breakage or uprooting by wind because rot becomes common

and black spruce has a shallow root system. Both breakage

and uprooting occur mainly along stand edges exposed to the

prevailing wind and in stands opened by partial cutting.

However, wind damage is not heavy on poor sites where

trees are short. Black spruce growing on peatlands is especially susceptible to mortality or reduced growth from impeded drainage, such as that caused by roads and beaver

damming (7). Although black spruce is apparently tolerant of

frost, new growth has been damaged by frost on young trees

planted on transitional and upland sites.

Black spruce encounters substantial competition where

associated trees and shrubs are abundant, especially on

peatland and transitional sites occupied by the black

spruce-speckled alder subtype. Although black spruce will

eventually grow above such vegetation on most of these sites,

slow growth and understocking result when it is severely

suppressed for several years. Fortunately, quaking aspen and

paper birch, which often reproduce well on peatland harvest

areas, should not severely suppress black spruce except on

the best sites. Aerial spraying of selective herbicides will

usually release black spruce in brushy stands (7, 12).

Under normal conditions, mature black spruce averages

from 40 to 65 feet (12.2 to 19.8 m) tall and about 9 inches (23

cm) in d.b.h. on good sites (12). However, height of

dominant trees at 50 years ranges from about 45 feet (13.7m)

on the best sites to less than 15 feet (4.6 m) on the poorest

(7). A site index of 25 feet (7.6 m) is about the minimum for

commercial forest land. The growth rate of black spruce

could undoubtedly be increased on peatlands by draining and

fertilizing, but specific practices have not been developed

(7)-

Cordwood rotations based on variable-density yield

tables for black spruce range from 60 to 150 years or more,

depending on stand age and basal area. Most rotations have a

range because the mean annual increment is near the maximum for a number of years. And young, well-stocked stands

usually have shorter rotations than older, poorly stocked

stands. However, except for excluding trees smaller than 3.6

inches (9 cm) in d.b.h., these rotations do not consider tree

size (7). Therefore, excessively dense stands or those on poor

sites may require longer rotations to produce merchantable

yields.

Mature, even-aged stands of black spruce on good sites

commonly yield 3,000 total cubic feet per acre (210.0 m^/ha)

or 30 cords per acre (189.0 m^/ha) for trees 3.6 inches (9 cm)

and larger in d.b.h. In contrast, many stands on poor sites

never produce merchantable quantities of pulpwood (7).

However, such stands have possible future use for producing

energy (biomass), especially in northern Minnesota where

they occupy large areas. Little is known about the growth and

yield of uneven-aged stands, but they apparently grow more

slowly and have lower volumes than even-aged stands (4).

Eastern dwarf mistletoe {Arceuthobium pusillum Peck)

is the most serious disease of black spruce in the Lake States.

Besides causing witches' brooms, it significantly reduces

volume growth and eventually kills infected trees. Thus

mistletoe should be controlled, especially on the better sites.

Butt and heart rot caused by such fungi as Phaeolus schweinitzii

(Fr.) Pat., Haematostereum sanguinolentum (Alb. & Schw.

ex Fr.) Pouz., Armillariella mellea (Vahl. ex Fr.) Karst., and

Phellinuspini (Thore ex Fr.) A. Ames can lead to windbreakage.

Rot becomes common after about 70 years in upland stands

and 100 years in peatland stands (3)- It is serious enough in

upland stands to usually limit their rotation to 70 years (7).

The spruce budworm {Choristoneurafumiferana (Clemens)) is generally the most important insect pest of black

spruce, particularly when black spruce is mixed with balsam

fir. Budworm defoliation for several years in succession may

result in moderate to severe mortality. The yellowheaded

spruce sawfly (Pikonema alaskensis (Rohwer)) sometimes

severely defoliates young, open-grown black spruce whereas

most dense stands (natural or planted) are practically immune

to attack.

Snowshoe hares may extensively damage black spruce

seedlings and saplings when hare populations are high. Red

squirrels gather cones in large quantities, and thus may

consume much of the seed supply in some areas during poor

seed years.

Black spruce is easily killed by both ground and crown

fires. However, the risk of wildfire is low on most black

spruce areas in the United States and good fire protection

now results in little loss (7).

Many of the present black spruce stands originated after

wildfire because mature trees (even if killed) bear persistent

cones that disseminate viable seed (3). These stands are

generally even-aged, although closed stands that escape fire

for more than 100 years usually become uneven-aged because new trees begin to fill in as overstory trees die. Also,

the less tolerant black spruce is eventually succeeded by

balsam fir and, to a lesser extent, northern white-cedar if

undisturbed by fire, especially on the better upland and

peatland sites (4, 5).

Broadcast burning of slash is a common practice for

favoring black spruce reproduction on peatland harvest areas

in the Lake States, especially Minnesota. Under prescribed

conditions, it is a safe and efficient way not only to dispose of

slash but also to simultaneously kill residual conifers, eradicate dwarf mistletoe, improve nonsphagnum seedbeds, and

kill the stems of brush species. Although the last two items

apparently require more severe burns than the others, burning

should not be done during abnormally dry periods when fires

can bum deeply in peat and become extremely difficult to

extinguish (7).

The black spruce type is usually managed to produce a

high sustained yield of pulpwood as efficiently as possible

without adversely affecting other forest resources. For this

objective, the type can probably be managed best in fairly

large, even-aged stands similar to those in virgin forests.

Such stands should be well suited for efficient cultural

operations and mechanized harvesting (7). Uneven- or allaged management is best applied on poor sites where stands

are windfirm and have abundant layering, and where only the

largest trees produce pulpwood anyway. The poorest sites

should be managed mainly for Christmas trees if a market

exists (7).

Black spruce is well adapted to even-aged management.

Clearcutting in strips or patches is generally considered the

best silvicultural system for managing the type (7, 12). This

97
is because clearcut areas provide the full light needed for

optimum survival and growth, and they have no wind

damage. However, adjacent strips or stands of mature timber

should not be exposed to the prevailing wind or serious

damage may occur along their edges. Clearcutting is definitely better than the shelterwood and seed-tree systems for

controlling dwarfmistletoe because all infected trees (including

advance reproduction) should be killed by cutting or broadcast burning (7).

In contrast, areas with a shelterwood have slower

growing reproduction, and in both the seed-tree and shelterwood

systems many of the reserved trees are broken or uprooted by

wind. However, the shelterwood system is a satisfactory

alternative in small, fairly windfirm stands in which clearcutting

is undesirable for esthetic or other reasons. An advantage of

the shelterwood system in mixed stands is that the proportion

of black spruce reproduction can probably be increased by

removing associated trees during the first or seed cutting.

So, except under special conditions or perhaps on poor

sites, black spruce stands should be clearcut at maturity,

either in strips to be seeded naturally or in large patches

followed by direct seeding. Strips (preferably progressive

rather than alternate) can be applied best in large, windfirm

stands that do not require broadcast burning. They should

generally be perpendicular to and progress toward the prevailing wind direction, and can be 260 feet (79.2 m) wide with

natural seeding from the windward side. An advantage of

burning large patches of 40 acres (16 ha) or more is that it

substantially reduces site preparation costs per unit area. A

disadvantage is that it is sometimes difficult to obtain enough

seed of acceptable provenance at reasonable cost to regenerate the area (7).

Broadcast burning of the slash will foster establishment

and growth of new stands when any of the following

conditions exist on the harvest area before or after a clearcut:

witches' brooms (from dwarf mistletoe) are readily noticeable;

undesirable residual stems are abundant; brush is readily

noticeable; sphagnum seedbeds are poorly distributed; or

slash cover is heavy (7). However, if slash cover is the only

problem expected, full-tree skidding can be used as a

satisfactory alternative to broadcast burning (8).

In the uneven-aged management of black spruce on poor

sites, individual tree selection is the best silvicultural system

to use, whether for producing pulpwood or Christmas trees.

Stands managed for Christmas trees should be partially cut

about every 10 years or some trees may become unmarketable (7). On better sites selection cutting will generally

increase the proportion of balsam fir and northern whitecedar in the succeeding stand.

Heavy thinning in dense, middle-aged black spruce

stands increases diameter increment but often decreases

volume increment, probably because the site is not fully

utilized (10, 11). Thinning of overstocked stands in the

sapling and pole stage is not recommended due to the low

economic return and risk of increasing wind damage (7).

The spruce grouse depends mainly on the black spruce

type for food and cover (7); the snowshoe hare and red

squirrel also use it to a large degree. Birds common in black

spruce stands during the summer include the ruby-crowned

kinglet, magnolia warbler, and Cape May warbler. Others

such as the pine grosbeak, pine siskin, and crossbills sometimes feed on black spruce seed (2). And the American

osprey, a sensitive species, often nests in lowland types such

as black spruce.

Small stands of black spruce add diversity to the

landscape, and ones that border other vegetation types—

especially tamarack, which turns yellow in the fall—are

esthetically appealing (9). Mature, nonbrushy stands with a

carpet of moss have special appeal, as do the crops of

blueberries (mainly Vaccinium angustifolium Ait.) that often

grow on harvest areas during the establishment period. The

impact of harvesting black spruce on esthetics can be

minimized by having harvest boundaries follow natural type

lines and disposing of slash or other debris to leave harvest

areas neat (7).

Clearcutting black spruce on peatland sites has little

effect on annual water yields or water tables. And nutrient

concentrations in streamflow should not increase significantly unless harvesting (with or without broadcast burning)

is on a massive scale (9). However, harvesting should be

done only in winter after the ground is frozen and snowcovered to minimize peat disturbance and its possible effect

on water quality. Also, the normal movement of water must

be maintained to prevent damage from impeded drainage (7).

Literature Cited

1. Damman, A. W. H.; Johnston, William F. Black spruce. In: Eyre, F.

H., ed. Forest cover types of the United States and Canada. Washington,

DC: Society of American Foresters; 1980: 11-14.

2. Dawson, Deanna K. Bird communities associated with succession and

management of lowland conifer forests. In: Management of north

central and northeastern forests for nongame birds: Workshop proceedings;

1979 January 23-25; Minneapolis, MN. Gen. Tech. Rep. NC-51. St.

Paul, MN: U.S. Department of Agriculture, Forest Service, North

Central Forest Experiment Station; 1979: 120-131.

3. Fowells, H. A., comp. Silvics of forest trees of the United States.

Agrie. Handb. 271. Washington, DC: U.S. Department of Agriculture;

1965. 762 p.

4. Hatcher, R. J. A study of black spruce forests in northern Quebec. Publ.

1018. Ottawa, ON: Canada Department of Forestry; 1963. 37 p.

5. Heinselman, Miron L. Fire in the virgin forests of the Boundary Waters

Canoe Area, Minnesota. Quat. Res. 3: 329-382; 1973.

6. Jeglum, J. K. Effects of some seedbed types and watering frequencies

on germination and growth of black spruce: a greenhouse study. Rep.

O-X-292. Sault Ste. Marie, ON: Department of the Environment,

Canadian Forestry Service, Great Lakes Forest Research Centre; 1979.

33 p.

7. Johnston, William F. Manager's handbook for black spruce in the north

central States. Gen. Tech. Rep. NC-34. St. Paul, MN: U.S. Department of Agriculture, Forest Service, North Central Forest Experiment

Station; 1977. 18 p.

8. Johnston, William F. Full-tree skidding favors black spruce reproduction under certain peatland conditions. Res. Note NC-252. St. Paul,

MN: U.S. Department of Agriculture, Forest Service, North Central

Forest Experiment Station; 1980. 4 p.

9. Ohmann, L. F.; Batzer, H. O.; Buech, R. R.; Lothner, D. C. [and

others]. Some harvest options and their consequences for the aspen,

birch, and associated conifer forest types of the Lake States. Gen. Tech.

Rep. NC-48. St. Paul, MN: U.S. Department of Agriculture, Forest

Service, North Central Forest Experiment Station; 1978. 34 p.

10. Steneker, G. A. Strip and spaced thinning in overstocked jack pine and

black spruce stands. Inf. Rep. MS-X-16. Winnipeg, MB: Canada

Department of Fisheries and Forestry, Forest Research Laboratory

1969. 14 p.

11. van Nostrand, R. S. Commercial thinning of 60-year-old black spruce in

Newfoundland. Inf. Rep. N-X-104. St. John's, NF: Department of

the Environment, Canadian Forestry Service, Newfoundland Forest

Research Centre; 1973. 13 p.

12. Vincent, A. B. Black spruce: a review of its silvics, ecology and

silviculture. Publ. 1100. Ottawa, ON: Canada Department of Forestry;

1965. 79 p.

98
Tamarack

William F. Johnston

North Central Forest Experiment Station

Robert E. Brittain

Eastern Region

Tamarack {Larix laricina (Du Roi) K. Koch) is pure or

comprises a majority of the stocking in the tamarack forest

cover type, Society of American Foresters type 38 (7).

Besides being a widespread type in Canada, it occupies

850,000 acres (344 000 ha) of commercial forest land in the

northern Lake States (55 percent of which occurs in Minnesota)

and 110,000 acres (45 000 ha) in the Northeastern States

(almost all in Maine).

In the Lake States the tamarack type grows mainly on

glacial lake beds and lake-swamp-moraine plains at elevations averaging about 1,000 feet (305 m). In Maine most of

the type is found between the Atlantic coast and New

England highlands from elevations of less than 500 feet (150

m) to more than 1,000 feet (305 m).

The tamarack type in the United States occurs mainly on

poorly drained sites and occupies extensive areas on such

sites in northern Minnesota. It commonly grows on wetter

sites than black spruce (Picea mariana (Mill.) B.S.P.) (7).

However, the type grows best on more favorable sites such as

moist but well-drained, loamy soils along streams, lakes, and

swamps; seep areas; and mineral soils with a shallow, surface

layer of organic matter (3).

The tamarack type is found especially on peatland sites

where the organic soil or peat is more than 12 inches (30 cm)

thick. It occurs on the full range of peatlands from rich

swamp (forested rich fen) to raised bog but is most characteristic of poor swamps where the soil water is weakly enriched

with mineral nutrients (4). Along the southern limits of the

type's range tamarack is found in small scattered stands on

poor peatland (bog) sites (7).

The climate in which the tamarack type grows in the

Lake States and Maine is generally humid, with short, cool

summers and long, somewhat severe winters. Average annual precipitation ranges from about 20 inches (510 mm) in

northwestern Minnesota to 48 inches (1220 mm) near the

Atlantic coast in Maine; most of the precipitation comes in

the summer. Average annual snowfall ranges from about 40

inches (1015 mm) to more than 150 inches (3810 mm).

Average July temperatures range from about 65° to 70° F

(18.3° to 21.1° C); January from 0° to 20° F (-17.8° to

-6.7° C). The average frost-free period ranges from about

90 to 150 days.

In mixed stands, black spruce is usually tamarack's

main tree associate on all sites. Other common associates in

the United States, especially on the better peatland (swamp)

sites, include northern white-cedar {Thuja occidentalis L.),

balsam fir (Abies halsamea (L.) Mill.), black ash (Fraxinus

nigra Marsh.), and red maple (Acer rubrum L.) (7). Paper

birch (Betula papyrifera Marsh.) and eastern white pine

(Pinus strobus L.) are common associates on transitional

sites between peatlands and uplands.

The tamarack type commonly supports an understory of

black spruce, and because of the light shade cast, it usually

has a dense undergrowth of shrubs and herbs. Dominant tall

shrubs include low birch (Betula pumila var. glandulifera

Regel), willows (Salix spp.), speckled alder (Alnus rugosa

(Du Roi) Spreng.), and red-osier dogwood (Cornus stolonifera

Michx.) (7).

Presently, natural seeding is the only important mode of

reproduction in the tamarack type. Although little tamarack

has been planted, tests indicate good growth on mineral soil

sites but not on peatland sites. Vegetative reproduction is

uncommon in tamarack. However, layering may occur when

branches are covered by fast-growing sphagnum moss

(Sphagnum spp.) and roots are known to produce shoots (3).

Practically no tamarack has been artificially (direct) seeded,

even experimentally.

Seed production in large quantities begins when tamarack trees are about 40 years old, with the optimum age being

about 75 years. Vigorous, open-grown trees produce the best

cone crops; seed production in stands is generally confined to

dominant and codominant trees. Tamarack bears good seed

crops at intervals of 3 to 6 years, with some seed produced in

intervening years. Seed dispersal occurs from September to

spring, but apparently most of the seed is released by the end

of October. Although little seed falls at a distance greater

than twice the tree height (3), tamarack can reproduce well as

far as 200 feet (61.0 m) from seed-bearing trees if favorable

seedbeds are present (6).

The best seedbed is warm (65° to 70° F (18.3° to 21.1°

C)), moist mineral or organic soil with no brush but a light

cover of grass or other herbaceous vegetation. Hummocks of

slow-growing sphagnum moss often make a good seedbed,

but some sphagnum mosses may offer too much competition

(3). Findings from peatland harvest areas in Minnesota show

that slash-burned seedbeds favor tamarack reproduction,

whereas slash hinders it (6). On uplands, tamarack apparently reproduces well on rock-raked areas after natural

seeding.

Up to half the tamarack seed that falls may be destroyed

by rodents. As a result of this loss plus that by fungi or

bacteria, only a small percent of the seed may germinate (3).

In addition, tamarack seed apparently germinates poorly,

even under greenhouse conditions.

For best growth tamarack seedlings need abundant light

and a constant water level. Seedlings established under fully

stocked stands do not survive beyond the sixth year; those

under little or no cover may be as tall as 18 to 25 inches (46 to

64 cm) by the third year. Early seedling losses are primarily

caused by damping-off; drought, flooding, and inadequate

light sometimes cause appreciable loss in the second and

third years, and snowshoe hares kill many seedlings in some

areas (3).

Tamarack is very intolerant of shade. Although it can

tolerate a little shade during the first 3 or 4 years, it must

become dominant to survive. Abnormally high water levels

often kill tamarack stands, and those that survive under very

wet conditions usually grow ver}^ slowly (3). Wetland road

crossings and beaver damming are the primary causes of such

flooding damage. Strong winds can uproot large tamarack

trees growing in swamps or other wet sites where rooting is

shallow (3). However, compared with black spruce, tama99
rack seems to be fairly windfirm, probably because of its

wide root system (1, 3).

Various tests, especially those on brushy peatlands in

Minnesota, indicate that competing vegetation hinders the

establishment of tamarack. Also, because tamarack is very

intolerant, it cannot compete with its associates (7). Thus

tamarack is practically never found in the understory when

mixed with other species, and it does not become established

in its own shade. Consequently, the more tolerant black

spruce eventually succeeds tamarack on poor (bog) sites;

northern white-cedar, balsam fir, and swamp hardwoods

succeed tamarack on good (swamp) sites (3).

With abundant light, tamarack is one of the fastest

growing conifers on uplands in the northern forest region (3).

And on peatlands it outgrows any other native conifer (1,3).

However, growth apparently drops sharply when the crowns

close (3) or after the age of 40 to 50 years.

Average height of mature, peatland tamaracks is 50 to

75 feet (15.2 to 22.9 m) and d.b.h.'s are usually 14 to 20

inches (36 to 51 cm) (3). However, the growth rate of

tamarack differs greatly, with the potential being much

greater on uplands than on peatlands. Height of dominant

trees at 50 years ranges from more than 60 feet (18.3 m) on

the best swamp sites to less than 15 feet (4.6 m) on the

poorest bog sites. A site index of 35 feet (10.7 m) is about the

minimum for commercial forest land.

No yield tables have been published for tamarack, so

rotations based on age at culmination of mean annual

increment cannot be recommended. Generalized rotations

derived from State and National Forest silvicultural handbooks or guides for Minnesota and Wisconsin are as follows:

90 years for a site index of 50 feet (15.2m), 100 years for 40

feet (12.2 m), and 120 years for 30 feet (9.1 m). However,

some agencies use a rotation of 90 or 100 years for all site

indexes. These rotations apply mainly to peatland sites. The

State of Wisconsin recommends a rotation of 70 years for all

mineral soil sites.

Little is known about the growth and yield of tamarack

stands. Limited data indicate that the annual growth of

poletimber stands in northern Minnesota is from 0.3 to 0.4

cord per acre (27.0 to 36.0 ft^/acre or 1.9 to 2.5 m^/ha). In

70- to 100-year-old stands, annual periodic growth averaged

0.6 cord per acre (54.0 ft-^/acre or 3.8 m-^/ha) on well-stocked

plots with a basal area of 93 square feet per acre (21.4 m^/ha)

and 0.3 cord per acre (1.9 m^/ha) on poorly stocked plots

with 35 square feet per acre (8.0 m^/ha) (3). Basal area

ranged from 55 to 102 square feet per acre (12.6 to 23.4

m^/ha) among six pure stands that were sampled when 72 to

119 years old (at breast height) on medium to poor peatland

sites in northern Minnesota (9).

The larch sawfly, Pristiphora erichsonii (Hartig), is the

most destructive insect enemy of the tamarack type. Epidemics occur periodically across the northern United States and

Canada (8), causing defoliation of tamarack stands over large

areas for several successive years. Growth is greatly reduced

and many trees are killed (3). Recurring outbreaks have

reduced the type's area and speeded the succession to black

spruce or other associates (7).

The larch casebearer, Coleophora laricella (Hübner),

is also a serious defoliator of tamarack. A native of Europe, it

is now widely distributed in eastern North America, including the Lake States (3, 8). The larch casebearer attacks

tamarack of all ages, and several severe outbreaks have

caused extensive mortality in some areas (10). However,

outbreak severity has lessened in recent years, probably

because imported parasites of the casebearer have also

become widely established (8).

Rusts, such as the leaf rust caused by the fungus

Melampsora medusae Thiim., are the only common foliage

diseases of tamarack and they do little damage (5). Root- and

butt-rot fungi include Armillariella mellea (Vahl. ex Fr.)

Karst, and Inonotus tomentosus (Fr.) S. C. Teng. The

principal heart-rot fungi are Fomitopsis ojficinalis (Vill. ex

Fr.) Bond. & Sing, and Phellinus pini (Thore ex Fr.) A.

Ames. Rot fungi, however, are not aggressive killers of

tamarack (5).

Porcupines commonly feed on the inner bark of tamarack and deform the stem or kill the tree. Many stands of

tamarack have been damaged by this pest in the Lake States.

The animal is also an enemy of tamarack in Maine (3).

Tamarack is highly susceptible to fire damage except

perhaps in older, upland stands. On peatlands it is usually

killed by all but very light bums (3). The habitat of tamarack

in the United States, however, is normally wet enough to

protect the type from fire.

Tamarack is fairly well adapted to reproduce successfully on burns. Thus it is a pioneer type, especially on burned

peatlands; and stands on peatlands have been reproduced in

the past mainly in areas cleared by wildfire (7). Although

slash-burned seedbeds favor tamarack reproduction, the use

of fire on harvest areas depends at least partly on stand

composition. Fire is not considered useful for pure tamarack

stands because pure tamarack slash is difficult to broadcast

burn (6). However, broadcast burning the slash from mixed

(or other) peatland conifer stands will probably increase the

tamarack component if the new stands receive ample tamarack seed.

The tamarack type is usually managed to produce a high

sustained yield of pulpwood, but other products such as poles

and sawtimber may also be grown. The intolerance of

tamarack dictates the use of even-aged management to

maintain the type or it will be succeeded by more tolerant

associates such as black spruce.

Some adaptation of clearcutting or seed-tree cutting is

generally considered the best silvicultural system for managing the type. This is because tamarack seeds apparently

germinate better in the open and the seedlings require

practically full light to survive and grow well. Also, tamarack is usually windfirm enough for the seed-tree system to

succeed. An advantage of this system in mixed stands is that

the proportion of tamarack reproduction can probably be

increased by leaving only tamarack seed trees during harvesting.

Research and experience on specific cutting practices

for reproducing tamarack are limited, but recommendations

are available from State and National Forest silvicultural

handbooks or guides for Minnesota and Wisconsin. Except in

small stands (less than 10 acres or 4.0 ha), a combination of

clearcut and seed-tree strips is recommended. Strips in sets of

three are suggested—the first two would be clearcut

progressively, with natural seeding from the adjacent uncut

strip(s), and the last strip would leave seed trees. If favorable

seedbeds are present, clearcut strips perpendicular to the

prevailing wind direction can be 200 feet (61.0 m) wide with

seeding from the windward side. Seed trees should be

well-spaced dominant tamaracks numbering about 10 per

acre (25/ha).

Though usually less efficient to administer than strips,

clearcutting in small patches is a satisfactory alternative for

reproducing tamarack by natural seeding. And in small

stands where harvesting in strips or patches is impractical,

the entire stand can be removed at one time, leaving seed

trees if necessary. Because tamarack is very intolerant, the

shelterwood system will favor more tolerant associates such

as black spruce. Thus it is an appropriate system only where

100
removal of all (or nearly all) trees is undesirable for esthetic

or other reasons. The first or seed cutting should be from

below and leave a residual basal area of about 30 to 40 square

feet per acre (6.9 to 9.2 m^/ha), with the objective of

obtaining a crown closure of 30 to 50 percent.

In addition to cutting practices, satisfactory reestablishment of tamarack will often require site preparation. Broadcast burning of slash is the preferred method because it not

only improves seedbeds by removing slash and the surface

organic layer but also controls competing vegetation by

killing residual conifers and the stems of brush species.

However, burning should not be done during abnormally dry

periods when fires can burn deeply in peat and become

extremely difficult to extinguish.

If broadcast burning is not feasible (for example, because of pure tamarack slash), the slash can be removed by

full-tree skidding and the area herbicide-sprayed to keep

brush from overtopping tamarack seedlings (6). Other alternatives include piling and burning the slash and shearing or

chopping the brush. Sedges and grasses can also hinder the

reestablishment of tamarack, but satisfactory control methods

have not been developed.

Little information is available on intermediate cutting

methods for tamarack except recommendations from State

and National Forest silvicultural handbooks or guides for

Minnesota and Wisconsin. Thinning is probably economically feasible only on good sites when the objective is to

grow high quality products such as poles and sawtimber. If a

market exists for smaller products such as posts and pulpwood,

a commercial thinning can be made as soon as the stand will

produce these products. Additional, periodic thinnings are

recommended up to 20 years prior to the end of the rotation.

Each thinning should leave a basal area of 80 to 90 square

feet per acre (18.4 to 20.7 m^/ha) in the faster growing, better

formed trees.

The tamarack type is utilized to some extent by such

mammals as the red squirrel, snowshoe hare, and porcupine.

Because tamarack stands are deciduous and usually have a

dense undergrowth of shrubs, their avian community includes bird species common in shrubby areas as well as

species generally associated with hardwood forests. Birds

common in tamarack stands during the summer include the

white-throated sparrow, song sparrow, veery, common

yellowthroat, and Nashville warbler (2). The American

osprey, a sensitive species, often nests in lowland types such

as tamarack. And the great gray owl, a rare winter visitor in

the northern Lake States, apparently nests there only in the

tamarack peatlands of northern Minnesota.

The tamarack type is esthetically appealing, especially

in early autumn when the trees turn yellow. Also, a tamarack

component frequently grows at the fringe around black

spruce peadands, providing a pleasing contrast of colors in

the fall. The impact of harvesting tamarack on esthetics can

be minimized by having harvest boundaries follow natural

type lines and leaving tamarack seed trees.

Management of the tamarack type probably has little or

no effect on water yield or quality because harvesting is

generally on a small scale. However, harvesting should be

done only in winter after the ground is frozen and snowcovered to minimize peat disturbance and its possible effect

on water quality. Also, the normal movement of water must

be maintained to prevent flooding damage.

Literature Cited

1. Curtis, John T. The vegetation of Wisconsin: an ordination of plant

communities. Madison, WI: University of Wisconsin Press; 1959.

657 p.

2. Dawson, Deanna K. Bird communities associated with succession and

management of lowland conifer forests. In: Management of north

central and northeastern forests for nongame birds: Workshop proceedings;

1979 January 23-25; Minneapolis, MN. Gen. Tech. Rep. NC-51. St.

Paul, MN: U.S. Department of Agriculture, Forest Service, North

Central Forest Experiment Station; 1979: 120-131.

3. Fowells, H. A., comp. Silvics of forest trees of the United States.

Agrie. Handb. 271. Washington, DC: U.S. Department of Agriculture;

1965. 762 p.

4. Heinselman, M. L. Landscape evolution, peatland types, and the

environment in the Lake Agassiz Peatlands Natural Area, Minnesota.

Ecol. Monogr. 40: 235-261; 1970.

5. Hepting, George H. Diseases of forest and shade trees of the United

States. Agrie. Handb. 386. Washington, DC: U.S. Department of

Agriculture; 1971. 658 p.

6. Johnston, William F. Reproducing lowland conifer forests. J. For.

73(1): 17-20; 1975.

7. Johnston, William F. Tamarack. In: Eyre, F. H., ed. Forest cover types

of the United States and Canada. Washington, DC: Society of American

Foresters; 1980: 15-16.

8. Rose, A. H.; Lindquist, O. H. Insects of eastern larch, cedar and

juniper. For. Tech. Rep. 28. Ottawa, ON: Department of the Environment,

Canadian ForestryService; 1980. 100 p.

9. Thompson, L. C; Kulman, H. M. Vegetation of tamarack stands in

north central Minnesota. Minn. For. Res. Notes 255 (rev.). St. Paul,

MN: University of Minnesota, School of Forestry; 1976. 4 p.

10. Wilson, Louis F. A guide to insect injury of conifers in the Lake States.

Agrie. Handb. 501. Washington, DC: U.S. Department of Agriculture;

1977. 218 p.

101
Balsam Fir

John W. Benzie

North Central Forest Experiment Station

Thomas M. Smith

Eastern Region

Robert M. Frank

Northeastern Forest Experiment Station

The balsam fir forest cover type is common in the

northern portions of New England, New York, Michigan,

Wisconsin, and Minnesota. It is type 5 of the Society of

American Foresters forest cover types and one of 12 that is

combined into the spruce-fir type group by the USDA

Forest Service (2). The balsam fir type totals more than 7

million acres (2.8 million ha) of commercial forest land or

about 60 percent of the spruce-fir type group. Recent forest

inventories show 5 million acres (2.0 million ha) in the

Northeastern States and 2 million acres (0.8 million ha) in the

Lake States. The balsam fir type often grades into one of the

other forest cover types included in the spruce-fir type

group and it may be more appropriately managed as spruce-fir,

particularly if the objective is to favor spruce.

Balsam fir {Abies balsamea (L.) Mill.) stands grow on a

wide range of sites from gravelly sands to peat swamps but

they develop best on moist, well drained, sandy loam soil

classified as Alfisols. They occur at elevations from sea level

along the New England coast to over 3,000 feet (915 m) in

the New England-Adirondack and Appalachian highlands

and between 700 and 1,400 feet (215 and 425 m) in the Lake

States. The climate is cool and moist with average temperatures 70° F (21.r C) or less and average monthly precipitation 3 inches (76 mm) or more during the growing season.

The frost free period is from 80 to 180 days. Average annual

minimum temperature ranges from 0° to -40° F (-17.7° to

-40.0° C) and average annual maximum temperature is

around 90° F (32.2° C) (3). Average annual precipitation

ranges from 20 to 50 inches (510 to 1270 mm).

Balsam fir stands have several associated tree species

that are common in both the Northeastern States and the Lake

States. They include paper birch {Betula papyrifera Marsh.),

quaking aspen (Populas tremuloides Michx.), bigtooth aspen

(Populas grandidentata Michx.), red maple (Acer rubrum

L.), sugar maple (Acer saccharum Marsh.), yellow birch

(Betula alleghaniensis Britton), eastern hemlock (Tsuga

canadensis (L.) Carr.), and eastern white pine (Pinus strobus

L.) on the moist uplands. On the wetter sites, associates are

white spruce (Picea glauca (Moench) Voss), black spruce

(Picea mariana (Mill.) B.S.P.), northern white-cedar (Thuja

occidentalis L.), tamarack (Larix laricina (Du Roi) K.

Koch), black ash (Fraxinus nigra Marsh.), and balsam

poplar (Populus balsamifera L.). Other common associates

in the Northeast are red spruce (Picea rubens Sarg.) and

American beech (Fagus grandifolia Ehrh.). Undergrowth

associated with the balsam fir type include speckled alder

(Alnus rugosa (Du Roi) Spreng.), beaked hazel (Corylus

cornuta Marsh.), mountain maple (Acer spicatum Lam.), pin

cherry (Prunuspensylvanica L.f.), red-osier dogwood (Cornus

stolonifera Michx.), red raspberry (Rubus idaeus L.), and

blueberries (Vaccinium spp.). Some of the common herbaceous plants are bracken (Pteridium aquilinum (L.) Kuhn),

twinflower (Linnaea borealis L.), bunchberry (Cornus

canadensis L.), starflower (Trientalis borealis Raf.), sedges,

and several mosses (2).

Seed production begins eariy in balsam fir and good

seed crops occur every 2 to 4 years after age 30. Cones

mature toward the latter part of August or eariy September and most of the seed is disseminated within a few weeks.

The cones shed their seeds and scales, which are often

coated with pitch, leaving the characteristic candle standing

erect near the tips of the upper branches. Many of the seeds

stick tothe cone scales and fall near the base of the tree.

Although not all balsam fir seed show dormancy, best

germination has been obtained by stratifying seeds in a wet

medium at 41° F (5.0° C) for 3 months or longer. Natural

seeding in the fall allows the seed to stratify over winter

on the forest floor (7).

Balsam fir seed averages about 60,000 per pound (132

280/kg) and 5 or more pounds per acre (6 or more kg/ha) are

produced in a good seed year (3). The effective seeding

distance from a mature tree is probably less than 200 feet

(61.0 m).

The frequent seed crops and the ability of seedlings to

become established and survive for several years in dense

shade assures a continuous supply of small seedlings in most

mature balsam fir stands (7). Most seed germinates from late

May to early July with an average germinative capacity of

about 26 percent (3). Almost any moist seedbed is considered

satisfactory but exposed mineral soil with some shade is best.

Humus layers deeper than 3 inches (8 cm) are less favorable

seedbeds especially if they are in the open. Seedling losses

the first year are often heavy due to late germinants, surface

temperatures exceeding 115° F (46.1° C), drought, frost

heaving, or smothering by leaves and other litter. Best

seedling establishment is under a light to moderate forest

cover.

Balsam fir is very tolerant of overstory competition. Of

all the commonly associated tree species only eastern hemlock,

American beech, and possibly red spruce and sugar maple,

are as tolerant. Seedlings can become established in fairly

dense shade with only 10 percent of full sunlight (1). Early

growth is determined by the amount of overhead shade.

Balsam fir can grow in dense shade for the first 6 or 8 years

and will survive for many years. After the first few years,

however, best growth is in 45 percent or more of full sunlight

where seedlings reach breast height in about 10 years.

Balsam fir is a small- to medium-sized tree reaching

average diameters of from 12 to 18 inches (30 to 46 cm) and

average heights of from 30 to 80 feet (9.1 to 24.4 m)

depending on site quality. Although individual trees have

been reported to live up to 200 years, balsam fir stands break

up at much younger ages. Pathological rotation age, especially on upland soils, is between 70 and 80 years, and

economic rotation is usually from 45 to 55 years.

Well-stocked even-aged balsam fir stands will yield

from 2,500 cubic feet per acre (175.0 m^/ha) on low quality

sites to more than 4,000 cubic feet per acre (280.0 m^/ha) on

high quality sites at 50 years of age (5). Uneven-aged stands

will yield about 400 to 800 cubic feet per acre (28.0 to 56.0

102
m^a) at 10-year cutting cycles on low-to-high quality sites,

respectively (1).

Site quality, as measured by 50 year site index, ranges

from 30 to 70 feet (9.1 to 21.3 m). Tree ages are determined

at breast height because the tolerant balsam fir seedlings may

be suppressed many years before trees are released and free

to grow. The use of some site index curves requires adding an

assumed average number of years to reach breast height

which may range from about 10 years for open-grown

seedlings to 15 years or more for suppressed seedlings.

Despite the problems associated with using site index in

balsam fir stands, it is the method most commonly used to

estimate productivity.

Insects and diseases are usually not serious limiting

factors in the production of seed because balsam fir is a

prolific seed producer and has frequent good seed crops.

However, little seed is produced during spruce budworm

(Choristoneurafumiferana (Clemens)) epidemics, and the fir

coneworm (Dioryctria abietivorella (Grote)) commonly attacks cones and may cause seed losses. The seeds are often

coated with pitch which may make them less attractive than

other food for insects as well as for birds and rodents. Balsam

fir seedling mortality due to insects and diseases is unknown

but total losses of seedlings in the open are few after the first

or second year.

Insects and diseases seldom threaten immature balsam

fir stands except during severe outbreaks. Mature trees,

however, are the prime hosts for the spruce budworm—one

of the tree's most damaging enemies. Overmature stands are

likely to have the heaviest damage. Extensive outbreaks have

occurred periodically both in the Lake States and in the

Northeastern States. Dense stands that are pure or have a high

proportion of balsam fir are the most susceptible but managing for better age class distribution of future stands may

reduce the risk of outbreaks. Other insects that feed on

foliage and damage balsam fir include the balsam woolly

adelgid {Adelges piceae (Ratzeburg)), hemlock looper

{Lambdina fiscellaria fiscellaria (Guenee)), eastern blackheaded budworm (Acleris variaría (Femald)), and the balsam

fir sawfly (Neodiprion abietis (Harris)).

Heart rot begins early in balsam fir and by age 50 about

20 percent of the trees are infected. It spreads rapidly,

doubling in the next decade, and by age 70 more than half the

trees are infected (1). Red heart trunk rot is caused by

Haematostereum sanquinolentum (Alb. & Schw. ex Fr.)

Pouz. Although trunk rot and top rot cause most of the cull in

standing trees, butt rots weaken trees and make them susceptible to wind breakage. White stringy butt rot is caused by a

number of fungi (Scytinostroma galactinum (Fr.) Donk.,

Resinicium bicolor (Alb. & Schw. ex Fr.) Farm., Poria

subácida (Pk.) Sacc, Sind Armillarielia mellea (Vahl. ex Fr.)

Karst.). Brown cubicle butt rot is caused by several different

fungi {Coniophoraputeana (Schum. ex. Fr.) Karst., Tyromyces

balsameus (Pk.) Murr., and Serpula himantioides (Fr. ex Fr.)

Karst.).

Balsam fir is subject to losses from wind breakage and

because of its shallow roots it is also subject to losses from

uprooting, especially on wet and thin soils. The shallow root

system, thin resinous bark, long crown, and flammable

needles make it difficult for balsam fir to survive fires.

Although trees are easily killed by fire, the moist wet sites

help reduce the chances of fires in the balsam fir type.

Because of thin bark, care also is required to reduce damage

during logging.

Both even-aged and uneven-aged silvicultural systems

are applicable to the balsam fir type. Even-aged systems are

preferred, but uneven-aged management is possible because

the tree is tolerant of shade and seedlings can and do become

established in the understory. Uneven-aged management

should be limited to sites where balsam fir can maintain itself

as a climax type without the need for excessive silvicultural

practices. On all other sites, even-aged management is

generally recommended.

Mature even-aged stands well stocked with advance

regeneration can be harvested by the clearcut method. Advance regeneration should be 3 feet (1 m) or taller on sites

with average brush competition and 6 inches (15 cm) or taller

on sites without competition or where it is only minor. In

mature stands that do not have adequate advance regeneration,

the shelterwood method applied in narrow strips, uniformly,

or in groups can be used to stimulate seedling establishment

(4). The shelterwood can be removed as soon as the seedling

stand is established. Artificial regeneration of balsam fir by

direct seeding or planting has only had limited success and is

generally not recommended, but sometimes the spruces (red,

white, or black) are planted to increase their proportion in the

next stand. The seed-tree method is not recommended

because of the high windfall risk before the area is successfully regenerated. Both the shelterwood and clearcut silvicultural systems produce large amounts of slash that may hinder

seedling establishment on some areas. Full-tree skidding or

forwarding will remove the tops and branches from the area

but some slash may be beneficial to seedlings especially on

hot, dry sites. In addition, scarification may be needed to

prepare seedbeds under the shelterwood system. Scarification

should be done by skilled operators with small, maneuverable equipment so the residual shelterwood and advance

reproduction will not be damaged.

Uneven-aged silvicultural systems include both single

tree selection and group selection regeneration cuttings.

Small openings can be used to favor regeneration of the more

tolerant species and large openings can be used to favor the

less tolerant species. The selection system is suitable for

stands with several age classes and size classes where

repeated light cuttings every 10 to 20 years can remove trees

of various size and age classes to make room for the

establishment of new seedlings and growth of the residual

stand (4). Although some uneven-aged stands have been

perpetuated by diameter limit cuttings, maximum benefits

require tree marking to leave about 80 square feet of basal

area per acre (18.4 m^/ha) and to control the distribution and

quality of the growing stock. On sites where balsam fir is not

the climax type, light selection cuttings will tend to advance

succession to less desirable hardwoods more rapidly and will

require additional weedings to maintain balsam fir.

Immature stands are not normally thinned because the

major product is fiber and little premium is placed on tree

size. Some thinning, however, may reduce the time for

balsam fir to reach minimum merchantable tree size and thus

allow harvest on shorter rotations before the trees become

prime targets for a spruce budworm outbreak or before the

net growth is severely reduced by heart rot. It is also possible

to increase the production of small saw logs with one or two

thinnings and a longer rotation.

Many of the associated species in balsam fir stands are

undesirable and should be removed in an improvement

cutting if they need to be controlled before the regeneration

harvest. Defective trees can be removed in a sanitation cut,

but this is seldom done as a separate operation. In the

selection system, immature trees are thinned, undesirable

trees are controlled, and defective trees are removed at each

cutting cycle. Selective herbicides can be used to eliminate

undesirable trees.

The balsam fir type is climax or near climax on many

sites and can be maintained by assuring the establishment of

advance regeneration before removing the mature overstory.

103
The type may be increased by allowing earlier successional

stages to advance, such as aspen or paper birch stands with a

balsam fir understory, or by controlling the more tolerant

species in later successional stages, such as American beech

or sugar maple stands with a balsam fir understory.

Balsam fir, probably the most symmetrical tree in the

north woods, adds beauty to the landscape through its

contribution of form, patterns of light, shade, and color. The

associated species, such as aspen, paper birch, and red

maple, provide variety for additional visual quality of the

forest type. Balsam fir stands have a distinct fragrance and

play an important role in the recreational use of the forest

land both in the Northeast and Lake States areas. They also

protect many watersheds and provide habitat for a number of

wildlife species including primary and secondary carnivores,

herbivores, and several songbirds of the boreal forests.

A multiple-use evaluation of the spruce-fir forest type

(predominantly balsam fir) in the Lake States rated the

impacts of even-age management with clearcutting 20 to 50

acres (8.1 to 20.2 ha) more favorable for timber, water

yields, and interior wildlife species than smaller clearcut

areas or uneven-age management. Selection cuttings were

considered the most favorable for edge wildlife species and

visual quality. Water yield was not affected by uneven-age

management and water quality was not affected by any of the

harvest options rated (6).

Wildlife inhabitants of balsam fir stands are typical of

those in the coniferous forests of the northern Lake States and

the Northeast. They characteristically have abundant populations of small mammals, many of which become browsers in

winter; a large variety of nesting birds, many of which

migrate for the winter; and a complete food chain from

herbivores to carnivores.

The bay-breasted warbler and Arctic three-toed woodpecker are unique associates in spruce budworm infested

balsam fir stands. The spruce grouse and ruffed grouse are

common inhabitants as are a variety of songbirds. Small

mammals that are common include the red-backed vole,

meadow vole, deer mouse, chipmunk, red squirrel, and

snowshoe hare. Larger herbivores associated with the balsam

fir type include beaver, white-tailed deer, and moose. Carnivores that frequent balsam fir stands include fisher, martin,

Canada lynx, and timber wolf (1).

Literature Cited

2

Bakuzis, E. V.; Hansen, H. L. Balsam fir. Minneapolis, MN: The

University of Minnesota Press; 1965. 445 p.

Eyre, F. H., ed. Forest cover types of the United States and Canada.

Washington, DC: Society of American Foresters; 1980. 148 p.

3. Fowells, H. A., comp. Silvics of forest trees of the United States. Agrie.

Handb. 271. Washington, DC: U.S. Department of Agriculture; 1965

762 p.

4. Frank, Robert M.; Bjorkbom, John C. A silvicultural guide for spruce-fir

in the Northeast. Gen. Tech. Rep. NE-6. Broomall, PA: U.S. Department of Agriculture, Forest Service, Northeastern Forest Experiment

Station; 1973. 29 p.

5. Gevorkiantz, S. R.; Olsen, Lucille P. Growth and yield of upland balsam

fir in the Lake States. Stn. Pap. 22. St. Paul, MN: U.S. Department of

Agriculture, Forest Service, Lake States Forest Experiment Station1950. 24 p.

6. Ohmann, L. F.; Batzer, H. O.; Buech, R. R.; Lothner, D. C. [and

others]. Some harvest options and their consequences for the aspen,

birch, and associated conifer forest types of the Lake States. Gen. Tech.

Rep. NC-48. St. Paul, MN: U.S. Department of Agriculture, Forest

Service, North Central Experiment Station; 1978. 34 p.

7. Roe, Eugene L Balsam fir in Minnesota—a summary of present

knowledge. Misc. Rep. 13. St. Paul, MN: U.S. Department of Agriculture,

Forest Service, Lake States Forest Experiment Station; 1950. 25 p.

104
Northern White-Cedar

William F. Johnston

North Central Forest Experiment Station

Robert G. Booker

Eastern Region

Northern white-cedar {Thuja occidentalis L.) is pure or

comprises a majority of the stocking in the northern whitecedar forest cover type, Society of American Foresters type

37. Although much of the type occurs in Canada, especially

in Ontario and Quebec (13), it totals about 2.0 million acres

(0.8 million ha) of commercial forest land in the Northern

Lake States and 1.4 million acres (0.6 million ha) in the

Northeastern States. Within the United States it is most

abundant in Michigan and Maine (13)—each has more than 1

million acres (0.4 million ha).

In the Lake States the northern white-cedar type grows

mainly on glacial lake beds and lake-swamp-moraine plains

at elevations averaging about 1,000 feet (305 m). In Maine it

is found from near sea level along the Atlantic coast to more

than 1,000 feet (305 m) in the New England highlands. Most

of the remaining type area in the Northeast is in the

Adirondack-New England highlands of northern New York

and Vermont from elevations of about 1,000 feet (305 m) to

more than 2,000 feet (610 m).

The northern white-cedar type occurs mainly in swamps,

where white-cedar can compete well with its associates (13)

and is normally protected from fire (8). The tree is usually

dominant in rich swamps (forested rich fens) that have a

strong flow of moderately mineral-rich soil water (9). The

best swamp sites have well-decomposed organic soil or peat

that is derived from woody plants and is neutral or slightly

alkaline. They also have actively moving soil water and are

usually near streams or other drainageways (12).

The type also occurs on seepage areas, limestone

uplands, and old fields. In fact, it generally grows best on

limestone-derived soils that are neutral or slightly alkaline

and moist but well drained. Northern white-cedar often forms

pure stands on old-field (upland) sites in Maine and southeastem Canada (13). Although old-field soils differ greatly, the

tree's form and volume growth are much better on old fields

than in poorly drained swamps (3).

The climate in which the northern white-cedar type

grows in the Lake States and Northeast is generally humid,

with short, cool summers and long, somewhat severe winters.

Average annual precipitation ranges from about 20 inches

(510 mm) in northwestern Minnesota to 48 inches (1220 mm)

along the Atlantic coast in Maine and in the Adirondack-New

England highlands; most of the precipitation comes in the

summer. Average annual snowfall ranges from about 40

inches (1015 mm) to more than 150 inches (3810 mm).

Average July temperatures range from about 65° to 70° F

(18.3° to 21. r C); January temperatures range from 0° to 20°

F (-17.8° to -6.7° C). The average frost-free period ranges

from about 90 to 150 days.

Although northern white-cedar grows in pure stands, the

white-cedar type more commonly occurs as mixed stands. In

the United States common tree associates on the wetter sites

(especially swamps) include balsam fir {Abies balsamea (L.)

Mill.), black spruce {Picea mañana (Mill.) B.S.P.), white

spruce {P. glauca (Moench) Voss), red spruce {P. rubens

Sarg.), tamarack {Larix laricina (Du Roi) K. Koch), black

ash {Fraxinus nigra Marsh.), and red maple {Acer rubrum

L.). Common associates on the better drained sites (especially

uplands) include yellow birch {Betula alleghaniensis Britton),

paper birch {B. papyrifera Marsh.), quaking aspen {Populus

tremuloides Michx.), bigtooth aspen {P. grandidentata Michx.),

balsam poplar {P. balsamifera L.), eastern hemlock {Tsuga

canadensis (L.) Carr.), and eastern white pine {Pinus strobus

L.)(13).

Vegetative reproduction and natural seeding are the two

main modes of reproduction in the northern white-cedar type.

Layering—where branches become buried in moss and develop adventitious roots—is the most important type of

vegetative reproduction. It probably accounts for more than

half the stems of white-cedar reproduction in northern Michigan and Maine swamps (6), especially on poor sites with

abundant sphagnum moss {Sphagnum spp.) (3). Natural

seeding is the main mode of reproduction in swamp openings

created by wildfire or by harvesting, especially if slash is

broadcast burned. It is also the main mode on abandoned

upland fields.

Effective and economical ways to artifically reproduce

the northern white-cedar type are still largely undeveloped.

Direct seeding has been attempted both experimentally and

operationally but with limited success. Some planting has

been done on upland sites, but success apparendy will often

require protection from animal damage such as deer and hare

browsing.

Seed production in large quantities begins when northem white-cedar trees are about 30 years old but is best after

75 years. White-cedar generally bears good or better seed

crops at intervals of 3 to 5 years (6), but in Wisconsin a

25-year record indicates that such crops are produced every 1

to 3 years with medium crops to failures in the intervening

years (7). Seed dispersal usually begins in September and

most of the seed is released by November; however, some

seed continues to fall throughout the winter. Because the tree

is usually of medium height, the effective seeding range is

estimated to be from 150 to 200 feet (45.7 to 61.0 m) under

normal conditions (6).

Apparently the main requirements for initial establishment of northern white-cedar seedlings are a constant moisture supply (4) and warm temperatures. Seedlings do best on

neutral or slighdy acid soil but will grow on slightly alkaline

soil (6). Decaying (rotten) wood—mainly logs in the middle

stage of decay and dominated by mat-forming bryophytes

(11)—is the most important seedbed type on undisturbed

areas, where it often accounts for more than 70 percent of the

seedlings (4, 11). On disturbed areas, white-cedar seedlings

are commonly aggressive on both upland and swamp bums

(4, 6). However, broadcast buming (or wildfire) apparently

must be fairly severe to expose favorable, mineral soil

seedbeds on uplands or to improve moss seedbeds in swamps

(12). White-cedar seedlings also reproduce well on skid

roads where the moss has been compacted and stays moist

throughout the summer (6).

105
Except in poorly stocked stands, harvesting can produce

a heavy cover of slash that buries suitable advance growth or

seedbeds. Thus slash disposal by broadcast burning or

full-tree skidding usually favors northern white-cedar reproduction (12).

Although moisture is often the most important factor

during the first few years, ample light is needed for continued

development of northern white-cedar seedlings. Growth is

greatest from about half to full light and larger seedlings

occur mainly in pronounced openings or on old fields.

Mortality of white-cedar seedlings during their early years is

evidently extremely high. Drought is probably the most

important cause, but other causes that are sometimes important include smothering by fast-growing spaghnum moss and

cutting or girdling by small rodents (3,6).

Northern white-cedar is generally classed as shade

tolerant, but vegetative reproduction is considered more

tolerant than seedlings (3). On wet sites such as swamps, an

abnormally high water level or slow-moving to stagnant

ground water usually reduces the growth rate of white-cedar

and in some cases kills entire stands (6). Wetland road

crossings and beaver damming are the primary causes of such

flooding damage. Uprooting and breakage by wind sometimes occur in older white-cedar stands on both upland and

swamp sites, especially along stand edges exposed to the

prevailing wind and in stands opened by partial cutting.

However, northern white-cedar is less susceptible to wind

damage than balsam fir and black spruce because it is usually

shorter and apparently has butt rot less commonly than

balsam fir (12).

Both even-aged and uneven-aged stands are common in

the northern white-cedar type. Even-aged stands usually

originate in large swamp openings created by wildfire or

harvesting and on abandoned upland fields (13). White-cedar

often invades thickets of speckled alder (Alnus rugosa (Du

Roi) Spreng.) that form in swamps following wildfire or

changes in water level. It can also reproduce directly on

burned peat (4).

Uneven-aged white-cedar stands develop when new

trees begin to fill small openings created by partial cutting or

wind damage (13). If growing in pure stands, white-cedar

will apparently perpetuate itself under such conditions (6),

especially on poor sites where reproduction is mainly of

vegetative origin (13). In mixed stands on better sites,

however, associates such as balsam fir or swamp hardwoods

(especially black ash) often reproduce in these openings (12)

and may eventually overtop the surrounding, older white-cedar.

Stands of northern white-cedar can also develop where it

gradually succeeds associates—such as balsam poplar, tamarack,

and black spruce—that are not as shade tolerant or long lived

(13). These stands may be even- or uneven-aged depending

on when the white-cedar became established.

Although northern white-cedar is commonly in the

understory, it is often not much younger (and may be older)

than the overstory species. Thus much of what appears to

have developed through succession may really be due to

suppression (8) or to white-cedar's inherently slow growth.

The tree can withstand severe suppression for several years

without appreciable ill effects, and it responds well to release

at nearly all ages (6). However, white-cedar apparently forms

stands on old fields only where competition from other

species is not severe (3).

In general, northern white-cedar grows more slowly and

so is shorter than associated trees, especially on swamp sites

(6). Mature white-cedars are commonly 40 to 50 feet (12.2 to

15.2 m) tall and 12 to 24 inches (30 to 61 cm) in d.b.h.

However, the tree's growth rate differs greatíy depending on

site productivity. In the Lake States height of dominant trees

at 50 years ranges from about 40 feet (12.2 m) on the best

sites to 15 feet (4.6 m) on the poorest. A site index of 25 feet

(7.6 m) is about the minimum for commercial forest land

(12).

Timber rotations for northern white-cedar differ greatly

with site productivity and the size of the main product. They

also have a range because the mean annual increment is near

the maximum for a number of years. Recommended rotations

for merchantable cubic volume—for trees 5 inches (13 cm)

and larger in d.b.h.—range from 70 to 90 years for a site

index of 40 feet (12.2 m) and from 80 to 100 years for an

index of 30 feet (9.1 m). Rotations for sawtimber volume—

for trees 9 inches (23 cm) and larger in d.b.h.—range from

110 to 140 years for a site index of 40 feet (12.2 m) and from

130 to 160 years for an index of 30 feet (9.1 m). In areas

where the white-cedar type provides important shelter for

white-tailed deer, rotations should generally be at least the

minimum ones for sawtimber (12).

Information on yield of northern white-cedar is limited

mainly to normal yield tables for pure, fully-stocked, evenaged stands in the Lake States. At rotation age on good sites,

such stands yield about 4,000 merchantable cubic feet per

acre (280.0 m^/ha) for trees 5 inches (13 cm) and larger in

d.b.h. Much of this volume is in logs and poles, whereas

many stands on poor sites produce only small posts (12).

Unfortunately, in terms of timber value, the tree commonly

has a curved butt and poor form, especially in swamps (3).

The northern white-cedar type is relatively free from

serious insect injury (3). Carpenter ants and leafminers are

probably its most important insect pests. The black carpenter

ant, Camponotus pennsylvanicus (De Geer), commonly reduces the timber value of larger trees and often makes them

subject to windbreakage. Outbreaks of the arborvitae leafminer,

Argyresthia thuiella (Packard), have severely damaged whitecedar stands in Maine (1).

Immature white-cedar stands are relatively free of disease (6). Although several root- and butt-rot fungi attack

white-cedar, they mainly attack old or damaged trees and

have not yet proved to be economically important (10). Poria

subácida (Pk.) Sacc, causing a white stringy butt rot, and

Tyromyces balsameus (Pk.) Murr, and Phaeolus schweinitzii

(Fr.) Pat., both causing a brown cubical rot, are apparently

common in trees on knolls or other drier parts of swamps (6).

Browsing by white-tailed deer often severely damages

northern white-cedar in the Lake States (6) and can prevent

the satisfactory reestablishment of the type after harvesting

(12), especially in deeryards. Snowshoe hare browsing does

damage equal to or greater than deer browsing in some areas

of the Lake States (6), but hares are apparently not greatly

destructive to white-cedar in Maine (3). Porcupines sometimes kill white-cedar trees or lower their growth and timber

quality by feeding heavily on foliage (3) and by partially or

completely girdling the stem and branches (6).

Northern white-cedar is highly susceptible to fire damage (8, 10), even by light ground fires. However, the risk of

wildfire is low on most white-cedar areas in the United States

and good fire protection now results in little loss (12).

Many of the present even-aged stands of northern

white-cedar originated after wildfire, probably because seedbed conditions on bums (including increased temperature and

light) seem to favor white-cedar seedlings. However, the

type usually occurs where it is protected from fire. Without

major disturbance such as fire, the type is exceedingly stable

because white-cedar is long lived and balsam fir is the only

important associate sufficiently shade tolerant to grow in

dense white-cedar stands (4). In fact, white-cedar may have

the highest potential for replacing other species in the

absence of fire (8).

106
Because northern white-cedar commonly reproduces

well on burns, broadcast burning is the preferred method of

slash disposal on peatland harvest areas unless residual trees

or advance growth are. to be saved. Under prescribed conditions,

it is considered a safe and effective way not only to eliminate

most slash but also to simultaneously kill residual conifers,

improve seedbeds, and kill the stems of hardwoods and brush

species. Although improving seedbeds and killing hardwood

and brush stems apparently require more severe bums than

the other items, burning should not be done during abnormally dry periods when fires can bum deeply in peat and

become extremely difficult to extinguish (12).

Tirnber management and deeryard management are

usually inseparable in the northem white-cedar type, especially in the northern Lake States where the type is particularly valuable for deeryards in severe winters. White-cedar is

highly preferred by deer for both shelter and browse; sapling

stands produce a great amount of deer food and much browse

is made available by cutting in mature stands (15). Thus the

type is most commonly managed to produce a moderate

sustained yield of merchantable timber, while maintaining or

increasing the quality and quantity of deeryards.

Wherever possible, the northem white-cedar type should

be managed in fairly large, even-aged stands because these

are apparently best for both timber production and deeryards.

However, an adequate sustained amount of deer shelter and

browse (in addition to timber) is possible only if the type is

managed so that stands at different stages of development are

properiy distributed throughout the forest (12, 15).

Northem white-cedar is fairly well adapted to even-aged

management. Clearcutting in narrow strips (or small patches)

is probably the best silvicultural system for managing the

type. This is because white-cedar seedlings, which are

preferable to vegetative reproduction for producing timber

and deer shelter, require ample light for greatest growth.

Also, hardwood competition (2) and wind damage are

generally less with clearcutting than with partial cutting.

However, shelterwood cutting is preferred for the last

set of strips (or patches) in large stands to ensure adequate

natural seeding of white-cedar (12). Also, the shelterwood

system is a satisfactory altemative in small stands in which

clearcutting is undesirable for esthetic or other reasons. An

advantage of the shelterwood system in mixed stands is that

the proportion of white-cedar reproduction can probably be

increased by removing associated trees during the first or

seed cutting.

So, in general, a combination of altemate or progressive

clearcut and shelterwood strips is recommended for reproducing the northem white-cedar type. The first or intermediate

set of strips should be clearcut and the last set cut in a

two-stage shelterwood, leaving a basal area of 60 square feet

per acre (13.8 m^/ha) in the first stage or seed cutting.

Clearcut strips should not exceed 150 to 200 feet (45.7 to

61.0 m) wide, while shelterwood strips should be narrower to

minimize their area (12).

Slash disposal is recommended for the clearcut strips

because unless a stand is poorly stocked, clearcutting produces a heavy cover of slash that hinders satisfactory reproduction of northem white-cedar. Broadcast buming should be

limited to the widest strips, whereas full-tree skidding is

recommended on narrower strips or where advance growth is

to be saved. To minimize overbrowsing of white-cedar

reproduction in deeryards, large patches of 40 acres (16 ha)

or more must be completely cleared in 10 years or less. And

if the yard is large, cutting in several different areas every

winter is desirable to distribute the deer more and to attract

them away from patches of young white-cedar (12).

Although uneven-aged stands of northem white-cedar

are common, they generally are not as productive for timber

and deeryards as even-aged stands. Also, uneven- or all-aged

management would probably increase the proportion of

balsam fir in the succeeding stand. Thus such management

should be considered mainly for poor sites where white-cedar

does not grow tall enough to provide optimum deer shelter

and where only the largest trees are merchantable anyway.

Individual tree selection is the best silvicultural system to use

for uneven-aged management.

Thinning and preparatory treatment should be limited to

white-cedar stands where intensive management for timber or

deeryards can be justified. Middle-aged stands can be thinned

to a residual basal area of 150 square feet per acre (34.4

m^/ha) and still provide adequate deer shelter and inhibit

undesirable undergrowth. Preparatory treatment—^by felling,

girdling, or applying herbicide—should be done at least 5,

and preferably 10, years before reproduction cutting to

control undesirable trees, especially hardwoods. To minimize regrowth after treatment, it is important to have a

residual basal area of about 150 square feet per acre (34.4

m^/ha) (12).

Besides providing winter habitat for white-tailed deer,

the northem white-cedar type is also utilized to some extent

by other mammals such as the snowshoe hare, porcupine,

and red squirrel. Birds common in white-cedar stands during

the summer include several warblers (northem pamla, blackthroated green, blackbumian, black-and-white, and magnolia),

white-throated sparrows, and kinglets (5). The pileated

woodpecker commonly bores into mature white-cedars for

carpenter ants (3).

Small stands of northem white-cedar add diversity to the

landscape and provide an attractive fringe around lakes and

peatlands. Stands with high basal area, large trees, and little

undergrowth are especially attractive (14). Also, the tree's

unusual bark and foliage pattems are esthetically appealing to

many forest users. The impact of harvesting white-cedar on

esthetics can be minimized by having harvest boundaries

follow natural type lines and disposing of slash or other

debris to leave harvest areas neat (12).

Clearcutting northem white-cedar on peatland sites haslittle

effect on annual water yields or water tables (14). Nutrient

concentrations in streamflow (14) or temperatures in trout

streams (12) should not increase significantly unless harvesting (with or without broadcast buming) is on a massive scale.

However, harvesting should be done only in winter after the

ground is frozen and snow covered to minimize peat disturbance and its possible effect on water quality. Also, the

normal movement of water must be maintained to prevent

flooding damage (12).

Literature Cited

1. Baker, Whiteford L. Eastern forest insects. Misc. Publ. 1175. Washington,

DC: U.S. Department of Agriculture; 1972. 642 p.

2. Benzie, John W. Cutting methods in mixed conifer swamps, Upper

Michigan. Res. Pap. LS-4. St. Paul, MN: U.S. Department of

Agriculture, Forest Service, Lake States Forest Experiment Station;

1963. 24 p.

3. Curtis, James D. Preliminary observations on northem white cedar in

Maine. Ecol. 27: 23-36; 1946.

4. Curtis, John T. The vegetation of Wisconsin: an ordination of plant

communities. Madison, WI: University of Wisconsin Press; 1959.

657 p.

107
Dawson, Deanna K. Bird communities associated with succession and

management of lowland conifer forests. In: Management of north

central and northeastern forests for nongame birds: Workshop proceedings;

1979 January 23-25; Minneapolis, MN. Gen. Tech. Rep. NC-51. St.

Paul, MN: U.S. Department of Agriculture, Forest Service, North

Central Forest Experiment Station; 1979: 120-131.

Fowells, H. A., comp. Silvics of forest trees of the United States.

Agrie. Handb. 271. Washington, DC: U.S. Department of Agriculture;

1965. 762 p.

Godman, Richard M.; Mattson, Gilbert A. Seed crops and regeneration

problems of 19 species in northeastern Wisconsin. Res. Pap. NC-123.

St. Paul, MN: U.S. Department of Agriculture, Forest Service, North

Central Forest Experiment Station; 1976. 5 p.

Heinselman, Miron L. Fire in the virgin forests of the Boundary Waters

Canoe Area, Minnesota. Quat. Res. 3: 329-382; 1973.

Heinselman, M. L. Landscape evolution, peatland types, and the

environment in the Lake Agassiz Peatlands Natural Area, Minnesota.

Ecol. Monogr. 40: 235-261; 1970.

10. Hepting, George H. Diseases of forest and shade trees of the United

States. Agrie. Handb. 386. Washington, DC: U.S. Department of

Agriculture; 1971. 658 p.

11. Holcombe, Jeffrey W. The bryophyte flora of Thuja seedbed logs in a

northern white-cedar swamp. Mich. Bot. 15: 173—181; 1976.

12. Johnston, William F. Manager's handbook for northern white-cedar in

the north central States. Gen. Tech. Rep. NC-35. St. Paul, MN: U.S.

Department of Agriculture, Forest Service, North Central Forest Experiment Station; 1977. 18 p.

13. Johnston, William F. Northern white-cedar. In: Eyre, F. H., ed. Forest

cover types of the United States and Canada. Washington, DC: Society

of American Foresters; 1980: 23-24.

14. Ohmann, L. F.; Batzer, H. O.; Buech, R. R.; Lothner, D. C. [and

others]. Some harvest options and their consequences for the aspen,

birch, and associated conifer forest types of the Lake States. Gen. Tech.

Rep. NC-48. St. Paul, MN: U.S. Department of Agriculture, Forest

Service, North Central Forest Experiment Station; 1978. 34 p.

15. Verme, Louis J. Swamp conifer deeryards in northern Michigan, their

ecology and management. J. For. 63(7): 523-529; 1965.

108
Eastern Redcedar

Edwin R. Lawson

Southern Forest Experiment Station

Jay R. Law

Eastern Region

Eastern redcedar {Juniperus virginiana L.) is the most

widely distributed conifer of tree size in the eastern United

States, occuiTing in every State east of the 100th meridian.

The species range extends northward into southern Ontario

and the southern tip of Quebec (18). Eastern redcedar is the

dominant commercial species on nearly 2.5 million acres

(1.0 million ha), primarily in Arkansas, Missouri, Kentucky,

and Tennessee.

Eastern redcedar grows on a wide variety of soils,

ranging from dry rock outcroppings to wet, swampy land. It

is most frequently associated with thin soils derived from

limestone and dolomite where rock outcroppings are common.

Like most tree species, however, eastern redcedar grows best

on deep, moist, well-drained alluvial sites where it may reach

a height of 55 to 60 feet (16.8 to 18.3 m) in 50 years (12).

The species also grows well on deep upland soils, particularly abandoned farmlands. On the better sites, however,

hardwood competition is often so severe that the species

rarely becomes dominant. Because of competition from more

tolerant species and perhaps its relatively slow growth rates,

eastern redcedar is generally confined to poorer sites having

thin, rocky soil and intermittent rock outcroppings. These

areas are called glades in the Ozarks and Tennessee. Soils on

glade sites are usually less than 12 inches (30.5 cm) deep,

medium sites have soil less than 24 inches (61.0 cm) deep

with large crevices, and good sites have soil deeper than 24

inches (61.0 cm) (5). Eastern redcedar grows on soils having

pH values ranging from 4.7 to 7.8 (4), and is not particularly

tolerant of high pH levels. Establishment of eastern redcedar

tends to increase the pH and improve the physical properties

of soil (8, 12, 21).

The wide natural distribution of eastern redcedar indicates its ability to grow under diverse and extreme climatic

conditions. Average annual precipitation over the species

range varies from about 15 inches (380 mm) in the Northwest

to 60 inches (1525 mm) in the southern parts of its range

(13). Over its habitat, annual snowfall averages extend from

0 to 100 or more inches (2540 mm). Average annual

temperatures vary from about 39° F (3.9° C) in the North to

68° F (20.0° C) in the southern part of the species range.

Temperature extremes, however, extend from -40° F (-40.0°

C) in the Central Plains and Minnesota to 115° F (46.1° C) in

the central and southern Great Plains (26). The average

growing season varies from about 120 days in the Dakotas to

250 days in the southern sections of its territory. Elevations at

which the species grows range from zero in the South to over

5,000 feet (1525 m) in western Nebraska and Kansas (26). In

the western portion of its range, the species is more commonly found on north-facing slopes and along streambanks

where it is sheltered from heat and drought (2).

Relatively pure stands of eastern redcedar are scattered

throughout the species' habitat, but they are most common on

abandoned farmlands and drier upland sites (13). Because of

its wide occurrence, the eastern redcedar forest cover type

(Society of American Foresters forest cover type 46) has

many associates (25). Variants of the eastern redcedar type

are eastern redcedar-pine, eastern redcedar-hardwood, and

eastern redcedar-pine-hardwood. In the eastern redcedarpine variant, shortleaf pine (Pinus echinata Mill.) and

Virginia pine {P. virginiana Mill.) are common associates in

the southern half of the species range. The eastern

redcedar-hardwood variant occurs throughout the central

part of its range and includes a mixture of northern red oak

{Quercus rubra L.), white oak {Q. alba L.), hickories {Garya

spp.), black walnut {Juglans nigra L.), and other hardwoods.

The eastern redcedar pine-hardwood variant includes all of

the above associations (13).

Eastern redcedar is among the first species to invade old

abandoned fields and areas cleared for pasture (11). On

deeper soils, common persimmon {Diospyros virginiana L.)

and sassafras {Sassafras albidum (Nutt.) Nees) are associated

invasion species and may crowd it out. On cedar glades,

eastern redcedar is commonly associated with blackjack oak

{Quercus marilandica Muenchh.), post oak {Q. stellata

Wangenh.), Ozark chinkapin {Castanea ozarkensis Ashe),

winged elm {Ulmus alata Michx.), fragrant sumac {Rhus

aromática Ait.), Carolina buckthorn {Rhamnus caroliniana

Walt.), rusty blackhaw {Viburnum rufidulum Raf.), and

Alabama supplejack {Berchemia scandans (Hill) K. Koch)

(25). Many herbaceous plants are associates of the eastern

redcedar type and the species occurs as a minor component of

several other forest types.

Most eastern redcedar natural reproduction occurs on

relatively poor hardwood or pine sites, along fence rows, or

in pastures that are not burned or mowed. Good seed crops

occur every 2 or 3 years, with lighter crops occurring in the

intervening years (12). Seeds are disseminated when birds

and other animals eat the fruit (15).

Eastern redcedar stands may also be established by

planting Wildlings or 2-0, 3-0, 1 -2, 2- 1, or 2-2 nursery

grown seedlings. Climatic conditions at the time of and

immediately following planting are also important (1). Eastem redcedar may be successfully established by hand-directseeding or machine sowing using about 0.5 to 0.75 pounds of

stratified seeds per acre (0.6 to 0.8 kg/ha) on sites where both

the hardwood overstory and the litter have been removed.

The rate of sowing must be adjusted to allow for variations in

germinative capacity of the seeds and degree of competition

control.

Seedling development on very dry sites is slow and

survival rates may be very low if competition is severe (19).

During the first year seedlings do not normally produce much

height growth, but they develop long, fibrous root systems.

However, under favorable environmental conditions, 2-0

and older nursery stock may have good height growth the

first year after planting. Once established, eastern redcedar

seedlings will survive for extended periods under heavy

competition, although growth is severely retarded. Eastern

109
redcedar also competes very well in shelterbelts, where it is

the species most frequently found in natural regeneration.^

Growth rates of eastern redcedar depend largely on site

quality, competition from other species, and stand density.

Trees 20 to 30 years old are generally 18 to 24 feet (5.5 to 7.3

m) tall and 2 to 3 inches (5 to 8 cm) diameter at breast height

(d.b.h.) (13). In the Arkansas Ozarks, annual d.b.h. growth

of well-stocked stands on medium to good sites averaged 0.2

to 0.3 inches (4 to 8 mm) (5). Trees on these sites averaged

26 to 32 feet (7.9 to 9.8 m) in height at age 30 (12).

Growth and yield of eastern redcedar are affected by

stand density and hardwood competition. In 45-year-old

stands, the highest volume growth was obtained in unthinned

stands from which hardwoods had been removed. These

stands averaged 28 cubic feet per acre (2.0 m^/ha) per year

during a 14-year period. This was double the growth where

the competing hardwoods were left. A stocking of 175 crop

trees per acre (430/ha), 3 inches (8 cm) d.b.h. and larger,

with 80 percent of the competing vegetation removed, had

nearly the same 14-year growth as unthinned stands having

440 trees per acre (1085/ha) (12).

Over a 10-year period in northern Arkansas, completely

released stands averaged higher d.b.h., basal area, and

volume growth than stands where only crown competition

was removed. The greatest mean diameter growth, 2.5 inches

(6 cm), occurred with the lightest stocking of 50 crop trees

per acre (125/ha). Mean d.b.h. growth decreased as stocking

increased. Basal area growth was greatest in stands having

400 crop trees per acre (990/ha). As stocking levels were

reduced, basal area and volume growth decreased. The

stands with 400 trees per acre (990/ha) produced more than

2,000 fbm (400 ft^)^ per acre (28.0 m^/ha) in 10 years. A

stocking of 175, 4-inch (10 cm) redcedar trees per acre

(430/ha) produced slightly more volume during the same

period on similar sites (12). In Missouri, recommended

stocking rates are based on crown closure and diameter,

using the numerical value for diameter in inches plus 6, D +

6, giving the recommended spacing in feet. Thus, a stand of

4-inch (10 cm) trees would have a spacing of 10 feet (3.0 m)

or about 436 trees per acre (1080/ha). As the trees develop,

they are thinned to the D + 6 spacing.-^

Aspect influences stand characteristics but not total

growth and yield. North and east aspects generally have

fewer eastern redcedar trees because of hardwood competition,

but individual trees tend to be taller than those on south and

west aspects. Topographic position is often related to depth

of soil, with lower slopes tending to produce taller trees

because of greater soil depth (5).

On many sites, growth rates of eastern redcedar are

relatively slow, and long rotations may be required to

produce conventional saw logs. However, the small sizes of

the speciality products manufactured from eastern redcedar

and the wide range in acceptable defects allows shortening of

rotations and periods between intermediate harvests. A period of 20 to 30 years is required for post material and 40 to

60 years for saw timber (12).

' Van Haverbeke, David F. Personal communication to Edwin R. Lawson.

Affiliated with the U.S. Department of Agriculture, Forest Service, Rocky

Mountain Forest and Range Experiment Station, Forestry Sciences Laboratory,

Lincoln, Nebr.

^ Cubic foot and metric conversions of measurements expressed in board

feet should be viewed as estimates because of the assumptions involved in

the conversion process.

^ Robinson, James L. Personal communication to Jay R. Law. 1981

October. Affiliated with U.S. Department of Agriculture, Soil Conservation

Service, Columbia, Mo.

Insects usually do not seriously damage eastern redcedar.

Several boring insects sometimes feed on living and dead

trees, and bagworms {Thyridopteryx ephemeraeformis

(Haworth)) occasionally completely defoliate trees. Roots of

seedlings are very susceptible to attack by nematodes and

grubs. Several weevils, bark beetles, and sawflies may also

attack various parts of redcedar (6).

Eastern redcedar, especially when weakened by stress or

insects, is very susceptible to damage by the root rot fungus,

Heterobasidium annosum (Fr.) Bref. This disease is considered to be the species' most serious pathogen over much of its

range. Two cubical rot fungi {Fomitopsis cajanderi (Karst.)

Kod. & Pouz. and Daedalea juniperina Murr.) and juniper

pocket rot fungus {Pyrof ornes demidoffii (Lev.) Kotl. &

Pouz.) may enter through dead branch stubs and attack the

heartwood (16). Because of this potential problem, pruning

of eastern redcedar is usually not recommended. If pruning is

done, branch stubs should be 8 to 10 inches (20 to 25 cm)

long to minimize fungal attack (12). Cedar-apple rust

{Gymnosporangiumjuniperi-virginianae Schw.) attacks eastem redcedar trees in all stages of development, but it rarely is

a serious disease. Phomopsis blight {Phomopsisjuniperovora

Hahn) and Cercospora blight (Cercospora sequoiae E. & E.)

are important foliage diseases. Phomopsis blight can be

controlled in nurseries by application of a suitable fungicide

and use of several management procedures (3). Control of

Cercospora blight is feasible through careful timing of

fungicide applications (20).

Fire is probably the worst enemy of eastern redcedar.

The thin bark and fibrous roots near the ground surface are

easily injured by fire. Fortunately, the foliage does not bum

readily, and litter accumulation beneath the trees is often

limited, especially on shallow soils (12). Protection from fire

has been the primary reason that eastem redcedar has

increased in many States (7), but it has also increased through

invasion of abandoned agricultural fields and discontinued

grazing in pastures.

Newly established seedlings are subject to frost heaving

and occasionally foliage may be damaged by severe winter

weather (17). Mice and rabbits may also damage young

eastem redcedar seedlings. Livestock generally avoid browsing seedlings and trees but may trample the plants and their

roots or mb trees while grazing. During times of food stress,

deer will heavily browse eastem redcedar (15) and destroy

much of the reproduction (12). Redcedar withstands the

weight of snow fairly well, but it has only moderate resistance to ice damage (9).

Studies in north Arkansas indicate that even-aged management is suitable for eastem redcedar (12). Many of the

better natural stands tend to be even aged, particularly on old

fields and pastures where fire or other catastrophes have

reduced competition from other tree species. On the cedar

glades, eastem redcedar stands tend to be uneven aged. This

occurs because these sites are not capable of supporting a

closed forest canopy.

Silvicultural practices used to manage eastem redcedar

in even-aged stands depend on site sensitivity, stand density,

tree quality, existing reproduction, and management objectives.

Shelterwood, seed-tree, and clearcut silvicultural systems are

all suitable for regenerating eastern redcedar. Control of

competing vegetation and protection of seedlings from livestock are essential under all systems. The shelterwood system

is effective in cedar and cedar-hardwood stands if the

understory competition is sparse. A light shelterwood cut,

leaving the best stems, maximizes diameter growth of residual trees. Fire and mechanical site preparation methods

should not be used with the shelterwood system.

110
The seed-tree cutting method requires leaving 10 or

more well-dispersed trees of seed-bearing age per acre

(25/ha). The residual trees should constitute a harvestable

volume and must represent both sexes, since the species is

essentially dioecious. Burning and mechanical site preparation methods may be used, but the shallow root systems and

above ground tree parts must be protected from injury.

The clearcut system is appropriate where the stand is

mature or where establishment of new redcedar stands is the

management objective. Under this system, all merchantable

materials are removed, undesirable trees deadened, and the

seedbed prepared by burning or mechanical site preparation.

The new stand may be established by planting or by direct

seeding. If vegetation control is adequate, sites to be planted

should not be burned.

Use of patch or strip clearcuts may be desirable for

managing stands of eastern redcedar on small ownerships,

since they form a mosaic of even-aged stands. However,

these cutting methods require a more extensive access road

network, make site preparation more difficult, increase the

potential for fire damage to residual trees from fuel build-up,

and in general are more costly to implement. The more

extensive road network would, however, provide firebreaks

and added protection against extensive fire losses.

Under an even-aged management system, intermediate

cuttings should be from below, leaving the best trees in the

residual stand. A cutting cycle of 10 years and a saw timber

rotation age of 60 years are recommended for eastern

redcedar. When the stands are young, stocking levels should

be between 175 and 400 trees per acre (430 and 990 trees/ha)

on the medium and better sites where the site index is at least

35 feet (10.7 m), or a sufficient number to keep the stand

canopies closed. As the stands develop, thinnings should

reduce the number of trees to about 175 per acre (430/ha).

The stands should be maintained at a dense stocking level or

where only the upper half of the canopy is open to full

sunlight. Closed and dense stocking levels are important in

maintaining tree height growth and development of a desirable heartwood-sapwood ratio in the tree bole.

Uneven-aged management of eastern redcedar on medium to good sites is probably not practical, since the species

requires closed canopies to maintain good height growth.

Opening up such stands through individual tree selection

would stimulate growth of undesirable species, reduce height

growth of redcedar, and allow excessive branching to develop on individual trees. On glade sites, individual tree

selection may be a suitable alternative, since these sites are

only capable ofsupporting sparse stands ofredcedar intermixed

with grasses. Natural regeneration on these sites can be

obtained by providing brush control and fire protection. On

many such areas, grazing by livestock is often considered to

be the primary management objective, even though it may

undermine fragile soils and eastern redcedar growth and

yield.

In most of the areas where eastern redcedar grows, the

number of trees and volume have increased (7). It is likely

that the area of the eastern redcedar type is expanding also,

but data are not available. Opportunities remain to expand the

type by converting poor hardwood stands to redcedar, since

the species has the ability to grow on sites that are too poor

either for hardwood saw log production or to justify the

expense of pine conversion. Conversion of such sites to

redcedar may increase the forest value and be of benefit to

other resources as well.

Much of the eastern redcedar type is on shallow soils

and glades with sparse stocking of redcedar. Grasses occupy

the spaces between trees and provide forage for livestock.

Range is the dominant use on most private ownerships and

some public ownerships are leased for this purpose. Grazing

must be carefully controlled on these areas in order to protect

the often fragile soils. These sites are among the few in

forested areas where overland flow occurs rather frequently;

therefore sheet erosion is a potential hazard if the soils are

disturbed through over-grazing or other activities. Watersheds containing a high proportion of shallow soils rank

among the highest for water yield, with storm flows of 50 to

75 percent of precipitation being common.

Eastern redcedar is one of the best tree species for

protecting soils from wind erosion and reducing the desiccating effects of wind. It ranked high in the Great Plains

shelterbelt plantings because of its ability to withstand

extremes of drought, heat, and cold (13). It is the most

suitable species for single-row field windbreaks (24). The

fibrous root system also helps to hold soil in place, especially

on shallow soils.

Eastern redcedar, with its wide distribution, is important

to wildlife. As an evergreen, it provides good nesting and

roosting cover for many birds. When in dense thickets it

provides good escape cover for deer. Glade sites provide

habitat for several rare and endangered plant species (22) and

birds (10). The abundant foliage, although low in nutritional

values, provides emergency food for deer during times of

stress. Fruits are high in crude fat and fiber, moderate in

calcium, and very high in total carbohydrates (15). Eastern

redcedar fruits are eaten by many wildlife species, including

waxwings, bobwhite quail, ruffed grouse, pheasants, wild

turkeys, rabbits, red foxes, gray foxes, raccoons, opossums,

skunks, and coyotes (15).

Eastern redcedar trees and stands add variety to a forest

and are esthetically very appealing. Many varieties of eastern

redcedar are used as ornamental plantings (14, 23). The

species is ranked among the five most desired species of trees

chosen for Christmas trees (11).

Eastern redcedar, with its bright to dull red heartwood

and white sapwood, has many special uses. The heartwood is

very resistant to decay, and has outstanding qualities of rich

color, aromatic odor, fine and uniform texture and workability.

The greatest quantity of eastern redcedar is used for fenceposts,

but its lumber is being increasingly used in the manufacture

of chests, wardrobes, closet linings, furniture, flooring,

novelties, woodenware, pencils, scientific instruments, and

small boats. Aromatic oils, medicine, perfumes, and alcohol

are also manufactured from eastern redcedar (11).

Literature Cited

1. Afanasiev, Michel; Engstrom, Albert; Johnson, Ernest W. Effects of

planting dates and storage on survival of eastern redcedar in central and

western Oklahoma. Bull. B-527. Stillwater, OK: Oklahoma Agricultural Experiment Station, Oklahoma State University; 1959. 19 p.

2. Albertson, F. W. Studies of native redcedar in west central Kansas.

Trans. Kansas Acad. of Sei. 43: 85-96; 1940.

3. Anderson, Robert L.; Martin, Margaret B.; Peterson, Glenn W. How to

identify and control Phomopsis blight of junipers. For. Bull. SA-FB/P25.

Altanta, GA: U.S. Department of Agriculture, Forest Service, Southeastern Area, State and Private Forestry; 1980. 2 p.

4. Arend, John L. Influence of fire and soil on distribution of eastern

redcedar in the Ozarks. J. For. 48(2): 129-130; 1950.

5. Arend, John L.; Collins, Robert F. A site classification for eastern

redcedar in the Ozarks. Soil Sei. Soc. of Amer. Proc. 13: 510-511;

1949.

6. Baker, Whiteford L. Eastern forest insects. Misc. Publ. 1175. Washington,

DC: U.S. Department of Agriculture; 1972. 642 p.

7. Boyce, Steven G.; Knight, Herbert A. Prospective ingrowth of southern

hardwoods beyond 1980. Res. Pap. SE-203. Asheville, NC: U.S.

Department of Agriculture, Forest Service, Southeastern Forest Experiment Station; 1980. 33 p.

Ill
8. Broadfoot, W. M. Redcedar litter improves surface soil. South. For.

Notes Number 71. New Orleans, LA: U.S. Department of Agriculture,

Forest Service, Southern Forest Experiment Station; 1951. 4 p.

9. Croxton, W. C. A study of the tolerance of trees to breakage by ice

accumulation. Ecology 20: 71-73; 1939.

10. Evans, Keith E.; Kirkman, Roger A. Guide to bird habitats of the Ozark

Plateau. Gen. Tech. Rep. NC-68. St. Paul, MN: U.S. Department of

Agriculture, Forest Service, North Central Forest Experiment Station;

1981. 79 p.

11. Ferguson, E. R.; Lawson, E. R. Eastern redcedar—an American wood.

FS-206, Washington, DC: U.S. Department of Agriculture, Forest

Service; 1974. 6 p.

12. Ferguson, E. R.; Lawson, E. R.; Maple, W. R.; Mesavage, C.

Managing eastern redcedar. Res. Pap. SO-37. New Orleans, LA: U.S.

Department of Agriculture, Forest Service, Southern Forest Experiment

Station; 1968. 14 p.

13. Fowells, H. A., comp. S ilvies of forest trees of the United States.

Agrie. Handb. 271. Washington, DC: U.S. Department of Agriculture;

1965. 762 p.

14. Hall, M. T.; Mukherjee, A. Chromosome numbers of cultivated

junipers. Bot. Gaz. 149(3): 364-370; 1979.

15. Halls, Lowell K. Eastern redcQÚar Juniperus virginiana L. In: Southern

fruit-producing woody plants used by wildlife. Gen. Tech. Rep.

SO-16. New Orleans, LA: U.S. Department of Agriculture, Forest

Service, Southern Forest Experiment Station; 1977: 105-107.

16. Hepting, George H. Diseases of forest and shade trees of the United

States. Agrie. Handb. 386. Washington, DC: U.S. Department of

Agriculture; 1971. 658 p.

17. Johnsen, Thomas N., Jr.; Alexander, Robert A. Juniperus L. Juniper.

In: Seeds of woody plants in the United States. Agrie. Handb. 450.

Washington, DC: U.S. Department of Agriculture; 1974: 460-469.

18. Little, Elbert L., Jr. Atlas of United States trees: Volume 1, conifers

and important hardwoods. Misc. Pub. 1146. Washington, DC: U.S.

Department of Agriculture; 1971.

19. Meade, Fayette M. Converting low-grade hardwood stands to conifers

in the Arkansas Ozarks. Bull. 551. Fayetteville, AR: University of

Arkansas, Agricultural Experiment Station; 1955. 26 p.

20. Peterson, Glenn W. Epidemiology and control of a blight of Juniperus

virginiana caused by Cercospora sequoiae var. juniperi. Phytopathology 67(2): 234-238. 1977.

21. Read, Ralph A.; Walker, Laurence C. Influence of eastern redcedar on

soil in Connecticut pine plantations. J. For. 48(8): 337-339; 1950.

22. Roedner, Beverly J.; Hamilton, David A.; Evans, Keith E. Rare plants

of the Ozark Plateau, a field identification guide. St. Paul, MN: U.S.

Department of Agriculture, Forest Service, North Central Forest Experiment Station; 1980. 238 p.

23. Smith, R. C. Woody plants that survive tough Texas environment.

Amer. Nursery. 146(12): 13, 52, 54; 1977.

24. Van Haverbeke, David F. Conifers for single-row field windbreaks.

Res. Pap. RM-196. Fort Collins, CO: U.S. Department of Agriculture,

Forest Service, Rocky Mountain Forest and Range Experiment Station;

1977. 10 p.

25. Van Haverbeke, David F.; Probasco, George E. Eastern redcedar. In:

Eyre, F. H., ed. Forest cover types of the United States and Canada.

Washington, DC: Society of American Foresters; 1980: 50-51.

26. Van Haverbeke, David F.; Read, Ralph A. Genetics of eastern

redcedar. Res. Pap. WO-32. Washington, DC: U.S. Department of

Agriculture; 1976. 17 p.

112
Aspen

Donald A. Perala

North Central Forest Experiment Station

James Russell

Eastern Region

The major portion of the Society of American Foresters

eastern aspen forest cover type 16 (6) spans the northern tier

of States from Minnesota to Maine. More than 80 percent of

this type occurs in the Lake States Region where it covers 13

million acres (5.3 million ha) of commercial forest land. The

bulk of the remainder is in Maine and New York (20), but the

type is found as far south as New Jersey and Pennsylvania,

westward to Iowa, and north to the Canadian border (9). For

information about aspen in the West and in Alaska (types 217

and 251), see discussions of Rocky Mountain Aspen, Southwestern Mixed Conifers, and Interior Alaska White SpruceHardwoods in this publication.

This wide-ranging type grows on a diversity of soils.

Fifty-year height growth ranges from less than 40 feet (12.1

m) on dry sands, rock outcrops, and poorly drained mineral

soils and peats, to more than 90 feet (27.4 m) on deep, well

drained, high calcium fertile loams (5, 7, 14).

Climates within the range of aspen are humid warmsummer continental (2). Daily minimum temperatures average as low as -5° F (-20.6° C) in January and July

maximums average as high as 86° F (30.0° C). Frost free

periods range from about 90 to 150 days. Mean total annual

precipitation ranges from about 20 inches (510 mm) to 50

inches (1270 mm), about one-sixth to one-third falling as

snow (10, 12). Precipitation is more or less evenly distributed

throughout the year and droughts are not common, except at

the western extent ofthe type. Occasional intense thunderstorms,

tornadoes, or—in the northeast—hurricanes produce damaging winds. Summer sunshine ranges from 8 to 10.5 hours

daily, grading with decreasing cloudiness from east to west

(18).

Principal components of this type are quaking aspen

(Populus tremuloides Michx.) and, especially in the Lake

States, bigtooth aspen {Populus grandidentata Michx.). Common associated tree species include paper birch (Betula

papyrifera Marsh.), pin cherry {Prunus pensylvanica L.f.),

sugar maple {Acer saccharum Marsh.), yellow birch {Betula

alleghaniensis Britton), American basswood {Tilia americana L.), eastern hophornbeam {Ostrya virginiana (Mill.) K.

Koch), balsam poplar {Populus balsamifera L.), balsam fir

{Abies balsamea (L.) Mill), red spruce {Picea rubens Sarg.),

white spruce {P. glauca (Moench) Voss), jack pine {Pinus

banksiana Lamb.), red pine (P. resinosa Ait.), and white

pine {P. strobus L.) (5, 6).

Despite abundant seed production, aspens reproduce

most commonly from adventitious root sprouts (suckers).

Suckering creates naturally occurring clones—the typical

genetic entity of aspens rather than the individual stem (3).

Aspen suckering is suppressed by auxin transported from

growing shoots (16), so the parent stand must be killed by

cutting, fire, or herbicides to relieve this apical dominance

and allow suckering to occur. Exposing the forest floor to

sunlight warms the soil, further enhancing sucker development (11). Initial sucker growth depends on stored root

carbohydrates (16). Except for some trials with genetically

improved stock (11, 19), aspen is seldom planted.

Aspens produce good spring seed crops every 4 or 5

years after age 10 to 20. The seeds are light, averaging 3

million per pound (6.6 million/kg). They are buoyed by long

silky hairs and may be carried for several miles by the wind.

A single tree may produce a million or more seeds, and

germinative capacity at seedfall usually exceeds 95 percent

(17). However, seedbed and microenvironment requirements

for seedling establishment are stringent. Mineral soil seedbeds are best but they must be continually moist during the

short period of seed viability (less than 4 weeks) and during

early root growth. Because these requirements are seldom

met in nature, pure seedling stands are uncommon (5, 11,

19).

Both seedlings and suckers are intolerant of shade and

can endure little suppression. Natural thinning in dense

young stands is rapid and trees that fall below the canopy stop

growing and die within a few years. Young sucker stands are

especially tolerant of drought because of their extensive root

systems and reduced évapotranspiration (13). Seedlings may

be killed by drought during their first year or two until roots

are well established but older stands are seldom killed by

drought. However, their growth and vigor may be reduced by

drought to the point of increased susceptibility to disease and

insects (5).

Depending on site quality and clonal ability (5, 21),

young trees grow rapidly and by age 20 may be from 20 to 75

feet (6.1 to 22.9 m) tall (14). During the first several years,

however, seedlings do not grow as fast as suckers, which

draw on the extensive parent root system to sustain their rapid

growth. Dominant suckers grow 4 to 6 feet (1.2 to 1.8 m) or

more in height during the first year—easily enough to

outgrow any competition of the same age. In contrast,

seedlings may grow only from 6 to 24 inches (15 to 61 cm)

the first growing season (5). Mature stands (50 years of age)

typically average 66 to 82 feet (20.1 to 25.0 m) tall. Under

the best conditions a few aspens may eventually exceed 100

feet (30.5 m) (5). On equivalent sites, bigtooth aspen will

usually outproduce quaking aspen, especially on sandy soils

(7).

According to site quality (site index 40 to 80 ft (12.2 to

24.4 m) at 50 years) and species, fully stocked aspen stands

on rotations of 30 to 40 years will produce about 0.7 to 4.4

tons per acre (1.6 to 9.9 t/ha) per year of biomass (fresh

weight). On rotations of 30 to 50 years, these same stands

can produce about 20 to 130 cubic feet per acre (1.4 to 9.1

m^/ha) per year of bolewood (14). Only the best sites (70 + ft

(21.3+ m) at age 50) will produce much sawtimber and they

will require close utilization and rotations of 50 years or

longer. The pathological rotation seldom exceeds 60 years so

few opportunities exist to grow aspen sawtimber except on

the very best sites (5, 14).

The aspens are vulnerable to a multitude of damaging

agents. They are injured by the feeding of birds and mammals and by leaf and shoot blights, rusts, and mildews.

Although few trees are killed by these agents, they do slow

the growth of aspen—particularly in young stands (19).

113
Viruses slow the growth of some quaking aspen clones

and regeneration by suckering maintains the infection (4).

Stain and wetwood reduce wood quality. Trunk rots, especially that caused by the fungus Phellinus tremulae (Bond.)

Bond, and Boris, are the major deterrent to growing aspen on

long rotations. Several stem cankers either reduce timber

quality or kill the tree. Hypoxylon mammatum (Wahl.) Mill,

is the most serious of these and kills up to 2 percent of the

aspen annually. Bigtooth aspen is more resistant to this

disease than is quaking aspen (19).

The aspens host at least 300 species of insects but only a

few are known to cause much damage. The most serious

defoliators are the forest tent caterpillar (Malacosoma disstria

Hubner) and the large aspen tortrix {Choristoneura conflictana

(Walker)). Outbreaks usually persist for 2 or 3 years, greatly

slowing growth but causing little direct mortality. The gypsy

moth {Lymantria dispar (L.)) is also an important defoliator in

the Northeast. Leaf tiers, leaf rollers, and leaf miners are less

important defoliators, but in aggregate they significantly

slow the growth of juvenile stands (19).

Wood-boring beetles of the genus Saperda, Oberia, and

Agrilus infest most juvenile sucker stands. Their activities

provide infection courts for stem cankers and wood rots. In

some cases they girdle and kill suckers outright by tunneling

under the phloem. The poplar borer {Saperda calcarata Say)

is the most important of the stem borers and is most serious in

pole stands. Other damaging but less important insects

include aphids, leafhoppers, scale insects, cutworms, and

carpenter ants (19).

Fire can be used to regenerate aspen if woody fuel

accumulations are sufficient to provide the heat required to

kill the stand. Light fuel accumulations will support only

relatively cool fires. These may reduce growth and quality by

scarring the lower bole to provide avenues for wood-rotting

fungi and by destroying surface feeding roots. Excessive fuel

accumulations will support intense fires that will diminish

sucker growth. Overall, the aspen type is low in flammability

unless there is slash on the ground. Consequendy, the type

forms a fuel break and fires in the type can be extinguished

easily (14).

Aspen can also be injured by frost, wind, hail, ice

storms, and sunscald (5, 7, 19). The only feasible way to

minimize losses by any of these damaging agents is to

maintain fully stocked stands (5, 7, 14).

The intolerance of aspens to shade and the physiological

requirements for suckering dictate even-aged management

systems using clearcutting to maintain the type at full

productivity (5, 7, 14). Single tree or group selection will

discriminate against the aspens. Shelterwood or seed-tree

systems are not needed and indeed shading by residual stems

is detrimental to sucker growth. However, selection systems

to leave associated species will hasten natural succession and

conversion to other forest types when they are desired. Aspen

stands often have a conifer understory that can be released

with a single careful cutting of the aspen (14). Openings of

about 1 acre (0.4 ha) in size provide minimally acceptable

conditions for regenerating aspen. Clearcuts of at least 40 to

50 acres (16 to 20 ha) are needed for efficient harvesting.

Maximum clearcut size has no silvicultural limit but size is

often constrained to 10 or 20 acres (4.0 or 8.1 ha) for other

multiple resource considerations (13).

Typically from 10,000 to 30,000 suckers per acre

(24 710 to 74 130/ha) are regenerated by complete

clearcutting (5, 7). As many residual trees (except those for

special purposes) and tall shrubs should be destroyed during

or soon after harvest as is economically practical. The

seasonal timing of harvest influences sucker vigor and

survival. It is desirable to harvest aspen during the dormant

season when root carbohydrate reserves are highest (16),

especially where brush or bracken fern compete (5, 14, 19).'

Dense sucker stands provide the best protection from insects

and disease and assure a healthy new forest (14). On well

drained sites, clearcutting stands containing as litde as 50

well distributed quaking aspens per acre (124/ha) will normally create a fully stocked stand of suckers (14).

The vast majority of aspen stands are suitable for

growing only pulpwood on rotations from 35 to 45 years

(depending on utilization standards) (13). However, some of

the best sites (site index 70 (21.3 m) or better) will produce

sawtimber if thinned at age 30 (5, 14). An additional thinning

at age 10, and optionally again at age 20, on exceptional sites

(site index 80 (24.4 m) or better) can dramatically improve

yields of large products. Sawtimber rotations of only 50 years

are needed but can be extended to 60 years in diseaseresistant stands for even greater yields. Fifty-year-old stands

that have been thinned three times can produce about 35

percent more sawtimber volume than 60-year-old unthinned

stands (15).

As far as is known, the aspen type can be maintained

indefinitely by clearcutting. However, the presence of viruses in some clones may gradually deteriorate some stands

(4). Also, because quaking aspen contains high amounts of

nutrients, nutrient drain in harvested products, especially

with whole tree systems, might lower the productivity of

some soils (1). Without cutting or other disturbance the type

will be succeeded by its more tolerant or longer-lived

associates. On dry sites, these are chiefly red pine, red maple

{Acer rubrum L.), and the oaks {Quercus spp.). On moist

fertile soils these are northern hardwoods, balsam fir, white

spruce, and eastern white pine, and on wet sites balsam fir,

black spruce {Picea mariana (Mill.) B.S.P.), and northern

white-cedar {Thuja occidentalis L.) (5). Pure aspen stands

lacking a tolerant species seed source will deteriorate to a

shrubwood containing only a few scattered aspen suckers

(19).

Despite the lush herbaceous component, especially in

regenerated stands, the aspen type is little used for pasture in

the East in contrast to its importance for range in the West.

However, the type is particularly good habitat for wildlife

associated with forest margins and openings, such as whitetailed deer, ruffed grouse, woodcock, snowshoe hare, and a

large number of songbirds (13). A diversity of aspen age

classes along with intermixed conifer stands provide the best

wildlife habitat. Aspens are predominately dioecious, and the

male flower buds are important winter food for grouse. For

increased grouse production, clearcuts should be no larger

than 10 acres (4.0 ha). When clearcuts are greater than 10

acres (4.0 ha) in size, some of the negative impacts to grouse

can be reduced by leaving the male clones of from 30 to 50

trees (8). Deer and moose habitat can be improved by

limiting aspen clearcuts to 40 acres (16 ha), or up to 100

acres (40 ha) for moose, and by short rotation management

(14). Although aspen snags deteriorate rapidly, they are

important for cavity-nesting ducks and other hole-nesting

species. No rare or endangered species are exclusively

associated with the aspen type. However, the type is critical

for white-tailed deer and beaver which are key prey species

for the gray wolf. Remnant old-growth red and eastern white

pines are especially important for bald eagle nesting and may

be reserved from cutting where they occur in the aspen tvoe

(13, 14). ^ ^^

Compared to conifer forests, aspen allows greater ground

water recharge and streamflow due to lower seasonal use and

smaller interception loss. Clearcutting entire small watersheds may temporarily increase streamflow up to 60 percent

but with rapid sucker regrowth, preharvest water yields are

114
restored in about 10 years. The impact of harvesting on large

watersheds is minor because only a small percentage of the

area is cut within any year. Clearcutting of aspen need not

alter water quality (13).

Aspen stands display bright yellow foliage in the fall

and strong color contrast between bark and leaves in the

spring and summer. When aspen is associated with other

species of hardwood or conifers, landscape variety is heightened because of the contrast of color and texture. Travel

corridors dominated by aspen are most pleasing when a

variety of age-classes are present. Good landscape planning

can mitigate the esthetic impact of clearcutting in the type,

and in somie cases, clearcuts can even improve landscapes by

providing interesting vistas (14).

The aspen type usually has a brushy understory and so,

except for hunters and mushroomers, is not heavily used by

recreationists. Aspen stands make poor campgrounds because they provide favorable habitat for mosquitoes and

black flies, are short lived, and cannot long endure injury

caused by trampling or vandalism (5).

Literature Cited

1. Alban, D. H.; Perala, D. A.; Schlaegel, B. E. Biomass and nutrient

distribution in aspen, pine, and spruce stands, on the same soil type in

Minnesota. Can. J. For. Res. 8: 290-299; 1978.

2. Bailey, Robert G. Description of the ecoregions of the United States.

Misc. Publ. 1391. Washington, DC: U.S. Department of Agriculture;

1980. 77 p. plus map.

3. Barnes, Burton V. The clonal growth habit of American aspens. Ecol.

47: 439-447; 1966.

4. Berbee, J. G.; Omuemu, J. O.; Martin, R. R.; Costello, J. D. Detection

and elimination of viruses in poplars. In: Intensive plantation culture.

Gen. Tech. Rep. NC-21. St. Paul, MN: U.S. Department of Agriculture,

Forest Service, North Central Forest Experiment Station; 1976: 85-91.

5. Brinkman, Kenneth A.; Roe, Eugene I. Quaking aspen: silvics and

management in the Lake States. Agrie. Handb. 486. Washington, DC:

U.S. Department of Agriculture; 1975. 52 p.

6. Eyre, F. H., ed. Forest cover types of the United States and Canada.

Washington, DC: Society of American Foresters; 1980. 148 p.

-7. Graham, Samuel A.; Harrison, Robert P., Jr.; Westell, Casey E., Jr.

Aspens: Phoenix trees of the Great Lakes Region. Ann Arbor, MI:

University of Michigan Press; 1963. 272 p.

8. Gullion, Gordon W. Improving your forested lands for ruffed grouse.

Publ. 1439. Misc. J. Ser. St. Paul, MN: Minnesota Agricultural

Experiment Station; 1972. 34 p.

9. Little, Elbert L., Jr. Atlas of United States trees. Vol. 1. Conifers and

important hardwoods. Misc. Publ. 1146. Washington, DC: U.S. Department of Agriculture; 1971. 9 p. plus 313 maps.

10. Lull, Howard W. A forest atlas of the Northeast. Upper Darby, PA:

U.S. Department of Agriculture, Forest Service, Northeastern Forest

Experiment Station; 1968. 46 p.

11. Maini, J. S.; Cayford, J. H., eds. Growth and utilization of poplars in

Canada. Departmental Publication 1205. Ottawa, ON: Canadian Department of Forestry and Rural Development, Forestry Branch; 1968; 257 p.

12. Merz, Robert W. Forest atlas of the Midwest. St. Paul, MN, and

Broomall, PA: U.S. Department of Agriculture, Forest Service, North

Central Forest Experiment Station and Northeastern Forest Experiment

Station; and St. Paul, MN: College of Forestry, University of Minnesota;

1978. 48 p.

13. Ohmann, L. F.; Batzer, H. O.; Buech, R. R.; Lothner, D. C. (and

others). Some harvest options and their consequences for the aspen,

birch, and associated conifer forest types of the Lake States. Gen. Tech.

Rep. NC-48.St. Paul, MN: U.S. Department of Agriculture, Forest

Service, North Central Forest Experiment Station; 1978. 34 p.

14. Perala, Donald A. Manager's handbook for aspen in the North-Central

States. Gen. Tech. Rep. NC-36. St. Paul, MN: U.S. Department of

Agriculture, Forest Service, North Central Forest Experiment Station;

1977. 30 p.

15. Perala, Donald A. Thinning strategies for aspen: a prediction model.

Res. Pap. NC-161. St. Paul, MN: U.S. Department of Agriculture,

Forest Service, North Central Forest Experiment Station; 1978. 19 p.

16. Schier, George A. Physiological research on adventitious shoot development in aspen roots. Gen. Tech. Rep. INT-107. Ogden, UT: U.S.

Department of Agriculture, Forest Service, Intermountain Forest and

Range Experiment Station; 1981. 12 p.

17. Schopmeyer, C. S., tech. coord. Seeds of woody plants in the United

States. Agrie. Handb. 450. Washington, DC: U.S. Department of

Agriculture; 1974. 883 p.

18. U.S. Department of Agriculture, Forest Service. Climate and Man:

Yearbook of Agriculture. Washington, DC: U.S. Department of

Agriculture, Forest Service; 1941. 1248 p.

19. U.S. Department of Agriculture, Forest Service. Aspen: symposium

proceedings. Gen. Tech. Rep. NC-1. St. Paul, MN: U.S. Department

of Agriculture, Forest Service, North Central Forest Experiment Station;

1972. 154 p.

20. U.S. Department of Agriculture, Forest Service. An assessment of the

forest and rangeland situation in the United States. Washington, DC:

U.S. Department of Agriculture, Forest Service; 1980. 631 p.

21. Zahner, Robert; Crawford, Ned A. The clonal concept in aspen site

relations. In: Youngberg, Chester T., ed. Forest-soil relationships in

North America. Corvallis, OR: Oregon State University Press; 1963:

229-243.

115
Oak -Hickory

Ivan L. Sander

North Central Forest Experiment Station

Charles E. McGee

Southern Forest Experiment Station

Kenneth G. Day and Ralph E. Willard

Eastern Region

The upland oak-hickory forest type occupies nearly

114 million acres (46.1 million ha) of commercial forest land

in the eastern United States—more than any other single

forest type in the country, excluding types in Alaska (38). It

is found along the prairie borders from Texas north to the

Dakotas, eastward throughout the Central States and Appalachian region into southern New England, and from the

northern hardwood transition zone southward into the Piedmont Plateau and Coastal Plain. The type is well developed

in the Cumberland Plateau and portions of the Appalachian

Mountains and most continuous in the Ozark and Ouachita

Highlands (3).

Within this vast area oak-hickory occurs on soils

ranging from cool-moist Boralf and Orthod Spodosols to

warm-dry Mollisols and Alfisols. These soils are derived

from glacial material, residual sandstone, shales, and limestones and from gneisses, schists, and granites and range

from clay to loamy. The type is found on all topographic

positions from dry rocky ridges to deep coves to well-drained

valley floors (8).

The climate over the range of the oak-hickory type is

humid except in the southwestern fringe where it is moist

subhumid to dry subhumid. Average annual precipitation is

22 inches (560 mm) in central Texas, from 30 inches (760

mm) to 40 inches (1015 mm) in the Central States, and about

80 inches (2030 mm) in the southern Appalachians. Generally,

about one-half or more of the annual precipitation falls in the

dormant season, and from 2 to 8 week periods with little or

no rainfall are common late in the growing season, particularly in the western part of the range. Average annual

snowfall is 100 inches (2540 mm) or more in the North, from

15 to 20 inches (380 to 510 mm) in the Central States, and a

trace in the South. Mean annual temperature averages 40° F

(4.4° C) in the North, 55° F (12.8° C) in the Central States,

and 65° F (18.3° C) in the South. The frost-free period

averages 100 days in the North, 180 days in the Central

States, and 290 days in the South (8).

Within the broad oak-hickory type, the Society of

American Foresters has defined nine forest cover types as oak

types. Oaks and hickories are also listed as components of 31

other forest cover types (7). The great range of climate, soil,

and topography results in widely different stand compositions.

White oak {Quercus alba L.), northern red oak {Q. rubra

L.), and black oak (ß. velutina Lam.) are found throughout

the type. Other common oaks on drier sites are scarlet oak

(ß. coccínea Muenchh.) and chestnut oak (ß. prinus L.) in

the Appalachians and adjoining areas; northern pin oak (ß.

ellipsoidalis E. J. Hill) and bur oak (ß. macrocarpa Michx.)

in the northern and western parts of the range; and post oak

(ß. stellata Wangenh.), blackjack oak (ß. marilandica

Muenchh.), bluejack oak (ß. incana Dartr.), and southern

red oak (ß. falcata Michx.) in the West and South. Pignut

hickory {Carya glabra (Mill.) Sweet), mockemut hickory

(C. tomentosa (Poir.) Nutt.), shagbark hickory (C. ovata

(Mill.) K. Koch), and bitternut hickory (C. cordiformis

(Wangenh.) K. Koch) are consistent but minor components

of the type.

The mixture may also contain yellow-poplar (Liriodendron

tulipifera L.), ashes {Fraxinus L. spp.), elms {Ulmus L.

spp.), sugar maple {Acer saccharum L.), red maple {A.

rubrum L.), blackgum {Nyssa sylvatica Marsh.), black locust

{Robinia pseudoacacia L.), black cherry {Prunus serótina

Ehrh.), black walnut {Juglans nigra L.), and many other

hardwood species. On suitable sites, shortleaf pine {Pinus

echinata Mill.), loblolly pine {P. taeda L.), pitch pine {P.

rigida Mill.), Virginia pine {P. virginiana Mill.), eastern

white pine {P. strobus L.), eastern hemlock {Tsuga canadensis

(L.) Carr.), and eastern redcedar {Juniperus virginiana L.)

may also be present. The oak-hickory type often grades into

the oak-pine type in the Piedmont Plateau (3).

Many species of understory trees and shrubs occur in

oak-hickory stands. Some of the most common ones are

flowering dogwood {Cornus florida L.), gray dogwood (C.

racemosa Lam.), sassafras {Sassafras albidum (Nutt.) Nees),

sourwood {Oxydendrurn arboreum (L.) DC), eastern redbud

{Cercis canadensis L.), downy serviceberry {Amelanchier

arbórea (Michx. f.) Fern.), blueberry {Vaccinium L. spp.),

mountain laurel {Kalmia latifolia L.), witch-hazel {Hamamelis

virginiana L.), beaked hazel {Corylus cornuta Marsh, var.

cornuta), and bramble {Rubus L. spp.) (3, 8).

Oaks and hickories produce large seed crops at 2- to

10-year intervals with great variation among species (32).

Acorn production differs greatly from year to year, species to

species, and tree to tree within the same species and forest

stand (2,8). In some years the seed crop of some species fails

completely and in most years animals, birds, and insects eat a

large proportion of the acorns and nuts.

Acorns and nuts are dispersed primarily by gravity, but

squirrels and mice or voles may be important dispersal agents

through their burial and caching activities. Buried acorns are

not always retrieved and those that are not may be in an

excellent position to germinate. Germination and first-year

seedling survival are best when acorns are buried about 1

inch (3 cm) deep in the soil. Germination is not inhibited by a

light litter covering but seedlings may not be able to emerge

through a heavy litter cover. In natural seedbeds most

1-year-old oak seedlings came from acorns that were in the

soil or in the lower humus layer and covered with litter (27).

Few oak or hickory seedlings will survive more than a

few years under crown cover (overstory and/or understory)

that allows little light to reach the forest floor (16, 27). Under

moderately dense canopies oak and hickory seedlings can

survive for several years, however, their tops usually die and

new sprouts originate from dormant buds near their root

collars (1, 29). Top dieback and resprouting may occur a

number of times with each successive shoot attaining a larger

size and a stronger root system than its predecessor. By this

process oak and hickory advance reproduction slowly develops to a size that allows it to be competitive with sprouts of

other woody species and other vegetation that develops after

complete overstory removal (28).

The oak and hickory reproduction following overstory

removal will consist of stump sprouts, new sprouts from

advance reproduction, and advance reproduction. The propor116
tion of stumps that will sprout is related to species, stump

size, and tree age. Chestnut, scarlet, and northern red oak

stumps sprout more frequently than black and white oak

stumps, and small stumps of all species sprout more frequently than large ones (1?, 30, 39). Stump sprouts grow

faster than any other kind of oak reproduction; low origin

sprouts from small stumps have a low likelihood of developing decay and can grow into good quality trees (29).

New sprouts from advance reproduction occur when the

old stem is cut off, broken, or damaged in the logging

operation (29); however, new sprouts sometimes occur even

if the old stem is not damaged. The growth of these sprouts is

related to the size of the stem from which they originate—the

larger the stem, the faster they grow (25). They are generally

of good form and the most desirable type of oak reproduction.

Oak and hickory seedlings that become established after a

harvest cutting grow very slowly and seldom live more than a

few years.

The oaks, hickories, and other more valuable species,

such as yellow-poplar, white ash {Fraxinus americana L.),

black walnut, and black cherry, in oak-hickory forests

range from intolerant to moderately tolerant of shade (8).

However, many associated trees, such as the maples, blackgum,

beech, dogwood, and sourwood, and most shrubs are tolerant

to very tolerant of shade. Consequently, if undisturbed, the

successional trend of the oak-hickory type is toward the

shade-tolerant species, particularly on the higher quality

sites. When a seed source is present, yellow-poplar will be a

component in new stands following overstory removal on the

higher quality sites (16, 29). Oaks and hickories are able to

become established and persist on the drier sites where stands

are usually more open and development of many of the more

tolerant species is restricted (4).

Many insects and diseases attack oaks and hickories. A

high proportion of acorns and nuts are destroyed by nut

weevils (Curculio spp.), gall forming cynipids {Callirhytis

spp.), and the acorn moth (Valentinia glandulella (Riley)).

Oaks are the preferred food of the imported gypsy moth

(Lymantria dispar (L.)) and defoliation for 2 or 3 years can

cause widespread mortality. In areas where gypsy moth

populations are heavy, it may be difficult to maintain oak

stands. Oak wilt {Ceratocystis fagacearum (Bretz) Hunt)

usually kills only scattered individuals or small groups of

trees. Stem borers are an important cause of lumber quality

degrade, but seldom successfully attack vigorously growing

trees. Decay by wood-rotting fungi often renders the entire

stem unusable for timber. The primary entry points for decay

fungi are wounds caused by fire or mechanical injury and

dead branch stubs (8). The most practical measure to control

insect and disease attacks in oak-hickory stands is to maintain

healthy, vigorous stands. Rapidly growing, vigorous trees

are often able to reject attacks or if attacked, have a good

chance to recover.

The oak-hickory type provides habitat for numerous

wildlife species. Creating and maintaining diverse vegetation

is the key to providing habitat for the greatest number of

wildlife species (21, 34). Regeneration cuttings in even-aged

systems create openings that provide the edge habitat needed

by some species. Even small openings used in group selection provide this edge. When regeneration cuts are made to

provide a range of well-dispersed age classes, several vegetation stages and diverse habitats will be present. Regeneration

areas provide browse; sapling stands are ideal for some

species of birds; and pole, immature sawtimber, and mature

sawtimber stands provide mast and cover. Mature oakhickory stands also contain dens for many species of birds

and animals. Trees left specifically for den trees should be

carefully selected because many defective trees do not make

good den trees. Some cull trees are also excellent mast

producers. Snags are valuable as nest sites or perches and can

be left standing. Killing instead of cutting cull and unmerchantable trees in regeneration cuts will provide snags.

Fire probably had an important role in the development

of existing oak-hickory stands over much of the range (18).

The frequent fires that followed cutting the original stands

probably reduced the numbers of the less fire-resistant

species. The oaks and hickories survived because of their

ability to sprout repeatedly and the ability of these sprouts to

grow rapidly. Little research has been conducted on the use

of fire as a silvicultural tool. A single burn in 4- and

5-year-old stands containing oak, yellow-poplar, and cherry

failed to have much influence on stand composition. Three

years after the fire, oaks were still plentiful but red maple had

increased in numbers and yellow-poplar maintained a doniinant position. The ultimate composition of the stands is still

uncertain (18). Research may ultimately show prescribed fire

to be beneficial to oak seedling establishment and growth but

its general use is not recommended at the present time.

Wildfires can do much damage and should be excluded from

oak—hickory stands.

Any silvicultural system applied to the oak-hickory

type will maintain a forest stand. However, species composition following cutting will differ by geographic location, site

conditions, other species present, and the intensity of the

cutting. The choice of silvicultural systems and regeneration

methods will depend greatly on the objectives of management and the requirements of the species desired. If the

management objective is to perpetuate the oaks, even-aged

systems will best satisfy the reproduction and growth requirements (5, 26, 28).

Of the three even-aged reproduction methods—seedtree, shelterwood, and clearcutting—the seed-tree method is

least useful for reproducing oaks and hickories. The heavy

seed is poorly distributed and the slow growing seedlings are

not able to compete with the other vegetation that will be

present.

Rapidly growing new stands containing oaks, hickories,

other shade-intolerant species, and some tolerant species will

follow clearcutting of any size and shape (13, 16, 19, 23, 26,

28). When the new stand is 10 years old on sites below oak

site index 70, oaks and hickories will usually be dominant;

blackgum, red maple, and other hardwood species may also

be present. In the southern and southwestern parts of the

range, loblolly, shortleaf, Virginia, or pitch pine may also be

present if a seed source is adjacent to the cut area and logging

resulted in the scarification needed for the pine seed to

germinate. On higher quality sites, except in the OzarkOuachita Highlands, the species mixture will be diverse. The

new stands will contain a component of oaks but along the

northern hardwood transition zone stands will also contain

sugar maple, elms, American basswood {Tilia americana

L.), white ash, black cherry, and other northern hardwoods.

In the Central States, the Appalachians, and southern areas

yellow-poplar will become a dominant component of the new

stands along with the oaks. Other mesic species including

white ash, American beech, ifagus grandifolia Ehrh.),

basswood, cucumber tree (magnolia acuminata L.), and

black locust may also be present (29).

If the regeneration objective is to reproduce oaks,

whether to use clearcutting or the shelterwood method

depends on the potential of existing advance reproduction

and stump sprouting to replace the stand. Clearcutting will be

successful if combinations of oak advance reproduction over

4.5 feet (1.4 m) tall and potential stump sprouts are equivalí?
lent to 435 well distributed, advance-reproduction stems per

acre (1075/ha). However, stump sprouts should not be relied

upon as the only source of reproduction (29).

After harvest, cutting or killing unmerchantable trees

larger than about 2 inches (5 cm) d.b.h. is an important step

in clearcutting. If left, these stems will suppress the reproduction (19, 23, 26). Preharvest herbicide control of species not

wanted in the new stand is effective (14). Unmerchantable

stems of oaks and other desired species can be forced to

sprout if cut close to the ground.

The size of clearcuts is an important consideration but

no size is optimum. The maximum size should be determined

by stand and site uniformity, esthetic impacts, and wildlife

needs. The minimum size is determined by silvical requirements,

wildlife impacts, logging economy, and mapping and recordkeeping limits. Although 0.5 acre (0.2 ha) openings will

satisfy most silvical requirements (35), a large proportion of

the opening will be affected by the surrounding stand.

Openings must be about 2 acres (0.8 ha) before a substantial

area of the opening is not affected by the surrounding stand

(29). And if deer populations are high, even larger openings

may be needed to provide more browse than the deer can eat.

The shelterwood method should be used when oaks and

hickories are wanted in the next stand but advance regeneration is absent or too small. A series of cuts will be necessary

to establish new oak seedlings and provide conditions that

will allow them or existing small advance reproduction to

develop into large sturdy stems (27, 28). The first cut should

reduce the stand to from 60 to 70 percent stocking according

to the stocking criteria for upland central hardwoods (9) and

the crown coverage should be as uniform as possible. At the

time of the first cut the density of the understory may also

need to be reduced to allow the establishment and development of the oaks because any existing understory will

respond to the increased light provided by reducing the

overstory density. If the first cut can coincide with a good

acorn crop, the likelihood of increasing the number of oak

seedlings is enhanced. From 20 to 30 years or more may be

required to develop adequate oak regeneration. Additional

cuts and/or understory control should be made as needed to

keep the oaks growing. When 435 oaks per acre (1075/ha)

more than 4.5 feet (1.4 m) tall are present, any remaining

overstory should be removed (27). With intensive silviculture,

thinnings made at about age 50 or 60 may actually be the

beginning of the shelterwood method.

Using the single tree selection system in the oak-hickory

type will not perpetuate the oaks or other intolerant species.

Harvesting single trees as they mature and cutting to maintain

the specified size (age) class distribution results in an

essentially complete crown cover at all times. Although oak

seedlings will become established, they will be unable to

survive and grow into the sapling and larger size classes.

Furthermore, as the existing pole and small sawtimber size

oaks pass through succeedingly larger size classes and are

harvested, the sapling and small tree component will become

dominated by whatever shade-tolerant species are present.

Eventually the entire stand will be composed of these

shade-tolerant species (32, 36, 37). However, if maintaining

an almost continuous canopy is more important than species

composition, the single tree selection system can be used.

Group selection is a successful regeneration method

when used in the oak-hickory type. Initial reproduction

establishment and species composition will be the same as in

clearcutting in openings of 0.1 to 0.25 acres (0.04 to 0.1 ha).

Oaks will be present only to the extent they were present as

large, advance reproduction or as stump sprouts (16, 29).

Reproduction growth, however, will be retarded near the

opening edges; maximum growth will occur only in the

central part of the opening not influenced by the surrounding

stand (29, 31, 35). If deer populations are high, browsing

may extensively damage the reproduction throughout the

opening. Although group selection is an effective regeneration method, the individual openings must be considered as

integral parts of the entire stand being managed. This makes

it difficult to regulate a size class distribution and a sustained

flow of products, particularly when the group size is 1 to 2

acres (22). If regulation and sustained yield are not important,

small openings can be used for regeneration.

Regeneration of the oak-hickory type by planting or

direct seeding has limited application at present. Upland oaks

can be planted and survival will generally be acceptable.

However, planted oaks usually grow very slowly and vegetation control is needed for several years before they will grow

well enough to become part of a new stand (12, 24).

However, planting may be the best way to establish oak

seedlings quickly in situations such as rehabilitating low

quality stands with too little acceptable growing stock and

inadequate potential for reproducing the stand with the

desired oak species. Direct seeded acorns must be protected

from squirrels and other rodents to prevent pilferage. Many

repellents have been tried but none have been successful. The

high cost of mechanical protection for seeded acorns make

direct seeding a marginal operation (24).

Thinnings should be an integral part of managing

even^aged, reasonably well-stocked, oak-hickory stands.

For maximum growth and yield, the first thinning should be

at about age 20 and thinnings should be continued at about

10-year intervals through about three-fourths of the rotation

(6, 10).

If a thinning at age 20 will not yield commercial products, crop trees with an average spacing of about 15 feet

(4.6 m) should be selected and released. Generally, competing trees smaller or of a lower crown class than the crop tree

can be ignored, but trees directly competing with the crown

of the crop tree should be removed. Stands should generally

be thinned from below to leave 60 percent stocking. However,

the first thinning in stands 30 years old or older should reduce

stocking to only 70 percent to reduce the tendency of the

residual trees to develop epicormic branches. Subsequent

thinnings should reduce stocking to about 60 percent (10,

26).

A single thinning will benefit an oak-hickory stand.

However, if the stand is more than 30 years old one thinning

will not put it in the best condition for growth. Some of the

residual trees will be defective or of unwanted species;

uniform spacing will be difficult to attain. If only one

thinning is planned because a stand is inaccessible or for

other reasons, it should be recognized that the stand will

develop much like an unthinned stand, the yield will not be

much affected.

As a result of past cutting, wildfire, insects, and disease,

many oak-hickory stands contain many culls and low

quality trees. The recommended treatment of these stands

depends on the potential stocking of acceptable trees in the

stand and management goals (20). Some low quality stands

can be rehabilitated by improvement cuts that remove culls

and undesirable stems. However, if a stand does not contain

enough acceptable growing stock trees to fully occupy the

site 10 years after treatment, cutting may further deteriorate

the stand and it should be regenerated immediately (19, 26).

Low quality stands on sites below about site index 55 for

black oak will produce higher timber yields if converted to

pine. Conversion should be considered primarily within the

parts of the oak-hickory range where pine occurs naturally

and where it is compatible with overall management objectives (19, 26). -^

118
The single tree selection system limits wildlife habitat

diversity. Edge habitat does not exist, browse production is

low, and although mast production is high initially, it will

decline as the oaks and hickories are harvested and replaced

by other species. The vertical structure of uneven-aged stands

provides good habitat for some birds but the number of

species is limited and the same structure can be provided

when even-aged stands are left well beyond normal rotation

age and become overmature.

Thinnings temporarily increase browse and if a few

defective trees are left, cavities or potential cavities are

provided for hole-nesting species. Leaving defective trees

may lower the yield of quality timber but to what extent is

unknown.

Special measures may be required to provide habitat for

rare or endangered animal or plant species (11). Wherever

rare or endangered species are found within the oak-hickory

type, silvicultural prescriptions must provide for their continued existence.

Carefully executed silvicultural operations will have

little effect on water quality from oak-hickory forests.

Water yield will increase in proportion to the amount of the

stand removed, with the highest yield coming after complete

overstory removal. However, after a few years water yield

will be the same as from an undisturbed stand. Most of the

increase occurs in late summer and although peak flows are

higher from areas where the overstory has been removed, the

increase does not usually contribute to flooding (15).

Erosion and sedimentation can occur regardless of

which silvicultural system is used but can be minimized by

taking proper precautions. Water will not flow over land even

in clearcut areas unless the forest floor is destroyed. Practically all erosion and sedimentation resulting from silvicultural operations occurs because of poorly located, constructed,

and maintained roads and skid trails. Planning and executing

silvicultural operations carefully should make it possible to

protect water quality (15).

If the water resource is of primary importance, such as

areas that contribute to municipal water supplies, the principles of good watershed management must be followed.

Although a silvicultural operation may temporarily degrade

water quality, regulating the timber resource and maintaining

a healthy vigorous forest should maintain a high quality water

resource over the long run.

Any type of logging will change the appearance of a

stand. To minimize adverse visual impacts, cut-over areas

particularly clearcut and shelterwood areas, should be planned

and located so they blend into the topographic and landscape

features as much as possible. If they are large, they should be

irregular in shape so that only portions are visible from one

observation point. Cutting areas should be clean and orderly

and roads and skid trails should be designed to minimize

landscape disruption.

Literature Cited

1. Beck, D. E. Effect of competition on survival and growth of red oak

seedlings. Res. Pap. SE-56. Asheville, NC: U.S. Department of

Agriculture, Forest Service, Southeastern Forest Experiment Station;

1970. 7 p.

2. Beck, D. E. Twelve-year acorn yields in southern Appalachian oaks.

Res. Note SE-244. Asheville, NC: U.S. Department of Agriculture,

Forest Service, Southeastern Forest Experiment Station; 1977. 8 p.

3. Braun, E. L. Deciduous forests of eastern North America. Philadelphia,

PA: The Blakiston Company; 1950. 596 p.

4. Carvell, K. L. Factors affecting the abundance, vigor, and growth

response of understory oak seedlings. In: Regenerating oaks in upland

hardwood forests; 1979 John S. Wright Forestry Conference; 1979

February 22-23; West Lafayette, IN. West Lafayette, IN: Purdue

University; 1979: 23-26.

5. Clark, F. B.; Watt, R. F. Silvicultural methods for regenerating oaks.

In: Proceedings, Oak Symposium; 1971 August 16-20; Morgantown,

WV. Upper Darby, PA: U.S. Department of Agriculture, Forest

Service, Northeastern Forest Experiment Station; 1971: 37-43.

6. Dale, M. E. Growth and yield predictions for upland oak stands. Res.

Pap. NE-241. Broomall, PA: U.S. Department of Agriculture, Forest

Service, Northeastern Forest Experiment Station; 1972. 21 p.

7. Eyre, F. H., ed. Forest cover types of the United States and Canada.

Washington, DC: Society of American Foresters; 1980. 148 p.

8. Powells, H. A., comp. Silvics of forest trees of the United States.

Agrie. Handb. 271. Washington, DC: U.S. Department of Agriculture;

1965. 762 p.

9. Gingrich, S. F. Measuring and evaluating stocking and stand density in

the Central States. For. Sei. 13: 38-53; 1967.

10. Gingrich, S. F. Management of young and intermediate stands of

upland hardwoods. Res. Pap. NE-195. Upper Darby, PA: U.S.

Department of Agriculture, Forest Service, Northeastern Forest Experiment Station; 1971. 26 p.

11. Humphrey, S. R.; Richter, H. R.; Cope, J. B. Summer habitat and

ecology of the endangered Indiana bat, Myotis sodalis. J. Mammal. 58:

334-346; 1977.

12. Johnson, P. S. Eight-year performance of interplanted hardwoods in

southern Wisconsin oak clearcuts. Res. Pap. NC-126. St. Paul, MN:

U.S. Department of Agriculture, Forest Service, North Central Forest

Experiment Station; 1976. 9 p.

13. Kellison, R. C; Frederick, D. J.; Gardner, W. E. A guide for

regenerating and managing natural stands of southern hardwoods. Bull.

463. Raleigh, NC: North Carolina State University, Agricultural Experiment Station; 1981. 23 p.

14. Loftis, D. Pre-harvest herbicide control of undesirable vegetation in

southern Appalachian hardwoods. South. J. Applied For. 2(2): 51-54;

1978.

15. Lull, H. W.; Reinhart, K. G. increasing water yield in the Northeast by

management of forested watersheds. Res. Pap. NE-66. Upper Darby,

PA: U.S. Department of Agriculture, Forest Service, Northeastern

Forest Experiment Station; 1967. 45 p.

16. McGee, CE. Regeneration alternatives in mixed oak stands. Res. Pap.

SE-125. Asheville, NC: U.S. Department of Agriculture, Forest

Service, Southeastern Forest Experiment Station; 1975. 8 p.

17. McGee, C. E. Size and age affect white oak stump sprouting. Res. Note

SO-239. New Orleans, LA: U.S. Department of Agriculture, Forest

Service, Southern Forest Experiment Station; 1978. 2 p.

18. McGee, CE. Fire and other factors related to oak regeneration. In:

Regenerating oaks in upland hardwood forests; 1979 John S. Wright

Forestry Conference; 1979 February 22-23; West Lafayette, IN. West

Lafayette, IN: Purdue University; 1979: 75-81.

19. McGee, C E. Expanding options for reforestation of Cumberland

Plateau. South. J. Applied For. 4(4): 158-162; 1980.

20. McGee, C E. Management of low quality hardwood stands. In:

Proceedings, National silviculture workshop; 1981 June 1-5; Roanoke,

VA. Washington, DC: U.S. Department of Agriculture, Forest Service;

1981:98-107.

21. Perkins, C J. Silvicultural practice impacts on wildlife. In: Proceedings,

timber-wildlife management symposium; 1974 January 22-24; Columbia,

MO. Jefferson City, MO: Missouri Academy of Science; 1974: 43-48.

22. Roach, B. A. What is selection cutting and how do you make it

work—What is group selection and where can it be used? Misc. Rep. 5.

Syracuse, NY: State University of New York, College of Environmental

Science and Forestry, Applied Forestry Research Institute; 1974. 9 p.

23. Roach, B. A.; Gingrich, S. F. Even-aged silviculture for upland central

hardwoods. Agrie. Handb. 355. Washington, DC: U.S. Department of

Agriculture; 1968. 39 p.

24. Russell, T. E. Seeding and planting upland oaks. In: Proceedings, Oak

Symposium; 1971 August 16-20; Morgantown, WV. Upper Darby,

PA: U.S. Department of Agriculture, Forest Service, Northeastern

Forest Experiment Station; 1971: 49-54.

25. Sander, I. L. Size of oak advance reproduction: Key to growth

following harvest cutting. Res. Pap. NC-79. St. Paul, MN: U.S.

Department of Agriculture, Forest Service, North Central Forest Experiment Station; 1972. 6 p.

26. Sander, I. L. Manager's handbook for oaks in the North Central Forest

States. Gen. Tech. Rep. NC-37. St. Paul, MN: U.S. Department of

Agriculture, Forest Service, North Central Forest Experiment Station;

1977. 35 p.

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Sander, I. L. Regenerating oaks with the sheiterwood system. In:

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Lafayette, IN: Purdue University; 1979: 54-60.

Sander, I. L. Silvicultural systems for the oak-hickory forest type. In:

North America's forests: Gateway to opportunity: 1978 Joint Convention of the Society of American Foresters and the Canadian Institute of

Forestry. 1978 October 23-26; St. Louis, MO. Washington, DC:

Society of American Foresters; 1979: 344-348.

Sander, I. L.; Clark, F. B. Reproduction of upland hardwood forests in

the Central States. Agrie. Handb. 405. Washington, DC: U.S. Department of Agriculture; 1971. 25 p.

Sander, I. L.; Johnson, P. S.; Watt, R. F. A guide for evaluating the

adequacy of oak advance reproduction. Gen. Tech. Rep. NC-23. St.

Paul, MN: U.S. Department of Agriculture, Forest Service, North

Central Forest Experiment Station; 1976. 7 p.

Sander, I. L.; Merritt, C; Tryon, E. H. Oak-hickory. In: Choices in

silviculture for American forests: Washington, DC: Society of American Foresters; 1981. 23-29.

Schlesinger, R. C. Sixteen years of selection silviculture in upland

hardwood stands. Res. Pap. NC-125. St. Paul, MN: U.S. Department

of Agriculture, Forest Service, North Central Forest Experiment Station1976. 6 p.

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States. Agrie. Handb. 450. Washington, DC: U.S. Department of

Agriculture; 1974. 883 p.

34. Shaw, S. P. Wildlife and oak management. In: Proceedings, Oak

Symposium; 1971 August 16-20; Morgantown, WV. Upper Darby,

PA: U.S. Department of Agriculture, Forest Service, Northeastern

Forest Experiment Station; 1971: 84-89.

35. Smith, H. C. Diameters of clearcut opening influence central Appalachian hardwood stem development. Res. Pap. NE-476. Broomall, PA:

U.S. Department of Agriculture, Forest Service, Northeastern Forest

Experiment Station; 1981. 8 p.

36. Trimble, G. R., Jr. Twenty years of intensive uneven-aged management:

effect on growth, yields, and species composition in two hardwood

stands in West Virginia. Res. Pap. NE-154. Upper Darby, PA: U.S.

Department of Agriculture, Forest Service, Northeastern Forest Experiment Station; 1970. 12 p.

37. Trimble, G. R., Jr. The regeneration of central Appalachian hardwoods

with emphasis on the effect of site quality and harvesting practice. Res.

Pap. NE-282. Upper Darby, PA: U.S. Department of Agriculture,

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38

39,

U.S. Department of Agriculture, Forest Service. An assessment of the

forest and range land situation in the United States. FS-345. Washington,

DC: U.S. Department of Agriculture, Forest Service; 1980. 631 p.

Wendel, G. W. Stump sprout growth and quality of several Appalachian

hardwood species after clearcutting. Res. Pap. NE-329. Broomall,

PA: U.S. Department of Agriculture, Forest Service, Northeastern

Forest Experiment Station; 1975. 9 p.

120
Northern Hardwoods

Carl H. Tubbs

Northeastern Forest Experiment Station

Rodney D. Jacobs

Northeastern Area

Dick Cutler

Eastern Region

The northern hardwood association comprises a group

of forest types that vary considerably in species composition

and whose species vary in silvical characteristics by geographic area. Consequently, responses to silvicultural practices vary by region. Separate bodies of silvicultural information have developed within each broad region. Some techniques

are widely applicable while others are applicable only to

specific areas. As a result, the silvics and silviculture of the

northern hardwoods are reported separately to take regional

differences into account.

North Central Northern Hardwoods

The northern hardwood forest of the North Central area

covers about 10 million acres (4 million ha). The terrain

generally is level to rolling, with elevations from 600 to

2,000 ft (185 to 610 m). Northern hardwoods are locally

important in all of the North Central States, but the largest

concentrations are in Wisconsin, Michigan, Ohio, Indiana,

and Minnesota.

Characteristic species are sugar maple {Acer saccharum

Marsh.), yellow birch {Betula alleghaniensis Britton), American beech {Fagus grandifolia Ehrh.), American basswood

{Tilia americana L.), and eastern hemlock {Tsuga canadensis

(L.) Carr.). Sugar maple, beech, and hemlock have a high

tolerance to shade and are principal components of the

northern hardwood climax forest (7), though hemlock is

more prominent as a member of a subclimax in the north. The

common associates, yellow birch and basswood, are intermediate in light requirements. Other associated species that are

locally important include the shade-tolerant balsam fir {Abies

balsamea (L.) Mill.), the moderately tolerant American elm

{Ulmus americana L.), black ash {Fraxinus nigra Marsh.),

red maple {Acer rubrum L.), northern red oak {Quercus

rubra L.), eastern white pine (Pinus strobus L.) and white

ash {Fraxinus americana L.), and the very intolerant paper

birch {Betula papyrifera Marsh.).

Society of American Foresters forest cover types included are: sugar maple (type 27), hemlock-yellow birch

(type 24), sugar maple-beech-yellow birch (type 25),

sugar maple-basswood (type 26), beech-sugar maple (type

60), red maple (type 108), black ash-American elm-red

maple (type 39), variants of the northern red oak (type 55),

and, rarely, eastern white pine (type 21) (7).

American beech is not found west of eastern Wisconsin;

eastern hemlock is most abundant in northern Michigan,

Wisconsin, and northeastern Ohio; yellow and paper birch

are rare or absent south of the northern parts of the Lake

States; American basswood can be locally abundant anywhere,

but is most common in the west; sweet birch {Betula lenta L.)

is found only in southern Michigan and Ohio (18). Red maple

is rare in the western part of the region but increases in

importance toward the east, where it may be very abundant.

Black ash is most abundant in the north. Black maple {Acer

nigrum Michx. f.) is most abundant in the Central States.

The northern area was glaciated repeatedly but extensive

unglaciated areas are found in Ohio, Indiana, and Wisconsin.

Northern hardwoods occupy a wide range of soils. In the

North, characteristic soils are the Haplorthods (Podzols and

Brown Podzolics) and Boralfs (gray wooded soils). Udalfs

(gray-brown podzolics) are northern hardwood soils characteristic in southern regions (40). Beech-maple, maplebasswood, and the mesophytic types are most common on

gray-brown podzolics. Other northern hardwood types grow

on Podzols (59). The elms, black ash, yellow birch, red

maple, eastern hemlock, and balsam fir survive best on

high-moisture sites, while sugar maple, white ash, basswood,

and beech generally are confined to better drained soils. The

latter species are especially intolerant of flooding while red

maple is very tolerant of flooding (3). Paper birch is

especially prominent on coarse-textured soils. Red maple and

eastern hemlock often are abundant on excessively welldrained soils. Species normally confined to very wet or very

dry soils grow well on well-drained soils when competition is

absent (54).

Average annual precipitation ranges from 25 inches

(635 mm) in the west to more than 40 inches (1015 mm) in

the most southerly areas. Average annual days with snow

cover range from about 140 in the northern region to about 20

in the southern region. Temperatures may drop as low as

-50° F (-45.6° C) and exceed 100° F (37.8° C) in the

northern area (56). Daily minimum temperatures in January

are about 0.0° F (-17.8° C) in the northwest and 25° F

(-3.9° C) in the south. July daily maximum temperatures

range from about 90° F (32.2° C) in the south to 75° F (23.9°

C) in the north. Frost-free days range from 40 to 190; in the

northern areas, freezing temperatures can occur in any

growing season month.

Regeneration is most commonly from seed (56), but

most species produce stump sprouts. Sugar maple and yellow

birch produce good seed crops about every 3 years, but as

many as 4 years have elapsed without good crops (13).

Among associated hardwoods, quaking aspen and bigtooth

aspen {Populus tremuloides Michx. and P. grandidentata

Michx.) are the most reliable seed producers and black ash

the least; associated conifers, northern white-cedar {Thuja

occidentalis L.) and hemlock, are most reliable and white

pine the least. Red and sugar maple, elm, and basswood

sprout vigorously (56); basswood reproduction is almost

entirely vegetative in many areas. Sprout-origin stands of

sugar and red maple cover large areas (8). Younger paper

birch stems sprout well. Yellow birch sprouts pooriy. Seedling sprouts of any species grow desirable trees and basswood

stump sprouts are considered desirable; red maple stump

sprouts are least desirable, though sprout clumps can be

improved by thinning at an early age. It has been observed

that sprouting of some northern hardwood declines toward

the south (2). In the United States, planting is occasional

because of the relative ease in obtaining natural regeneration.

Lighter seeded species such as yellow birch and eastern

121
hemlock generally require seedbed disturbances to reduce the

physical impediments to rooting, provide the seed and young

seedlings with proper moisture and germination temperatures,

and reduce competition from advanced growth. Sugar maple

and beech all establish themselves on undisturbed litter.

Requirements for establishing basswood and white ash seedlings are unknown. Drought, extreme temperatures, and

competition from other plants are common factors that affect

seedling mortality. Heavy shade adversely affects the less

tolerant species.

The long-lived, tolerant sugar maple, American beech,

and eastern hemlock can respond to release after long periods

of suppression. The short-lived, tolerant balsam fir, red

maple, and yellow birch respond well to release only after

relatively short periods of suppression. Average annual

diameter growth of sugar maple and yellow birch more than 6

inches (15 cm) d.b.h. in managed all-aged stands ranges

from about 0.21 inch (0.5 cm) in stands of low residual

basal area densities to 0.14 inch (0.4 cm) in stands of high

density (4). Maximum rates range between 0.35 to 0.40

inch (0.9 to 1.0 cm) per year over 20 years. In even-aged

stands, the diameter growth of heavily thinned yellow birch

saplings can average 0.36 inch (0.9 cm) per year; poles

grow 0.26 inch (0.7 cm) per year, and sawlogs equal 0.16

inch (0.4 cm) per year (5). American elm, white ash, and

basswood have the highest potential diameter growth rates.

Gross basal area production of managed selection stands is

usually between 2.0 and 2.5 square feet per acre (0.5 and 0.6

m^/ha) per year, but it is possible to sustain 3 square feet per

acre (0.7 m^/ha) per year. Gross cubic-foot volume growth

ranges from 65 to 75 cubic feet per acre (4.6 to 5.3 m^/ha) per

year in mature stands, and from 102 to 123 cubic feet per acre

(7.1 to 8.6 m^/ha) per year in young stands (6). Maximum

growth is about 300 board feet (fbm) (International '/4-inch) or

60 cubic feet per acre' (4.2 m'^/ha) in all-age stands. Cutting

cycles typically range from 5 to 15 years. Longer cycles

typically are used in conjunction with low residual stocking in

lowlands or areas of difficult accessibility.

Financial maturity objectives in managed stands are

about 19 inches (48.3 cm) d.b.h. but vary with grade,

growth, and interest rate (14). Larger diameter trees are

commonly grown to fulfill multiple-use management objectives,

to maintain recommended stand density levels in stands

undergoing rehabilitation, or to fulfill industrial requirements.

Long-term yields from managed all-aged stands have

averaged 250 fbm (50 cubic feet) per acre (3.5 m^/ha) per

year plus about 45 cubic feet (0.5 cord or 3.2 m^) of chemical

wood (6, 14). Published normal yields are variable perhaps

because of variations in species composition, and difficulty

in aging stands of tolerant trees and determining site index

accurately. Total volume from normal stands at 80 years on

medium sites range from 2,970 to 3,600 cubic feet (33 to 40

cords) per acre (208 to 252 m^/ha). Yields from managed

even-aged stands are not available.

Quality yield is as important as volume yields and is the

top priority silvicultural goal in managing stands for timber

production. For example, grade 1 trees were 20 times more

valuable than grade 3 trees (41). Initial partial cuts of

previously unmanaged stands, whether old growth or cutover,

typically produce only 20 to 30 percent of the harvested

volume in high-quality sawlogs (23, 55). Improvement cuts,

skillfully done, improve the value of yields dramatically;

after several partial cuts, it is possible to both increase the

' Cubic foot and metric conversions of measurements expressed in board

feet should be viewed as estimates because of the assumptions involved in

the conversion process.

yield of grade 2 and better logs to 85 percent and maintain a

residual stand of equally high quality (55). The investment

yields of well-managed stands have compared favorably with

leading standards of investment (45).

Pruning is a biologically acceptable way of increasing

quality yields, but this practice should be preceded by careful

cost-return analysis.

Few insects and diseases cause catastrophic mortality in

the northern hardwood type. The exceptions include the

widely spread Dutch elm disease {Ceratocystis ulmi (Buism.)

C. Mor.) and the locally important crown diebacks and

declines. Many kinds of defoliating insects attack northern

hardwood species, though defoliation alone seldom causes

mortality. Suggested strategies for reducing the incidence of

diebacks and declines include encouraging species diversity,

maintaining vigorous trees through stand improvement measures'

and cutting trees before they are overmature (21). A number

of insects and diseases, as well as logging injuries, cause

degrade, discoloration, and decay; affected trees should be

removed in improvement and harvest cuts. Trees with Nectria

canker {Nectria galligena Bres.) and maple canker (Eutypella

parasítica Davids. & Lorenz) in particular should be removed before shelterwood seeding cuts (11). Bud-mining

insects cause serious forking of sugar maple in even-aged

stands not maintained at high-density levels during the

sapling and pole growth stages (11).

The northern hardwood types can support relatively high

populations of deer without serious injury; damage will be

minimal if management practices favor dense reproduction

and vigorous shoot growth (22). Damage from feeding by the

yellow-bellied sapsucker can be serious, especially to yellow

birch, in open stands, but such damage is minimal in mixed

stands maintained at recommended density levels (11).

Sugar maple forest types usually are found on welldrained, upland loamy soils. The major type associations

include sugar maple, sugar maple-beech-yellow birch,

beech-sugar maple, and sugar maple-basswood. Sugar

maple is the characteristic tree throughout.

Advanced regeneration on moist sites is composed of

shade-tolerant, long-lived species, most commonly sugar

maple. Good seed crops occur frequently enough to reseed

selection forests, though poor crops are common (13) and

contribute to variations in regeneration success under evenage practices (42).

In the upland sugar maple types, forest owners can

choose from among several silvicultural systems depending

on their management objectives.

All-aged management by individual-tree selection is

well suited for continuous production of high-quality veneer

and sawlogs. Although shade-tolerant species predominate,

other species are produced; their abundance depends primarily on variations in soil characteristics. Advance reproduction

of desirable shade-tolerant species is almost always present.

Periodic cuttings develop a distribution of size classes and

concentrate growth on the more desirable trees with long

clear boles (4, 6). Residual density ranges from 50 to 90

square feet per acre ( 11.5 to 20.7 m^/ha) depending on average

tree diameter and owner objectives.

Even-aged silviculture is necessary to maximize the

number of light-demanding species such as yellow birch (60)

or less aggressive tolerant species such as eastern hemlock.

Shelterwood cuttings provide the greatest flexibility and

consistency in establishing even-aged stands. The amount

and composition of residual overstory can be varied to meet

species requirements for establishment and early growth

while reducing the danger of losing the site to herbaceous

vegetation. Control of advance regeneration and scarification

before logging encourages the establishment of light-seeded

122
species; without such understory treatment, tolerant species

will continue to dominate the new stands. Normally, only

one cutting is required in upland stands of seed-bearing age to

assure adequate establishment. The remaining overstory can

be removed in stages to develop regeneration slowly, or in a

single cut after suitable regeneration is fully established (15).

Size of seedlings is the most important criterion for gauging

establishment. Suitable size varies by species and locality

(58). . ^ ^

Alternate clear-strip cutting has shown potential, but

results have been unpredictable. Better results with this

method have been obtained when plentiful, vigorous advance

reproduction was present, or during good seed years when

competition was eliminated (42). Large-area (0.5 acre or 0.2

ha and larger) clearcutting without advance reproduction

should be avoided. These cuttings, as well as the unsuccessful alternate clear-strip cuttings, have resulted in patchy

communities of trees, grassy openings, and shrub-dominated

areas that persist for several decades (43).

Guidelines for even-aged management include: precommercial thinnings to ensure the survival and growth of yellow

birch, elimination of defective overstory trees, and periodic

thinning whose residual stocking varies substantially by

species composition (57).

Conversion of northern hardwoods to pine on upland

sites by clearcutting and planting results in substantial increase in volume. Economic returns are likely to be greatest

on sites with a low site index for sugar maple that are

occupied by stands of low actual or potential quality (52).

Planting must be followed by repeated weeding and cleaning

to ensure the survival of pine.

The major northern hardwood associations on poorly

drained sites are hemlock, hemlock-yellow birch, or black

ash-American elm-red maple and variants of the red maple

type. These are mostly long-lived subclimax types (2). The

ash-elm-red maple type is an edaphic climax on the wettest

areas. The types commonly grade into each other and into

variations of the maple and conifer types. Sugar maple

usually is present on all but the wettest sites. Logging and fire

on these sites have resulted in a variety of secondary

successions in which almost any species common to the

region may be dominant.

On the most poorly drained sites, it is difficult to

regenerate species other than black ash, American elm, or red

maple. To regenerate yellow birch and hemlock, the desired

species on the somewhat poorly drained sites, scarification or

burning is needed to create suitable seedbeds, undesirable

advance reproduction must be eliminated, and adequate seed

must be available.

Regeneration methods suitable on these sites include

individual-tree and group selection, shelterwood cutting, and

alternate clear-strip cuttings. Selection will favor tolerant

hardwoods but all species present in the overstory usually

will be represented in the reproduction (56). With unevenaged methods, because of the danger of windthrow and

postlogging decadence, the first cutting in previously unmanaged

stands should leave relatively high stocking levels (57). After

5 years, a second cut should be made to reduce the stands—

trees 10 inches (25.4 cm) or more in d.b.h.—to 70 feet^ of

basal area per acre (16.1 m^/ha); succeeding cuts also should

be to this stocking level. When heavy cuts are necessary,

cutting should not be less than 50 feet^ (11.5 m^) of basal area

since lower residual stands result in reduced sawtimber

volume growth and poor quality development of the remaining stems (10).

Group selection is possible in the hemlock types and can

be used with site preparation to favor regeneration of yellow

birch (8). However, the method creates management problems.

It is unwieldy for large tracts; it does not stimulate growth of

trees in the areas between groups; and the quality of border

trees may be reduced around larger openings. Some of these

disadvantages can be overcome when group cuttings are

combined with thinning in the adjacent areas (57).

The proportion of yellow birch and hemlock can be

increased by shelterwood treatments that include removing

advance reproduction or scarification before the seed cut

(60). Without site preparation, shelterwood cuttings generally favor those more tolerant species which establish themselves easily on forest duff. Choice of overstory density and

number of preparatory cuts depends on the abundance of the

regeneration, stand age and vigor, soil depth, and on other

factors related to wind firmness and postlogging mortality.

Generally, the first cut should leave around 80 percent crown

cover.

Large-area (0.5 acre or 0.2 ha and larger) clearcutting

to produce regeneration should be avoided. Regeneration is

unpredictable on such sites in the Lake States. Because

successful alternate clear-strip cutting requires both the

elimination of competition and the presence of plentiful

established, advanced regeneration (42), this method is

essentially a shelterwood strip. When these requirements are

not met, grass-shrub-herbaceous communities can develop

and persist for several decades before they are replaced by

desirable tree species (43). Clearcutting without advance

regeneration when appreciable numbers of red maple and

American elm are present usually results in undesirable

fast-growing sprouts which suppress seedling stems (12).

When swamp conifers are prevalent, regeneration can be

accomplished by alternate clear-strip cuttings of one or two

tree heights in width (57). Swamp conifers are mixtures of

white spruce (Picea glauca (Moench) Voss), black spruce

(Picea mañana (Mill.) B.S.P.), white cedar, balsam fir, and

eastern hemlock.

In abused stands of any species, timber stand improvement practices generally should remove undesirable trees in

several cuttings to develop residual stands with stocking

levels similar to those recommended for mature stands (57).

Where the major portion of the stand is defective or undesirable,

shelterwood treatments can be used for regeneration as soon

as desirable species reach seed-producing age.

Each of the stages of forest growth is associated with a

different group of animals and birds. Even-aged and all-aged

management tend to create habitats for separate groups of

animal species or different visual characteristics, but methods

can be modified to meet a variety of nontimber objectives.

Where demands for recreation and esthetic considerations

require a continuous cover of sizeable trees, the selection

system is preferred. All of the even-aged systems can be used

to enhance the habitat for forest-edge game and nongame

species. The shelterwood method is especially good for

browse production and offers the best opportunity for establishing hemlock, an important cover species for deer and

other wildlife in the northern Lake States. The clearcutting

system produces a greater variety of plant species. The

long-lived, brush-grass-herbaceous communities that result

from clearcutting without established tree regeneration provide excellent summer wildlife habitat (61). Unless precautions are taken, reproduction cuts by even-aged methods may

have negative impacts on visual quality, particulariy during

the 3 to 5 years that logging slash is visible.

Northeastern Northern Hardwoods

The northern hardwood forest in the northeastern United

States, covering neariy 15 million acres (6 million ha), is

characterized by sugar maple, American beech, and yellow

123
birch. These species are found in various combinations in the

following Society of American Foresters cover types: sugar

maple (type 27), sugar maple-beech-yellow birch (type

25), beech-sugar maple (type 60), and red spruce-sugar

maple-beech (type 31). On well-drained soils of moderate

texture, successional types such as red maple (type 108),

gray birch-red maple (type 19), and eastern white pine (type

21) include varying amounts of key northern hardwood

species depending on the stage of development (7). Other

common associations are beech-red maple and hemlockbeech. Concentrations of northern hardwoods are found in

northeastern and central Maine, Vermont and central New

Hampshire, New York, northern Pennsylvania, and western

Massachusetts. In scattered areas in southern New England

and New York, northern hardwood species blend with oak

and mesophytic types. Types similar to those mentioned are

found from Wisconsin to northern Virginia but do not

necessarily react similarly to silvicultural treatment (59).

In the Northeast, beech, yellow birch, and sugar maple

dominate older stands, while younger, even-aged stands

commonly contain paper birch, white ash, red maple, and

other hardwoods such as aspen, red oak, and sweet birch.

Conifers such as eastern hemlock, white pine, balsam fir, and

red spruce {Picea rubens Sarg.) grow with the hardwoods,

especially on excessively dry, wet, or shallow soils (26) on

cool steep slopes, and on poorly drained soils at lower

elevations. Repeated cuttings, wildfire, and past land use

have created numerous combinations of stand conditions, age

classes, and species. Yellow birch, sugar maple, paper birch,

and white ash are the most desirable hardwoods for timber

production; all species contribute to pleasant fall color.

Total average annual precipitation ranges from 40 to 50

inches (1015 to 1270 mm) in northern hardwood areas; as

much as 25 percent of this precipitation occurs as snow.

Average annual days with snow cover range from 60 to 140.

Average maximum temperatures range from 74° F (23.3° C)

to 84° F (28.9° C). January maximums range from 24° F

(-4.4° C) to 36° F (2.2° C). Frost-free days range from 120

to 150 and mean annual water surplus is 10 to 34 inches (255

to 865 mm) where northern hardwoods are prevalent (35).

Hurricane force winds occur sporadically; glaze or wet snow

damage is common over wide areas, especially at high

elevations.

Species composition of stands depends on stand age,

site characteristics, geographical region, and past land use.

Northern hardwood sites are found at elevations up to 2,500

feet (760 m) (31) on land that is rolling to mountainous. The

hardwoods generally occupy a zone between white pine and

spruce types in the river valleys and the spruce-fir type.

Hardwoods grow in a wide range of soils, the most productive of which are fine- to medium-textured tills or organically

enriched areas (25).

All important commercial species characteristically reproduce from seed, and some also reproduce by vegetative

means. Yellow and paper birches seed prolifically, producing

reasonably good crops every other fall. White ash, sugar

maple, and beech produce good crops at intervals as long as 5

years. Red maple produces abundant seed nearly every

spring. Red maple sprouts prolifically from stumps of poletimber

and small sawtimber. Sugar maple, beech, and birches sprout

reasonably well from stumps of small (sapling or small

pole-size) trees. Beech sprouts on larger stumps generally are

short lived. Beech root suckers prolifically, especially following cutting. Striped maple also sprouts prolifically. Brambles

{Rubus spp.) and pin cherry {Prunus pensylvanica L. f.)

reproduce from seed buried in the upper soil horizon for as

long as 100 years, though numbers decline sharply after 40

years (17).

Planting has been confined largely to paper birch and

conifers such as white spruce, red pine, and white pine.

Experience in other regions suggests that white ash and

basswood may be plantable on a large scale. Current trials

with sugar maple have been successful where seedlings have

been protected from animal damage.

Species in the type differ in shade tolerance, longevity,

and growth rate. Yellow birch is intermediate in tolerance

and growth rate. White ash and red maple also are intermediate in shade tolerance and have moderately fast growth rates.

Paper birch is one of the fastest growing commercial species,

but the typical variety is short lived and very intolerant.

Sugar maple, beech, hemlock, and red spruce are shade

tolerant, long-lived species. Sugar maple, beech, and red

spruce have moderately slow growth rates while hemlock

grows rapidly in diameter, though not in height (36, 49, 59).

Tolerant small trees and shrubs such as striped maple {Acer

pensylvanicum L.), eastern hophombeam {Ostrya virginiana

(Mill.) K. Koch), and hobblebush {Viburnum alnifolium

Marsh.) affect silvicultural procedures. Pin cherry, a very

shade-intolerant small tree, can be a serious competitor in

clearcuts.

The highly shade-tolerant beech and sugar maple are the

most common tree species in the understories of northern

hardwood stands on well-drained sites. Red spruce and

hemlock are more commonly found on wet or excessively

well-drained sites. These species and the other long-lived

tolerant species, when established, can respond to release

after long periods of suppression. Tolerant shrubs and small

trees also respond well to release. Yellow birch and paper

birches need overhead light and seedbeds of moist humus or

mineral soil for optimum eariy establishment and development (38). Paper and yellow birch must become dominant

eariy in life to survive to maturity. The capacity of the

birches and other less than tolerant species to respond to

release after suppression is moderate to poor.

On average northern hardwood sites, mean annual

growth in cubic and board feet culminates at about age 50 and

160, respectively, in even-aged stands (32). In managed

stands, culmination of total board-foot production is expected

at age 100 to 120. At maturity, fully stocked northern

hardwoods commonly support gross volumes of 2,500 to

3,500 feet^ per acre (175 to 245 m^/ha) and 8,000 to 17,000

fbm per acre (112 to 238 m^/ha) depending on site and

species mix (27). Intermediate yields from managed stands

vary greatly depending on the intensity of management and

markets, but there is some evidence that as an upper limit,

long-term total yields from managed stands can be twice that

from no management (28). In managed, uneven-aged stands,

quality yields have declined due to beech bark disease

{Cryptococcus fagisuga (Lindinger) and Nectria coccínea

Pers. ex Fr. war.faginata Loh., Wats, & Ay.) (9).

Appropriate residual stocking in even-aged stands ranges

from about 55 to 95 square feet of basal area per acre (12.6 to

21.8 m^/ha) as mean stand diameter increases from 5 to 18

inches (13 to 46 cm). In uneven-aged stands managed by

either group or individual-tree selection, residual basal areas

in trees 5 inches (13 cm) or more in d.b.h. should be a

minimum of 60 to 70 square feet per acre (13.8 to 16.1

m^/ha) with a minimum of 30 square feet (6.9 m^) in

acceptable sawtimber (30). Cutting cycles typically are 15 to

20 years.

Northern hardwoods in this region have several natural

enemies that influence the application of silvicultural treatments.

Beech bark disease is a lethal disease of beech (46). Harvesting beech before it attains a diameter of 18 inches (46 cm)

will reduce losses from beech bark disease (9). Group

selection or clearcutting of mature beech promotes other

124
desirable species and is an effective way to reduce losses.

Birch dieback has caused heavy mortality in both birch

species; and even when the disease has subsided, a recurrence is possible. Postlogging decadence often develops in

birches and eastern hemlock exposed by heavy partial cutting.

Cankers caused by sugar maple borer {Glycohius speciosus

(Say.)) (48) increase the susceptibility of maple to wind

breakage. Lumber grades of all hardwoods are lowered by

discoloration and decay organisms which enter through

branch stubs and logging wounds (47). Birch is killed by

severe defoliation by the saddled prominent (Heterocampa

guttivitta (Walker)) (50).

Choice of silvicultural systems and intensity of management in the northern hardwood types of the Northeast is

influenced by species composition, habitat, site productivity,

animal damage, local markets, and management objectives.

Individual tree selection favors sugar maple on enriched

habitats in New England (26) and better maple-ash sites

throughout the Northeast. In New England, individual tree

selection favors beech on coarser, less fertile soils, and

tolerant conifers on moist or excessively well-drained sites.

Group selection favors the less tolerant species whose proportions depend on the size of the opening. This technique can

be used in conjunction with single-tree selection to increase

the diversity of tree species (29), to reduce undesirable

species such as beech and striped maple, or to salvage

overmature and defective stems. Low residual basal areas

favor sugar maple reproduction over beech or red maple on

some sites (1, 26). Low stocking may result in reduced

quality in residual maple stems due to increased branchiness

Shelterwoods have been used to produce even-aged

stands of hardwoods. The final removal of shelterwood

overstories simply releases established natural regeneration,

so it is necessary to consider treatment of preexisting

understories to ensure that desirable species are represented

in the next stand, and to control stand density or crown cover

during the earlier cuts. In the Adirondacks, a two-cut system

is used to favor yellow birch and sugar maple. The removal

of beech understories and control of deer populations are

necessary (24). Farther east, paper birch becomes a more

important component of the new stand if shelterwood overstories

are adjusted to provide good growing conditions for this

intolerant species. Although both yellow and paper birch

regeneration are encouraged by scarification or logging

disturbance (37, 38), scarification or summer logging may

not be necessary on moist sites, or if competition from

understory vegetation is minimal (60). Mortality of released

regeneration is reduced when the final removal is done in the

winter. In New York and southern New England, shelterwoods

produce rich mixtures of hardwoods, including black cherry

{Prunus serótina Ehrh. var. serótina), oaks, white ash,

yellow-poplar (Liriodendron tulipifera L.), and butternut

(Juglans cinérea L.) (34). Three-cut shelterwoods have been

reported (60) and can be used to develop advanced regeneration of tolerant species where they are absent, to control

browse production, or to provide for certain elements of

scenic vistas.

Clearcutting by patch, strip, or block enhances chances

for intolerant and moderately tolerant species in the next

stand and suppresses undesirable tolerant trees and shrubs.

The size of the clearcut often influences the relative proportion of tolerant and intolerant species. Greater exposure in

larger areas favors intolérants; the reverse is true for tolerant

species (33). Summer logging and clearcutting areas larger

than two tree heights reduce striped maple; this species

endures suppression for about 30 years (19, 20) and responds

quickly to release when openings are small. Clearcutting can

be followed by scarification to ensure suitable seedbeds and

to reduce competition on sites which are dry or occupied by

unwanted species. Clearcutting of stands before seed-bearing

age results in sprouts, shrubs, and herbaceous growth (44).

Large block clearcuttings (more than 5 acres (2.0 ha))

result in conditions suitable for the establishment of roughly

equal numbers of intolerant and tolerant tree species, though

individual areas may vary considerably. Patch cutting up to

0.75 acre (0.3 ha) encourages the more intolerant species but

may be unwieldly to manage. Cutting strips 50 to 100 feet

(15.2 to 30.5 m) wide usually increases the number of

species intermediate in tolerance, such as yellow birch and

white ash, while reducing the number of intolerant species

(32). Other things being equal, the proportion of species

resulting from each of the silvicultural systems varies by

soil-site (26) and geographic area. For example, in New

England, white ash may be the predominant intermediate

after alternate clear-strip cutting on enriched habitats while

yellow birch replaces ash after clear-strip cutting on other

habitats. The aggressiveness of paper birch in clearcuts

diminishes from east to west so that the clearcutting of large

blocks toward the west may result in few, if any, paper birch.

Precommercial stand tending may be necessary to preserve an acceptable species composition in young even-aged

stands. Most desirable species compete pooriy with fastgrowing weed species such as pin cherry, red maple sprouts,

or advanced growth of any species. Early tending is essential

for the survival of birch. Thinnings and timber stand improvement in intermediate size classes maintain individual tree

growth rates, reduce cull, harvest mortality, and upgrade the

quality of even-aged stands (62). Commercial thinnings are

especially important in stands of both long- and short-lived

species. Partial cutting in uneven-aged stands have the same

objectives but the focus usually is on the larger size classes of

the more tolerant species.

Northern hardwoods are found on steep slopes and on

the finer textured or compacted soils which are erodable; they

also border streams and lakes, and harbor various animal life.

On steep slopes, partial cutting along streams has minimal

adverse impact upon water quality. Clearcutting may temporarily change streamwater and nutrient cycling patterns.

When clearcutting is indicated, progressive strip clearcutting

with a buffer strip produces the least change (39). Logging

roads are planned to prevent erosion during and after logging,

and the use of water bars is effective in reducing erosion (32,

53).

Recreation-area silviculture may include long rotations,

higher residual stand basal areas, and stand structures which

favor large trees. Frequent salvage, or short cutting cycles, or

both, are needed to reduce losses from mortality and defect,

which increase with length of the cutting cycle, rotation,

maximum tree size, and stocking level. Rotations of several

hundred years are possible with the tolerant long-lived

species if growth loss from decay and mortality are acceptable or if frequent salvage is possible.

Generally, clearcutting creates abundant and varied

browse for short periods (51). Shelterwoods provide as much

browse as clearcutting, but species variety declines. Individual tree selection produces the least browse per acre. Group

selection and patch cutting concentrate browse on small

areas. On lower slopes, partial cutting at intervals shorter

than 15 years promotes hobblebush, a food source for

wintering deer (16).

Literature Cited

1. Barrett, John W.; Famsworth, C. Eugene; Rutherford, WiUiam, Jr.

Logging effects on regeneration and certain aspects of microcHmate in

northern hardwoods. J. For. 60(9): 630-639; 1962.

125
2. Braun, E. Lucy. Deciduous forests of eastern North America. New

York: Hafner; 1964. 596 p.

3. Broadfoot, W. M.; Williston, H. L. Flooding effects on southern

forests. J. For. 71(9): 584-587; 1973.

4. Crow, Thomas R.; Tubbs, Carl H.; Jacobs, Rodney D.; Oberg, Robert

R. Stocking and structure for maximum growth in sugar maple selection

stands. Res. Pap. NC-199. St. Paul, MN: U.S. Department of

Agriculture, Forest Service, North Central Forest Experiment Station1981. 16 p.

5. Erdmann, Gayne G.; Godman, Richard M. Tending young northern

stands. In: Proceedings, National Silvicultural Workshop; 1981 June

1-5; Roanoke, VA. Washington, DC: U.S. Department of Agriculture,

Forest Service; 1981: 124-150.

6. Erdmann, Gayne, G.; Oberg, Robert R. Fifteen-year results from six

cutting methods in second-growth northern hardwoods. Res. Pap.

NC-100. St. Paul, MN: U.S. Department of Agriculture, Forest

Service, North Central Forest Experiment Station; 1973. 12 p.

7. Eyre, F. H., ed. Forest cover types of the United States and Canada.

Washington, DC: Society of American Foresters; 1980. 148 p.

8. Eyre, F. H.; Zillgitt, W. M. Partial cuttings in northern hardwoods of

the Lake States: twenty-year experimental results. Tech. Bull. 1076.

Washington, DC: U.S. Department of Agriculture; 1953. 124 p.

9. Filip, Stanley M. Impact of beech bark disease on the uneven-age

management of a northern hardwood forest. Gen. Tech Rep. NE-45.

Broomall, PA: U.S. Department of Agriculture, Forest Service, Northeastern Forest Experiment Station: 1978. 7 p.

10. Godman, R. M.; Books, David J. Influence of stand density on stem

quality in pole-size northern hardwoods. Res. Pap. NC-54. St. Paul,

MN: U.S. Department of Agriculture, Forest Service, North Central

Forest Experiment Station; 1971. 7 p.

11. Godman, R. M.; Erdmann, G. G. Production of quality hardwoods. In:

Proceedings, National Silvicultural Workshop; 1981 June 1 -5; Roanoke,

VA. Washington, DC: U.S. Department of Agriculture, Forest Service'

1981: 151-162.

12. Godman, R. M.; Krefting, Laurtis W. Factors important to yellow birch

establishment in upper Michigan. Ecology 41: 18-28; 1960.

13. Godman, Richard M.; Mattson, Gilbert A. Seed crops and regeneration

problems of 19 species in northeastern Wisconsin. Res. Pap. NC- 123.

St. Paul, MN: U. S. Department of Agriculture, Forest Service, North

Central Forest Experiment Station; 1976. 5 p.

14. Godman, Richard M.; Mendel, Joseph J. Economic values for growth

and grade changes of sugar maple in the Lake States. Res. Pap.

NC-155. St. Paul, MN: U.S. Department of Agriculture, Forest

Service, North Central Forest Experiment Station; 1978. 16 p.

15. Godman, Richard M.; Tubbs, Carl H. Establishing even-age northern

hardwood regeneration by the shelterwood method—a preliminary

guide. Res. Pap. NC-99. St. Paul, MN: U.S. Department of Agriculture,

Forest Service, North Central Forest Experiment Station; 1973. 9 p.

16. Gould, Walter P. The ecology of Viburnum alnifolium Marsh. Syracuse,

NY: State Univ. of New York, College of Forestry: 1966. 246 p.

Thesis.

17. Graber, R. E.; Thompson, D. F. Seeds in the organic layers and soil of

four beech-birch-maple stands. Res. Pap. NE-401. Broomall, PA:

U.S. Department of Agriculture, Forest Service, Northeastern Forest

Experiment Station; 1978. 8 p.

18. Hariow, William M.; Harrar, Ellwood S. Textbook of dendrology

covering the important forest trees of the United States and Canada.

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forest, 1929-1976. J. For. 75(1): 22-24; 1977.

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northern Great Lakes Region. Res. Pap. NC-150. St. Paul, MN: U.S.

Department of Agriculture, Forest Service, North Central Forest Experiment Station; 1977. 20 p.

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North Central States. Gen. Tech. Rep. NC-39. St. Paul, MN: U.S.

Department of Agriculture, Forest Service, North Central Forest Experiment Station; 1977. 29 p.

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types of the northern Appalachian highlands of Northeastern United

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Society of American Foresters; 1979: 329-333.

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under shelterwood cutting. For. Chron. 45: 333-337; 1969.

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127
Eastern Spruce -Fir

Barton M. Blum

Northeastern Forest Experiment Station

John W. Benzie

North Central Forest Experiment Station

Edward Merski

Eastern Region

The eastern spruce-fir forest cover type is one in which

red spruce {Picea mbens Sarg.), white spruce {Picea glauca

(Moench) Voss), and balsam fir {Abies balsamea (L.) Mill.)

individually or collectively make up a plurality of the

stocking. It includes a number of forest cover types recognized by the Society of American Foresters (3). These

include paper birch-red spruce-balsam fir (type 35), red

spruce-balsam fir (type 33), red spruce (type 32), red

spruce-yellow birch (type 30), and red spruce-sugar

maple-beech (type 31). Also included are white spruce

(type 107), and sometimes balsam fir (type 5) when the

objective is to favor spruce. A common managerial objective

is to favor spruce and increase its proportion in the mixtures.

If the objective is to favor balsam fir, then the appropriate

guides are found in the discussion of the balsam fir type.

Throughout most of the spruce-fir type, forest site

characteristics are a result of past glacial action. Unsorted

drift and till are the better forest sites; they are composed of

heterogeneous material deposited on the midslopes of hills

and higher mountains. The coarser, water-transported, sorted,

and often stratified drifts found in kames, eskers, outwash

plains, and glacial lake shores and bottoms are usually the

poorer sites (1). Spruce-fir forests occupy the shallow soils

of these poorer sites on the steeper mountain slopes and also

on the flats. On the better sites and deeper soils on the lower

slopes, hardwoods grow in various mixtures with the conifers

(1,9, 11).

The eastern spruce-fir type occurs primarily in the

northern portions of Maine, New Hampshire, Vermont, New

York, Michigan, Wisconsin, and Minnesota. There are about

12.3 million acres (5.0 million ha.) of commercial spruce-fir

forests in these States, including 7.2 million acres (2.9

million ha) of balsam fir. The red spruce type occurs

primarily in New England and New York but is also found at

higher elevations in the mountains as far south as Tennessee

and North Carolina. The white spruce type occurs in New

England, New York, and the Lake States but does not extend

southward. In the Lake States it is found mostly in plantations.

Balsam fir is the most widespread type and grows at higher

elevations in Virginia and West Virginia, but to the south it is

replaced by Fraser fir {Abies fraseri (Pursh) Poir.).

The soils where red spruce, white spruce, and balsam fir

grow are mostly acid Spodosols, Inceptisols, Alfisols, and

sometimes Histosols with a thick mor humus and a welldefined A2 horizon—characteristics commonly associated

with abundant rainfall and conifer forests (1,5,9). Commonly,

these soils range in pH from 4.0 to 5.5. Spruce-fir is often

found on shallow till soils with an average depth to a compact

layer of 18 inches (45.7 cm).

The climate is cool and moist, with long, cold winters.

Annual precipitation is well distributed, amounting to 24 to

52 inches (610 to 1320 mm); annual snowfall is 48 to 160

inches (1220 to 4065 mm); days with snow cover are 100 to

140; daily maximum January temperatures average 15° to 30°

F (-9.4° to -1. r C); daily minimum January temperatures

average -5° to 20° F (-20.5° to -6.6° C); and frost free

days are between 90 and 150.

Associated species include northern white-cedar {Thuja

occidentalis L.), eastern hemlock {Tsuga canadensis (L.)

Carr.), eastern white pine {Pinus strobus L.), black spruce

{Picea mariana (Mill.) B.S.P.), tamarack {Larix laricinia

(Du Roi) K. Koch), red maple {Acer rubrum L.), paper birch

{Betulapapyrifera Marsh.), aspen {Populus spp.), ash {Fraxinus

spp.), American Beech {Fagus grandifolia Ehrh.), sugar

maple {Acer saccharum Marsh.), yellow birch {Betula

alleghaniensis Britton), and basswood {Tilia americana L.).

Depending on successional stage and site conditions, various

combinations of the associated hardwoods and softwoods

may be found within the spruce-fir type (3).

Spruce-fir stands in New England are regenerated

primarily by natural seeding (5). In recent years, however,

container-grown seedlings have been planted to increase the

proportion of spruce in new stands. Many acres of abandoned

farm land were also planted with bareroot spruce seedlings in

past years. In the Lake States the white spruce type is

dependent on planting.

Good seed crops occur about every 4 to 8 years for red

spruce, 2 to 6 years for white spruce, and 2 to 4 years for

balsam fir (4). Seed is disseminated primarily by wind and

gravity, over relatively short distances. Seed production

begins at about age 30 for the spruces and balsam fir although

instances of earlier production have been noted (4, 9).

Cones of all three species ripen early in the fall of the

same year that flowering occurs. Most seed is dispersed in

the fall and germinates in late May to early July the next

spring (4). Little viable seed remains in the forest floor

beyond 1 year (5).

Germination will take place on almost any seedbed

except sod and duff more than 3 inches (7.6 cm) thick, but

mineral soil is probably the best, followed by rotten wood

and shallow duff (4, 9).

Initial establishment of the spruces and balsam fir is best

under a high canopy that admits up to 15 percent of full

sunlight. However, as the seedling develops, it needs at least

50 percent of full sunlight for optimum growth. The faster

growing, somewhat deeper root system of balsam fir seedlings gives them a competitive advantage over the spruces

Temperatures of 68° to 86° F (20.0 to 30.0° C) are

favorable for the germination of red spruce and probably also

for white spruce and balsam fir. Soil surface temperatures

higher than 115° F (46.1° C) will cause heavy mortality if

seedhngs are exposed for even a short period. Drought, frost

heaving, and crushing by hardwood litter and snow cause

heavy losses, especially during the first year (4, 5, 9).

Balsam fir, red spruce, and white spruce are all tolerant

or very tolerant to low light conditions (4). Advance spruce-fir

reproduction will persist under an overstory and responds

readily to increasing light intensities as the overstory is

removed (9). Where advance growth is well established and

128
of sufficient size, satisfactory new stands will usually develop when the mature overstory is removed, unless fire

occurs.

Management practices that salvage trees that die naturally and increase the percentage of red and white spruce in

the stand will greatly influence net growth (5). The mean

annual growth in spruce-fir stands (66 percent or more

softwood species) receiving a minimal silvicultural input is

about 50 cubic feet per acre (3.5 m^/ha.) (10). Well-managed

stands on productive sites can produce nearly twice as much

merchantable wood as unmanaged stands over the course of a

rotation, primarily because trees that die are salvaged (5).

Site index is difficult to measure in spruce-fir stands

because tolerant species often survive for years in a suppressed state. However, it has been shown to be as good a

measure of productivity as any of several growth functions.

Site index curves are available for even-aged spruce-fir

stands in northern Maine and the Lake States. Recently,

polymorphic site index curves have been developed for

spruce-fir stands in northern Maine (8).

In New England, spruce-fir sites may be grouped into

primary softwood sites and secondary softwood sites, classifications that are meaningful in terms of potenfial growth, stand

composition, and ease of regenerating softwoods. Priniary

sites include spruce swamp, upper spruce slope, old field

spruce, spruce flat and balsam fir flat, and lower spruce

slopes. Usually drainage is impeded in these sites, and they

are occupied mostly by softwoods. Secondary softwood sites

occur on the better drained parts of intermediate topographic

positions. Hardwoods can successfully compete with the

softwoods on these sites (5).

Red and white spruce and balsam fir are subject to

damage from a number of insects and diseases. The greatest

impact on the type is from the spruce budworm {Choristoneura

fumiferana (Clemens)) which defoliates and eventually kills

great amounts of timber in periodic outbreaks. In spite of its

name, its preferred host is balsam fir, which bears the brunt

of each epidemic in growth loss and mortality. Another insect

that causes serious mortality of balsam fir is the balsam

woolly adelgid (Adelges piceae (Ratzeburg)) (5, 9). In parts

of the Lake States, severe damage from the yellowheaded

spruce sawfly (Pikonema alaskensis (Rohwer)) can occur in

white spruce plantations.

Two important diseases of spruce are red ring rot

{Phellinus pini (Thore ex Fr.) A. Ames) and red brown butt

rot (Phaeolus schweinitzii (Fr.) Pat.), both usually confined

to overmature or damaged trees. Red heart {Haematostereum

sanguinolentum (Alb. & Schw. ex Fr.) Pouz.) causes 90

percent of all trunk rot in living balsam fir trees (5). Several

fungi are important causes of decay in living balsam fir trees;

they include a top rot and a number of butt rots (9). They

occur so frequently in balsam fir that it is usually managed on

a pathological rotation of about 50 years on poorer sites and

about 70 years on better sites.

Wind damage is extensive in the spruce-fir forest

because of the shallow root systems, generally thin soils, and

prevalence of butt rots in balsam fir. Wind, in combination

with snow and ice, can cause top breakage. Shallow root

systems, thin bark, and flammable needles make spruce-fir

forests very susceptible to killing by fire (5).

Animals may cause damage to spruce-fir forests.

Rodents and birds consume and store large quantities of seed.

Damage to the terminal buds of young spruce and fir,

presumably by birds, has also been noted. Some injury and

mortality are occasionally caused by porcupine, bear, deer,

moose, and yellow-bellied sapsuckers (5). Red squirrels clip

twigs and terminals and eat reproductive and vegetative buds.

Spruce-fir stands are amenable to either even-aged or

uneven-aged management and most of the associated silvicultural systems except seed tree cutting—^the seed trees are

likely to be windthrown before the stand is regenerated (5,7,

11).

Individual tree selection is applicable to stands that are

uneven-aged, like many older stands that have been lightly

disturbed by man or nature. The shade-tolerant spruce and fir

are well adapted to the selection system, and the repeated

light harvests create favorable conditions for the establishment of abundant regeneration. A continuous high forest

cover is maintained, which is desirable for esthetics and for

maximum site protection, especially along streams and rivers.

Some control over regeneration is possible by manipulating

the overstory seed source. The frequent harvests at 5- to

20-year intervals allow salvage of wood that might otherwise

be lost to mortality. Under the selection system, growing

space is more fully utilized in the vertical plane. Also, the

shorter-lived fir component of the stand may be effectively

reduced, rendering the stand less vulnerable to spruce budworm

damage (1, 5, 6,9, 11).

The selection system is more complicated than evenaged systems because of the mixture of age and size classes;

harvesting occurs over a larger area to get the allowable cut;

and logging damage to growing stock is difficult to prevent.

Wind damage is a constant threat if too much volume is

removed in one harvest. Present mechanical harvesting

machines are probably not practical (1, 5, 9, 11).

Group selection, a variant of individual tree selection,

creates larger openings but has many of the same advantages

and disadvantages. It has no silvicultural advantage for

tolerant species such as spruce and fir; the somewhat larger

opening, however, may have advantages from an operational

standpoint and may aid in rapidly developing desirable

regeneration.

The shelterwood system is applicable in spruce-fir

stands that lack adequate advance regeneration and where

soils are deep enough, sites protected enough to prevent

windthrow, and there are no insect or disease problems of

concern. One-third to one-half of the stand basal area may be

removed in two or more harvests (on sites known to have a

windthrow problem removing less than one-third of the basal

area may be prudent), opening up the stand uniformly to

permit establishment of reproduction under the shelter of the

remaining trees. The system allows some control over

species composition of the regeneration and provides good

growing conditions for the residual overstory, but it may

require 10 to 15 years before regeneration has developed

enough that the remaining overstory can be removed, and

some damage to new seedlings may result from the final

harvest. It is more pleasing esthetically than clearcutting,

especially in the years immediately following cutting (1,2,

5,11).

Clearcutting is probably the most common even-aged

silvicultural system used in spruce-fir today. It is recommended for mature, overmature, or insect- and diseaseridden stands where partial removal could result in considerable mortality or damage to residual trees (1, 5, 11). It is the

system best adapted to mechanical harvesting (2).

Although most definitions of clearcut harvesting allow

for the presence of advance regeneration, there is usually no

deliberate effort to control initial species composition or

quality. If excessive seedling losses due to drastic exposure

or mechanical damage are anticipated, harvesting should be

done in narrow strips (progressive or alternate clear-strip

cuttings) as wide as half the height of the border trees or

small patches of about 1 acre (0.4 ha) or less in size. Thus,

129
adjacent uncut areas can provide partial shade to protect the

seedhngs and provide new seed if regeneration is not adequate.

In a sense these are variants of the shelterwood system.

Extensive clearcut areas lacking in established advance

seedlings may require planting. Such areas may have high

surface temperatures and excessive drying that is detrimental

to natural regeneration. Large accumulations of slash and the

development of heavy herbaceous cover, such as raspberries

{Rubus spp. L.), may inhibit natural regeneration in any size

clearcut (1, 2, 5, 11).

The initial operations in uneven-aged stands to be

managed by the selection system are usually salvage cutting,

improvement cutting, and/or thinnings. The object is to rid

the stand of overmature trees of poor vigor, rough or rotten

trees, and trees of undesirable species. Deadening of completely unmerchantable trees is also silviculturally desirable.

Thereafter, harvesting, improvement cutting, thinning, weeding,

and cleaning are part of the same operation (2, 5).

Even-aged stands of spruce—fir usually regenerate very

densely and need early thinning for trees to reach mechantable

size in a relatively short time. The initial thinning in

even-aged stands is recommended at about 25 years of age,

and periodic thinnings at 10- to 20-year intervals thereafter.

A precommercial thinning can be a combined cleaning and

thinning to establish a species priority and may be needed

when trees are from 6 to 15 feet (1.8 to 4.6 m) tall depending

upon density. Timber removals from intermediate cuttings

should not exceed 10 to 40 percent of total basal area,

depending on the site, or windthrow may result (2, 5, 11).

The pulp and paper industry has been the dominant user

of the spruce-fir resource, but solid wood products have

always been important and in recent years demand for

structural softwood lumber has increased. Spruce is also used

for poles, piling, boatbuilding stock, cooperage, and specialty products such as piano sounding boards.

The runoff water from the spruce-fir forest type is

stored in the many lakes and ponds which, along with the

streams and rivers, provide habitat for fish and other aquatic

life. The spruce-fir type supports a diverse wildlife population including both game and nongame species of birds and

animals. Spruce-fir stands are especially valuable as winter

cover for deer, and timber harvesting has generally improved

browse conditions for deer and moose. Of particular importance is the juxtaposition of an adequate winter cover of older

forest with younger openings where browse production is

high.

The low human population, many lakes and streams,

and reasonably good fish and wildlife populations throughout

most of the range of the spruce-fir type provide excellent

opportunities for outdoor recreation. Because of the remoteness of most of the region it is generally associated with

activities such as canoeing, wilderness trips, hunting, fishing,

snowmobiling, and skiing. And of course, the natural spruce-fir

forest scene is esthetically pleasing to many people (2).

Literature Cited

1. Barrett, John W. Regional silviculture of the United States. 2nd Ed.

New York: John Wiley; 1980; 551 p.

2. Blum, Barton M.; Klaiber, Harold M.; Randall, Arthur G. Northeastern

spruce-fir. In: Choices in silviculture for American forests. Washington,

DC: Society of American Foresters; 1981: 11-15.

3. Eyre, F. H., ed. Forest cover types of the United States and Canada.

Washington, DC: Society of American Foresters. 1980; 148 p.

4. Fowells, H. A., comp. Silvics of forest trees of the United States.

Agrie. Handb. 271. Washington, DC: U.S. Department of Agriculture;

1965; 762 p.

5. Frank, Robert M.; Bjorkbom, John C. A silvicultural guide for

spruce-fir in the Northeast. Gen. Tech. Rep. NE-6. Broomall, PA:

U.S. Department of Agriculture, Forest Service, Northeastern Forest

Experiment Station; 1973; 29 p.

6. Frank, Robert M.; Blum, Barton M. The selection system of silviculture

in spruce-fir stands—procedures, early results, and comparisons with

unmanaged stands. Res. Pap. NE-425. Broomall, PA: U.S. Department of Agriculture, Forest Service, Northeastern Forest Experiment

Station; 1978. 15 p.

7. Gibbs, Carter B. Northeastern spruce-fir. In: Silvicultural systems for

the major forest types of the United States. Agrie. Handb. 445.

Washington, DC: U.S. Department of Agriculture; 1973: 71-72.

8. Griffin, Ralph H.; Johnson, James E. Polymorphic site index curves for

spruce and balsam fir growing in even-aged stands in northern Maine.

Bulletin 765. Orono, ME: Life Sciences and Agriculture Experiment

Station, University of Maine at Orono; 1980; 22 p.

9. Hart, Arthur C. Spruce-fir silviculture in northern New England. Proc.

Soc. Am. For. 1963: 107-110.

10. Safford, Lawrence O. Ten year average growth rates in the Spruce-fir

region of northern New England. Res. Pap. NE-93. Broomall, PA:

U.S. Department of Agriculture, Forest Service, Northeastern Forest

Experiment Station; 1968. 20 p.

11. Westveld, Marinus. Ecology and silviculture of the spruce-fir forests

of eastern North America. J. For. 51(6): 422-430; 1953.

130
Eastern White Pine Including Eastern Hemlock

G. W. Wendel

Northeastern Forest Experiment Station

Lino Della-Bianca

Southeastern Forest Experiment Station

James Russell

Eastern Region

Kenneth F. Lancaster

Northeastern Area

Eastern white pine {Pinas strobus L.) is an important

forest type in northeastern United States, southern Ontario

and west to southeastern Manitoba, the Lake States, and

throughout the Appalachian Mountains to north Georgia,

eastern Kentucky, and eastern Tennessee. Eastern hemlock

(Tsuga canadensis (L.) Carr.) is a common associate of white

pine. Its range coincides closely with that of white pine

except that it stops south of Duluth, Minn., and does not

extend as far west and north as white pine (23).' Together,

eastern white pine and hemlock constitute type 22 of the

Society of American Foresters forest cover types (8).

White pine is a major component in 3 other forest types

and an associate in 23 others including conifers and hardwoods.

Eastern hemlock occurs in pure stands or is a major component in 4 types and is listed as an associate in 25 other conifer

and hardwood types. White pine commonly occurs in mixture with many other eastern species. Pure stands seldom

occur in nature though some developed along with shortlived pioneer hardwoods after hot fires or on abandoned old

fields.^ Hemlock on the other hand is most commonly a

species that occupies the lower strata of mixed forests.

Hemlock seedlings and saplings can endure decades of

suppression yet they retain the capacity to respond to release.^

White pine grows on many sites: from wet swamps to

dry sand plains or rocky ridges and from moist stream

bottoms and coves to upper slopes and ridgetops (24). In

New England and the Lake States, white pine is usually

found on more or less freely drained, sandy, or stratified sand

and gravel derived from glacio-fluvial deposits. The most

common soils supporting white pine in the central Appalachians are derived from acid sandstones and shales. In general,

white pine has grown on most soils within its range.

The soil requirements of eastern hemlock are not exacting but are usually characterized as moist to very moist but

with good drainage.^ Typical Lake States soils are loamy

sands, sandy loams, and silt loams of glacial or fluvial origin.

In the Northeastern States and Canada, hemlock grows

on rocky acid soils and on loams and silt loams that are nearly

neutral in soil reaction. Hemlock does best on moist, welldrained soils but it will grow well on sandy loam to clay loam

soils with high humus contents; on limestone soils, if not too

dry; and on almost swampy, loamy clay soils (11). In the

Quebec lowlands, hemlock colonizes sand, marine, or fluvial

banks with generally acid, well- to imperfectly-drained lithic

Regosols, lithic and gleyed Podzols, or orthic Gleysols (8).

White pine occurs at elevations ranging from sea level in

the north to about 3,500 ft (1065 m) and occasionally 4,000 ft

(1220 m) in the southern Appalachians. Hemlock grows at

similar elevations but in the southern Appalachians is found

mostly from 2,000 to 5,000 ft (610 to 1525 m) in elevation.^

' Ahlgren, Clifford E. Personal communication. 1981. Duluth, MN:

Quetico-Superior Wilderness Research Center.

^ Smith, David M. Personal communication. 1981. New Haven, CT: Yale

University School of Forestry.

^ Godman, FLichard M. Personal communication. 1981. Rhinelander, WI:

Forestry Sciences Laboratory, North Central Forest Experiment Station.

The climatic requirements for white pine and hemlock

are similar. Generally, distribution coincides reasonably well

with that part of eastern North America where July temperatures average between 65° and 74° F (18.3° and 23.3° C).

Precipitation ranges from 20 to 80 inches (510 to 2030 mm)

over most of the range with about half falling during the

growing season. The growing season ranges from 90 to 180

days (22). Hemlock and white pine are regenerated more

easily in New England than in the Lake States because the

New England area has somewhat warmer temperatures and

higher and better distribution of precipitation during critical

periods.

White pine trees begin to bear cones before age 20, but

the optimum seed-bearing period is between the ages of 50

and 150 years (20). Good white pine seed crops occur at

intervals of 3 to 10 years (19). Cones mature in two seasons

and seeds may be dispersed 200 feet (61 m) within a white

pine stand and more than 700 feet (213 m) in the open. During

good seed years and depending on stand density, 2 to 4

million seeds per acre (4.9 to 9.9 million/ha) may be

produced (16). Hemlock trees begin to produce seeds at 20 to

30 years of age (30). Cones mature in one season, and though

some seed is produced each year, large crops occur at 2- to

3-year intervals. Germination capacity of hemlock seed is

commonly less than 25 percent, but it is better than 90

percent for white pine (19, 30).

Seedbed condition is important in regenerating white

pine. In full sunlight, favorable seedbeds are moist mineral

soils, polytrichum moss, or a short grass cover of light-tomedium density. Unfavorable seedbeds include dry soil,

conifer litter, lichen, and very thin or very dense grass covers

(24). Partial shade, mechanical scarification, and burning

improves the seedbed. However, frequent and severe fires

can eliminate white pine from natural stands. White pine is

often a pioneer, and it grows in either relatively pure stands

or mixtures with other pioneer species on abandoned fields

and pastures (25).

Favorable seedbeds for hemlock include moist, welldecomposed litter, rotten wood, mineral soil, and moss mats

on soil, rocks, and fallen trees (9). The best seedbeds are

mixed mineral soils and humus (32). Hemlock seedlings

cannot tolerate direct sunlight and shading is usually necessary in the first 1 or 2 years after germination.^ Even though

hemlocks can endure more shade than white pine, under

extremely dense shade, survival of both species is reduced.

On shaded, moist sites in New England, white pine seedlings

in mixture with hemlock seedlings need release or they will

be crowded out by the hemlocks. Hemlock roots are shallow

and sensititve to low soil moisture and may dry out when

stands are opened up (11). In this circumstance, white pine

when mixed with hemlock will dominate. In the Lake States,

some overhead shade usually is retained to maintain better

soil moisture regimes and increase the hemlock survival.^

^Hocker, Harold W. Personal communication. 1981. Durham, NH:

University of New Hampshire.

131
Hemlock germinates best at 59° F (15.0° C), but between 44°

and 64° F (6.7° to 17.8° C), high germination percentages can

be achieved.^ Germination peak for hemlock is between 45

and 60 days. Dormancy in hemlock seed can be broken by

stratification for 10 weeks at or slightly above freezing.

Unstratified seed must be exposed to light to break dormancy.

Under natural conditons, germination is seldom delayed

because of seed dormancy.

Embryo dormancy is common in white pine. For nursery sowing, stratification of seeds for 60 days at 33° to 41° F

(0.6° to 5.0° C) is recommended (19). Under field conditions,

white pine embryo dormancy is usually broken over winter,

and most seeds germinate in 10 to 15 days in spring when

temperature is favorable for germination. Optimum white

pine germination in the Lake States and Canada occurs at

temperatures between 64° and 74° F (17.8° to 23.3° C) (10).

On sandy and relatively dry sites in New England, white

pine, white oak, and scarlet oak may form a physiographic

climax. On fertile and relatively moist soils, white pine

eventually is displaced by more shade tolerant species such as

beech (Fagus grandifolia Ehrh.), sugar maple (Acer saccharum

Marsh.), and red oak {Quercus rubra L.).^ Throughout most

of its range, however, white pine is a minor component of the

climatic climax forest. Although white pine may play an

ecological role similar to that of the most light demanding

species, it is intermediate in shade tolerance. In the seedling

stage, it can survive and grow, if slowly, with as little as 20

percent full sunlight. Light intensity less than full sunlight

will prevent seedling losses due to high surface soil temperatures (20). White pine grows slowly during the first 5 years of

establishment and competes well with the hardwoods on

poorer sites. On better sites, hardwood control is essential.

Once established, optimum growth occurs under full sunlight

(24). Establishment of eastern hemlock is much better under

shade than full sunlight, which may cause direct heat injury

to young stems.^ Shade provides more stable moisture

conditions for developing seedlings, but under hardwood

cover, small seedlings may be smothered by leaves.

Hemlock responds well to release. Often seedlings with

a history of suppression and release may make better late

growth than those that were free to grow from the start (9).

Hemlock can survive a suppression period that ranges from

25 to about 200 years.

White pine can be regenerated naturally or artificially.

Planting is generally used in situations where there is no

natural seed source or whenever genetically improved planting stock is to be used. This is true in northern Minnesota

where limited amounts of blister rust resistant white pine are

being planted. Clearcutting of hardwood stands, followed by

planting without site preparation and herbicide release of the

white pine 3 years later, has worked well in the southern

Appalachian white pine belt (27). Areas that have dense

stands of laurel and rhododendron are sprayed with an

herbicide, burned if necessary, and planted the following

winter sometime after February 1 to reduce seedling winter

kill. Mortality of white pine is increased in the southern

Appalachians and height growth may be reduced by 50

percent in the first 4 years if the organic layer is removed

(27). On fair-to-medium hardwood sites in the Central

Appalachians, Maine, Canada, and South Carolina, underplanted

white pines respond to overstory removal (3, 12, 14).

Normally 3 to 5 years are required for white pine to become

established. If the underplanted pines are released sometime

after establishment, a large proportion will successfully

compete with the hardwood sprouts. Release is generally

more successful on medium and fair sites. On better sites,

two or more releases may be required. Site quality and

spacing strongly influence volume production in white pine

plantations, but thinnings can reduce the overall number of

sawlog-size trees (2, 5, 20).

Reports on hemlock planting are scarce. In northwestern

Pennsylvania, planting of 3-0 hemlock stock for grouse

cover in north aspect, understocked hardwood, orchard-type

stands was highly successful (18). Direct seeding hemlock in

open areas, even with site preparation, usually failed. In

Maine, removal of humus layers or mixtures of humus and

mineral soil under shade provided receptive seedbeds for

seeding hemlock for at least 3 years (4). Direct seeding of

stratified seed in the spring or unstratified seed in the fall at a

rate of 0.5 pound per acre (0.56 kg/ha) on well-scarified sites

is recommended for artificially regenerating hemlock in the

Lake States (32). Planting of large seedling stock soon after

cutting may be used to supplement seeding if necessary.

Growth characteristics of white pine indicate that it can

be managed best under even-aged stand conditions, though

considerable leeway is allowed in choosing regeneration

methods. White pine has been naturally regenerated by

clearcutting in blocks and strips, and by seed-tree, shelterwood,

and group selection methods. Single tree selection cutting has

usually not proven satisfactory and the seed-tree method has

little to recommend it (24).

Abundant, established, advance white pine regeneration

can be released by cutting the remaining pines or hardwoods.

Clearcutting during, or just after, a heavy seed crop often

results in well-stocked stands on light soils (20, 24, 27).

Release from competing hardwoods is often necessary at

some time after overstory removal. Clearcutting in small

patches or strips with seed dispersed from adjacent stands is

also possible, but the constraints imposed by periodicity of

seed crops and future release requirements should be considered.

In lower Michigan and the upper Piedmont of South Carolina,

the competing ability of released pine was directly related to

height of the pine before release (7, 14). White pine has been

successfully regenerated by group selection (25). However,

other methods are more economical, especially where mechanical means are used to improve seedbed conditions or

eliminate competition. Where esthetics are important, group

selection may have merit (24).

The most versatile system for regenerating white pine is

the shelterwood. Control of overstory density through a

series of shelterwood cuts is used to improve seedbed

conditions; to allow accumulation of seedlings over a period

of years; to protect seedlings on hot, dry aspects; and to help

suppress competition from herbaceous vegetation and hardwood sprouts. Three or more cuts spread over a number of

years may be used, but white pine can be successfully

regenerated with only a two-cut shelterwood system. The

seed cutting should be timed to take advantage of a good seed

crop, but considerable leeway exists in timing the removal

cut (24). The two-cut shelterwood method is recommended

for regenerating white pine in New England (20). The first

cut removes 40 to 60 percent of the overstory and 5 to 10

years later, after the pines are established, the shelter trees

are removed. In the Lake States, the shelterwood method is

also recommended for regenerating white pine (13). White

pine regeneration methods work well in areas with a low

incidence of blister rust. In the cool, moist northwestern part

of the range, white pine is no longer managed commercially

because of extremely high seedling and sapling mortality

from blister rust.'

Growth rates of white pine vary with site and stocking

density. Over a rotation, white pine will produce more

volume than hardwoods on poor and good sites in New

England (20). On the better sites in the region, white pine

does not compete well with hardwoods. On the mediumtextured and lighter, sandy and gravelly soils, white pine

132
competes well with the hardwoods and usually dominates. In

the southern Appalachians, white pine has the highest site

index of its 10 most common associates. It is surpassed only

by yellow-poplar (Liriodendron tulipifera L.) on the best

sites (2). Over the range of sites in which it grows in the

Appalachians, white pine volume production is substantially

greater in a given length of time than that of associated

hardwoods.

In the southern Appalachian white pine belt, with a

rotation of 40 years, thinnings made at age 21 and 30 remove

about 10,000 board feet (fbm) (2,000 cubic feet)^ per acre

(140 m^/ha), and the final harvest yields about 16,000 fbm

(3,200 cubic feet per acre (224 m^/ha)) (27). For stands in the

Northeast, white pine stocking guides, can be followed to

maintain rapid growth rates and maximize production (20,

28). However, Leak (21) has pointed out some shortcomings

in the guides, and these should be considered when using

them.

Because of its tolerance to shade, hemlock can regenerate under low-light conditions. To increase the proportion of

hemlock and hasten growth of the understory hemlock in

mixed stands, single tree selection can be used (11). This

requires removal of mature trees or groups of trees periodically to increase hemlock growth, but it should not open up

the stand excessively or windfall may occur. To regenerate

hemlock in the Lake States on poorly to moderately welldrained sandy loam or heavier soils, the two-cut shelterwood

system may be used (32). Leave at least 50 percent—110

square feet per acre residual basal area (25.3 m /ha)—of the

canopy in evenly spaced trees, reduce hardwood competition,

and scarify soil before cutting. The overstory is removed

when reproduction is 3 to 5 feet (0.9 to 1.5 m) tall. On drier

sites, in overmature stands, or where grass-brush invasion

may occur, the three-cut shelterwood system should be used.

Leave 70 to 80 percent of the crown cover after the first cut;

reduce this to 50 percent 8 to 12 years later, and make the

final cut when reproduction is 4 to 5 feet (1.2 to 1.5 m) tall.

Scarify the site before the first cut and control unwanted

hardwoods during the first and second cut.

Hemlock stands are usually thinned from below leaving

about 70 to 80 percent crown cover, which corresponds to 100

to 125 square feet per acre (23.0 to 28.7 m^/ha) of basal area

in pole stands and 120 to 150 square feet per acre (27.6 to 34.4

m^/ha) in sawlog stands. Thinning should be repeated when

crowns begin to touch (32). To encourage hemlock development in well-stocked northern hardwood pole stands with 50

percent or more hemlock, improvement cuttings should be

made to remove poor quality sugar maple and other hardwoods (31). Fully stocked stands of eastern hemlock often

have in excess of 300 square feet per acre (68.9 m^/ha) of

basal area, and no more than one-third of the basal area

should be removed in a single cut to prevent overcutting and

mortality from shock.^

The white pine weevil {Pissodes strobi (Peck)) and

white pine blister rust (Cronartium ribicola J. C. Fisch.) are

the most damaging pests of white pine. The white pine

weevil is the most troublesome in New England and the

central part of its range. Blister rust tends to increase with

increasing latitude, in fog and dew pockets and in belts along

the shores of the Great Lakes. Root rot caused by

Heterobasidium annosum (Fr.) Bref, is found on white pines

growing on poorly aerated soils; damage increases when

stands are thinned (17). The white pine cone beetle

(Conophthoms coniperda (Schwarz)) occurs throughout the

'^ Cubic foot and metric conversions of measurements expressed in board

feet should be viewed as estimates because of the assumptions involved in

the conversion process.

range of white pine and in certain instances may destroy the

entire cone crop as it did in Maine in 1962 (15). The gypsy

moth (Lymantria dispar (Linnaeus)) will also attack

white pine when it grows in mixtures with a preferred

hardwood host (1). In nursery beds, damping-off and

root-collar rots are common. Other damaging agents of

white pine are white-tailed deer; glaze and/or snow,

which often cause limb and stem breakage; sulfur dioxide

emissions from large-scale burning of coal and from oil

refining; flourine gas from brick kilns; atmospheric

ozone; and ocean spray (17).

With increasing age and size, hemlock is subject to wind

shake, radial stress cracks, and often, sudden exposure may

cause bark sunscald on young trees (17). Hemlock is also

sensitive to sulfurous smelter fumes. Although there are

many fungi that attack hemlock at various stages of its

development, few cause widespread damage. The strawberry

root weevil {Otiorhynchus ovatus (L.)) is very destructive to

hemlock and other conifer seedlings in nurseries. Two

species of hemlock looper (Lambdina fiscellaria fiscellaria

(Guenee) and L. athasaria athasaria (Walker)) and one

species of the hemlock borer (Melanophila fulvoguttata

(Harris)) cause sporadic or local tree mortality and are the

only insect species of economic importance (9). When

hemlock occurs in mixtures with oaks, it sustains high

mortality following the first defoliation by gypsy moth.

Drought is probably the most damaging agent to eastern

hemlock during its seedling stage.^ Hemlock along highways

is highly sensitive to road salt during winter months (29).

The white pine type is not extensively grazed in the

East. However, in the past, light to moderate grazing by

livestock has resulted in the removal of grasses, weeds, and

hardwoods. In fact, grazing accounts for many of the pure

stands of pine we have today (29). White pine and eastern

hemlock seeds can be an important local source of food to

upland game birds, songbirds, and small mammals (26).

When browse is scarce, white pine foliage is often heavily

browsed. However, in the presence of a variety of browse

species, browsing of white pine is light (6). However, no rare

or endangered species is exclusively associated with the

white pine or hemlock types. Large, old-growth white pines

are used for nesting trees by osprey and bald eagles in the

Lake States. When these large horizontally branched trees are

present in existing or potential eagle territories, preservation

for nest trees should be considered. The dense, low foliage of

young hemlocks makes excellent winter cover for ruffed

grouse, deer, and other wildlife (26).

White pine and hemlock stands are popular for recreational activities. This is particularly true for remnant oldgrowth stands near lakes and streams. Understory vegetation

can be controlled or modified to enhance the opportunity for

recreation by providing a park-like appearance. In travel

corridors, mixed stands of white pine, hemlock, and hardwoods enhance variety. The esthetic impact of shelterwood

or clearcutting can be minimized by good landscape planning.

Literature Cited

1. Baker, Whiteford L. Eastern forest insects. Misc. Pub. 1175. Washington,

DC: U.S. Department of Agriculture; 1972. 642 p.

2. Beck, Donald E. Growth and yield of white pine. In: Proceedings,

Symposium for the management of pines of the interior South. Tech.

Pub. SA-TP2. Atlanta, GA: U.S. Department of Agriculture, Forest

Service, Southeastern Area State and Private Forestry; 1979: 72-89.

3. Clements, J. R. Development of a white pine underplantation in thinned

and unthinned aspen. For. Chron. 42: 244-250; 1966.

4. Davis, Grant; Hart, Arthur C. Effect of seedbed preparation on natural

reproduction of spruce and hemlock under dense shade. Stn. Pap. 161.

Broomall, PA: U.S. Department of Agriculture, Forest Service, Northeastern Forest Experiment Station; 1961. 12 p.

133
5. Della-Bianca, Lino. Thinning eastern white pine in the southern

Appalachians. South. J. Appl. For. 5(2): 68-73; 1981.

6. Della-Bianca, Lino; Johnson, Frank M. Effect of an intensive cleaning

on deer-browse production. J. Wildl. Manage. 29(4): 729-733; 1965.

7. Engle, Lamont G. Releasing white pine from oak and aspen. Res. Note

346. St. Paul, MN: U.S. Department of Agriculture, Forest Service,

Lake States Forest Experiment Station; 1951. 2 p.

8. Eyre, F. H., ed. Forest cover types of the United States and Canada.

Washington, DC: Society of American Foresters; 1980. 148 p.

9. Fowells, H. A., comp. Silvics of forest trees of the United States.

Agrie. Handb. 271. Washington, DC: U.S. Department of Agriculture;

1965. 762 p.

10. Fraser, J. W. Cardinal temperatures for germinating of white, red and

jack pine seed. Inf. Rep. PS-X-15. Ontario, Canada: Canadian

Forestry Service, Petawawa Forest Experiment Station; 1970. 24 p.

11. Frothingham, E. H. The eastern hemlock. Bull. 152. Washington, DC:

U.S. Department of Agriculture; 1915. 43 p.

12. Geerinck, Paul A.; Getchell, Willis A.; Chapman, Gordon L. Response

to release of underplanted white and red pine. Tech. Note 29. Orono,

ME: University of Maine, Forestry Department; 1954. 2 p.

13. Godman, Richard M. The shelterwood regeneration method. In:

Proceedings, National Silviculture Workshop; 1979 September 17-21;

Charleston, SC. Washington, DC: U.S. Department of Agriculture,

Forest Service, Division of Timber Management; 1979: 189-200.

14. Goebel, N. B.; Cool, B. M. Releasing white pines after 20 years of

suppression in the upper Piedmont of South Carolina. For. Farmer

27(2): 9, 22; 1968.

15. Graber, Raymond E. Impact of the white pine cone beetle on a pine seed

crop. J. For. 62(7): 499-500; 1964.

16. Graber, Raymond E. Natural seedfall in white pine stands of varying

density. Res. Note NE-119. Broomall, PA: U.S. Department of

Agriculture, Forest Service, Northeastern Forest Experiment Station;

1970. 6 p.

17. Hepting, George H. Diseases of forest and shade trees of the United

States. Agrie. Handb. 386. Washington, DC: U.S. Department of

Agriculture; 1971. 658 p.

18. Jordan, James S.; Sharp, Ward M. Seeding and planting hemlock for

ruffed grouse cover. Res. Pap. NE-83. Broomall, PA: U.S. Department of Agriculture, Forest Service, Northeastern Forest Experiment

Station; 1967. 17 p.

19. Krugman, S. L.; Jenkinson, J. L. Pinus L. Pine. In: Schopmeyer, C. S.,

tech. coord. Seeds of woody plants in the United States. Agrie. Handb.

450. Washington, DC: U.S. Department of Agriculture; 1974. 838 p.

20. Lancaster, Kenneth F.; Leak, William B. A silvicultural guide for white

pine in the Northeast. Gen. Tech. Rep. NE-41. Broomall, PA: U.S.

Department of Agriculture, Forest Service, Northeastern Forest Experiment Station; 1978. 13 p.

21. Leak, William B. Do stocking guides in the eastern United States relate

to stand growth? J. For. 79(10): 661-664; 1981.

22. Little, Elbert L., Jr. Atlas of United States trees, volume I, conifers and

important hardwoods. Misc. Pub. 1146. Washington, DC: U.S. Department of Agriculture; 1971. 9 p.

23. Little, Elbert L., Jr. Checklist of United States trees (native and

naturalized). Agrie. Handb. 541. Washington, DC: U.S. Department of

Agriculture; 1979. 375 p.

24. Little, Silas; Beck, Donald E.; Della-Bianca, Lino. Eastern white pine.

In: Silvicultural systems for the major forest types of the United States.

Agrie. Handb. 445. Washington, DC: U.S. Department of Agriculture;

1973: 73-75.

25. Lutz, R. J.; Cline, A. C. Results of the first 30 years experimentation in

silviculture in the Harvard Forest 1908-1938. Part 1. The conversion

of stands of old field origin by various methods of cutting and

subsequent cultural treatments. Harvard Forest Bull. 23; Petersham,

MA: Harvard For. Bull.; 1947. 182 p.

26. Martin, Alexander C; Zim, Hubert S.; Nelson, Arnold L. American

wildlife and plants. A guide to wildlife food habitats. New York: Dover

Pub. 1951. 500 p.

27. Moyers, George B. Mangement of eastern white pine in the south. In:

Proceedings, Symposium for the Management of Pines in the Interior

South. Tech. Pub. SA-TP2. Atlanta, GA: U.S. Department of Agriculture,

Forest Service, Southeastern Area State and Private Forestry; 1979:

18-47.

28. Philbrook, James S.; Barrett, J. P.; Leak, W. B. A stocking guide for

eastern white pine. Res. Note NE-168. Broomall, PA: U.S. Department of Agriculture, Forest Service, Northeastern Forest Experiment

Station; 1973. 3 p.

29. Rich, Avery E. Effect of de-icing chemicals on woody plants. New

Hampshire For. Notes; Spring 1971: 26-27.

30. Ruth, Robert H. Tsuga (Endl.) Carr. Hemlock. In: Schopmeyer, C.S.,

tech. coord. Seeds of woody plants in the United States. Agrie. Handb.

450. Washington, DC: U.S. Department of Agriculture; 1974. 838 p.

31. Tubbs, Cari H. Manager's handbook for northern hardwoods in the

North Central States. Gen. Tech. Rep. NC-39. St. Paul, MN: U.S.

Department of Agriculture, Forest Service, North Central Forest Experiment Station; 1977. 290 p.

32. Tubbs, Cari H. How to manage eastern hemlock in the Lake States. St.

Paul, MN: U.S. Department of Agriculture, Forest Service, North

Central Forest Experiment Station; 1978. 2 p.

134
Pitch Pine

Peter W. Garrett

Northeastern Forest Experiment Station

Harvey Fleming

Eastern Region

Pitch pine (Pinus rígida Mill.) occupies a wide geographic range from central Maine to northern Georgia. It

occurs in pure stands as Society of American Foresters forest

cover type 45 and is also a major component of at least eight

other recognized forest types (3). Pitch pine as a pure type

covers more than 1.5 million acres (607 000 ha), and an

additional 1.0 million acres (405 000 ha) are classified as

pitch pine-Virginia pine-hardwood type.

Pitch pine occurs in fairly humid climates with annual

precipitation between 37 and 56 inches (940 to 1420 mm).

The length of the frost-free season ranges from 112 to 190

days, and temperature extremes range from -40° F (-40.0°

C) in the north to more than 100° F (37.8° C) in most sections

of the range.

Competition often restricts pitch pine to soils low in

natural fertility. In New England and along the Atlantic Coast

it occurs on sandy soils of alluvial or marine origin, and in

the Mid-Atlantic and Southern States it generally occurs on

ridges, steep slopes with a southwest aspect, and plateaus

where soils tend to be shallow (5).

Pitch pine is a prolific seeding species with good cone

crops at intervals of approximately 3 years (4). Dissemination

of seed varies between areas and between trees on the same

area. Cones on trees growing in areas with a history offrequent

severe fires tend to be serotinous such as areas in the central

portion ofthe New Jersey Pine Barrens. Heat from severe fires

is required to open the serotinous cones, whereas the more

common nonserotinous cones open at maturity (1, 5). Seeds

have the large wings associated with pines but do not travel

far—usually not in excess of 300 feet (91 m) from the source

tree. Germination averages better than 75 percent under ideal

conditions (8).

Deep litter is a serious deterrent to establishment, and

few seedlings are found on undisturbed sites. Where fires or

mechanical scarification have occurred before seed dispersal,

as many as 23,000 seedlings per acre (56 830/ha) have been

found.

Planting of improved pitch pine seedlings would be the

preferred regeneration option on most sites. Adequate genetic

variation within the species economically justifies such a

program. The use of hybrids that combine the hardiness to

cold and the resistance to disease of pitch pine with the

excellent form and growth rate of loblolly pine (Pinus taeda

L.) could improve yield even more on most sites occupied by

pitch pine. Selected hybrids have outgrown seed orchard

pitch pine seedlings by 50 percent in some plantings (6, 7).

Pitch pine is intolerant of shade and can be maintained

best in stands by forms of even-aged management, such as

clearcutting where advance reproduction is present, or the

retention of seed-trees where nonserotinous cones are present.

Fires have been primarily responsible for the present distribution of this type, but fire is also responsible for the slow

growth and characteristic poor form of the species on some

sites. Pitch pine is outstanding among eastern conifers in its

ability to survive all but the most severe fires. Trees will

produce new needles even if all foliage is killed, and new

sprouts will develop from dormant buds on trees with

pronounced basal crook if the main stem is killed by fire.

Although this ability is an asset in survival of the species, it

can be a liability. Stems deformed by fire and forced to

develop new crowns are poorly formed and slow growing.

Also, the ability to survive and recover from such damage

may be greater in slow-growing strains that in fast-growing

ones.

Pitch pine can be killed by intense heat and resulting

stands, if from sprout origin on older trees, may be inferior to

either seeded or planted stands. On the Pine Barrens of New

Jersey, it is common practice to bum periodically to eliminate fuel buildup and thereby reduce the danger of uncontrolled wild fires. Prescribed burning is also used to prepare

seedbeds before final harvest cuts.

If natural regeneration from seed is expected following

harvest operations, it is essential that proper seedbeds be

prepared and that openings be no smaller than 1 acre.

Either controlled burning or some form of scarification

before harvesting has been effective in exposing the necessary mineral soil. Direct seeding on prepared sites will also

produce fully stocked stands if moisture conditions are

adequate for several years following seeding. Small rodents,

birds, and insects consume some seed on exposed sites, but

the supply of seed is usually more than adequate for regeneration purposes.

The primary market for pitch pine throughout its range

has been fiber production with lesser amounts being used for

solid products. Pure, fully stocked stands of pitch pine have

growth rates averaging 50 percent faster than oak {Quercus

spp.) and other associated species on the same sites. Maximum total volume occurs at about 90 years when fully

stocked stands may yield as much as 25,000 board feet (fbm)

(5,000 cubic ft) per acre (350 m^/ha).^ Mean annual growth

on most sites is at a maximum between 30 and 40 years with

up to 83 feet^ per acre (5.8 m^/ha) on site quality I sites (57 ft

(17.4 m) at age 50) and 42 feet^ per acre (2.9 m'^/ha) on site

quality III sites (38 ft (11.6) at 50 years)(2, 4).

Rotation age for fiber production should be between 30

and 45 years depending on site quality, and larger solid

products can be harvested between 50 and 70 years. Older

stands of pitch pine are subject to many insect and disease

problems, and net volume decreases rapidly after age 90 as

stands begin to break up.

Seedlings and trees in young stands are attacked by a

number of fungi that cause minor damage. Eastern gall rust

(Cronartium quercuum (Berk.) Miy. ex Shirai), Fusiform

rust (C. quercuum (Berk.) Miy. ex Shirai f. sp. Fusiforme

Burds. & Snow), comandra blister rust (C. commandrae

Pk.), sweetfem rust (C comptoniae Arth.), needle casts

(Meloderma desmazierii (Duby) Dark., Ploioderma lethale

' Cubic foot and metric conversions of measurements expressed in board

feet should be viewed as estimates because of the assumptions involved in

the conversion process.

135
(Dear.) Dark., P. hedgcockii (Deam.) Sigg., and Scirrhia

acicola (Deam.) Sigg.), and needle rust {Coleosporium spp.)

all occur on pitch pine. Heart rot occurs in older trees and is

not uncommon in trees over 75 years old. A number of

insects attack the foliage and stem of this species throughout

its life. Tip moth, sawfly, southern pine beetle {Dendroctonus

frontalis Zimmermann), web worms, and needle miners are

among the most serious. Cone insects, including the webbing

coneworm (Dioryctria disclusa Heinrich), cause significant

reductions in seed production, but in a normal year enough

seed should still be available for regeneration purposes.

Pitch pine and associated types provide important cover

and food supplies for many forms of wildlife including

white-tail deer and rabbits. Clearcutting or seed-tree cutting,

which is essential for regeneration of this species, provides

openings and edges favored by wildlife. Because the pitch

pine types are usually found on lighter, drier soils, management options seldom influence either water quality or fish

habitat.

Literature Cited

1. Andressen, J. W. Germination characteristics of Pinus rigida seed borne

in serotinous cones. Broteria 32(3-4): 151-178; 1963.

2. Aughanbaugh, J. E. Yield of the oak-chestnut-hard pine forest type in

Pennsylvania. J. For. 32(1): 80-89; 1934.

3. Eyre, F. H., ed. Forest cover types of the United States and Canada.

Washington, DC: Society of American Foresters; 1980. 148 p.

4. Illick, J. S.; Aughanbaugh, J. E. Pitch pine in Pennsylvania. Research

Bulletin No. 2. Harrisburg, PA: Pennsylvania Department of Forests and

Waters; 1930. 108 p.

5. Little, S. Pitch Pine {Pinus rigida Mill.) In: Fowells, H. A., comp.

Silvics of forest trees ofthe United States. Agrie. Handb. 271. Washington,

DC: U.S. Department of Agriculture; 1965: 404-410.

6. Little, S.; Trew, I. F. Pitch x loblolly hybrids: loblollies for the north*^ J

For. 77(11): 709-716; 1979.

7. Little, S.; Wolf, W. E., Jr. Pitch x loblolly hybrids . . . fast growing hard

pine for Pennsylvania? Penn. For. Jul-Aug: 6-7; 1980.

8. Schopmeyer, C. S., tech. coord. Seeds of woody plants in the United

States. Agrie. Handb. 450. Washington, DC: U.S. Department of

Agriculture; 1974. 838 p.

136
Cherry -Maple

David A. Marquis

Northeastern Forest Experiment Station

Porter Gearhart

Eastern Region

The cherry-maple or Allegheny hardwood forest type

(type 28 of the Society of American Foresters (2)) covers

about 12 million acres (4.9 million ha) in the Allegheny

Plateau and Allegheny Mountain sections of New York,

Pennsylvania, Maryland, and West Virginia. It occurs at

elevations from 1,000 to 2,600 ft (305 to 790 m) on both

glaciated and unglaciated areas. Soils are mostly derived

from sedimentary parent materials and have textures that

range from sandy loam to silty clay loam.

The climate in cherry-maple forest areas is generally

cool, moist, and temperate, with average annual precipitation

of 38 to 44 inches (965 to 1120 mm) well distributed

throughout the year. Droughts are not common. The frostfree season is 120 to 155 days (11).

The cherry-maple type is composed primarily of black

cherry {Prunus serótina Ehrh.), red maple {Acer rubrum L.),

sugar maple {Acer saccharum Marsh.), and white ash {Fraxinus

americana L.), with American beech {Fagus grandifolia

Ehrh.), eastern hemlock {Tsuga canadensis (L.) Carr.),

yellow birch {Betula alleghaniensis Britton), sweet birch

{Betula lenta L.), yellow-poplar {Liriodendron tulipifera L.),

and cucumbertree {Magnolia acuminata L.) as common

associates. Cherry and the maples usually dominate stands in

Pennsylvania and southward; white ash and sugar maple tend

to be more important, and red maple less important, in the

New York portions of the range (2).

Allegheny hardwoods are second- and third-growth

forests that followed extensive commercial clearcutting during the railroad logging era of 1890 to 1930 (12). Although

generally considered even-aged, many stands contain residuals from the previous stand, and some stands that were cut

less heavily are mixtures of two to four age classes. Allegheny hardwoods represent an early- to mid-successional

stage that would ultimately lead to a climax forest dominated

by beech, hemlock, and sugar maple if left undisturbed for a

long period (9).

Allegheny hardwood forests yield many products and

services. They are the source of nearly all the world's supply

of cherry lumber for furniture and veneer, and provide

substantial proportions of fine ash and maple sawtimber.

Pulpwood and bulk products are also important. Allegheny

hardwood forests represent one of the few major blocks of

contiguous forest land in the Eastern United States, yet they

are within a day's drive of nearly one-third of the U.S.

population. Thus, they are heavily used for many types of

outdoor recreation and serve as watersheds for many eastern

cities.

Natural regeneration is relied on for the reestablishment

of nearly all cherry-maple stands after cutting and natural

disturbance. Artificial seeding and planting are rarely used,

except in those unusual cases where natural regeneration is

impossible for some reason. Natural regeneration originates

from advance seedlings present beneath the canopy before

cutting, from seed stored in the forest floor, from seed

dispersed into the areas after cutting, and from sprouts and

suckers.

Black cherry and red maple are frequent seed producers,

with good crops every 2 or 3 years. White ash and sugar

maple have good seed crops somewhat less frequently, while

beech is least frequent with good crops only one in 6 or more

years (1, 3). In addition, black cherry, white ash, and

yellow-poplar seeds remain dormant but viable in the forest

floor for 3 to 5 years, insuring a relatively constant seed

supply. Red maple and birch seeds sometimes remain dormant in the forest floor for a year or two, whereas sugar

maple and beech seeds commonly germinate the year following dispersal. Pin cherry {Prunus pensylvanica L. f.)—a

noncommercial tree—brambles, grasses, and other herbaceous plants also have seeds that may remain viable in the

forest floor for decades, providing reproduction of these

plants in cutover areas where they were not previously

apparent (13, 28).

Cherry seeds and beech nuts fall to the ground near the

seed tree, and the abundance of advance seedlings of these

species is closely related to the number and distribution of

seed trees in the overstory. However, small mammals also

provide wider distribution of seeds, and songbirds and

omnivorous mammals sometimes account for a surprising

abundance of cherry advance seedlings in stands that lack

cherry seed producers. Seeds of most of the other Allegheny

hardwood species are wind disseminated, and dispersal is

somewhat wider than for beech and cherry. Birch seeds are

especially small and light and they are sometimes dispersed

over considerable distances, especially late-falling seeds that

blow over crusted snows. Seeds of the Allegheny hardwood

species mentioned here except red maple are dispersed in the

fall; red maple is dispersed in the late spring or early summer.

The birches are the only Allegheny hardwood species

for which scarified seedbeds are required for seedling

establishment, although red maple, white ash, and hemlock

also germinate somewhat better on seedbeds where the

surface organic layers have been disturbed or mixed with

mineral soil. Sugar maple, beech, and black cherry germinate

as well on undisturbed humus or litter as on disturbed

seedbeds. For all species, maintenance of high surface

moisture is required for good germination, and the shade of a

moderately heavy overstory is beneficial in providing such a

stable moisture supply. Germination of even the shadeintolerant species is consistently higher in partial shade than

in areas exposed to direct solar radiation (15).

Fire generally destroys the advance seedlings that are a

primary source of regeneration in Allegheny hardwood stands.

Since disturbed seedbeds are not necessary or even desirable

for many of the favored species, controlled burning is not

useful for the establishment of regeneration in this type.

However, fire may have some potential as a means of

removing understory competition of beech or other unwanted

species (26).

Advance reproduction is of major importance in the

regeneration of black cherry, white ash, red maple, sugar

maple, beech, and hemlock. The latter three species are quite

tolerant of shade, and seedlings of these species are capable

137
of surviving and growing beneath uncut or lightly cut stands

for extended periods. Cherry, ash, and red maple are less

tolerant of shade, but seedlings of these species will become

established and survive for 3 to 5 years under a moderately

heavy canopy. Although considerable canopy opening is

necessary for these seedlings to survive for longer periods or

make appreciable growth, those that die are constantly being

replaced by new seedlings. Thus, advance seedlings of all the

important species are often present beneath seed-bearing

trees to form a new stand when the overstory is removed.

All species in the Allegheny hardwood type except

hemlock reproduce from sprouts or root suckers. Red maple

is a prolific sprouter, and black cherry, white ash, sugar

maple, and the birches sprout readily from dormant buds

around the base of cut stumps. Sprouts are most numerous

from stumps of small trees less than 40 to 50 years old. Beech

often sprouts from the cambium region on the surface of cut

stumps, and suckers from roots of both living and cut beech

trees are common. The beech underbrush common in many

Allegheny hardwood stands is composed primarily of root

suckers.

Although seedlings and seedling-sprouts are generally

preferred for timber production, most stump sprout clumps

contain one or two stems that are capable of growing into

quality sawtimber. The incidence of butt rot from the parent

stump is not great from stumps that are 10 inches (25 cm) or

less in diameter or that have been healed over by 35 years of

age (10, 29). Beech root-suckers seldom develop into highquality sawtimber.

Because Allegheny hardwoods contain species that span

the full range of shade tolerance and growth rate, stands

usually have a complex structure. Black cherry and yellowpoplar usually outgrow and eventually overtop all other

species. Sugar maple, beech, and hemlock generally grow

slower than their associates, but being shade tolerant, they

survive when overtopped, and often form a distinct lower

canopy and diameter strata in mixed species, even-aged

stands (19).

Economic timber rotation ages differ widely among

species because of the large differences in growth rates. In

unmanaged stands, black cherry reaches large sawtimber size

and is considered financially mature at 80 to 90 years of age.

Red maple and white ash require 90 to 100 years, while sugar

maple and beech may require 120 to 160 years or more (4,

24).

Stocking and yield vary considerably in Allegheny

hardwoods, depending upon species composition. For example,

stands that have a 10 inch (25 cm) average stand diameter

will be at average maximum stocking with 138 feet^ per acre

(31.7 m^/ha) of basal area if 20 percent cherry, ash, or

yellow-poplar is present, but would require 184 feet^ per acre

(42.2 m^/ha) to be at maximum stocking if those intolerant

species represent 80 percent of the basal area (25). At age 80,

cubic and sawlog volumes in stands containing 20 percent

cherry, ash, and yellow-poplar average 4,690 feet"^ per acre

(328.3 m^/ha) and 9,321 board feet (fbm) (International V^-

inch) per acre (130.5 m^/ha)^ Comparable values in stands

with 80 percent cherry, ash, and poplar are: 5,578 feet^ per

acre (390.5 m^/ha) and 13,787 fbm per acre (193.0 m^/ha).

There are a variety of insect and disease pests in

cherry-maple stands, but none that limit effective management or require major alterations in silvicultural procedures.

Mice and voles cause considerable mortality of seedlings by

' Cubic foot and metric conversions of measurements expressed in board

feet should be viewed as estimates because of the assumptions involved in

the conversion process.

girdling the stems near the ground. These small mammals are

especially important in grass or other herbaceous cover which

provides suitable habitat, and their damage is probably one of

the major causes of planting failure in old fields or clearcuts

where natural regeneration has not become established.

White-tailed deer cause extensive damage by feeding on

Allegheny hardwood seedlings. In parts of Pennsylvania

where deer populations are especially high, deer browsing is

a major obstacle to new stand establishment. In such areas,

reproduction is sometimes completely eliminated by browsing,

and most regeneration cuts are affected by reduced stocking,

delays in establishment, and shifts in species composition

toward less palatable beech and striped maple (18, 22).

Damage is dramatic after clearcutting, but damage to advance reproduction is also important. Thinnings and shelterwood

cuts that would normally encourage establishment of advance

seedlings often result in development of understory plants

such as ferns, grasses, beech root-suckers, and striped maple

that interfere with desired reproduction (5, 6). Preferential

browsing on the desired tree species prevents their establishment,

permitting the understory to be taken over by the interfering

plants.

The choice of silvicultural systems in Allegheny hardwood forests would be wide were it not for the unusual deer

damage to regeneration in some parts of the range. All-age

silviculture, as exemplified by selection cutting, requires that

new seedlings be established at each partial cut, and that they

gradually grow into the main crown canopy to fill small

openings created by cutting. But such seedlings are exposed

to deer browsing over a long time, and repeated selection

cutting in areas of high deer population eventually results in

the complete removal of present trees without replacement by

new seedlings and saplings. Only the less palatable beech and

noncommercial striped maple are likely to survive, creating a

forest of very low value, perhaps lacking in tree cover of any

type in many spots (22).

Therefore, all-age silviculture cannot safely be practiced

in areas of high deer population. Only even-age methods that

provide abundant sunlight for seedlings to grow quickly out

of reach of deer are practical in such areas. However, all-age

silviculture can be used successfully in those portions of the

Allegheny hardwood range where deer populations are in

better balance with their habitat.

Detailed guidelines have been developed to help foresters analyze stand conditions and prescribe appropriate silvicultural treatments in Allegheny hardwood forests (23, 25).

Where management objectives call for maximizing highquality timber production, or maximizing habitat for such

wildlife as deer, grouse, rabbits, or hares, even-aged silviculture is the proper choice. All-age silviculture is usually better

where timber production and management of these game

species are secondary to maintenance of a high forest canopy

for visual or recreational objectives (assuming that deer

populations will permit regeneration establishment) (27).

Modifications of both major silvicultural systems are also

possible to help reconcile conflicting resource uses where this

is necessary.

Regeneration under even-age silviculture is obtained in

Allegheny hardwood stands using either clearcutting or

shelterwood cutting methods. If advance seedlings of desired

species are abundant and well distributed before final harvest,

the overstory can be removed in a single cut. Overstory

removal or clearcutting will release the advance seedlings.

Along with new seedlings and sprouts that start after cutting,

they will provide the basis for a new stand.

Where advance seedlings are scarce before final harvest,

they must be established by a sequence of shelterwood cuts.

The first, or seed, cut of the shelterwood sequence should

138
reduce the overstory to 60 percent of average maximum

stocking in areas of high deer population (50 percent elsewhere)

to make additional sunlight, moisture, and nutrients available

for the establishment of new seedlings (16, 17).

However, these conditions also provide for rapid expansion of ferns, grasses, beech root-suckers, and striped maple,

which can interfere with desired seedlings. Areas where these

plants are prevalent before cutting, or where soil conditions

are conducive to their spread, must be treated with an

herbicide before the seed cut (7, 8).

Once an adequate number of seedlings has become

established, the remaining overstory may be removed in one

additional cut. Usually, 5 to 10 years will be required after

the seed cut. The overstory removal cut in this two-cut

shelterwood sequence is essentially identical to the overstory

removal or clearcutting recommended where advance seedlings are naturally abundant.

The final removal cut in Allegheny hardwoods should

remove all trees larger than about 2 inches (5 cm) diameter at

breast height (d.b.h.) to insure that unmerchantable trees left

on the site do not interfere with regeneration. However, a few

good quality, vigorous saplings and poles of tolerant sugar

maple, beech, and hemlock may be retained to insure

perpetuation of these species and help them achieve a

position in the main crown canopy of the next stand. These

residuals survive and grow well after release. Faster growing

intolérants will catch up with these residuals in 40 to 60

years, creating a mixed stand in which all species are more

uniform in size than if all started at the same time. The

immediate value of the residuals as pulpwood is very low, so

little income is lost by reserving them. But they will grow

into sawtimber sooner than new reproduction and help make

early commercial thinnings possible in the next stand (20,

21).

Once a new even-aged stand has been established, it can

usually be left to develop naturally without silvicultural

intervention until it is at least 25 years old. Thereafter, the

stands can be opened up to encourage rapid diameter growth

in the clean-boled trees present. Commercial thinnings become feasible when the basal area in saplings (trees less than

5.5 inches (14 cm) in diameter at breast height (d.b.h.))

drops below about 20 feet^ per acre (4.6 m^/ha). Before this

time, saplings are such a large proportion of the stand

stocking that attempts to cut only merchantable-size trees and

ignore saplings result in high-grading that removes the cherry

and ash and seriously reduces future stand value.

Intermediate cuttings in even-aged Allegheny hardwoods must be planned carefully because of the complex

mixture of species with widely different growth rates and

stand structures. Two major species groups are recognized:

intolerant, fast-growing cherry, ash, and yellow-poplar; and

tolerant, slower growing maples, beech, and other species.

Within each group, trees removed in early thinnings should

come predominantly from the smaller diameters in an attempt

to favor the bigger, better quality trees. This increases the

average diameter of the group and reduces the time it will

take for the residuals to reach financial maturity. The general

goal is to concentrate diameters in a narrow range within the

crop tree portion of each species group.

In all intermediate cuts, stand density should be reduced

to 60 percent of average maximum stocking, as measured by

stocking charts (25). This density provides excellent individual tree growth and near maximum net stand growth without

loss of tree quality from epicormic branching that is sometimes experienced at lower densities. The major exception to

the 60 percent residual density rule is for stands that are at or

near maximum stocking. Trees in such stands tend to have

small crowns, and opening the stand to 60 percent in one cut

often leaves growing space unused for many years until the

crowns can expand to fill the space. Degrade from excessive

exposure also may occur. No thinning should remove more

than one-third of the existing stocking in a single cut.

Under all-aged silviculture, regeneration must be obtained in each stand after every cut. Since considerable

overstory is always present, regeneration is dominated by

tolerant species such as sugar maple, beech, and hemlock.

But some small proportion of intolérants can be maintained if

residual densities are kept low, and if small openings are

created at scattered places in the stand. Therefore, single-tree

selection cutting supplemented with small openings up to

about 0.25 acres (0.10 ha) is the recommended all-aged

practice in Allegheny hardwoods.

Where deer populations are very high, as in northern

Pennsylvania, excessive browsing often results in failure of

regeneration to become established. All-age silviculture should

not be used in these localities. Each cutting under all-age

silviculture should create and maintain a residual stand that

contains all sizes and ages of trees at the same time. To

achieve this, a residual stand goal must be established, and

each cut must remove only trees of a size that are excess to

that goal. In this way, regular sustained yields are assured

(14). Recommendations are available on the combinations of

residual stand density, maximum tree size, and diameter

distribution (or stand structure) that produce best results in

Allegheny hardwood stands.

Literature Cited

1. Bjorkbom, John C. Seed production and advance regeneration in

Allegheny hardwood forests. Res. Pap. NE—435. Broomall, PA: U.S.

Department of Agriculture, Forest Service, Northeastern Forest Experiment Station; 1979. 10 p.

2. Eyre, F. H. Forest cover types of the United States and Canada.

Washington, DC: Society of American Foresters; 1980. 148 p.

3. Grisez, Ted J. Flowering and seed production in seven hardwood

species. Res. Pap. NE—315. Broomall, PA: U.S. Department of

Agriculture, Forest Service, Northeastern Forest Experiment Station;

1975. 8 p.

4. Grisez, Ted J.; Mendel, Joseph J. The rate of value increase for black

cherry, red maple, and white ash. Res. Pap. NE—231. Broomall, PA:

Department of Agriculture, Forest Service, Northeastern Forest Experiment Station; 1972. 26 p.

5. Horsley, Stephen B. Allelopathic inhibition of black cherry by fern,

grass, goldenrod, and aster. Can. J. For. Res. 7(3): 205-216; 1977.

6. Horsley, Stephen B. Allelopathic inhibition of black cherry. II. Inhibition by woodland grass, ferns, and club moss. Can. J. For. Res. 7(3):

515-519; 1977.

7. Horsley, Stephen B. Development of reproduction after herbicideclearcut herbicide-shelterwood cut treatment of Allegheny hardwood

stands. Res. Note NE-306. Broomall, PA: U.S. Department of

Agriculture, Forest Service, Northeastern Forest Experiment Station;

1981. 4 p.

8. Horsley, Stephen B. Control of herbaceous weeds in Allegheny hardwood forests with herbicides. Weed Sei. 29: 655—662; 1981.

9. Hough, A. F.; Forbes, R. D. The ecology and silvies of forests in the

high plateaus of Pennsylvania. Ecology Monogr. 13: 299-320; 1943.

10. Lamson, Neil I. Appalachian hardwood stump sprouts are potential

sawlog crop trees. Res. Note NE-229. Broomall, PA: U.S. Department of Agriculture, Forest Service, Northeastern Forest Experiment

Station; 1976. 4 p.

11. Lull, Howard W. A forest atlas of the Northeast. Broomall, PA: U.S.

Department of Agriculture, Forest Service, Northeastern Forest Experiment Station; 1968. 46 p.

12. Marquis, David A. The Allegheny hardwood forests of Pennsylvania.

Gen. Tech. Rep. NE-15. Broomall, PA: U.S. Department of Agriculture,

Forest Service, Northeastern Forest Experiment Station; 1975. 32 p.

13. Marquis, David A. Seed germination and storage under northern

hardwood forests. Can. J. For. Res. 5: 478-484; 1975.

139
14. Marquis, David A. Application of uneven-aged silviculture and management on public and private lands. In: Uneven-aged silviculture and

management in the United States. Washington, DC: U.S. Department of

Agriculture, Forest Service; 1978: 25—61.

15. Marquis, David A. The effect of environmental factors on the natural

regeneration of cherry-ash-maple forests in the Allegheny Plateau

region of the eastern United States. In: Proceedings, Symposium

Fevillus Précieux; 1978 September 11-15; Nancy, France. Nancy,

France: Institut National de la Recherche Agronomique, Centre Nationale

de Recherches Forestières; 1978: 90- 99.

16. Marquis, David A. Ecological aspects of shelterwopd cutting. In:

Proceedings, National Silviculture Workshop; 1979 September 17-21;

Charleston, SC. Washington, DC: U.S. Department of Agriculture,

Forest Service; 1979: 40-56.

17. Marquis, David A. Shelterwood cutting in Allegheny hardwoods. J.

For. 77(3): 140-144; 1979.

18. Marquis, David A. Effect of deer browsing on timber production in

Allegheny hardwood forests of Northwestern Pennsylvania. Res. Pap.

NE—475. Broomall, PA: U.S. Department of Agriculture, Forest

Service, Northeastern Forest Experiment Station; 1981. 10 p.

19. Marquis, David A. Even-age development and management of mixed

hardwood stands: Allegheny hardwoods. In: Proceedings, National

Silviculture Workshop on Hardwood Management; 1981 June 1-5;

Roanoke, VA. Washington, DC: U.S. Department of Agriculture,

Forest Service, 1981: 213-226.

20. Marquis, David A. Removal or retention of unmerchantable saplings in

Allegheny hardwoods: Effect on regeneration after clearcutting. J. For.

79(5): 280-283; 1981.

21. Marquis, David A. Survival, growth, and quality of residual trees

following clearcutting in Allegheny hardwood forests. Res. Pap. NE—477.

Broomall, PA: U.S. Department of Agriculture, Forest Service, Northeastern Forest Experiment Station; 1981. 9 p.

22. Marquis, David A.; Brenneman, Ronnie. The impact of deer on forest

vegetation in Pennsylvania. Gen. Tech. Rep. NE—65. Broomall, PA:

U.S. Department of Agriculture, Forest Service, Northeastern Forest

Experiment Station; 1981. 7 p.

23. Marquis, David A.; Grisez, Ted J.; Bjorkbom, John C; Roach,

Benjamine A. Interim guide to regeneration of Allegheny hardwoods.

Gen. Tech. Rep. NE—19. Broomall, PA: W.S. Department of Agriculture, Forest Service, Northeastern Forest Experiment Station; 1975.

14 p.

24. Mendel, Joseph J.; Grisez, Ted J.; Trimble, G. R., Jr. The rate of value

increase for sugar maple. Res. Pap. NE-250. Broomall, PA: U.S.

Department of Agriculture, Forest Service, Northeastern Forest Experiment Station; 1973. 19 p.

25. Roach, Benjamin A. A stocking guide for Allegheny hardwoods and its

use in controlling intermediate cuttings. Res. Pap. NE-373. Broomall,

PA: U.S. Department of Agriculture, Forest Service, Northeastern

Forest Experiment Station; 1977. 30 p.

26. U.S. Department of Agriculture, Forest Service. Eastern deciduous

forests. In: Effects of fire on flora—a state of the art review. Gen. Tech.

Rep. WO-16. Washington, DC: U.S. Department of Agriculture,

Forest Service; 1978: 34-38.

27. U.S. Department of Agriculture, Forest Service. National Forest landscape management. Vol. 2, Chapter 5: Timber. Agrie. Handb. 559.

Washington, DC: U.S. Department of Agriculture, Forest Service;

1980. 283 p.

28. Wendel, G. W. Longevity of black cherry seed in the forest floor. Res.

Note NE-149. Broomall, PA: U.S. Department of Agriculture, Forest

Service, Northeastern Forest Experiment Station; 1972. 4 p.

29. Wendel, G.W. Stump sprout growth and quality of several Appalachian

hardwood species after clearcutting. Res. Pap. NE-239. Broomall,

PA: U.S. Department of Agriculture, Forest Service, Northeastern

Forest Experiment Station; 1975. 9 p.

140
Appalachian Mixed Hardwoods

H. Clay Smith

Northeastern Forest Experiment Station

Lino Della-Bianca

Southeastern Forest Experiment Station

Harvey Fleming

Eastern Region

Appalachian mixed hardwoods, commonly called cove

hardwoods, are found on moist slopes of the Appalachian

Mountains and adjacent portions of the Allegheny and

Cumberland Plateaus (37). However, these hardwoods are

not specifically identified as forest cover types (15). Appalachian mixed hardwoods are found within the oak-hickory

ecological forest classification (6) and are associated with the

oaks, yellow-poplar {Liriodendron tulipifera L.), and northem hardwood forest cover types. Cove hardwoods are found

from southeastern New York and east-central Pennsylvania

south to northern Georgia and Alabama. These hardwoods

predominate on an estimated 26 million acres (10.5 million

ha). Ownership consists of small holdings except on Federal,

state, and industrial lands.

Certain Appalachian mixed hardwood species can produce high-quality sawlogs, veneer logs, pulpwood, fiber, and

fuelwood on relatively short rotations. These stands are

characteristic of rich, moist sites and typically are found in

coves, on lower slopes with a northern or eastern aspect, and

on gentle terrain (41). Cove hardwoods occupy good to

excellent sites, 65 to 90 feet at age 50 years (19.8 to 27.4 m)

on the oak site-index scale (26), 70 to 120 feet (21.3 to 36.6

m) on the yellow-poplar site-index scale (2, 14). Soils are

fairly deep, medium textured, and well drained. Annual

precipitation ranges from 40 to 60 inches or more (1015 to

1525 mm) and is well distributed throughout the year, mostly

as rainfall. Temperatures range from an annual minimummaximum of -20° to 100° F (-28.8° to 37.7° C) in the north

to an annual minimum-maximum of 15° to 100° F (-9.4° to

37.7° C) in the south. Frost-free days range from 120 in the

north to 240 in the south.

Stands are characterized by a large number and variety

of plant species. Overstory composition may range from

nearly pure stands of northern red oak {Quercus rubra L.) or

yellow-poplar to typical mixtures of 20 or more commercial

species. Other more important species include black cherry

(Prunus serótina Ehrh.), sugar maple (Acer saccharum

Marsh.), white ash (Fraxinus americana L.), southern red

oak (Quercusfalcata Michx.), red maple (Acer rubrum L.),

American beech (Fagus grandifolia Ehrh.), hickories (Carya

spp.), white oak (Quercus alba L.), black locust (Robinia

pseudoacacia L.), American basswood (Tilia americana L.),

and white basswood (Tilia heterophylla Vent.). Conifer

species include eastern white pine (Pinus sirobus L.), red

spruce (Picea rubens Sarg.), and eastern hemlock (Tsuga

canadensis (L.) Carr.). On good sites at higher elevations,

Appalachian mixed hardwoods merge with types dominated

by sugar maple, yellow birch (Betula alleghaniensis Britton),

American beech, and eastern hemlock and/or mixtures of

black cherry, red maple, white ash, and sweet birch. On drier

sites with shallow soils, the Appalachian mixed hardwoods

merge with oak and hickory types.

Sources of reproduction in these hardwood stands include buried seed, stump sprouts, root suckers, and advance

regeneration. Seed of several species such as yellow-poplar,

basswood, white ash, black locust, and black cherry remain

viable in the forest floor for at least three winters (38).

Acorns and seed from maples, birches, and American beech

commonly remain viable over one winter. Nearly all hardwood species sprout vigorously especially when young, but

as stems mature, sprouting decreases (16). Advance regeneration of tolerant species such as maples and American beech

occurs under dense canopies. Advance oak regeneration

composed of seedlings an inch or more in base diameter, with

a well-developed root system, is generally necessary for

satisfactory growth after release. Logging usually does not

kill advance regeneration because damaged stems sprout

vigorously (21). During their early years, sprouts grow

rapidly, often dominating other forms of reproduction. Stump

sprouts can produce high-quality trees for a number of

species (3, 17, 42). Prolific sprouters include oaks, yellowpoplar, American and white basswood, black cherry, red

maple, black locust, and American beech.

Reproduction of intermediate tolerant species usually

follows a moderate opening of the canopy on Appalachian

mixed hardwood sites. This reproduction can persist for

several years. Seeds of white ash, yellow-poplar, black

cherry, and the basswoods germinate when favorable conditions of light, temperature, and moisture are created by

canopy removal (37).

Because of the abundance of different species in the

Appalachian mixed hardwood stands, it is rare that seed

crops do not occur for several of these species (16). Consistent seed producers are the basswoods, yellow-poplar, black

cherry, sugar maple, and, to a lesser degree, hickories; acorn

production is extremely variable. Wind is the primary agent

in disseminating light-weight seeds such as basswoods,

yellow-poplar, sugar maple, and birches. Heavier seed such

as acorns, hickory nuts, and seeds of beech and black cherry

are distributed largely by gravity, animals, and birds.

Since there are so many available species and management objectives in these mixed hardwood stands, a variety of

seedbed conditions are acceptable. Logging disturbance usually is sufficient to create adequate exposure of mineral soil.

Exposed mineral soil provides good germination for seeds of

American beech, birches, yellow-poplar, and basswood.

Acorns and hickory nuts germinate under leaf cover; black

cherry seed does not have rigid germination requirements,

though compacted soil is undesirable (16). Conditions usually exist for some species to become established regardless

of the climatic regime or stand disturbance. However,

regenerating specific species can present problems.

Among major Appalachian mixed hardwood species,

shade tolerance ranges from very tolerant American beech,

eastern hemlock, and sugar maple to the intermediately

tolerant oaks, hickories, birches, and white ash to intolerant

black cherry, black locust, basswoods, and yellow-poplar

(37). Most intolérants and some intermediates will not

survive long under a dense canopy. Sugar maple, American

beech, and, to a lesser degree, oak saplings and pole-size

trees can persist for a long time under a dense canopy and

then respond to release (33). Many intermediate and intoler141
ant species in these mixed hardwood stands developed in

large openings due to windthrow, fire, snow, ice, logging,

etc. Intolerant species exposed to light are faster growing

than tolerant species, especially in sapling- and pole-size

stands. Also, stump sprouts generally grow faster than

seedlings in sapling- and pole-size stands. As stands mature,

differences in growth between seedling- and sprout-origin

stems narrow considerably, but when this occurs is unknown

(28). Some species such as oaks can respond with good

diameter growth when released. Often, the response is

comparable to or even surpasses that of the more intolerant

species (36, 37), but the duration is unknown.

Mature cove hardwood stands commonly range in volume from 10,000 to 20,000 board feet (fbm) (International

'/4-inch) (2,000 to 4,000 cubic feet)' per acre (140 to 280

m^/ha), though it is not uncommon for volumes to exceed

20,000 fbm (4,000 cubic feet) per acre (280 m^/ha). On

some sites, trees 20 to 24 inches (51 to 61 cm) diameter at

breast height (d.b.h.) can be grown on a 70-year rotation,

but more often such trees are produced with rotations of

80 to 100 years. Annual growth for mature stands varies

for 250 to 50 fbm (50 to 100 cubic feet) per acre (3.5 to

7.0 m^/ha).

Principal insects and disease affecting hardwood species

have been summarized (16). Currently, insects and diseases

are not a significant factor in Appalachian mixed hardwood

stands. However, this situation could change with gradual

migration of the gypsy moth {Lymantria dispar Linnaeus)

south from the northeast. Foliage of oaks, basswoods,

American beech, red maple, sugar maple, birches, hickories,

and black cherry are preferred food of the gypsy moth (1,7).

Initially, oak wilt {Ceratocystis fagacearum (Bretz) Hunt)

was thought to be a major problem in the Appalachians, but

its occurrence generally has stabilized and is limited to

specific areas. However, oak borers, especially the red oak

borer (Enaphalodes rufulus (Haldeman)), and associated

decay cause serious damage, particularly with northern red

oak (5, 13).

Sweet birch is readily attacked by several fungi and

frequently becomes defective at an early age. Of all the

pathogens that attack it, sweet birch is most susceptible to

Nectria canker {Nectria galligena Bres.). Maple canker

Eutypella parasítica Davids & Lorenz) is common in sugar

maple. In general, sugar maple is not highly susceptible to

insect injury, though the sugar maple borer {Glycobius

speciosus Say) is a serious pest. Black cherry is defoliated by

the eastern tent caterpillar {Malacosoma americanum (Fabricius))

and the uglynest caterpillar (Archips cerasivorana (Fitch)).

Black knot fungus (Apiosporina mohosa (Schw.) von Arx)

commonly occurs on black cherry. Cankers caused by

Strumella and Nectria fungi are serious diseases of northern

red oak. Trunk-boring insects seldom kill oaks, but they

seriously degrade products cut from infected logs. Weevils

(Curculio spp.) are a common pest of acorns. Neither white

ash nor the basswoods have serious insect and disease

enemies. However, basswoods, along with most species in

mixed hardwood stands (particularly young stems), are

highly susceptible to fire damage. Fires often result in

wounds that serve as entry points for insects and disease.

Fire has been considered as a possible silvicultural tool,

especially to control unwanted vegetation and to establish

specific desirable species. Prescribed burning may be an

option in certain limited situations. However, we must learn

more about the role of fire in managing hardwoods before fire

can be recommended (20, 24).

' Cubic foot and metric conversions of measurements expressed in board feet

should be viewed as estimates because of the assumptions involved in the

conversion process.

In cove hardwood stands there are a number of species

that reproduce successfully following any regeneration cutting,

thus reproduction usually is not difficult. However, species

differences in shade tolerance and other silvical characteristics combined with site variation lead to changes in species

composition. Species composition is affected by the silviculture and management systems used.

Even-aged and uneven-aged silvicultural practices have

been used to manage Appalachian mixed hardwood stands.

Even-aged practices such as clearcutting result in a greater

variety of species and a higher ratio of intolerant to tolerant

species than uneven-aged practices. The intolerant to intermediate species usually are fast-growing, high-value trees such as

black cherry, black walnut, red oak, and white ash (32).

Other fast-growing species include yellow-poplar and

basswoods. Where uneven-aged practices are used, the

tolerant, slow-growing, less valuable commercial species

eventually dominate; these include American beech, sugar

maple (high value), and red maple. Frequently, noncommercial tolerant species such as dogwood or striped maple are

found in the understory. Their presence can result in costly

silvicultural treatments to minimize their influence or to

eliminate them from the new stand (30).

In stands where even-aged silviculture is practiced, one

reproduction cut usually is done at the end of each rotation.

As the new stand develops, thinnings are made at appropriate

intervals until the next reproduction cut or clearcut. In stands

where uneven-aged practices are used, regeneration and

thinning occur concurrendy at each cutting period. Intermediate cuttings may increase the yield of wood products by

salvaging mortality. Time until final harvest is shortened by

the increased diameter growth that results from these intermediate cuts. More quality trees may be available at final harvest.

There are three regeneration cutting practices to consider in even-aged management—clearcutting, shelterwood,

and seed tree. Clearcutting generally is recommended to

regenerate Appalachian mixed hardwood stands. Both intolerant and tolerant species are reproduced by this method,

though the month in which a clearcut is applied can influence

the amount of regeneration due to late seed germination,

particularly with yellow-poplar (39). Planned clearcuts provide stands of differing ages in the forest; each stand

contributes wildlife food and habitat which allows a variety

of wildlife to prosper (12, 25).. Clearcutting has a more

immediate impact on the forest environment than any other

cutting practice. Critics of clearcutting usually are concerned

about the unsightly appearance of areas that have been

clearcut. Methods to improve visual appearance such as

blending clearcuts into the landscape, good planning and

road maintenance, and follow-up post logging, felling and

lopping, and seeding of logged areas, are being introduced.

Most recreation areas are considered unsuitable for clearcutting—a notable exception is the use of clearcuts to provide

scenic vistas.

Shelterwood cutting includes removing trees in the

Appalachian mixed hardwood stands in two or more cuts,

usually over a maximum period of 20 years. Shelterwood

cutting may be promising for reproducing species of intermediate tolerance such as oaks. The method often is recommended where there is no desirable advance regeneration.

However, the shelterwood system has not proven consistent

in providing adequate advance oak regeneration, though

periodic thinnings are recommended during the latter part of

the rotation to maintain understory oaks in a vigorous

condition (8). Effects of the shelterwood cutting depend on

density and duration of the residual overstory. Results of

current shelterwood studies in cherry—maple stands in northwest Pennsylvania may be applicable to even-aged Appalachian mixed hardwood stands. Regeneration research is

142
being conducted in mixed hardwood stands in the southern

Appalachians (18); to date, shelterwood cuts and clearcuts

have yielded similar results.

Regeneration by seed trees is seldom used or needed in

these Appalachian mixed hardwood stands. Under most

circumstances, regeneration comprising the new stand is

already established or will become established the first

growing season after cutting, regardless of the presence or

absence of seed trees. Where seed trees are left in the stand,

windthrow and loss of bole quality are of concern to

foresters.

Regeneration methods to consider for uneven-aged management are single-tree selection and group selection. Singletree selection results in least disturbance to the forest canopy

and is used where a nearly continuous forest canopy is

preferred, or when stand and site disturbance must be

minimized (29). However, a selection method cannot be used

if a high portion of intolerant species are desired for this

practice encourages shade-tolerant trees and shrubs. Eventually,

the mixed character of the cove hardwood stands will be

reduced by the single-tree selection method to a few commercial tolerant species, such as sugar maple, American beech,

and red maple (19, 28, 35). As species composition changes

to more tolerant species, volumes per acre decrease and the

number of years for trees to mature increases. Also, some

wildlife species will be influenced by changes in nut, forage,

and browse production and edge habitat (25). The use of

single-tree selection cuts that remove enough trees to encourage regeneration and development of light-demanding, more

valuable species poses the risk of reducing stand growth and

quality through understocking and high grading (37). Singletree selection is especially suitable in areas where esthetic or

recreational values are high. This practice generally is less

favorable than other cutting methods for increasing water

yield or diversifying wildlife habitat (19). Also, potential

logging damage to residual trees is a major concern.

Group selection provides a mixture of desirable tolerant

and intolerant species in mixed hardwood stands, if the

openings are at least 0.5 acre (0.2 ha) (31). Group selection is

difficult to apply at periodically short intervals (25). If

openings are small and well scattered, esthetic qualities

remain high and group selection produces excellent wildlife

habitat, forage, browse, edge, and mast-producing trees.

However, quality of border trees can be reduced by epicormic

branching. If deer populations are high, reproduction in small

openings may be browsed severely, even eliminated. Group

selection is well suited to small woodlots where occasional

cuts are desired, but where regulation of yield is not

important (25, 29).

Intermediate cuttings in immature mixed hardwoods

provide a means of improving stands by removing undesirable species; increasing growth of more desirable, better

quality species; and shortening the time until final harvest.

There are no stocking guides specifically for mixed hardwood stands, although the Allegheny stocking guide (23)

currently is being applied in West Virginia on the Monongahela National Forest. The yellow-poplar stocking guide is

applicable to mixed hardwood stands dominated by yellowpoplar (4). Precommercial thinnings are questionable in

even-aged Appalachian hardwood stands less than 10 years

old, or with trees less than 25 ft (7.6 m) tall (11, 31).

Thinnings should start at age 15 to 20 and continue at about

10-year intervals until age 60 or 70 (25). Thinnings should be

intensive enough to provide rapid growth on leave trees, but

not so intensive as to stimulate epicormic branching, early

stem forking, or grapevine development. However, yellowpoplar stands can be thinned intensively without incurring

serious butt-log degrade due to epicormic sprouting (10).

In Appalachian mixed hardwood stands where evenaged management is practiced, wild grapes and other vines

can be a major problem to management of high-quality

hardwoods. Vines bend, break, and kill young hardwood

stems (40). Methods of controlling vines include herbicide

treatments and cutting grapevines near ground level when the

overstory canopy of young or mature stands is closed. When

grapevine control is necessary, wildlife and recreation interest must be considered.

There is little evidence that conventional silvicultural

practices will deplete nutrient levels in Appalachian mixed

hardwood stands (22). Soil erosion and reduction of water

quality are dependent on logging and road construction

techniques rather than silvicultural practices. Also, the organic soil layers in these stands have an exceptional capacity

for absorbing water and protecting soil against erosion (25).

When erosion and consequent sedimentary runoff do occur

on logged areas, the cause is usually poorly designed,

constructed, and maintained haulroads and skidroads. Fish,

especially trout, are sensitive to changes in water temperature.

Protective tree borders can be left along streams to maintain

prevailing stream temperature regimes and to minimize

sediment before runoff water enters the stream (34). There

are many species of wildlife in Appalachian mixed hardwood

stands so it is necessary to maintain a variety of vegetation to

provide diverse food and habitat (25). Silvicultural practices

such as periodic regeneration cuts provide a forest with a

variety of vegetative stages including seedlings, saplings,

poles, immature sawtimber, and mature sawtimber. Silvicultural practices cannot be designated as beneficial or detrimental to birds per se (9). Certain practices may change habitats

enough to decrease the total bird population of certain

species; however, other bird species that are better adapted to

the modified habitat will occupy the site (9).

Because Appalachian mixed hardwoods are found on

good sites and generally contain a number of desirable

species, these stands are highly productive. The rich mixture

of species and the wide variation in silvical characteristics

allow flexibility in applying silvicultural practices yet complicate management decisions. Even-aged management generally is recommended for maintaining Appalachian mixed

hardwoods. Through this practice, intolerant and tolerant

species can be retained together. But, there are so many

forest stands, site conditions, and management objectives

that there is no single silvicultural cutting practice that can be

considered the most appropriate for managing the complex

hardwood stands (27).

Literature Cited

1. Anderson, John F. The gypsy moth. Fron. Plant Sei. 32(3): 1 -8; 1980.

2. Beck, Donald E. Yellow-poplar site index curves. Res. Note 180.

Asheville, NC: U.S. Department of Agriculture, Forest Service, Southeastern Forest Experiment Station; 1962. 2 p.

3. Beck, Donald E. Growth and development of thinned versus unthinned

yellow-poplar sprout clumps. Res. Pap. SE-173. Asheville, NC: U.S.

Department of Agriculture, Forest Service, Southeastern Forest Experiment Station; 1977. 11 p.

4. Beck, Donald E.; Della-Bianca, Lino. Growth and yield of thinned

yellow-poplar. Res. Pap. SE-101. Asheville, NC: U.S. Department of

Agriculture, Forest Service, Southeastern Forest Experiment Station;

1972. 20 p.

5. Berry, Frederick H. Decay associated with borer wounds in living oaks.

Res. Note NE-268. Broomall, PA: U.S. Department of Agriculture,

Forest Service, Northeastern Forest Experiment Station; 1978. 2 p.

6. Braun, E. Lucy. Deciduous forests ofeastern North America. Philadelphia,

PA: Blakiston Co.; 1950. 596 p.

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7. Campbell, Robert W. Gypsy moth: Forest influence. Agrie. Info. Bull.

423. Washington, DC: U.S. Department of Agriculture; 1979. 45 p.

8. Carvell, Kenneth L. Factors affecting the abundance, vigor, and growth

response ofunderstory oak seedlings. In: J.S. Wright Forestry Conference

Proceedings: Regenerating oaks in upland hardwood forests; 1979; West

Lafayette, IN. Lafayette, IN: Purdue Univ.; 1979: 23-26.

9. Crawford, H.S.; Hooper, R.G.; Titterington, R.W. Songbird population

response to silvicultural practices in central Appalachian hardwoods. J.

Wildl. Manage. 45(3): 680-692; 1981.

10. Della-Bianca, Lino. Screening some stand variables for post-thinning

effect on epicormic sprouting in even-aged yellow-poplar. For. Sei. 18(2):

155-158; 1972.

11. Della-Bianca, Lino. An intensive cleaning ofmixed hardwood saplings—

10-year results from the southern Appalachians. J. For. 73(1): 25-28;

1975.

12. Della-Bianca, Lino; Johnson, Frank M. Effect ofan intensive cleaning on

deer-browse production in the southern Appalachians. J. Wildl. Manage.

29(4): 729-733; 1965.

13. Donley, David E. Wood borer losses in Appalachian oak. South.

Luberman 229: 115-118; 1974.

14. Doolittle, Warren T. Site index comparisons for several forest species in

the Southern Appalachians. Soil Sei. Soc. Am. Proc. 22: 455-458; 1958.

15. Eyre, F. H., ed. Forest cover types of the United States and Canada.

Washington, DC: Society of American Foresters; 1980. 148 p.

16. Powells, H. A., comp. Silvics of forest trees of the United States.

Agrie. Handb. 271. Washington, DC: U.S. Department of Agriculture;

1965. 762 p.

17. Lamson, Neil I. Appalachian hardwood stump sprouts are potential

sawlog crop trees. Res. Note NE—229. Broomall, PA: U.S. Department

of Agriculture, Forest Service, Northeastern Forest Experiment Station;

1976. 4 p.

18. Loftis, David L. Partial cuts to regenerate upland hardwoods in the

Southeast. In: the Shelterwood Regeneration Method: Proceedings,

National Silvicultural Workshop; 1979 September 17-29; Charleston,

SC. Washington, DC: U.S. Department of Agriculture, Forest Service;

1979: 92-100.

19. Marquis, David A. Silviculture of eastern hardwoods. In: The scientific

base for silviculture and management decisions in the National Forest

system; 1976 March 22-23; Washington, DC. Washington, DC: U.S.

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20. McGee, Charles E. Fire and other factors related to oak regeneration. In:

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upland hardwood forests; 1979; West Lafayette, IN. Lafayette, IN:

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21. McGee, C. E.,Beck,D. E.;Sims,D. H. Natural regeneration of upland

hardwoodsin the south. New Orleans, LA: U.S. Department ofAgriculture,

Forest Service; Southern Forest Experiment Station; 1979. 4 p.

22. Patrie, James H. Effect of wood products harvest on forest soil and water

resources, with emphasis on clearcutting in moist climates. In: The

scientific base for silviculture and management decisions in the National

Forest system; 1976 March 22-23; Washington, DC. Washington, DC:

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23. Roach, Benjamin A. A stocking guide for Allegheny hardwoods and its

use in controlling intermediate cuttings. Res. Pap. NE—373. Broomall,

PA: U.S. Department of Agriculture, Forest Service, Northeastern Forest

Experiment Station; 1977. 30 p.

24. Sander, Ivan L. Regenerating oaks with the shelterwood system. In: John

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hardwood forests; 1979; West Lafayette, IN. Lafayette, IN: Purdue Univ.;

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25. Sander, Ivan L.; Merritt, Clair; Tryon, E. H. Oak-Hickory. In:

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27. Smith, David M. Dangers in over-simplification of forestry. North.

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31. Smith, H. Clay. Diameters of clearcut openings influence central Appalachian hardwood stem development—a 10-year study. Res. Pap. NE-476.

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the Eastern United States; 1975 July 15-17; Morgantown, WV. Broomall,

PA: U.S. Department of Agriculture, Forest Service, Northeastern Forest

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144
Paper Birch

L. O. Safford

Northeastern Forest Experiment Station

Rodney D. Jacobs

Northeastern Area

Paper birch, Society of American Foresters forest cover

type 18, occupies about 2.4 million acres (1.0 million ha) in

New England, New York, and northern Pennsylvania, and in

the northern portion of the Lake States. It also extends

northward into Canada and westward across Canada into

interior Alaska where it occupies 5.1 million acres (2.1

million ha) (6, 15). (See Interior Alaska White SpruceHardwoods type for information on silvicultural practices in

Alaska.)

Paper birch {Betulapapyrifera Marsh.) is a pioneer type

that revegetates land disturbed by natural catastrophe such as

wildfire or man-caused disturbance such as clearcutting. It

grows best on deep, well-drained soils with good fertility, but

is found on nearly any soil type and moisture regime. This

forest cover type extends nearly to the limit of tree growth in

the north and at high elevations on cool north- and east-facing

slopes in the southern portions of its range (6). In general,

paper birch is found where the climate has short, cool

summers and long, cold winters (12). Annual precipitation

varies greatly over the range, from 30 inches (760 mm) or

less in the Lake States to as much as 60 inches (1520 mm) in

northern New England. Typically, one-third to one-half of

the precipitation falls as snow.

Large stands of pure paper birch are uncommon. Species commonly associated with the paper birch type include

quaking and bigtooth aspen (Populas tremuloides Michx. and

P. grandidentata Michx.), pin cherry (Prunus pensylvanica

L.), yellow and gray birch (Betula alleghaniensis Britton and

B. populifolia Marsh.), sugar and red maple (Acer saccharum

Marsh, and A, rubrum L.), and in the northern parts of the

range, spruce and balsam fir (Picea glauca (Moench) Voss,

P. mariana (Mill.) B.S.P., P. rubens Sarg, and Abies

balsamea (L.) Mill.). Young regenerating stands frequently

contain abundant raspberries and blackberries (Rubus spp.),

hobblebush (Viburnum alnifolium Marsh.), and elder (Sambucus

spp.) (6).

In the absence of disturbance the paper birch type is

replaced by tolerant types, commonly by northern hardwoods

on well-drained mineral soils and spruce-fir on shallow or

poorly drained soils. In Minnesota it is often replaced by

communities dominated by shrubs, particularly beaked hazel

(Corylus cornuta Marsh.), and scattered trees (11).

Paper birch normally reproduces from seed. Poor natural seed supplies may be supplemented by broadcasting

additional seeds. Stumps of trees younger than about 60 years

produce vigorous sprouts that can be counted on to supplement seedling regeneration (14). Where natural regeneration

cannot be obtained or where introduction of genetically

improved stock is desired, bareroot nursery stock or container grown seedlings can be planted (9). Site preparation to

reduce competition is required, especially on old-field sites

with heavy sod. Protection of planted seedlings from girdling

by rodents and browsing by deer may be required (3).

Paper birch begins producing seed at about 15 years of

age; optimum seed bearing age is 40 to 70 years. In the

Northeast, good seed crops occur every other year, but some

seed is produced every year, with a bumper crop 1 year in 10.

In Wisconsin, the seed crop failed or was classed as poor for

5 consecutive years (8). Some seed may fall in July due to

wind storms or birds feeding on catkins, but seedfall generally starts in August and continues through winter into

spring. The bulk of the seed (about 90 percent) falls from

September through November.

The light-winged seed of paper birch is readily dispersed

by the wind. Some seed travels great distances, particularly

when blown across the surface of snow. However, the

majority of seed falls within the stand where it is produced,

and the amount of seed dispersed into openings drops off

rapidly with distance from stand edge. Two million seeds per

acre (4.9 million/ha) would be adequate to regenerate openings up to 100 feet (30 m) wide; 8 million per acre (19.8

million/ha) would be adequate for openings 300 feet (100 m)

wide (1).

Seed germination and seedling development are affected

by soil moisture, soil temperature, light, and seedbed conditions.

Best germination and early survival are on exposed mineral

soil and in partial shade. However, growth is better on humus

seedbeds and in 50 percent or greater sunlight. Scarification,

disking, or light burning provide the best seedbeds (13).

Although paper birch is not known as a dry-site species,

it is found on some droughty sites, particularly in the Lakes

States. During drought, paper birch survives water stress by

shedding foliage (7). It is generally wind firm despite its

generally shallow root system. Often, the root system of trees

blown over by the wind has been injured by a pathogen like

Armillariella mellea (Vahl. ex Fr.) Karst. (17). Saplings and

small poles bend under the weight of heavy wet snow or

glaze, but most of the trees recover and straighten if the snow

or ice falls off quickly.

Because of its intolerance, paper birch does not become

established under dense forest canopies. In the early stages of

suppression, paper birch most often requires release from

aspen and pin cherry that overtop and threaten to suppress it.

Unless suppressed trees are released early, they soon die.

Intermediate trees survive longer, but gradually succumb

after struggling for years at a low rate of growth (12).

Young paper birch grows rapidly but the growth rate

declines with age, becoming negligible when trees reach

maturity. The average diameter of trees in mature stands is 10

to 12 inches (25 to 30 cm), and the average height is 70 feet

(21 m) (8, 12). On the best sites, an occasional tree in old

stands may exceed 30 inches (76 cm) in diameter and 100

feet (30 m) in height. The diameter of trees of the variety

cordifolia, mountain paper birch, can be as large as 40 inches

(102 cm) (12).

Average yields at maturity (80 years) on good sites are

about 3,500 cubic feet per acre (245.0 m^/ha), a high

proportion of which may be in sawlogs and veneer logs.

Average yields on poor sites are about 2,000 cubic feet per

acre (140.0 m-^/ha), of which few trees reach sawlog size (4).

The bulk of the material can be used for pulpwood, fuelwood,

or millwood. Yields in New England are higher than Ontario,

145
especially on the poorer sites where yields from stands in

New England exceeds those in Ontario by more than 80

percent.

Insects and disease attack only a small percentage of

paper birch seed and seedlings (5, 17). Sapling and older

trees may be attacked by several defoliating insects, including the forest tent caterpillar (Malacosoma disstria Hubner),

the birch skeletonizer (Bucculatrix canadensisella Chambers),

the birch leafminer (Fenusa pusilla (Lepeletier)), the birch

casebearer (Coleophora serratella (L.)), the birch leafminimg

sawflies {Heterarthrus nemoratus (Fallen) and Profenusa

thomsoni (Konow)), and such general forest defoliators as the

saddled prominent {Heterocampa guttivitta (Walker)) and the

gypsy moth (Lymantria dispar (Linneaus)). Defoliation alone

seldom kills otherwise healthy trees. However, growth is

reduced and trees become susceptible to other damaging

agents, particularly the bronze birch borer {Agrilus anxius

Gory), which damages and kills substantial numbers of trees

(5). Cambium miners such as Phytobia spp. attack healthy

trees, and ambrosia beetles like Trypodendron betulae Swaine

or Xyloterinus politus (Say) attack dying trees and recently

cut logs, causing degrade and defects in paper birch wood

(14).

Paper birch trees are very susceptible to discoloration

and decay caused by microorganisms that enter the bole of

the tree through branch stubs or wounds. A defect known as

red heart (cause uncertain) is common in some areas. The

wood is darkened, but may be sound enough for some uses.

Principal decay-causing fungi include Inonotus obliqua (Pers.

ex Fr.) Pilat, Phellinus igniarius (L. ex Fr.) Quel., Pholiota

spp. Stem cankers that ruin a tree for timber purposes are

often caused by Inonotus obliqua, Inonotus glomeratus (Pk.)

Murr., and Nectria galligena Bres. (18). A condition known

as collar crack sometimes arises when the root-rotting fungus

Armillariella mellea (Vahl. ex Fr.) Karst, infects paper birch

trees, cracking the bark at the base of the stem (17).

Postlogging decadence, which sometimes develops following

partial cutting in young birch sawtimber stands, causes

premature mortality.

Browsing by white-tailed deer and moose in paper birch

seedling stands can reduce the stocking of birch and impair

the quality of surviving stems. The yellow-bellied sapsucker

pecks rows of holes through the bark of upper stems of

saplings to mature trees; these holes provide entry for

discoloration and decay organisms and may cause ring shake

(17). A dense band of holes will girdle the stem and kill most

or all of the crown, leading to a weakened state that invites

attack by the bronze birch borer or by decay organisms.

Wildfire has been responsible for the establishment of

many paper birch stands. Controlled burning can be used to

prepare sites for regenerating paper birch (2). Fire is a serious

enemy of established stands of paper birch. Because the bark

of paper birch is thin and highly flammable, even large trees

can be killed by moderate fires (12).

Paper birch is an intolerant species and as a type can be

established and maintained only under some form of evenage management. In the Northeast, blocks, strips, and small

patches can be clearcut. In the Lake States, where summer

drought is common and aspen reproduction often dominates

large clearcuttings, regeneration methods that provide partial

shade for several years are the best means of regenerating

paper birch. Here, the shelterwood method, strip cutting, and

small patches are most likely to succeed.

The arrangement and size of clearcuts depend on stand

and site conditions as well as the manager's objectives. In the

Northeast, block clearcuts of up to 40 acres (16 ha) can be

used on sites that have gentle slopes and good soils where

there are no watershed management conflicts. If a problem

with seed supply is anticipated, 3 to 5 seed trees per acre (7 to

12/ha) should be left, or additional seed should be broadcast.

Regeneration cuttings using the progressive strip method,

clearcutting in small patches of an acre or less, or the

shelterwood method provide more protection to the site,

partial shade for the regeneration, and a better seed supply

than obtained with larger clearcuts. These methods can be

used in the Lake States in general and in the Northeast on

steeper slopes, droughty sites, or in any location where large

clearcuts are undesirable. Although the shelterwood method

is applicable for these conditions, there are little data for

developing treatment prescriptions.

Small patch cuttings are difficult to fit together systematically to cover the entire area of a stand and result in

administrative problems for subsequent stand management.

However, patches are particularly useful for small-area

management where esthetics are important. Patches also can

be used to provide a birch component in stands of hardwoods

managed by the selection system of uneven-age management

(14).

Regardless of the regeneration method, seedbed disturbance is required. The goal of scarification should be to

expose and mix mineral soil with the humus layers on about

50 percent of the regeneration area. Attempts to regenerate

birch from young stands may be hampered by an abundance

of other vegetation, such as Rubus and pin cherry arising

from seed stored in the forest litter (10). Advance reproduction of tolerant species as well as shrub understories also may

hamper reproduction attempts.

Most paper birch regeneration treatments result in stands

with a mixture of species. To ensure survival and increase the

growth of birch, cleaning and weeding and precommercial

thinning treatments are often needed and desirable. These

practices are only recommended for stands with site index 60

(18.3 m) or better (14, 19). Cleaning and weeding, if needed

to insure survival, should be applied when the stands are 5 to

10 years old. To minimize costs, only about 150 crop trees

per acre (370/ha) should be released (14). For rapid growth,

one or more precommercial thinnings should be applied

between ages 25 to 35. Approximately 250 to 300 paper birch

crop trees per acre (620 to 740/ha) should be released (14).

At later stages, a stocking guide (14) should be consulted for

appropriate levels of residual stocking. In previously untreated old stands, two treatments about 5 years apart may be

required to reach this level and avoid opening the stand to

winter snow damage.

The attractive white bark and graceful form of paper

birch make it esthetically pleasing. Single trees or sprout

clumps are often transplanted as ornamentals and shade trees

for landscaping. Stands of birch along roadsides and adjacent

to campgrounds are attractive to hikers, campers, and tourists

traveling the highways. Special practices to perpetuate stands

in these locations include clearing in small patches, early

cleaning and weeding, and favoring birch stump sprouts.

Young regenerating stands of paper birch and associated

species provide prime browse and summer cover for deer and

moose (16). Patches used in conjunction with uneven-age

management create a diversity of vegetation and source of

browse. Paper birch also is an important source of food for

birds. The red poll, pine siskin, and chickadee feed on seeds

and the ruffed grouse eats male catkins and buds during the

winter (16).

Literature Cited

1. Bjorkbom, John C. Production and germination of paper birch seed and

its dispersal into forest opening. Res. Pap. NE-209. Broomall, PA:

U.S. Department of Agricuhure, Forest Service, Northeastern Forest

Experimentstation; 1971. 14 p.

146
10.

Bjorkbom, John C. Stand changes in the first 10 years after seedbed

preparation for paper birch. Res. Pap. NE-238. Broomall, PA: U.S.

Department of Agriculture, Forest Service, Northeastern Forest Experiment Station; 1972. 10 p.

Bjorkbom, John C. Ten-year growth of planted paper birch in old fields

in Maine. Res. Pap. NE-246. Broomall, PA: U.S. Department of

Agriculture, Forest Service, Northeastern Forest Experiment Station;

1972. 6 p.

Cooley, John H. Site requirements and yield of paper birch in northern

Wisconsin. Stn. Pap. 105. St. Paul, MN: U.S. Department of Agriculture,

Forest Service, Lake States Forest Experiment Station; 1962. 11 p.

Conklin, James G. Insect enemies of birch. In: Proceedings, Birch

Symposium; 1969 August 19-21; Durham, NH. Broomall, PA: U.S.

Department of Agriculture, Forest Service, Northeastern Forest Experiment Station; 1969: 151-154.

Eyre, F. H., ed. Forest cover types of the United States and Canada.

Washington, DC: Society of American Foresters; 1980. 148 p.

Fédérer, CA. Paper birch and white oak saplings differ in response to

drought. For. Sei. 26: 313-324; 1980.

Godman, Richard M.; Mattson, Gilbert A. Seed crops and regeneration

problems of 19 species in northern Wisconsin. Res. Pap. NC-123. St.

Paul, MN: U.S. Department of Agriculture, Forest Service, North

Central Forest Experiment Station; 1976; 5 p.

Graber, Raymond E. Summer planting of container-grown northern

hardwoods. Res. Note NE-263. Broomall, PA: U.S. Department of

Agriculture, Forest Service, Northeastern Forest Experiment Station;

1978: 5 p.

Graber, Raymond E.; Thompson, Donald F. Seeds in the organic layers

and soil of four beech-birch-maple stands. Res. Pap. NE-401.

Broomall, PA: U.S. Department of Agriculture, Forest Service, Northeastern Forest Experiment Station; 1978. 8 p.

Hansen, Henry L.; Kurmis, Vilis. Natural succession in north-central

Minnesota. In: Aspen Symposium Proceedings. Gen. Tech. Rep.

NC-1. St. Paul, MN: U.S. Department of Agriculture, Forest Service,

North Central Forest Experiment Station; 1972: 59-66.

12. Hutnik, Russell J.; Cunningham, Frank E. Paper birch {Betula papyrifera

Marsh.) In: Silvics of the forest trees of the United States. H. A.

Fowells, comp. Agrie. Handb. 271. Washington, DC: U.S. Department

of Agriculture; 1965: 93-98.

13. Logan, K. T. Growth of tree seedlings as affected by light intensity. I.

White birch, yellow birch, sugar maple, and silver maple. For. Publ.

1121. Ottawa, ON: Canadian Dep. For.; 1965. 16 p.

14. Marquis, David A.; Solomon, Dale S.; Bjorkbom, John C. A silvicultural guide for paper birch in the northeast. Res. Pap. NE-130.

Broomall, PA: U.S. Department of Agriculture, Forest Service, Northeastern Forest Experiment Station; 1969. 47 p.

15. Quigley, Kenneth L.; Babcock, Harold M. Birch timber resources of

North America. In: Proceedings, Birch Symposium; 1969 August

19-21; Durham, NH. Broomall, PA: U.S. Department of Agriculture,

Forest Service, Northeastern Forest Experiment Station; 1969: 6-14.

16. Shaw, Samuel P. Management of birch for wildlife habitat. In:

Proceedings, Birch Symposium; 1969 August 19-21; Durham, NH.

Broomall, PA: U.S. Department of Agriculture, Forest Service, Northeastern Forest Experiment Station; 1969: 181-183.

17. Shigo, Alex L. Diseases of birch. In: Proceedings, Birch Symposium;

1969 August 19-21; Durham, NH. Broomall, PA: U.S. Department of

Agriculture, Forest Service, Northeastern Forest Experiment Station;

1969: 147-150.

18. Shigo, Alex L. How Poria obliqua and Polyporus glomeratus incite

cankers. Phytopathology 59: 1164-1165; 1969.

19. Tubbs, Carl H. Managers' handbook for northern hardwoods in the

North Central States. Gen. Tech. Rep. NC-39. St. Paul, MN: U.S.

Department of Agriculture, Forest Service, North Central Forest Experiment Station: 1977. 29 p.

147
Loblolly Pine

James B. Baker

Southern Forest Experiment Station

William E. Balmer (retired)

Southeastern Area

Loblolly pine {Pinus taeda L.) is the most important

forest species in the southern United States, where it is

dominant on about 29 million acres (11.7 million ha) and

constitutes over one-half of the standing pine volume (6). Its

natural range encompasses 14 States extending from southern

New Jersey south to central Florida and west to eastern Texas

(17). The range includes the Atlantic Plain, the Piedmont

Plateau, and the southern extremities of the Cumberland

Plateau, the Highland Rim, and the Valley and Ridge

Provinces of the Appalachian Highlands (15). Loblolly pine

is an adaptable species that has been successfully planted

along the periphery of its natural range and has been

introduced on other continents with varying degrees of

success.

Loblolly pine occurs on a wide variety of soils, ranging

from the poorly drained Aquults and Aquods of the coastal

portion of the Atlantic Plain to the relatively dry Psamments,

Udults, and Udalfs of the inland portion of the Atlantic Plain,

Piedmont, and upland Provinces (27). Best growth is on

moderately acid soils having imperfect to poor surface

drainage, a deep medium-textured surface layer, and a

fine-textured subsoil. These soils are common in the uplands

of the Atlantic Plain and on floodplains and terraces of rivers

and streams. Poorest performance is on shallow soils, eroded

soils, and very wet sites.

The climate over most of the loblolly pine range is

humid, warm-temperate with long, hot summers and mild

winters. The frost-free period varies from 5 months in the

northern parts of the range to 10 months along southern

coastal States. Mean annual precipitation varies from 40

inches (1015 mm) in the northeastern and western extremes

of the range to 60 inches (1525 mm) along the Gulf Coast.

The species is found in pure stands and in mixtures with

other pines or hardwoods. When loblolly pine predominates

it forms Loblolly Pine type 81 as described by the Society of

American Foresters (9). Within their natural ranges, longleaf

{Pinus palustris Mill.), shortleaf {P. echinata Mill.), or

Virginia pine {P. virginiana Mill.), are frequent associates on

well drained sites; pond pine (P. serótina Michx.) and spruce

pine {P. glabra Walt.) are common associates on moderately

to poorly drained sites. In the southern part of its range

loblolly may be frequently found with slash pine {P. elliottii

Engelm.).

Loblolly pine is a dominant pioneer arboreal species in

secondary succession on the uplands; however, in later stages

of succession it is commonly found with and often replaced

by a broad spectrum of hardwood species when the successional trend is unchecked. While oaks, gums, and hickories

are the most common associates, species composition varies

by soil, moisture regime, and topographic position. The

hardwoods are more shade tolerant than loblolly, and often

form dense understories in pine stands. When the pines are

harvested or die of natural causes, the understory hardwoods

tend to dominate the site unless they are controlled.

Loblolly pine is easily regenerated by natural or artificial means. It is commonly regenerated by hand or machine

planting 1-0 nursery-grown bareroot or containerized seedlings.

Seedlings are generally planted at spacings to provide approximately 500 to 800 trees per acre (1240 to 1980 trees/ha),

depending on landowner objectives and expected survival

rates. Loblolly can also be reproduced on suitable sites by

direct seeding 0.25 to 1.0 pounds per acre (0.3 to 1.1 kg/ha)

of high quality bird- and rodent-repellent treated seed.

Direct-seeding is especially suitable on inaccessible terrain or

rocky soils. When artificial regeneration methods are used,

attention should be given to the provenance or geographical

origin of the seed. Unless better sources are known, an effort

should be made to obtain seed from trees of native stock

growing as close as possible to the planting site. In most

cases, seed should be collected from good phenotypes that

are within 100 miles (161 km) horizontally and approximately 1,000 feet (305 m) vertically of the point where it is to

be used. When there is an adequate seed crop, a receptive

seedbed, and adequate soil moisture, loblolly pine stands can

be regenerated by natural seeding. Successful regeneration of

loblolly pine by natural or artificial means usually requires

site preparation where hardwood competition exists.

Seed production of loblolly pine varies by physiographic

region, climatic factors, and tree or stand condition. In the

southern coastal portions of the Atlantic Plain, loblolly is

generally a prolific and consistent seed producer, but in some

of the inland portions of the Atlantic Plain, the Piedmont, and

in the western extremities of its range, seed production is

often lower and more erratic. Even though year-to-year

fluctuations in seed production occur, loblolly usually produces some seeds every year and good seed crops normally

occur at intervals of 3 to 6 years. More than 80,000 sound

seeds per acre (197 680 seeds/ha) is considered a good seed

crop; 30,000 to 80,000 seeds per acre (74 130 to 197 680/ha)

is an average crop, while less than 30,000 seeds per acre (74

130/ha) is considered marginal, depending on seedbed characteristic and weather conditions. During bumper seed years,

more than a million sound seeds per acre (2.5 million/ha) are

often produced. Seed production of individual trees increases

with tree age, size, and freedom from crown competition.

Enough seed may be produced in widely spaced stands by

age 25 to regenerate a stand; however, trees at 40 years

generally produce 3 to 5 times more seeds than those of 25

years. Rotations shorter than 30 years usually do not lend

themselves to natural regeneration.

Loblolly pine seedfall usually begins in October with the

bulk of the seeds being released in November and early

December. Seedfall is hastened by dry, warm, windy weather

and retarded by cool, wet weather. Seed dispersal in or

adjacent to a stand varies with height and stocking level of

the seed source trees, magnitude of the seed crop, terrain,

and weather and wind conditions at time of seedfall. The

effective seeding distance ranges from 200 to 300 feet (61 to

91 m) in a downwind direction from the seed source and 75 to

100 feet (23 to 30 m) in other directions. Viability of loblolly

pine seeds varies with seed crop size and the month that the

148
seed is dispersed. Seed viability is often lower in years of

poor seed crops and in seeds dispersed late in the season.

Seed germination as well as seedling establishment and

survival are strongly affected by weather conditions, soil

moisture, seedbed condition, age of the seedbed, and soil

texture. Seedbed preparation, either by scarification or burning,

greatly increases seed germination and seedling survival.

Scarifying the seedbed exposes mineral soil and increases

contact of the seeds with moist soil surfaces. During years,

with good seed crops, soil disturbance from logging may be

adequate, particularly when combined with a pre- or postharvest

prescribed bum. Favorable seedbeds usually exist for only

one year after disturbance, after which they rapidly deteriorate.

Loblolly pine is intolerant to moderately tolerant of

shade. Its shade tolerance is similar to shortleaf and Virginia

pines, less tolerant than most hardwoods, and more tolerant

than slash and longleaf pines (9, 28, 29). Loblolly is

moderately tolerant of drought. Extremely high summer

temperatures and drought, expecially in areas of low summer

rainfall and on sites that normally have high summer water

tables, often cause mortality of seedlings and saplings and in

some cases even larger trees are killed. Loblolly pine

seedlings or saplings cannot withstand prolonged flooding.

Complete inundation for more than two weeks during the

growing season results in significant mortality. Larger trees

are classed as moderately tolerant of flooding, since they can

typically survive one season, but usually succumb during the

second growing season if they are continuously in a flooded

condition. Loblolly pine is basically a wind-firm species;

however, some wind damage can occur in large dominant

trees growing on shallow soils. Wind damage is more likely

to occur in stands that have had a recent heavy thinning. Ice

and cold damage can also be a problem in some parts of the

loblolly range. Damage resulting from low or freezing

temperatures is confined primarily to seedling injury or

mortality. Sapling-size and larger trees are often damaged by

ice or glaze storms in the form of branch and stem breakage,

severe bending, and in some cases uprooting of trees. Ice

damage is usually more severe in plantations that have been

recently thinned or fertilized and in heavily stocked stands

made up of slender, small-crowned trees. Even though

loblolly pine occurs on a wide range of sites, there are

soil-site limitations that affect its growth and development.

For example, loblolly pine does not do well on deep, dry

sands (sandhills), soils having a shallow hardpan but no

clayey horizon (Spodosols), or extremely wet sites. The

adverse properties associated with these sites result in stress

that often leads to insect and disease problems.

Loblolly pine expresses dominance early, and various

crown classes develop rapidly under competition on good

sites; but in dense stands on poor sites, expression of

dominance and crown differentiation are slower. Competition from hardwoods can seriously reduce merchantable

volume in pine stands. For example, a study in North

Carolina indicated that 10 square feet per acre (2.3 m^/ha) of

competing hardwood basal area at stand age 10 would reduce

merchantable volume of pine more than 50 percent by age 20

(3). In Arkansas, understory hardwood competition in a 47-

year-old pine stand has reduced cubic-foot volume growth by

43 percent and board-foot volume growth by 59 percent (11).

Trees that have developed in a suppressed condition respond

in varying degrees to release. Increases in diameter growth

after release are related to live crown ratio and crown growing

space, but trees of large diameter generally respond less than

trees of small diameter (10). Trees with well-developed

crowns usually respond best to release. Trees long suppressed

may also grow much faster in both height and diameter after

release but never attain the growth rate of trees that were

never suppressed.

Dense natural stands of loblolly pines usually respond

well to precommercial thinning (16). To insure the best

volume gains, stocking should be reduced to 500 to 700

stems per acre (1240 to 1730 stems/ha) by age 5. Although

commercial thinnings seldom increase cubic volume yields of

loblolly pine, light thinnings that salvage suppressed or dying

trees can increase net yields by 10 to 20 percent. When

managing for sawtimber, thinnings increase diameter growth

of residual trees and allow growth to be put on the better trees

in the stand, thus maximizing sawlog volume growth and

profitability. Thinnings also provide intermediate returns on

investment.

Seedling height growth occurs annually in series of two

to five growth flushes and is dependent on such variables as

temperature, day length, soil moisture, nutrients, competition,

and genetics. On the best sites, loblolly pine averages 3 to 4

feet (0.9 to 1.2 m) in height growth per year through the

sapling stage.

Growth of loblolly pine stands, from sapling to maturity,

is inherently good when compared to most hardwood competitors and on many sites doubles or triples the production of

common associates (28). Individual trees tend to express

dominance at an early age. The most vigorous individuals

and those located in favorable microsite environments become dominants as the stand develops. In sapling stands,

differences in growth rates of individual trees become evident

when competition between the individual trees begins.

Diameter growth of individual trees generally increases

as crown surface area and live crown ratio increase, with

optimal diameter growth occurring when trees have at least a

40 percent live crown ratio. Annual diameter growth is

greatest within the crown and decreases with increased

distance below the crown. This phenomenon causes the bole

of a loblolly pine tree to become cylindrical with increasing

age.

Yield estimates for natural, even-aged loblolly pine in

fully stocked stands were first made more than 50 years ago

(1, 26). Additional estimates have been made in more recent

years for stands of various stocking level (5, 7, 18, 19, 22,

23). Normal yields of natural, even-aged loblolly pine stands

on good sites, such as those with a site index of 90 feet (27.4

m) at 50 years, have ranged from 1,900 cubic feet per acre

(133.0 m^/ha) in trees 3.6 inches (9 cm) diameter at breast

height (d.b.h.) and larger at age 20 to 6,110 cubic feet per

acre (427.7 m^^/ha) at age 60. Comparable board foot yields

from trees 9.6 inches (24 cm) and larger in the same stands

have ranged from 2,100 board feet (fbm) using the International '/4-inch rule (420 cubic feet)' per acre (29.4 nr'/ha) to

40,000 fl5m (8,000 cubic feet) per acre (560.0 m^/ha). Mean

annual cubic volume growth generally culminates at about

age 40 on these sites with appproximately 115 cubic feet per

acre (8.0 m^/ha). As a result of larger sawtimber merchantability limits, mean annual board foot growth culminates at

about age 50 at a rate of 680 fbm (136 cubic feet) per acre

(9.5 m^/ha)^

Yields of planted loblolly pine vary with plantation age,

site quality, number of trees planted, and interactions of these

variables. Yields generally increase with age and site quality.

Depending on the site and the product objectives, stands of

lower densities or wider planting spacings often produce

more sawlog volume and dollar value than stands with high

densities. Closer spacings tend to produce higher total cubic

' Cubic foot and metric conversions of measurements expressed in board

feet should be viewed as estimates because of the assumptions involved in

the conversion process.

^ Langdon, O. Gordon. Loblolly pine. 1981. Unpublished data: table

supplied to author by O. Gordon Langden, North Carolina University,

Raleigh, N.C.

149
volumes at younger ages than do wider spacings; however,

average tree sizes are larger on wider spacings than on closer

ones. If sawtimber is a primary management objective, then

wider spacings or lower densities would be advantageous. In

Arkansas, through intensive culture (heavy thinning, understory control, and pruning), an average d.b.h. of 15 inches

(38 cm) and 13,000 fbm (International 'Á-inch rule) (2,600

cubic feet) per acre (182.0 m^/ha) were achieved in 27 years

(8). Stands under conventional management produced 40

percent more cubic volume but 60 percent less board foot

volume in the same period. Average yields of loblolly pine

plantations with 750 seedlings per acre (1,850 seedlings/ha)

on good sites for various locations within its range have

increased from 880 cubic feet per acre (61.6 m-^/ha) at age 15

to 2,715 cubic feet per acre (190.0 m^/ha) at age 30.^ Mean

annual increment for these stands have averaged 90 cubic feet

per acre (6.3 m^/ha).

Growth and yield in uneven-aged loblolly pine stands is

dependent on stand structure, stocking, and site quality. On

good sites in southern Arkansas, where the site index is 90

feet (27.4 m) at 50 years, managed uneven-aged loblolly pine

stands that are well-stocked have averaged 3 square feet per

acre (0.7 m^/ha) of basal area growth (20), 80 cubic feet per

acre (5.6 m^/ha) of merchantable or 432 fbm per acre of

sawlog volume growth per year for a 29-year period (21). On

somewhat poorer sites in the Georgia Piedmont where the site

index is 75 feet (22.9 m) at 50 years, annual growth has

averaged 76 cubic feet per acre (5.3 m^/ha) or 319 fbm per

acre over a 21-year period (4).

Insects and diseases that affect loblolly pine at various

stages of development are described by Baker (2) and

Hepting (14). Loblolly pine serves as host to a multitude of

insect pests. With few exceptions, the majority of the insects

that attack loblolly are insignificant in terms of damage or

mortality. The most serious insect pests are: bark beetles,

particularly the southern pine beetle {Dendroctonusfrontalis

Zimmermann), whose attacks may result in extensive mortality,

and pine engraver beetles {Ips spp.) which can cause death of

isolated or small groups of trees; pine tip moths (Rhyacionia

spp.) which often infest young trees; seedling debarking

weevils {Hylobius spp. and Pachylobius spp.) which sometimes girdle and kill young seedlings up to 0.5 inches (1.3

cm) in d.b.h.; and cone and seed insects {Dioryctria spp. and

Leptoglossus spp.) which can materially reduce seed crops.

Loblolly pine is generally the preferred host of the southern

pine beetle, which is the most destructive insect pest for this

species (24). Most infestations originate in stands that are

under stress because of poor site, adverse weather, overstocking,

or overmaturity. Once a build-up of southern pine beetles

occurs, adjacent well-managed stands may also be attacked.

Preventive measures include avoidance of planting off-site

and maintenance of vigorous stands through such silvicultural practices as controlling density through thinnings and

harvesting trees at or before maturity.

The major disease problem in loblolly pine is fusiform

rust (Cronartium quercuum (Berk.) Miy. ex Shirai f. sp.

fusiforme Burds. & Snow). It is recommended that seedlings

from rust resistant seed sources be used in areas of high

fusiform incidence. Other diseases that can affect loblolly

pine are: seedling susceptibility to black root rot (Fusarium

spp., Macrophomina spp., and possibly others); root rot by

Heterobasidium annosum (Fr.) Bref, in thinned stands; and

heart rot in old stands with Phellinus pini (Thore ex Fr.) A.

Ames in the bole and mostly Phaeolus schweinitzii (Fr.) Pat.

in the butts.

Although young loblolly pine stands less than 12 to 15

feet (3.7 to 4.6 m) tall are highly susceptible to wildfire,

prescribed fire, when used judiciously, is an excellent management tool for stands over 15 feet (4.6 m) tall. Prescribed

fire is effective for manipulating understory vegetation,

reducing excessive fuel (hazard reduction), disposing of

logging slash, preparing planting sites and seedbeds, and

improving wildlife habitat. Responses of the understory to

prescribed fire varies with frequency and season of burning.

Periodic winter burns will keep hardwood understories in

check, while a series of annual summer bums will usually

reduce vigor and increase mortality of the hardwood rootstocks.

A series of prescribed bums, such as a winter bum followed

by three annual summer burns prior to a harvest cut, has been

more effective than disking in controlling competing hardwood vegetation and in improving pine seedling growth in

the Atlantic Coastal Plain after establishment of natural

regeneration (25).

Either even-aged or uneven-aged management systems

can be used with loblolly pine. Even-aged stands can be

established by natural or artificial regeneration methods.

Uneven-aged stands are usually maintained by selection

cutting methods that promote natural regeneration. Evenaged management is generally more practical and economically efficient on such large holdings as industry lands and

the National Forests. Even-aged methods allow cultural

operations to be concentrated in time and space and permit

management areas to be easily defined and treated. The most

common regeneration method used in the last decade on most

southern forest lands has been clearcutting and planting.

Planting has proven to be a reliable regeneration method for

loblolly and has the advantages of providing control of

spacing and stocking, providing for rapid and timely restocking,

allowing the use of genetically improved seedlings, and

permitting shorter rotations. Also, planting is not dependent

on an on-site seed source. However, clearcutting, followed

by site preparation and planting, is the most costly regeneration method. It requires a large capital investment and there is

a long waiting period before financial retums can be realized

from a given stand. But for large forest tracts, regulation of

yields can be set up to provide a steady sustained flow of

multiple forest products and income over time.

A variety of silvicultural systems are suited to loblolly

pine. Reproduction cutting methods such as seed-tree,

shelterwood, and clearcutting establish even-aged stands

while selection cutting develops or maintains an uneven-aged

forest.

Success of the seed-tree method depends on proper

manipulation of the seed supply and seedbed conditions. The

reproduction cut should be made prior to seed fall in a good

seed year leaving 4 to 12 evenly distributed, well-formed

trees per acre (10 to 30 trees/ha). The number of seed trees

left depends on tree size and site conditions. The seed trees

should be at least 10 inches (25.4 cm) d.b.h., but preferably

12 to 16 inches (30.5 to 40.6 cm) (31). Crown release of the

seed trees 3 years before the main harvest cut can increase

seed production of loblolly pines that have been grown in

closed stands. Disking prior to seed fall or prescribed buming

in advance of the reproduction cut will prepare a seedbed and

assist in controlling small hardwoods. Larger hardwoods are

often controlled with herbicides. Well-stocked stands usually

result if adequate seed fall occurs within a year after seedbed

preparation and the reproduction cut. Delayed seed fall may

require the receptive seedbed to be maintained—normally by

prescribed fire. The seed trees should be removed within 3 to

5 years after adequate reproduction has become well established.

This would be approximately 1,000 well-distributed seedlings per acre (2470 seedlings/ha).

The shelterwood system has been most successful in the

central and eastern parts of the range, where greater summer

rainfall enhances seedling establishment. A two-cut shelterwood

150
system is normally used in loblolly pine. In the first cut, all

but 20 to 30 of the best seed trees per acre (49 to 74 trees/ha)

are removed. The leave trees should comprise 20 to 30 square

feet of basal area per acre (4.6 to 6.9 m^/ha). Prescribed

burning is the most practical method of site preparation and

control of small hardwoods, and should be done before the

first cut is made. The overwood, which helps retard the

growth of competing hardwoods, is usually removed as the

second cut within 5 years after establishment of reproduction..

Shelterwood cutting can result in too much reproduction,

particularly when a good seed crop occurs following intensive site preparation. If overly dense stands develop they

should be precommercially thinned within 3 to 5 years after

overstory removal.

The clearcutting method can be used to naturally regenerate small blocks, patches, or narrow strips, if there is an

available seed source from adjacent stands. The longer axis

of the clearcut areas should be made perpendicular to the

direction of prevailing winds and in most cases the clearcut

should not exceed 300 to 400 feet (approximately 90 to 120

m) in width to insure adequate seeding over the entire area.

Larger clearcut areas can be regenerated naturally with either

seed- or seedlings-in-place. Seed-in-place involves clearcutting

the stand after peak seedfall but prior to germination. It

requires logging during the late fall and winter following a

good seed fall.

Seedlings-in-place involves clearcutting the stand during the summer after seedlings have become established.

Ample seed crops are necessary for successful use of these

methods and a preharvest prescribed bum is often recommended.

With clearcutting methods other than seed- or seedlings-inplace, a prescribed bum following logging is beneficial for

slash disposal, site or seedbed preparation, and control of

small hardwoods. The reproduction may also require additional release from hardwood competition within 2 to 5 years

after establishment.

If the management objectives are to maintain an unevenaged stand, where seedlings, saplings, pulpwood, and small

and large sawtimber are all represented, and to harvest at

relatively frequent intervals, selection cutting is the best

alternative. The selection method involves periodic cutting,

at 5 to 10 year intervals, of selected trees from all merchantable diameter classes. In fully stocked stands, harvest-cut

volumes generally approximate growth for the cutting period

or cutting cycle. In stands that are not fully stocked, only a

portion of the periodic growth is cut. Trees selected for

harvest can be single isolated trees or groups of trees. If

regeneration is not necessarily needed following a particular

harvest cut, single-tree selection is suitable. However, if

regeneration is badly needed, the group selection or a

combination of group and single-tree selection may be

required. In many cases, site and seedbed preparation is

achieved by the logging operation and the use of chemicals to

control larger competing hardwoods. In some cases more

intensive control of competing vegetation is required. This

can be accomplished mechanically with chemicals and

sometimes with prescribed fire. However, blanket application of prescribed burning or nonselective herbicides should

be avoided where new regeneration is present. Throughout

much of the loblolly pine range, uneven-aged management is

an effective means of rehabilitating understocked stands and

is especially suitable for small forest properties. It requires a

low capital investment, provides periodic income without

interruption for stand regeneration, permits net income to be

spread out over time, and affords a reserve of large timber to

take advantage of favorable market conditions.

Silvicultural systems that depend primarily on natural

regeneration have some inherent shortcomings that must be

accepted. Natural regeneration results in less control over

spacing and initial stocking than does planting and some

forms of direct seeding. The irregular stands that develop can

cause problems with mechanical harvesting and provide poor

access for fire equipment. If overly dense natural stands

become established, precommercial thinning is often required to maintain maximum growth of crop trees and

promote early sawlog production. In addition, managing for

natural regeneration does not permit the use of genetically

improved stock; however, it does permit leaving seed trees of

good form, fast growth, and disease resistance, all of which

contribute to stand improvement. Despite the shortcomings

of natural regeneration systems, they can be used effectively

and cheaply in many situations. For example, on those

nonindustrial holdings or on sensitive sites where the vigorous and expensive site preparation measures required for

artificial regeneration are not feasible, natural regeneration

systems may be the only alternative.

Management of loblolly pine involves many important

multiple-use opportunités such as maintenance of wildlife

habitat, protection of rare and endangered species, urban

forestry, soil stabilization and erosion control, and biomass

and energy production.

Natural loblolly pine stands as well as intensively

managed plantations provide habitat for a variety of game

and nongame wildlife species. The primary game species that

inhabit pine and pine-hardwood forests include white-tailed

deer, gray and fox squirrel, bobwhite quail, mourning doves,

wild turkey, and rabbits. Some of these species utilize the

habitat through all stages of stand development while others

are attracted for only a short time during a particular stage of

development. A loblolly pine plantation can provide forage

for deer, for example, only from the time of planting to

crown closure. Without modifying management practices

this usually occurs in 8 to 10 years. Management modifications such as wider planting spacings and early and frequent

thinnings will delay crown closure and periodic prescribed

bums will stimulate wildlife food production. Bobwhite quail

tend to use the plantations until a decline in favored food

species occurs. As the habitat deteriorates in plantations with

crown closure, deer and quail usually move to mature pine or

pine-hardwood forests (13), or to other newly established

plantations. Pine seeds provide a major food source for many

rodents and birds. Turkeys also inhabit upland pine and

pine-hardwood forests, and do particularly well on large

tracts of mature timber with frequent openings and where

prescribed burning is conducted (13).

Loblolly pine and mixed pine—hardwood stands provide excellent habitat for nongame animals and birds. Pine

lands are the chief habitat for some birds such as the pine

warbler, brown-headed nuthatch, and Bachman's sparrow

(12).

Old-growth loblolly stands are very important to the

existence of the red-cockaded woodpecker. Large loblolly

pine trees are favorite roosting places for many birds and

provide an important nesting site for ospreys and the bald

eagle.

Another important special use of loblolly pine is in

urban forestry and specialty plantings. Loblolly pines are

often used as shade trees, and for wind and noise barriers in

urban areas throughout the South. It has also been used

extensively for soil stablilization and erosion control in areas

subject to severe surface erosion and gullying (32) as well as

on roadbanks (30). Loblolly pine provides rapid growth and

site occupancy and good litter production for these purposes.

In the future, loblolly pine may provide an important

wood energy resource. Biomass for energy is presently being

obtained from precommercial thinnings and from logging

151
residue in loblolly pine stands. Utilization of these energy

sources are predicted to increase, and loblolly pine energy

plantations may become a reality.

Literature Cited

1. Ashe, W. W. Loblolly or North Carolina pine. Survey Bulletin 24.

Raleigh, NC: North Carolina Geological and Economic Survey. 1915;

176 p.

2. Baker, Whiteford L. Eastern forest insects. Misc. Pub. 1175. Washington,

DC: U.S. Department of Agriculture; 1972. 642 p.

3. Balmer, William E.; Utz, Keith A.; Langdon, O. Gordon. Financial

returns from cultural work in natural loblolly pine stands. South. J.

Appl. For. 2: 111-117; 1978.

4. Brender, E.V. Silviculture of lolbolly pine in the Georgia Piedmont.

Report 33. Macon, GA: Georgia Forestry Research Council; 1973.

74 p.

5. Brender, E. V.; Clutter, J. L. Yield cf even-aged natural stands of

loblolly pine. Report 23. Macon, GA: Georgia Forestry Research

Council; 1970. 7 p.

6. Brender, Ernest V.; Belanger, Roger P.; Malac, Barry F. Loblolly pine.

In: Choices in silviculture for American forests. Washington, DC:

Society of American Foresters; 1981: 37—45.

7. Burkhart, H. E.; Parker, R. C; Strub, M. R.; Oderwald, R. G. Yields

of old-field loblolly pine plantations. Pub. FWS —3 —72. Blacksburg,

VA: Virginia Polytechnic Institute and State University; 1972. 51 p.

8. Burton, J. D. How a timberland owner can grow sawlogs in a pulpwood

rotation. Forest Farmer 36: 8-9, 20; 1976.

9. Eyre, F. H., ed. Forest cover types of the United States and Canada.

Washington, DC: Society of American Foresters; 1980. 148 p.

Fowells, H. A., comp. Silvics of forest trees of the United States.

Agrie. Handb. 271. Washington, DC: U.S. Department of Agriculture;

1965. 762 p.

Grano, Charles X. Small hardwoods reduce growth of pine overstory.

Res. Pap. SO-55. New Orleans, LA: U.S. Department of Agriculture,

Forest Service, Southern Forest Experiment Station; 1979. 9 p.

12. Halls, L. K., ed. Southern fruit-producing woody plants used by

wildlife. Gen. Tech. Rep. SO- 16. New Orleans, LA: U.S. Department

of Agriculture, Forest Service, Southern Forest Experiment Station;

1977. 235 p.

13. Halls, L. K.; Stransky, J. J. Atlas of southern forest game. New

Orleans, LA: U.S. Department of Agriculture, Forest Service, Southern

Forest Experiment Station; 1971. 24 p.

14. Hepting, G. H. Diseases of forest and shade trees of the United States.

Agrie. Handb. 386. Washington, DC: U.S. Department of Agriculture;

1971. 658 p.

15. Hunt, Charles B. Physiography of the United States. San Francisco,

CA: W. H. Freemont Co.; 1967. 480 p.

10

11

16. Jones, E. P., Jr. Precommercial thinning for slash and loblolly pines. In:

Proceedings, Symposium on management of young pines. 1974 December 3-5; Charleston, SC. Atlanta, GA: U.S. Department of Agriculture,

Forest Service, Southeastern Area, State and Private Forestry, Southern

and Southeastern Forest Experiment Stations. 1974: 229-233.

17. Little, Elbert L., Jr. Adas of United States trees; Volume 1. Conifers

and important hardwoods. Misc. Pub. 1146. Washington, DC: U.S.

Department of Agriculture; 1971. 218 p.

18. MacKinney, A. L.; Chaiken, L. E. Volume yield and growth of loblolly

pine in the mid-Atlantic coastal region. Tech. Note 33. Asheville, NC:

U.S. Department of Agriculture, Forest Service, Southeastern Forest

Experiment Station; 1939. 58 p.

19. Murphy, Paul A.; Stemitzke, Herbert S. Growth and yield estimation

for loblolly pine in the West Gulf. Res. Pap. SO-154. New Orleans,

LA: U.S. Department of Agriculture, Forest Service, Southern Forest

Experiment Station; 1979. 8 p.

20. Murphy, P. A.; Farrar, R. M. Interim models for basal area and volume

projection of uneven-aged loblolly-shortleaf pine stands. South. J.

Appl. For. 6(2): 115-119; 1982.

21. Reynolds, R. R. Twenty-nine years of selection timber management on

the Crossett Experimental Forest. Res. Pap. SO-40. New Orleans, LA:

U.S. Department of Agriculture, Forest Service, Southern Forest

Experiment Station; 1969. 19 p.

22. Schumacher, F. X.; Coile, T. S. Growth and yield of natural stands of

the Southern pines. Durham, NC: T. S. Coile; 1960. 115 p.

23. Sullivan, A. D.; Clutter, J. L. A simultaneous growth and yield model

for loblolly pine. Forest Science 18(1): 76-86; 1972.

24. Thatcher, Robert C; Searcy, Janet L.; Coster, Jack E.; Hertel, Gerard

D., eds. The southern pine beetle. Tech. Bull. 1631. Washington, DC:

U.S. Department of Agriculture; 1980. 267 p.

25. Trousdell, K. B. Disking and prescribed burning: sixth year residual

effects on loblolly pine and competing vegetation. Res. Note SE-133.

Asheville, NC: U.S. Department of Agriculture, Forest Service, Southeastern Forest Experiment Station; 1970. 6 p.

26. U.S. Department of Agriculture, Forest Service. Volume yield and

stand tables for second-growth Southern stands. Misc. Pub. 50. Washington,

DC: U.S. Department of Agriculture; 1929. 202 p.

27. U.S. Department of Agriculture, Soil Conservation Service. Soil

Taxonomy: a basic system of soil classification for making and

interpreting soil surveys. Agrie. Handb. 436. Washington, DC: U.S.

Department of Agriculture; 1975. 754 p.

28. Wahlenberg, W. G. Loblolly pine. Its use, ecology, regeneration,

protection, growth, and management. Durham, NC: Duke University;

School of Forestry; 1960. 603 p.

29. Wenger, K. F. Silvical characteristics of loblolly pine. Res. Pap.

SO-98. Asheville, NC: U.S. Department of Agriculture, Forest

Service, Southeastern Forest Experiment Station; 1958. 32 p.

30. Williston, H. L. Guidelines for planting and maintaining loblolly pine

and other cover for roadbank stabilization. Tree Planters Notes 22(2):

14-17; 1971.

31. Williston, Hamlin L.; Balmer, William E. Managing for natural

regeneration. Forest Management Bull. Atlanta, GA: U.S. Department

of Agriculture, Forest Service, Southeastern Area, State and Private

Forestry; 1974. 6 p.

32. Williston, H. L.; Ursic, S. J. Planting loblolly pine for erosion control:

a review. Tree Planters Notes 30(2): 15-18. 1979.

152
Longleaf Pine

William D. Boyer

Southern Forest Experiment Station

Donald W. Peterson

Southern Region

The natural range of longleaf pine (Pinas palustris

Mill.) includes most of the Atlantic and Gulf Coastal Plains

from southeastern Virginia, south to central Florida and west

to eastern Texas, with extensions into the Piedmont, Ridge

Valley, and Mountain Provinces of Alabama and northwest

Georgia (9, 20). Longleaf pine forests may have occupied as

much as 60 million acres (24.3 million ha) before settlement

(25). Intensive exploitation since pioneer days and a lack of

regeneration efforts have shrunk the once vast longleaf pine

forests to less than 5 million acres (2.0 million ha) today.

Much of the remaining forests are natural second growth that,

mostly by chance, sprang up following logging of the

old-growth timber. Longleaf pine remains a commercially

important timber tree throughout much of its natural range,

although close to 60 percent of the standing volume is found

in Alabama, Florida, and Georgia (24).

Longleaf pine occurs on a wide variety of sites, from

low, wet, poorly drained flatwoods near the coast to dry,

rocky mountain ridges. Elevations extend from near sea level

on the Lower Coastal Plain up to about 2,000 feet (610 m) in

the Alabama mountains. For the most part, the species is

found on the coastal plains at elevations between sea level

and 600 feet (185 m). Soils are derived from marine

sediments and range from deep, coarse, excessively drained

sands of the sandhills and sand ridges to poorly drained clays.

Throughout most of the coastal plains, surface soils are

sandy, acid, low in organic matter, and relatively infertile.

Climate in the longleaf pine region is warm and wet,

with hot summers and mild winters. Annual mean temperatures range from 60° to 74° F (15.6° to 23.3° C). Length of

the frost-free period ranges from 210 days in North Carolina

and North Alabama to more than 300 days in central Florida.

Annual precipitation ranges from 43 to 68 inches (1090 to

1725 mm). Precipitation is the lowest, from 43 to 50 inches

(1090 to 1270 mm), in the Carolinas and Texas and highest,

from 59 to 68 inches (1500 to 1725 mm), on the Gulf Coast

of Alabama, northwest Florida, Mississippi, and eastern

Louisiana. Fall is the driest time of the year, although dry

spells are common in the spring and may occur at any season.

The principal longleaf pine cover types, as described by

the Society of American Foresters, are the Longleaf Pine

(type 70), Longleaf Pine-Scrub Oak (type 71), and Longleaf

Pine-Slash Pine (type 83) (14). Longleaf pine may also

occur as a minor component of other forest types within its

range. The longleaf pine forest is considered a fire subclimax

type that has developed and maintained itself in close

association with periodic fires. The species is resistant to fire.

It is also very sensitive to competition, especially as seedlings.

This has restricted longleaf largely to sites that have been

periodically burned and to poor sites supporting only a sparse

cover of competing vegetation. Longleaf pine is a pioneer

species that, given an adequate seed source, can invade

abandoned fields or areas cleared by a catastrophic event

such as blowdown or severe wildfires (6, 14).

Once established, longleaf pine tends to perpetuate itself

in areas where fires occur frequently. Needle litter from

overstory pines support hot surface fires. These fires slow or

prevent the encroachment of hardwoods and other pines; they

also provide a favorable seedbed by removing accumulated

litter and exposing mineral soil. Grass-stage longleaf seedlings are highly resistant to fire and can even tolerate growing

season fires in the open or under light pine overstories. But

under medium to heavy pine overstories, most seedlings

cannot survive the combination of slow growth resulting

from overstory competition plus hot fires fueled by abundant

needle litter. Therefore, longleaf pine usually orginates in

openings or under light parent overstories where less intense

fires still suppress hardwoods but do little harm to vigorous

longleaf seedlings.

Reduction in the frequency or exclusion of fire leads to

substantial changes in the longleaf pine ecosystem. The

open, park-like longleaf forests, with an understory comprised mainly of grasses and forbs, is invaded and eventually

superceded by hardwoods as succession on these upland sites

moves through pine-hardwood types toward eventual dominance by climax hardwoods. Dominance by other pines may

precede hardwoods where presence of a slash pine (Pinus

elliottii Engelm.) or loblolly pine {P. taeda L.) seed source

permits these species to gain a foothold on longleaf uplands.

In the absence of fire, the grass-stage of longleaf pine

seedlings gives them a great competitive disadvantage in the

presence of the fast-growing seedlings of other pines and

hardwoods.

Longleaf pine has long been considered the most difficult of the southern pines to regenerate, either naturally or

artificially. Although planning and care are required, the

species can be and has been regularly regenerated naturally

(13), by direct seeding (22), and also by planting (21).

Longleaf pine is a poor seed producer compared to the

southern pines, and good cone crops are infrequent. Stand

and site characteristics are most important in evaluating

potential seed production (12). Tree size, crown class, stand

density, site quality, and genetic predisposition are all

important factors influencing seed production. Equally important are favorable weather conditions at critical periods to

insure good seed crops. The best seed producers are dominant trees with well-developed crowns, a diameter at breast

height of 15 inches (38 cm) or more, and a history of past

cone production. Given an average site and the optimum

number and quality of seed-bearing trees, seed crops adequate for regeneration should occur, on the average, once

every 4 years (13). The best seedling establishment and

survival is usually associated with the good seed years.

Longleaf pine has large winged seeds that are dispersed

by wind. Seed fall begins in late October and continues

through November, with most seeds shed over a period of 2

to 3 weeks. Dispersal range is short, with 71 percent of sound

seeds falling within a distance of 66 feet (20.1 m) of parent

trees.

Seeds require contact with mineral soil for satisfactory

germination and establishment. Longleaf seeds, with their

large wings, cannot easily reach mineral soil through a heavy

153
cover of grass and litter. The accumulated material must be

removed before seed fall, either mechanically or by burning.

Seedbed bums within a year of seed fall will usually provide

an adequate seedbed (13).

Seeds germinate soon after they are dispersed, often in

less than a week, if moisture and temperature conditions are

favorable. Prompt germination reduces the period of exposure to seed predators, although these seedlings are then

exposed to other risks (13). Most seedling losses can be

expected during the first year after establishment. Thereafter,

risk of loss is substantially reduced.

Competition and brown-spot needle blight (Scirrhia

acicala (Deam.) Sigg.) are the two factors with the greatest

impact on seedling development after the first year. Longleaf

seedlings can survive for years, even under a dense overstory

of parent pines, provided they are not burned before reaching

a fire resistant size. Growth, however, is very slow (1). Once

released from overstory competition, longleaf seedlings will

respond promptly with increased growth (5). Brown-spot

infection rarely reaches serious levels on seedlings under a

pine overstory (4), and 10 to 20 percent of a natural seedling

stand usually exhibits resistance to brown-spot (3).

Growth rate of longleaf pine seedlings varies considerably among individuals of the same age, and vigorous,

brown-spot resistant seedlings express early dominance. A

seedling stand will rapidly develop a range of size classes,

reducing the risk of stagnation and consequent need for

precommercial thinning. A low level of competition permits

early initiation of height growth by grass-stage seedlings.

Plantings on well-prepared sites can have the majority of

seedlings in height growth by the end of the second growing

season. Early initiation of height growth averts a brown-spot

problem, as the disease usually takes 2 to 3 years to reach

serious levels, and only grass-stage seedlings are affected.

Seedling stands should be protected from livestock, as

light-to-moderate cattle grazing causes some mortality plus

reduced growth of survivors (2). Hogs can completely

destroy a seedling stand (25).

Longleaf pine's reputation as a slow-growing tree may

not be deserved. Growth on relatively poor sites can equal or

exceed that of other pines. Natural stands on medium sites,

where the site index is between 70 and 80 feet (21.3 to 24.4

m) at 50 years, can produce from 1.2 to more than 1.6 cords

(108 to 144 cubic feet) per acre (7.6 to 10.1 m^/ha) of mean

annual increment to age 30, with 5-year periodic annual

increments of 2 to 4 cords (180 to 360 cubic feet) per acre

(12.6 to 25.2 m'^/ha) between ages 20 and 30. The optimum

density range for maximizing early volume yield is 500 to

1,000 trees per acre (1240 to 2470 trees/ha) (16). Growth

information on plantations is scarce. However, rate of height

growth is strongly related to degree of competition on the

planting site, and during the first 8 to 10 years it is much

faster on old fields and prepared sites than on unprepared

sites (8). If everything else is equal, yields for both planted

and natural stands should be similar. Growth and yield tables

for thinned, even-aged natural longleaf pine have been

published (17).

Rotations selected for longleaf pine depend on management objectives, site quality, cultural treatments, and thinning schedules, but usually range from 60 to 80 years for

sawtimber. Thinning is important if management objectives

are sawlog-sized products. Some results indicate that on a

medium site the periodic cubic-foot growth of 35- to 40-yearold longleaf pine does not increase much with increasing

stand density above 60 square feet of basal area per acre

(13.8 m^/ha). Periodic thinning from below, to leave about

70 square feet per acre (16.1 m^/ha) of best dominants, costs

little in potential volume growth, concentrates growth on

quality crop trees, and minimizes the investment in growing

stock (15).

Longleaf pine is a low-risk species to manage. In

addition to its fire resistance it is also rarely bothered by the

serious diseases and insects that afflict the other major

southern pines. Site requirements are not demanding, and it

can grow well on droughty, infertile soils. Once out of the

seedling stage, mortality is low. Suppressed trees may

eventually die, but the greatest single cause of loss is

lightning, frequently followed by bark beetle attack (Ips

spp.). Mortality from all causes among dominant members of

maturing longleaf stands has averaged about one tree per 2.5

acres (1 ha) annually, and for half of the observed stands

averaged one tree or less per 5 acres (2 ha) annually (7).

The major management problems for longleaf pine, in

common with other southern pines, are associated with stand

regeneration, especially natural regeneration. Problems with

artificial regeneration are less imposing, so this approach is

preferred despite its high cost. Natural regeneration requires

effective competition control and seedbed preparation, which

can be achieved only through broadcast cultural treatments

using mechanical equipment, chemicals, or fire. With the

exception of fire in longleaf stands, such treatments are

nearly impossible to apply to a management unit comprised

of pines of all ages and sizes. Longleaf pine can tolerate

prescribed fire at all ages, except for young seedlings less

than about 0.3 inch (0.8 cm) in root-collar diameter. Therefore,

this species should be better adapted to uneven-aged management than any other southern pine, as regular burning can be

used to control hardwood competition. Although this type of

management may best suit the goals of some landowners,

especially those with a limited acreage, even-age management is, and undoubtly will continue to be, the predominant

form of management for longleaf pine.

Most natural second-growth stands are even aged,

dating back to the time the old-growth overstory was removed.

The association of regeneration with a catastrophic event

(land clearing, blowdown, logging, hot fire, etc.) led to the

predominance of even-age stands, often of considerable

extent. Since fire is such an integral part of longleaf pine

management, the management unit, where an even-age stand

is established and maintained, should also be a convenient

burning unit, bounded by roads and streams, to minimize the

length of maintained firebreaks.

Clearcutting, seed-tree, and shelterwood systems have

all been applied to longleaf, but serious drawbacks have

eliminated clearcutting and seed-tree systems as practical

alternatives for natural regeneration (13). Clearcutting a

mature stand can destroy much of the advanced reproduction,

if any is present. Because of past difficulties in successfully

planting longleaf pine, loblolly, slash, or sand pine frequently are substituted following clearcutting. Increasing

success with containerized seedlings may overcome some of

the planting problems.

The limited seed dispersal range requires that most of

the cleared area be within 100 feet (30.5 m) of a seed source.

If there is an extended wait for a seed crop, the growing space

will be occupied by low quality hardwoods and brush that

must be eliminated, at some cost, to prepare for a seed crop

that may or may not be adequate to regenerate the area. With

8 to 10 scattered seed trees per acre (20 to 25/ha), the land is

essentially out of production during the wait for a good seed

crop. Even with periodic burning, the lower fire intensity

resulting from a lack of heavy needle-litter fuels permits

some encroaching hardwoods to regularly escape into a

relatively fire-resistant size. When too much of this occurs,

mechanical or chemical site preparation is required.

154
Early observations of longleaf regeneration in nature

indicated that some form of shelterwood system for natural

regeneration might be best suited to this species (10). Several

advantages are immediately apparent. Final harvest of mature

crop trees is delayed until adequate advanced reproduction is

present on the site. This keeps the site in production with

growth occurring to high-quality dominants while waiting for

a seed crop. Shelterwood stands produce enough needle litter

to fuel the hot fires needed to restrict hardwood and brush,

encroachment, and maintain an understory comprised largely

of grasses and forbs. The presence of a shelterwood overstory

also inhibits development of the brown-spot needle blight on

established seedlings (4). An overstory of 30 to 40 square

feet of basal area per acre (6.9 to 9.2 m^/ha) maximizes seed

production, and in a good seed year produces three times as

many seeds as a seed tree stand.

The shelterwood system can be applied only in existing

stands with sufficient dominant-codominant trees of seedbearing size. Guidelines for use of the system have been

published (6, 13). Briefly, either a two-cut or three-cut

shelterwood system may be applied, the latter only in stands

needing a thinning or improvement cut. The first cut in a

three-cut system would be a preparatory cut. This should

leave 60 to 70 square feet of basal area per acre (13.8 to 16.1

m^/ha) in dominant and codominant trees. Removal of all

other trees permits crown development on the residuals. A

well-managed longleaf stand periodically thinned will not

need a preparatory cut. The first cut in the two-cut system

(second in the three-cut system) is the seed cut. This cut is

made 5 or more years ahead of the planned harvest date and

reduces stand density to about 30 square feet of basal area per

acre (6.9 m^/ha), leaving the best dominant trees. Residual

large hardwoods are also removed. Even though stand

density may be cut in half, per acre volume production of 50-

to 70-year old trees would be reduced by only about one-third

(17). Regular prescribed burning keeps down hardwoods.

Growing season burns may be needed where brush is heavy.

Usually, a seedbed burn the year before a good seed crop is

the only site preparation that is needed.

Seed crop prospects are monitored through annual

springtime counts of flowers and conelets on selected sample

trees in the regeneration area. Normally 750 to 1,000 cones

per acre (1855 to 2470 cones/ha) are needed for regeneration,

although two or three successive lighter cone crops combined

may do the job. Stocking surveys of established seedlings

should be made annually, beginning after the seed cut.

Sometimes an adequate stand of seedlings is already present

on the site, so further measures to obtain regeneration are

unnecessary.

The regeneration goal should be establishment of about

6,000 seedlings per acre (14 830 seedlings/ha) under the

shelterwood overstory. Distribution should be such that 75

percent or more of milacre (0.001 acre or 0.0004 ha) sample

plots are stocked with one or more seedlings. This number

will allow for logging losses and still provide enough

surviving seedlings so that the superior 10 to 20 percent can

supply all the crop trees. Regeneration success must be based

on seedlings at least one year old, due to the high risk of

mortality during the first year after establishment.

Once an adequate seedling stand is established, the

parent overstory can be removed. Prompt seedling release is

not required for survival, so harvest of the overstory can be

scheduled to meet the needs of management. Given a choice,

overstory removal at seedling age 1 or 2 will have the least

impact on the new stand (5).

The regeneration area should not be burned during the

first 2 years after overstory removal, as accumulated logging

slash and undecomposed litter can result in a fire too hot for

newly released seedlings. After 2 years, seedling growth plus

decomposition of organic debris reduces fire risk considerably.

Prescribed burning can be resumed and applied as needed for

control of brush and the brown-spot needle blight. A brownspot survey sampling only crop seedlings will indicate if a

burn is needed (11). If these seedlings have an average of 20

percent or more of their foliage destroyed by the disease, a

winter brown-spot burn should be prescribed (13). Spring

burns may be most beneficial to the seedling stand during the

early years after release. These burns not only kill hardwoods

more effectively than fires in any other season but also may

stimulate longleaf seedling height growth more than either

burns at other seasons or no burns at all (19, 23).

Precommercial thinning usually is not needed in longleaf

stands, so the first commercial thinning brings the stand

toward the desired density for optimum future growth.

Dominant crop trees can be easily identified and leave trees

marked for this and all subsequent thinnings. All other trees

are removed during thinning if they have reached commercial

size. Otherwise they are left until the next thinning.

All available information indicates that in the past, the

longleaf pine forest type was maintained primarily as a result

of wildfires that periodically burned through established

longleaf forests. Exclusion of fire leads to serious regeneration problems, as past experience amply demonstrates. Management of longleaf forests should include prescribed fire at

2- to 5-year intervals through the rotation, as needed to

prevent hardwood encroachment and excessive risk of wildfire damage through build-up of fuel on the forest floor.

Longleaf pine has long been recognized as an excellent

timber tree, better suited than other pines to the whole range

of forest products: sawlogs, poles, piling, posts, plywood,

and naval stores. The needle litter has been harvested and

even old stumps have been removed and destructively distilled for chemicals. The longleaf forest, regularly burned,

has an open, park-like appearance often commented on by

early travelers and settlers in the region. The forest provides

an excellent habitat for game, especially deer, quail, and

turkey. Quail hunting has long been associated with the

longleaf forest. Cattle made themselves at home in the forest,

beginning with the earliest settlement. On many sites, the

understory can produce large amounts of forage for both

cattle and deer (18, 26). A mature longleaf forest also

provides a good home for the red-cockaded woodpecker and

the fox squirrel.

The characteristics of longleaf pine make it highly

adaptable to a range of management goals and silvicultural

systems. This timber type is well adapted to multiple-use

management because of the many forest products it supplies,

the forage it produces, the wildlife it supports, and the

recreation it affords.

Literature Cited

1. Boyer, W. D. Development of longleaf pine seedlings under parent

trees. Res. Pap. SO-4. New Orleans, LA: U.S. Department of

Agriculture, Forest Service, Southern Forest Experiment Station; 1963.

5 p.

2. Boyer, W. D. Grazing hampers development of longleaf pine seedhngs

in southwest Alabama. J. For. 65(5): 336-338; 1967.

3. Boyer, W. D. Brown-spot resistance in natural stands of longleaf pine

seedlings. Res. Note SO-142. New Orleans, LA: U.S. Department of

Agriculture, Forest Service, Southern Forest Experiment Station; 1972.

4 p.

4. Boyer, W. D. Brown-spot infection on released and unreleased longleaf

pine seedlings. Res. Pap. SO-108. New Orleans, LA: U.S. Department of Agriculture, Forest Service, Southern Forest Experiment

Station; 1975. 9 p.

5. Boyer, W. D. Timing overstory removal in longleaf pine. J. For. 73(9):

578-580; 1975.

155
6. Boyer, W. D. Regenerating the natural longleaf pine forest. J. For.

77(9): 572-575; 1979.

7. Boyer, W. D. Mortality among seed trees in longleaf shelterwood

stands. South. J. Appl. For. 3: 165-167; 1979.

8. Boyer, W. D. Site and stand factors affecting height growth curves of

longleaf pine plantations. In: Proceedings, First biennial southern

silvicultural research conference; 1980 November 6—7; Atlanta, GA.

Gen. Tech. Rep. SO-34. New Orleans, LA: U.S. Department of

Agriculture, Forest Service, Southern Forest Experiment Station; 1981:

184-187.

9. Critchfield, W. D.; Little, E. L., Jr. Geographic distribution of the

pines of the world. Misc. Publ. 991. Washington, DC: U.S. Department

of Agriculture; 1966. 97 p.

10. Croker, T. C., Jr. Can the shelterwood method successfully regenerate

longleaf pine? J. For. 54(4): 258-260; 1956.

11. Croker, T. C, Jr. Crop-seedling method for planning brown-spot bums

in longleaf pine. J. For. 65(7): 488; 1967.

12. Croker, T. C, Jr. Longleaf pine cone production in relation to site

index, stand age, and stand density. Res. Note SO-156. New Orleans,

LA: U.S. Department of Agriculture, Forest Service, Southern Forest

Experiment Station; 1973. 3 p.

13. Croker, T. C, Jr.; Boyer, W. D. Regenerating longleaf pine naturally.

Res. Pap. SO-105. New Orleans, LA: U.S. Department of Agriculture,

Forest Service, Southern Forest Experiment Station; 1975. 21 p.

14. Eyre, F. H., ed. Forest cover types of the United States and Canada.

Washington, DC: Society of American Foresters; 1980. 148 p.

15. Farrar, R. M., Jr. Thinning longleaf pine on average sites. J. For.

66(12): 906-909; 1968.

16. Farrar, R. M., Jr. Growth and yield of young longleaf pine. In:

Proceedings, 1974 symposium on management of young pines; 1974

October 22-24; Alexandria, LA; 1974 December 3-5; Charleston,

SC. Atlanta, GA: U.S. Department of Agriculture, Forest Service,

Southeastern Area State and Private Forestry; 1974: 276-287.

17. Farrar, R. M., Jr. Growth and yield predictions for thinned stands of

even-aged natural longleaf pine. Res. Pap. SO-156. New Orleans, LA:

U.S. Department of Agriculture, Forest Service, Southern Forest

Experiment Station; 1979. 78 p.

18. Grelen, H. E.; Enghardt, H. G. Burning and thinning maintain forage in

a longleaf pine plantation. J. For. 71(7): 419-425; 1973.

19. Grelen, H. E. May bums stimulate growth of longleaf pine seedlings.

Res. Note SO-234. New Orleans, LA: U.S. Department of Agriculture,

Forest Service, Southem Forest Experiment Station; 1978. 5 p.

20. Hodgkins, E. J., ed. Southeastem forest habitat regions based on

physiography. Forestry Departmental Series No. 2. Aubum, AL;

Aubum University, Agricultural Experiment Station; 1965. 10 p.

21. Mann, W. F., Jr. At last—longleaf pine can be planted successfully.

Forest Farmer. 28(6): 6-7 & 18-19; 1969.

22. Mann, W. F., Jr. Direct-seeding longleaf pine. Res. Pap. SO-57. New

Orleans, LA: U.S. Department of Agriculture, Forest Service, Southem

Forest Experiment Station; 1970. 26 p.

23. Maple, W. R. Spring bum aids longleaf pine seedling height growth.

Res. Note SO-228. New Orleans, LA: U.S. Department of Agriculture,

Forest Service, Southern Forest Experiment Station; 1979. 2 p.

24. Stemitzke, H. S.; Nelson, T. C. The southern pines of the United

States. Economic Botany. 24: 142-150; 1970.

25. Wahlenburg, W. G. Longleaf pine; its use, ecology, regeneration,

protection, growth, and management. Washington, DC: Charles Lathrop

Pack Forestry Foundation and U.S. Department of Agriculture, Forest

Service; 1964. 429 p.

26. Wolters, G. L. Southem pines overstories influence herbage quality. J.

Range Manage. 26: 423-426; 1973.

156
Shortleaf Pine

Edwin R. Lawson

Southern Forest Experiment Station

Robert N. Kitchens

Southern Region

Shortleaf pine (Pinus echinata Mill.) is the most widespread of any pine in the southeastern United States. It grows

in 22 States over more than 440,000 square miles (1.14

million km^). It extends from southeastern New York and

New Jersey into Pennsylvania, southern Ohio, Kentucky,

southwestern Illinois, and southern Missouri, south to eastern

Oklahoma and eastern Texas, and east to northern Florida

and Georgia. Its range extends from 41° 10' to 30° O' N.

latitude and from 73° 50' to 96° 0' W. longitude.

The adaptability of shortleaf pine to a great variety of

site and soil conditions partly accounts for its wide occurrence.

The species' best growth rate, however, is on the South

Atlantic and Gulf Coastal Plain soils. The most productive

soils are the deep, well-drained sandy loams, such as those

on flood plains. The least productive are the shallow, rocky

upland soils. Site indices at age 50 on the better sites may

exceed 100 feet (30.5 m) (21) and be as low as 33 feet (10.1

m) on poorer sites (11). Shortleaf pine does not grow well on

soils having high pH values or high calcium content (9).

Shortleaf pine grows at elevations as low as 10 feet (3.0

m) in southern New Jersey, up to 1,000 feet (305 m) in

Pennsylvania, and up to 3,000 feet (915 m) in the Appalachian Mountains. Its best development is attained at elevations of 600 feet (185 m) to 1,500 feet (455 m) in the

Piedmont and 150 feet (45 m) to 1,000 feet (305 m) in

Louisiana and Arkansas (9), although it grows up to 2,000

feet (610 m) in Arkansas, Missouri, and Oklahoma (7).

Over shortleaf pine's range, average annual temperatures vary from 48° F (8.9° C) in New Jersey to 70° F (21.1°

C) in southeast Texas. The 50° F (10.0° C) average annual

temperature isoline closely parallels the northern limit of

shortleaf pine. Annual precipitation over the species range

averages between 40 inches (1015 mm) on the western edge

and 60 inches (1525 mm) at the southern tip of its range.

Precipitation over the region of shortleaf pine's best development ranges from 45 to 55 inches ( 1145 mm to 1400 mm) and

averages 50 inches (1270 mm). Average annual snowfall

ranges from near zero in the southern sections to nearly 60

inches (1525 mm) in the northeastern parts of the species

range, but averages less than 16 inches (405 mm). The

average growing season ranges from about 140 days in the

North to 280 days in the South (32). The average number of

clear days varies from about 100 to 160 over the range of

shortleaf pine.

Shortleaf pine is a major component of three forest

cover types described by the Society of American Foresters:

Shortleaf Pine (type 75), Shortleaf Pine-Oak (type 76), and

Loblolly Pine-Shortleaf Pine (type 80). It is also a minor

species in at least 15 other forest cover types, where it grows

in association with at least 8 other conifer and 21 hardwood

species. Major associated tree species include: loblolly pine

(Pinus taeda L.), longleaf pine {P. palustris Mill.), Virginia

pine (P. virginiana Mill.), eastern white pine (P. strobus L.),

pitch pine {P. rigida Mill.), eastern redcedar {Juniperus

virginiana L.), post oak {Quercus stellata Wangenh.), black

oak (ß. velutina Lam.), northern red oak (ß. rubra L.),

southern red oak (ß. falcata Michx.), white oak (ß. alba

L.), chestnut oak (ß. prinus L.), bear oak (ß. ilicifolia

Wangenh.), and blackjack oak (ß. marilandica Muenchh.)

(7).

Shortleaf pine reproduces naturally from seed and may

be artificially reproduced by direct seeding or planting. Good

to excellent cone crops occur every 3 to 10 years in the

Northeast and 3 to 6 years in the South. Some seeds are

produced nearly every year, and significant amounts of seeds

are likely to be produced during 3-year periods (40). Shortleaf

pine seeds are dispersed by gravity and wind, beginning in

late October or early November. About 70 percent of the

seeds fall within a month after maturity and 90 percent within

2 months (6, 38). Some seeds continue to fall into April,

and cones persist on the tree long after they are empty (9).

Most of the winged seeds fall within a distance of about two

times the height of the seed tree or the adjacent shortleaf pine

stand seed source (38), but the distance may be affected by

prevailing winds (17). Shortleaf pine cones contain 25 to 38

full seeds each or about 2 pounds (0.9 kg) of seed per 100

pounds (45.4 kg) of cones (15). The number of cleaned seeds

averages about 46,300 per pound (102 070/kg). Releasing

seed trees from competition may increase seed yields per

cone and number of cones per tree (22, 39). In recent years,

seed orchards have produced significant amounts of the seeds

needed for nursery production of genetically improved shortleaf

pine seedlings (33). Seeds that are to be sown in a nursery or

seeded on regeneration areas in the spring are usually

stratified for 15 to 60 days at 30° F (-1.1° C) to 41°F (5.0°

C). Shortleaf pine seeds that lie on the ground during the

winter are naturally stratified and germinate in early spring.

Many of the seeds from natural seed fall are eaten by birds

and small mammals and only about 1 percent actually

germinate and produce seedlings (40).

Seedbed treatments which expose mineral soil tend to

increase the initial establishment of seedlings. Scarification

during logging and burning provide effective site preparation

for natural regeneration. Control of hardwoods and other

vegetative competition is also necessary to insure adequate

survival of seedlings for full stocking, although some residual hardwoods provide the beneficial effect of shade and

protection from drying winds, especially on southerly aspects

during the first few years after establishment (16, 40).

Shortleaf pine seedlings may also be established by

direct seeding. Its success depends on selecting suitable sites,

providing suitable seedbeds, protecting seeds from birds and

rodents, sowing sufficient seeds at the right time, and

controlling competition. Seedbeds are prepared by mechanical methods such as disking, furrowing, or bulldozing,

burning, or hand methods such as kicking or raking off litter

(24). Hardwood competition is controlled by mechanical

seedbed preparation or by properly timed herbicide application.

For broadcast seedings, about 0.5 pound per acre (0.6 kg/ha)

is recommended, although about one-half this amount is

adequate for well-prepared seedbeds (4). Furrow seeding

requires one seed per 9 to 12 inches (23 to 30 cm), while spot

157
seeding requires at least five seeds per spot. It is better to sow

at relatively high rates initially with any seeding method; then

adjust rates for local conditions as experience dictates (24).

Shortleaf pine seedlings are commonly produced in

nurseries and planted as 1-0 stock on prepared sites.

Planting may be done by hand or machine at a rate of 450 to

2,000 seedlings per acre (1110 to 4940/ha), depending on

management objectives and site characteristics. However,

most forest land managers prefer to plant 750 to 900 trees per

acre (1850 to 2220/ha). Seedlings may also be grown in

various containers, such as tubes, blocks, and plastic molds,

and may be planted with or without the container (2).

Shortleaf pine can be vegetatively propagated by rooting,

grafting of scions, or air layering (5). Vegetative propagation

is generally done for genetic control purposes; grafting of

scions on trees of the same species is the most common

method. Shortleaf pine seedlings and saplings sprout readily

from the base after injury, as incurred following fire, cutting,

or grazing (30).

Shortleaf pine seedlings grow slowly as the root system

develops during the first year or two after establishment.

Seedlings develop a taproot at an early age, which may

become very massive if allowed to grow uninhibited (19). In

much of the region where shortleaf grows, however, taproots

do not develop because of shallow, rocky, heavy clay, or

poorly drained soils. Lateral roots tend to grow near the soil

surface and are generally concentrated in the upper 18 inches

(46 cm) of soil. The developing seedlings and saplings attain

most of their height growth early in the growing season,

usually by early July. However, shortleaf pines will show

growth response to late season rainfall if it is sufficient to

substantially replenish soil moisture. Average annual height

growth during the sapling stage ranges between 12 and 36

inches (30 and 91 cm) depending on locality and site

conditions (9, 28).

Shortleaf pine is a shade intolerant species and does not

survive or grow well when in the understory, although it can

maintain dominance on most sites after it overtops competing

vegetation. Overstory competition from other pines or hardwoods greatly reduces survival and growth of shortleaf pine

seedlings (10, 16, 24). Elimination of such competition can

increase survival and height growth of seedlings four or five

times (9). Young trees in well-stocked shortleaf pine stands

begin to compete with each other within a few years after

establishment, and diameter growth rates decline (37). The

species will, however, persist in very dense stands without

stagnation. Natural pruning occurs as the canopies close,

although it is slower than on loblolly or longleaf pines.

Shortleaf pine responds well to release at all ages up to

mature trees (9, 39).

On good sites, shortleaf pine trees attain heights of 100

feet (30.5 m) or more and diameters of 24 to 36 inches (61 to

91 cm). Heights of nearly 130 feet (39.6 m) and diameters of

48 inches (122 cm) have been recorded (9). However,

growing trees to more than 70 years of age is uncommon in

managed stands, because after that time net growth declines

rapidly.

Despite the large acreages of natural even-aged shortleaf

pine, the growth and yield information is essentially limited

to that developed in well-stocked stands of the Piedmont

(26), limited regional data (34), and some growth relationships for north Mississippi (37). Data are almost totally

lacking for other circumstances.

Growth and yield of a given stand depends on the

quality of the site, current number of trees, stand age, and

silvicultural practices administered. Stand structure and yield

data for unthinned shortleaf pine plantations in the highlands

of Tennessee, Alabama, and Georgia show that mean annual

increment for total volume culminates near tree age 30 on

poor sites; on the better sites it culminates at about age 20.

Mean annual increment of stands having a site index of 40

(base age 25) and planting density of 1,000 trees per acre

(2470/ha) culminates at 75 cubic feet inside bark (i.b.) per

acre (5.2 mVha) at age 30. For the same site, age, and

planting density, the standing volume is about 3,192 cubic

feet per acre (223.4 m'^/ha). Basal area of this stand is 166

square feet per acre (38.1 m^/ha), and the estimated number

of trees is 621 (1535/ha). When the site index is 50 with the

same planting density, the mean annual increment (i.b.)

culminates at a maximum of 110 cubic feet per acre (7.7

m^/ha) at age 25 (29). Culmination of mean annual increment

will likely occur at older ages in natural stands, depending on

stocking levels and site quality (3, 21).

Natural shortleaf pine stands in Missouri showed significantly greater net volume yields when thinned to about 90

square feet per acre (20.7 m^/ha) or above than when thinned

to lower densities. Unthinned stands had the highest net

volume, 4,909 cubic feet per acre (343.6 m^/ha), at age 51

(25). This yield is somewhat higher than would be calculated

using regional natural stand yield data (21). In south Arkansas,

annual growth of uneven-aged, shortleaf-loblolly pine stands

thinned at three cutting cycles averaged 84 cubic feet per acre

(5.9 m^/ha) during a 24-year measurement period (23).

Annual sawtimber growth of these stands averaged 432 board

feet (fbm) (86 cubic feet)' per acre (6.0 m^/ha).

Thinning in well-stocked stands will generally increase

diameter growth rates of residual stems, and thus provide

larger products over a specified period. However, the specific thinning levels and frequencies, as well as other

silvicultural options selected, depend on management objectives.

Only a few insects are known to attack seeds and cones

of shortleaf pine. Among these are the shortleaf pine cone

borer (Eucosma cocana Kearfott) which occurs throughout

shortleaf pine's range and the shortleaf pine cone beetle

{Conophthorus echinatae Wood) occurring in Missouri (13).

Shortleaf pine seedlings are subject to damping off and

root rot caused by several fungi, usually when soils have a

pH above 6 and high water content. Foliage of shortleaf pine

normally does not develop serious diseases, but several

needle rusts are known to attack the species (14). Reproduction weevils, particularly pales {Hylobius pales (Herbst)) and

pitch-eating {Pachylobius picivorus (Germar)) weevils, are

the most serious insect pests of pine seedlings, reportedly

killing 20 to 30 percent of seedlings planted in cut-over lands

(8). Young shortleaf pines are also attacked by Nantucket

pine tip moth {Rhyacioniafrustraría (Comstock)). This insect

has become a major pest in the eastern United States (1) and

may have greater impacts than previously believed (8).

The southern pine beetle {Dendroctonus frontalis

Zimmermann) is the most destructive insect pest of pine

forests in 13 Southern and Southeastern States and parts of

Central America and Mexico. When populations are epidemic,

the beetles can kill healthy, vigorous trees. Outbreaks have

upset management plans, reduced potential yields, and devastated many forest holdings. Where infestations are small and

scattered, salvaging is impractical and less than half of total

loss is recovered for use (31). The redheaded pine sawfly

(Neodiprion lecontei (Fitch)) is the most destructive of the

sawflies feeding on southern pines (8) and shortleaf is one of

its preferred species (1). Other important insect pests include

pine engraver beetles {Ips spp.), which are especially destrucCubic foot and metric conversions of measurements expressed in board

feet should be viewed as estimates because of the assumptions involved in

the conversion process.

158
tive during severe droughts, and the black turpentine beetle

(Dendroctonus terebrans (Olivier)).

Shortleaf pine saplings and some older trees are moderately susceptible to attack by annosus root rot {Heterobasidium

annosum (Fr.) Bref.), although losses have been only occasional.

Littleleaf disease, associated with root destruction by

Phytophthora cinnamomi Rands, is the most serious pathological threat to shortleaf pine, occurring on poorly drained soils

from Virginia to Mississippi and south to the Gulf Coast (14).

Red ring rot {Phellinus pini (Thore ex Fr.) A. Ames) may

occur in older trees, but is rare in stands under 80 years old.

Shortleaf pine is generally fire resistant, although wildfires in young stands are very damaging, since they easily

extend into the crowns. The crowns are usually killed, but

shortleaf pine seedlings and small saplings can sprout from

the base and form new stems (20). Larger trees may be killed

by very hot fires, particularly if there is a large amount of fuel

near the tree base. Fire-damaged trees are also more susceptible to attack by insects and diseases. After the trees grow to

large sapling- or small pole-size, prescribed fire can be used

to reduce both understory competition and wildfire hazards.

Under proper conditions, fire can be used to improve wildlife

habitat and is used extensively for site preparation for both

natural and artificial regeneration.

Shortleaf pine is generally managed in even-aged stands,

primarily because it is intolerant of shade. In the past, fire

undoubtedly played an important role in establishing and

maintaining the species. Both natural and artificial regeneration methods are used to establish even-aged stands. In recent

years management has shifted from dependence on natural

regeneration to planting and direct seeding. Artificial regeneration methods reduce the time required for establishment,

provide better control of spacing, and allow establishment of

genetically improved trees. Since fast-growing, better formed,

pest-resistant strains of shortleaf pine are now generally

available, artificial regeneration will likely predominate.

Even-aged stands of shortleaf pine are established artificially by planting or direct seeding. Both of these options

require removal of all merchantable trees, control of competing vegetation, and, for direct seeding, removal of litter. The

most common site preparation procedure following clearcutting

is chopping or crushing of residual trees followed by a hot

fire to control hardwoods, reduce ground cover, and expose

mineral soil. Residual trees also may be sheared and burned

or sheared and windrowed. The prepared sites are then

machine- or hand-planted, or seeded.

Trees planted in cutover areas are susceptible to damage

and loss by pales weevils. To avoid the problem, seedlings

should be dipped in insecticide prior to planting, treated with

insecticide at planting time or in late winter, or planting

should be delayed 1 year. This delay, however, results in the

loss of a year's growth and allows competing vegetation to

develop 1 year ahead of regeneration.

Establishment of even-aged stands with natural regeneration may be accomplished by clearcutting strips or patches no

greater than 200 feet (61 m) wide to allow seeding from

nearby trees, felling the entire stand after seed fall or cone

ripening, leaving seed trees, or shelterwood cutting (18).

Of these natural regeneration methods, clearcutting of strips

or patches is most compatible with the use of fire and heavy

equipment to control competing hardwoods and prepare a

suitable seedbed. A major disadvantage of depending on

natural regeneration is the lack of adequate seed production

every year, especially in the inland and westerly areas.

Sufficient seeds must be available soon after site preparation

or development of competing vegetation will necessitate

retreatment of the area (18).

The second method, felling the entire stand in conjunction with cone and seed maturity, has been successful in

some areas of the Southeast. Seedbed preparation is completed in advance of cutting, and seeds from the existing trees

regenerate the area. One disadvantage of this method is that

harvesting must be done after cone ripening and must be

completed before seed germination in late winter or early

spring. Seeds will be better distributed over the area if most

are allowed to fall before harvesting. Regeneration can be

obtained by cutting the trees between cone ripening and seed

fall, since the cones usually remain in the slash instead of

being removed during logging (18). A second major disadvantage is that the method can only be used when an adequate

seed crop is present.

The seed-tree method involves leaving 10 to 16 of the

best seed trees per acre (25 to 40/ha) to regenerate the area

after harvesting. Where stands are dense, crown release of

the seed trees about 3 years before the main harvest will

improve seed production. Well-stocked stands should result

in 1 to 3 years if seed fall is adequate. Mechanical site

preparation can be used, but care must be taken to avoid

damaging the seed trees, which could induce disease or insect

attack. Prescribed burning can be done before or after the

main stand is cut, but requires great care. Disturbance during

logging may provide adequate seedbed preparation (40).

Seed trees are also more vulnerable to loss or damage from

lightning, wind, and insects than those in fully stocked

stands. The loss may be substantial since these are high value

trees and are the only source of natural regeneration.

The shelterwood system has been successful, particularly where summer rainfall usually is sufficient for good

first-year survival and where half of the stand or approximately 50 to 60 square feet of basal area per acre (11.5 to

13.8 m^/ha) remains. Prescribed burning is the most practical

method of site preparation because the residual stand is too

dense for easy operation of equipment. In many areas, litter

decomposes rapidly, thus eliminating the need for burning.

Chemical hardwood control, if needed, is usually easier to

accomplish before the initial harvest, but may be done

afterward.

Shortleaf pine can be managed in uneven-aged stands

with the selection silvicultural system, an alternative that

may be especially attractive to managers of small tracts (23,

36). The selection harvesting method utilizes natural regeneration and involves removal of trees singly or in small groups

with the objective of achieving a balanced uneven-aged

structure. This structure is determined by the selected basal

area, diameter, and number of trees in each diameter class—

all of which depend on the land manager's objectives, site

quality, and other factors. Selection harvesting has been

primarily used in understocked stands where cutting of trees

and controlling hardwoods has created openings large enough

for reproduction to become established (23). Usually, the

primary product target is sawlogs, but smaller trees are

removed to achieve the desired number of trees in each

diameter class. The selection harvesting method could be

used to grow smaller trees as a primary objective if enough

trees (10 to 15/acre or 25 to 37/ha) of seed-bearing size are

produced, although it would probably not be very efficient

for simple fiber production. In general, the method is more

difficult to use, requires more care, and may be economically

less efficient than alternative methods.

Fire generally cannot be used with the selection harvesting method for seedbed preparation since seedlings in nearby

openings would be killed. Openings may also be too small

for efficient use of machines, therefore seedbed preparation

is usually limited to disturbance during logging. Regenera159
tion must be obtained promptly or expensive hand methods

may be needed to maintain control of encroaching hardwoods.

Regeneration systems depending primarily on natural

regeneration have several additional disadvantages. Loss of

growth during the extended establishment time can be

substantial, since seed crops may not occur for 3 to 4 years.

Also, they are not amenable to establishment of genetically

improved trees, and there may be problems with either too

few or too many trees per unit area. Too few trees may

require additional site preparation and artificial regeneration,

while too many will likely require precommercial thinning.

Despite the shortcomings of natural regeneration systems,

they can be used effectively and cheaply in some situations,

and may be the best choice for small ownerships. Also, the

greater expense and soil disturbance usually associated with

artificial regeneration may not be justified on sensitive sites

or those that have low productive potential.

The shortleaf pine and associated forest types are

important for multiple-use considerations. During the early

stages of stand development, regeneration areas provide

forage for grazing and abundant food and shelter for a variety

of wildlife species (12). Thinnings and prescribed burns

increase the amount and palatability of wildlife food plants.

Hardwood associates that occur as single trees, groups, or

stringers add variety and quality to wildlife habitat. Size,

shape, distribution, and timing of silvicultural treatments

provide diversity to meet the habitat requirements of many

wildlife species. Some shortleaf pine trees are managed in

over-mature stands to provide special habitat requirements

for endangered species, such as the red-cockaded woodpecker (27).

Shortleaf pine has been widely planted for erosion

control, although it does not produce as much litter as its

common associate, loblolly pine (35). The species does

provide excellent watershed protection, as evidenced by the

high quality of water flowing from shortleaf pine forests.

Shortleaf pine stands with their diversity of associated

species are esthetically pleasing to forest visitors and

recreationists.

Literature Cited

1. Baker, Whiteford L. Eastern forest insects. Misc. Pub. 1175.

Washington, DC: U.S. Department of Agriculture; 1972. 642 p.

2. Bamett, J. P.; McGilvray, J. M. Container planting systems for the

South. Res. Pap. SO-167. New Orleans, LA: U.S. Department of

Agriculture, Forest Service, Southern Forest Experiment Station; 1981.

18 p.

3. Burton, J. D. Growth and yield in managed natural stands of loblolly

and shortleaf pine in the West Gulf Coastal Plain. Res. Pap. SO- 159.

New Orleans, LA: U.S. Department of Agriculture, Forest Service,

Southern Forest Experiment Station; 1980. 23 p.

4. Derr, Harold J.; Mann, William F., Jr. Direct-seeding pines in the

South. Agrie. Handb. 391. Washington, DC: U.S. Department of

Agriculture; 1971. 68 p.

5. Dormán, Keith W. The genetics and breeding of southern pines. Agrie.

Handb. 471. Washington, DC: U.S. Department of Agriculture; 1976.

407 p.

6. Dormán, K. W.; Barber, J. C. Time of flowering and seed ripening in

southern pines. Stn. Pap. 72. Asheville, NC: U.S. Department of

Agriculture, Forest Service, Southeastern Forest Experiment Station;

1956. 15 p.

7. Eyre, F. H., ed. Forest cover types of the United States and Canada.

Washington, DC: Society of American Foresters; 1980. 148 p.

8. Flavell, T. H. Insect pests of young pines. In: Proceedings, Symposium

on management of young pines; 1974 October 22-24; Alexandria, LA;

1974 December 3-5; Charleston, SC. Atlanta, GA: U.S. Department

of Agriculture, Forest Service; 1974: 243-248.

9. Fowells, H.A., comp. S ilvies of forest trees of the United States. Agrie.

Handb. 271. Washington, DC: U.S. Department of Agriculture; 1965.

762 p.

10. Graney, David L. Site index relationships for shortleaf pine and upland

oaks in the Ozark-Ouachita Highlands of Missouri, Arkansas and

Oklahoma. In: Fralish, J. S.; Weaver, G. T.; Schlesinger, R. C, eds.

Proceedings, central hardwood forest conference I; 1976 October

17-19; Carbondale, IL. Carbondale, IL: Southern Illinois University;

1976: 309-326.

11. Graney, D. L.; Burkart, H. E. Polymorphic site index curves for

shortleaf pine in the Ouachita Mountains. Res. Pap. SO-85. New

Orleans, LA: U.S. Department of Agriculture, Forest Service, Southern

Forest Experiment Station; 1973. 12 p.

12. Halls, L. K. Growing deer food amidst southern timber. J. Range

Management. 23: 213-215; 1970.

13. Hedlin, Alan F.; Yates, Harry O.; Tovar, David Cibrian [and others].

Cone and seed insects of North American conifers. Ottawa, Ontario:

Canadian Forestry Service, Washington, DC: United States Forest

Service; 1980. 122 p.

14. Hepting, George H. Diseases of forest and shade trees of the United

States. Agrie. Handb. 386. Washington, DC: U.S. Department of

Agriculture; 1971. 658 p.

15. Krugman, Stanley L.; Jenkinson, James L. Pinus L. Pine. In: Schopmeyer,

C. S., tech. coord. Seeds of woody plants in the United States. Agrie.

Handb. 450. Washington, DC: U.S. Department of Agriculture; 1974:

598-638.

16. Lawson, E. R. Natural regeneration of shortleaf pine. In: Proceedings,

Symposium for management of pines of the interior South. 1978

November 7-8; Knoxville, TN. Tech. Pub. SA-TP2, Atlanta, GA:

U.S. Department of Agriculture, Forest Service, Southeastern Area

State and Private Forestry; 1979: 1-6.

17. Little, Silas, Jr. Seed fall of shortleaf pine. Tech. Note 27. Broomall,

PA: U.S. Department of Agriculture, Forest Service, Allegheny

(Northeastern) Forest Experiment Station; 1940. 1 p.

18. Mann, William F., Jr. Loblolly-Shortleaf Pine. In: Silvicultural

systems for the major forest types of the United States. Agrie. Handb.

445. Washington, DC: U.S. Department of Agriculture; 1973: 95-98.

19. McQuilkin, W. E. Root development of pitch pine, with some comparative observations on shortleaf pine. J. Agrie. Res. 51: 983-1016; 1935.

20. Moore, E. B. Seedling-sprout growth of shortleaf and pitch pine in New

Jersey. J. For. 34(9): 879-882; 1936.

21. Murphy, P. A.; Beltz, R. C. Growth and yield of shortleaf pine in the

West Gulf Region. Res. Pap. SO-169. New Orleans, LA: U.S.

Department of Agriculture, Forest Service, Southern Forest Experiment

Station; 1981. 15 p.

22. Phares, Robert E.; Rogers, Nelson F. Improving shortleaf pine seed

production in Missouri. J. For. 60(5): 322-324; 1962.

23. Reynolds, R. R. Twenty-nine years of selection timber management on

the Crossett Experimental Forest. Res. Pap. SO-40. New Orleans, LA:

U.S. Department of Agriculture, Forest Service, Southern Forest

Experiment Station; 1969. 19 p.

24. Russell, T. E. Planting and seeding shortleaf pine. In: Proceedings,

Symposium for management of pines of the interior South; 1978

November 7-8; Knoxville, TN. Tech. Pub. SA-TP2. Atlanta, GA:

U.S. Department of Agriculture, Forest Service, Southeastern Area

State and Private Forestry; 1979: 7-13.

25. Sander, I. L.; Rogers, R. Growth and yield of shortleaf pine in

Missouri: 21-year results from a thinning study. In: Proceedings,

Symposium for the management of pines of the interior South; 1978

November 7-8; Knoxville, TN. Tech. Pub. SA-TP2. Atlanta, GA:

U.S. Department of Agriculture, Forest Service, Southeastern Area

State and Private Forestry; 1979: 14-47.

26. Schumacher, F. X.; Coile, T. S. Growth and yields of natural stands of

the southern pines. Durham, NC: T. S. Coile, Inc.; 1960. 115 p.

27. Scott, Virgil E.; Evans, Keith E.; Patton, David R.; Stone, Charies P.

Cavity-nesting birds of North American forests. Agrie. Handb. 511.

Washington, DC: U.S. Department of Agriculture; 1977. 112 p.

28. Shoulders, E.; Walker, F. V. Soil, slope, and rainfall affect height and

yield in 15-year-old southern pine plantations. Res. Pap. SO-153. New

Orleans, LA: U.S. Department of Agriculture, Forest Service, Southern

Forest Experiment Station; 1979. 52 p.

29. Smalley, G. W.; Bailey, R. L. Yield tables and stand structure for

shortleaf pine plantations in Tennessee, Alabama, and Georgia Highlands.

Res. Pap. SO-97. New Orieans, LA: U.S. Department of Agriculture,

Forest Service, Southern Forest Experiment Station; 1974. 57 p.

160
30. Stone, E. L., Jr.; Stone, M. H. Root collar sprouts in pine. J. For.

52(7): 487-491; 1954.

31. Thatcher, Robert C; Searcy, Janet L.; Coster, Jack E.; Hertel, Gerard

D., eds. The southern pine beetle. Tech. Bull. 1631. Washington, DC:

U. S. Department of Agriculture, Forest Service and Science and

Education Administration; [1981]. 267 p.

32. U.S. Department of Agriculture. Climate and Man. Yearbook of

Agriculture 1941. Washington, DC: U.S. Department of Agriculture;

1941. 1248 p.

33. U.S. Department of Agriculture, Forest Service. Forest tree seed

orchards, a directory of industry, state, and federal forest tree seed

orchards in the United States. Atlanta, GA: U.S. Department of

Agriculture, Forest Service, Southeastern Area State and Private Forestry;

1974. 33 p.

34. U.S. Department of Agriculture, Forest Service. Volume, yield, and

stand tables for second-growth southem pines. Misc. Pub. 50. Washington,

DC: U.S. Department of Agriculture; 1929 (Revised 1976). 202 p.

35. Williston, H. L. Thinning shortleaf pine plantations in northern Mississippi.

South. J. Appl. For. 2(4): 137-140; 1978.

36. Williston, H. L. Uneven-aged management in the loblolly-shortleaf

pine type. South. J. Appl. For. 2(3): 78-82; 1978.

37. Williston, H. L.; Dell, T. R. Growth of pine plantations in North

Mississippi. Res. Pap. SO—94. New Orleans, LA: U.S. Department of

Agriculture, Forest Service, Southem Forest Experiment Station; 1974.

15 p.

38. Yocom, Herbert A. Shortleaf pine seed dispersal. J. For. 66(5): 422;

1968.

39. Yocom, Herbert A. Releasing shortleaf pine increases cone and seed

production. Res. Note SO—125. New Orleans, LA: U.S. Department of

Agriculture, Forest Service, Southem Forest Experiment Station; 1971.

2 p.

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regenerated shortleaf pine. South. J. Appl. For. 1(2): 10-11; 1977.

161
Slash Pine

Eugene Shoulders

Southern Forest Experiment Station

Glenn Parham

Southern Region

Slash pine {Pinus elliottii Engelm.) occupies about 12.3

million acres (5.0 million ha) of commercial forest land in the

southern United States.* Included in this total are natural and

planted stands in which yellow pines make up at least

one-half of the stocking, and slash pine is the predominant

pine.

Slash pine occurs naturally within 150 miles (240 km) of

the Atlantic and Gulf Coasts from Berkeley County, South

Carolina, to Tangipahoa Parish, Louisiana, and throughout

most of Florida (40). It is represented by two varieties: from

central Florida northward by the common variety, typical

slash pine {P. elliottii Engelm. var. elliottii), and in southern

Florida by the South Florida strain (P. elliottii var. densa

Little and Dormán) (41).

The commercial range of slash pine in the United States

has been extended by planting to the Upper Coastal Plain of

North Carolina, north central Georgia, central Alabama,

northern Mississippi, western Louisiana, and eastern Texas.

Virgin stands of slash pine were largely confined to

ponds or pond margins and to narrow strips along creeks,

bays, and other minor drainages where ample soil moisture or

standing water protected the young trees from wild fires, and

to hummocks in the Everglades that provided sufficient

elevation above the water level for pines to grow. With

clearcutting of the virgin forests and protection from wildfire,

slash pine spread naturally to better drained sites formerly

occupied by longleaf pine {P. palustris Mill.). Extensive

planting of the species has further extended the slash pine

type so that it now occurs on a broad array of sites from

poorly drained flat areas to droughty sandhills. Elevation

ranges from sea level to a few hundred feet and topography

from level to hilly.

Most of the soils supporting plantations or natural stands

of slash pine are Alfisols, Entisols, Spodosols, or Ultisols.

Frequently occurring suborders include Aqualfs, Udalfs,

Aquents, Psamments, Aquods, Aquults, and Udults. Moisture regimes in these soils range from excessively wet to very

dry.

Although slash pine adapts to a wide variety of soil

conditions, it grows best on deep, well-aerated soils that

supply ample quantities of moisture during the growing

season. Generally, growth and site index increase with depth

to a restrictive soil layer or seasonally high water table if

these features occur within 20 to 30 inches (51 to 76 cm) of

the soil surface. Where depth to a restrictive layer exceeds

about 30 inches (76 cm), site index declines with increasing

depth to a reliable source of moisture, such as a stable water

table or a soil horizon with a large moisture storage capacity.

Soil properties useful in estimating site index of slash pine

include depth to grey mottles, depth to a spodic horizon,

depth to the least permeable layer or to a fine-textured

' Unpublished data on file at U.S. Department of Agriculture, Forest

Service, Southeastern Forest Experiment Station, Asheville, N.C. 1981.

horizon, thickness of the Al horizon, and texture of the least

permeable or finest textured horizon (2, 14, 29, 39, 45, 52).

Slash pine growth on many sites is improved by application of phosphorus or nitrogen and phosphorous fertilizer

(23, 34, 50). Additions of other nutrients are not normally

required for satisfactory growth.

The climate within the natural range of slash pine varies

from tropical in the Florida Keys to transitional between

temperate and subtropical in the North (55). Summers are

long, warm, and humid; winters are relatively mild. Mean

January temperatures decrease northward from about 70° F

(21.r C) in south Florida to about 50° F (10.0° C) in Georgia

and South Carolina. Mean July temperatures are less affected

by latitude and average about 80° to 82° F (26.7° to 27.8° C)

throughout the range. Length of the frost-free season ranges

from 365 days in south Florida to 240 days in the North.

Average annual precipitation varies from 44 inches (1120

mm) in portions of Georgia and South Carolina to 64 inches

(1630 mm) or more in Louisiana, Mississippi, and southern

Florida. Peak periods of precipitation in the northern portion

of the range occur in late winter (February through March)

and mid-summer (July through August). In the South, most

of the rainfall occurs in mid-summer, and winter droughts are

rather common. Stands found along coastal areas throughout

the species' range are vulnerable to damage from hurricanes.

The frequency of these storms is greater at the southern tip of

Florida and along the Gulf Coast from Tampa westward than

in other localities. Plantations in the extreme northern portions of the commercial range are subject to damage from ice

storms.

Slash pine is a major component of four cover types

recognized by the Society of American Foresters (20):

Longleaf-Slash Pine (type 83), Slash Pine (type 84), Slash

Pine-Hardwood (type 85), and South Florida Slash Pine

(type 111). Associated tree species in these types vary with

the site moisture regime. On well-dr-ained upland soils they

include longleaf, loblolly (P. taeda L.), and sand pines {P.

clausa (Chapm. ex Engelm.) Vasey ex Sarg.); post {Quercus

stellata Wangenh.), blackjack {Q. marilandica Muenchh.),

southern red (Q. falcata Michx.), sand live (ß. virginiana

var. geminata (Small) Sarg.), myrtle (ß. myrtifolia Willd.),

bluejack (ß. incana Bartr.), and turkey (ß. laevis Walt.)

oaks; hickories {Garya spp.); flowering dogwood {Cornus

florida L.); yaupon {Ilex vomitoria Ait.); persimmon {Diospyros

virginiana L.); and hawthorn {Crataegus spp.). Common

associates on wetter sites are red maple {Acer rubrum L.),

sweetgum {Liquidamhar styraciflua L.), blackgum {Nyssa

sylvatica Marsh.), swamp túpelo {Nyssa sylvatica var. biflora

(Walt.) Sarg.), sweetbay {Magnolia virginiana L.), loblollybay {Gordonia lasianthus (L.) Ellis), southern redcedar

{Juniperus silicicola (Small) Bailey), Atlantic white-cedar

{Ghamaecyparis thyoides (L.) B.S.P.), Carolina ash {Fraxinus

caroliniana Mill.), American elm {Ulmus americana L.),

cabbage palmetto {Sabalpalmetto (Walt.) Lodd. ex J. A. and

J. H. Schult.), pond pine {Pinus serótina Michx.), pondcypress

(Taxodium distichum var. nutans (Ait.) Sweet), and water

162
iQuercus nigra L.), laurel (ß. laurifolia Michx.), and live

(ß. virginiana Mill.) oaks. Baldcypress {Taxodium distichum

(L.) Rich. var. distichum), pondcypress, blackgum, and

water túpelo (Nyssa aquatica L.) also occur as associates on

sites that are flooded periodically.

Slash pine is not a climax species. Without man's

intervention and with the absence of fire or any other

catastrophic event, natural succession will proceed to a

mixed hardwood forest (47, 51).

Slash pine reproduces naturally from seed throughout its

native range (16, 24), as well as in western Louisiana where

it is an introduced species (43). It is reproduced artificially

both by direct seeding and by planting. Vegetative propogation

by grafting, air layering, and rooting of cuttings is used in

seed orchards (19).

Slash pine is a relatively good seed producer and yields

some seeds almost every year (59). Typical slash pine

produces good crops about every 3 years; the South Florida

variety will produce good seed crops every 1 to 5 years (33).

Trees reach seed-bearing age in 7 or 8 years, but do not reach

their full reproductive potential until much later. Yields

greater than 200 cones per tree are not unusual for large,

full-crowned trees in good seed years (58). Cone production

may be more than doubled by stem injury, fertilization

applied before flower bud initiation, or crown release after

heavy thinning (30, 54).

Cones ripen in September and shed most of their seeds

in October (16, 24). More than 90 percent of the seeds fall

within 150 feet (45.7 m) of their source, but some may be

carried by wind as far as 250 feet (76.2 m).

Seed viability is usually good, and germination may be

rapid if soil moisture is adequate. Ordinarily, however,

germination occurs over an extended period from November

to April (16, 24). In years of heavy seedfall, many thousands

of seedlings per acre may become established.

Seed germination and seedling survival may be increased several fold by burning or by any type of scarification

that exposes mineral soil prior to seedfall (46, 48). Such

treatments are recommended in direct seeding of slash pine

(18). They may be necessary for natural regeneration only if

a poor seed crop is anticipated (35) or the vegetative cover is

very dense (36). Heavy understories of saw-palmetto (Serenoa

repens (Bartr.) Small), gallberry {Ilex glabra (L.) A. Gray),

or hardwoods should be controlled prior to regeneration by

any method. Poorly drained sites where seeds or seedlings

will be submerged for more than 1 or 2 weeks ( 18) need to be

drained or have elevated seedbeds prepared for successful

stand establishment.

Unprotected seeds are eaten by birds and small mammals and by a variety of insects. When direct seeding,

repellent coatings are required to protect seeds from these

predators (18). Insects, rabbits, and other animals also clip

young seedlings, especially during late winter and early

spring when other green vegetation is scarce.

Slash pine is considered intermediate in tolerance to

shade by some authors (16, 24, 32, 36) and intolerant by

others (35). It will reproduce naturally in small openings and

will invade poorly stocked longleaf pine stands. But competition from overstory and understory vegetation reduces growth

and causes much mortality.

The two varieties of slash pine differ in their patterns of

growth. Typical slash pine makes excellent early height

growth, whereas South Florida slash pine has a grasslike,

almost stemless stage, that lasts from 2 to 6 years (41).

Moreover, South Florida slash pine lacks the straight axis or

leader characteristic of the typical variety and often develops

forked boles with large branches and an open, spreading,

irregularly shaped crown. In varietal trials at three locations

in southern Florida, typical slash pine averaged 3 to 6 feet

(0.9 to 1.8 m) taller at 10 years than South Florida slash pine

(37).

Information is largely lacking on growth and development of South Florida slash pine under good forest management.

The remainder of this section, therefore, applies primarily to

typical slash pine, unless stated otherwise.

Slash pine is slow to express dominance in dense,

even-aged stands. As a consequence, height growth is slower

in very dense stands than in moderately or lightly stocked

stands (7, 31).

Young stands respond promptly to thinning or release.

Older stands whose height growth rate has declined and those

in poor growing condition may respond slowly or occasionally fail to respond at all (4, 16, 24, 35). For these reasons,

precommercial thinning before stand age 5 is recommended

if densities exceed 2,000 trees per acre (4940 trees/ha),

especially if the objective of management is the production of

sawtimber, veneer logs, or naval stores (32, 35). Residual

densities should be about 500 to 700 trees per acre (1235 to

1730 trees/ha). When sawtimber is to be produced and high

initial density is not a problem, or if a precommercial

thinning has been made, commercial thinnings will maintain

good stand vigor, promote diameter growth, shorten the time

required for individual trees to reach sawtimber-size, and

concentrate volume on trees to be carried to rotation age.

These thinnings should be initiated as early as economically

feasible, at least by age 20. Commercial thinnings will

increase diameter growth of residual trees. They will not

increase total yields of stands managed for pulpwood on a 20-

to 25-year rotation or those managed for sawlogs if the

rotation is long enough for a majority of trees to reach

sawtimber-size and competition for growing space has not

caused excessive mortality (8, 13).

Rotation lengths vary according to product objective.

The optimum pulpwood rotation may be about 25 years, as

this age is intermediate among those at which mean annual

cubic volume growth culminates. In unthinned plantations,

this age increases to 30 from 23 years as density increases

and site index declines (6). Site and stocking level also affect

diameter growth and the age at which trees reach sawtimbersize. Available information (8, 22, 31, 42) suggests that on

good sites, stands averaging 16 inches (41 cm) diameter at

breast height (d.b.h.) can be grown in 45 to 55 years if initial

dense stocking is adjusted before age 5 to about 500 to 700

trees per acre (1235 to 1730 trees/ha) and if commercial

thinnings at about 5-year intervals reduce residual basal areas

below 85 square feet per acre (19.5 m^/ha).

Plantations and natural stands have similar rates of

growth on sites of a given quality if they are comparable in

genetic makeup, are maintained at comparable densities, and

are given the same level of management (35).

Except as previously noted, product yields increase with

density, age, and site index. Estimates of yields at 30 years

for unthinned plantations on average sites where the site

index is 60 feet (18.3 m), base age 25, range from 2,717 to

3,325 cubic feet per acre (190.2 to 232.8 m^/ha) with 300

surviving stems per acre (740/ha) and from 3,291 to 4,097

cubic feet per acre (230.4 to 286.8 m^/ha) with 500 survivors

per acre (1235/ha) (9, 12, l5, 17). For managed natural

stands on similar sites where the site index is 80 feet (24.4

m), base age 50, Bennett (5) estimated standing volumes at

50 years to range from 1,959 cubic feet per acre (137.1

m^/ha) with a basal area stocking of 50 square feet per acre

(11.5 m^/ha) to 5,246 cubic feet per acre (367.2 m^/ha) with a

stocking of 150 square feet per acre (34.4 m^/ha). Cubic

volumes were computed using all trees 4.6 inches (12 cm)

d.b.h. and larger to a 4.0 inch (10 cm) top outside bark.

163
Corresponding sawlog volumes were 6,253 and 11,682 board

feet (fbm) (International y4-inch Rule) (1,251 and 2,336

cubic feet)^ per acre or 87.5 and 163.5 m^/ha for trees 9.6

inches (24.4 cm) d.b.h. to an 8.0 inch (20.3 cm) top.

Numerous insects and diseases attack slash pine during

its life cycle (1, 57). Only those that seriously affect

establishment and management of plantations and natural

stands will be discussed here.

Reproduction weevils, the pales weevil {Hylobius pales

(Herbst)) and the pitch-eating weevil (Pachylobius picivorus

(Germar)) are attracted by the odor of pine resin to recently

logged areas where they lay their eggs in lateral roots of fresh

pine stumps. Both the egg-laying adults and the emerging

brood feed on the tender bark of seedlings. This damage can

be avoided by delaying planting of cutover areas for at least 9

months or by treating seedlings with a.suitable insecticide.

Texas leafcutting ants {Atta texana (Buckley)) are serious

pests of young seedlings on well-drained sites in western

Louisiana and eastern Texas. The ants may completely

defoliate and debark the stems of newly established pines

during winter when other green plants are scarce. Control of

the pest is by fumigation of the nest area.

Older stands are subject to attack by engraver beetles

{Ips spp.), the black turpentine beetle (Dendroctonus terebrans

(Olivier)) and the southern pine beetle (D. frontalis

Zimmermann). Outbreaks of these insects are usually associated with wildfire, lightning strikes, and logging operations.

The best protection against attack is to maintain vigorous,

healthy stands through good forest management. Control is

mainly by salvage and rapid removal of infested trees before

new adults emerge from brood trees.

Fusiform rust (Cronartium quercuum (Berk.) Miy. ex

Shirai f. sp. fusiforme Burds. & Snow) is the most serious

disease of slash pine. Aside from planting rust-resistant

families in high rust-hazard areas, there is no practical

method of controlling the disease. Its impact on existing

stands can be lessened by sanitation cuts to salvage high-risk

trees if sufficient healthy stems remain after such operations

to give an acceptable yield at rotation age (3).

Other important diseases of slash pine forests are annosus

root rot (Heterobasidium annosum (Fr.) Bref.) and pitch

canker {Fusarium moniliforme Sheld. emend. Snyd. and

Hans. var. subglutinans Wollenw. and Reink.). Annosus

root rot most frequently causes serious damage in thinned

stands on sites having deep, well-drained sandy or loessial

soils that lack an argillic horizon within 10 to 12 inches (25 to

30 cm) of the surface. On such sites it may be prudent to

grow trees to rotation without thinning or to thin only during

warm months when the disease is unable to compete with

other wood-rotting fungi that destroy the stump. Prescribed

burning before and after thinning may reduce severity of the

disease. High-value stands can be protected by treating the

freshly cut stumps (and other exposed wood) with borax.

Harvesting of infected trees is about the only practical

defense against pitch canker.

Fire is both an agent of destruction and a valuable tool in

the management of slash pine. Young trees are quite susceptible to injury by fire until they are 10 to 15 feet (3.1 to 4.6 m)

tall and have bark thick enough to insulate the cambium from

lethal temperatures (27, 44). Even mature stands may be

damaged by head fires in areas with large fuel accumulations

(53). The principal uses of fire in slash pine management are

for site preparation, hazard reduction, and control of under-

^ Cubic foot and metric conversions of measurements expressed in board

feet should be viewed as estimates because of the assumptions involved in

the conversion process.

Story vegetation. Fire also improves forage production for

livestock and habitat for wildlife (32).

Slash pine may be regenerated naturally in uneven-aged

stands by the group-selection method and in even-aged stands

by either the seed-tree or shelterwood system. Regeneration

can also be achieved in even-aged stands by clearcutting with

seed- or seedlings-in-place (32, 35, 36). Because the species

is intolerant, or nearly so, even-aged systems are preferred.

Another reason for favoring even-aged systems is that they

permit the use of prescribed fire to control stand composition

and understory development.

Both the seed-tree and shelterwood systems entail removal of the overstory in two stages. They differ from each

other only in the number of trees retained to regenerate the

area, 6 to 10 trees per acre (15 to 25 trees/ha) in the seed-tree

method and 25 to 40 trees per acre (60 to 100 trees/ha) in the

shelterwood method. These trees should be full-crowned,

disease-free dominants that are proven cone producers. They

should be well spaced over the area to insure adequate seed

dispersal.

Areas being regenerated by these methods should be

prescribe burned prior to the harvest cut to control understory

vegetation and prepare the seedbed. This bum should be

made no earlier than the winter immediately preceding

dispersal of a seed crop adequate to restock the area.

Mechanical site preparation may be substituted for prescribed

burning to ready the site for natural regeneration. But care

must be taken to avoid injury to roots of the seed trees.

Mechanical injury to roots renders the trees susceptible to

attack by insects and disease organisms. Seedbeds deteriorate

rapidly and must be refreshed if an adequate stand of

seedlings is not established within about 2 years. The seed or

shelterwood trees should be retained for 1 year after an

adequate seed crop as insurance against drought losses during

the critical first summer following germination. They should

be harvested as soon thereafter as practical, certainly within 3

to 5 years, to insure vigorous growth of the new crop and to

minimize logging damage to seedlings (21).

Occasionally an adequate stand of natural regeneration

becomes established under lightly stocked mature stands

where there has been no preparatory cut. Under these

conditions the overstory should be harvested immediately to

promote growth of the seedling stand. A variation of this

clearcutting with seedling-in-place system is clearcutting

with seed-in-place. In this method, the overstory is harvested

during or immediately after seed dispersal. The system is less

reliable than other even-aged systems, because the seed

source is removed before the new stand is established.

Widespread success in direct seeding of slash pine suggests

that this disadvantage may not be serious if the seed crop

exceeds approximately 5 pounds per acre (5.6 kg/ha) (18).

Another disadvantage of this system is that seed crops must

be estimated from flower or conelet counts unless the site

preparation bum is made in late summer, after cones are fully

grown.

Successful use of the group-selection method of unevenaged management requires the harvesting of groups of mature

trees to create openings about 1 acre (0.4 ha) in size.

Larger openings are impractical because the seeds are not

dispersed over large distances. Smaller openings are undesirable because the surrounding overstory trees retard seedling

growth. Area-wide stand management treatments, such as

prescribed buming, are not practical with uneven-aged

management.

The preferred method of regenerating slash pine among

large forest landowners is clearcutting followed by chemical

or mechanical site preparation, then direct seeding or planting of nursery or container-grown stock. In 1981, plantations

164
comprised 56 percent of the acreage in slash pine forest types

in North Carolina, South Carolina, Georgia, and Florida.*

The proportion of slash pine acreage established by artificial

methods is probably higher in the Gulf region than in the

Southeast because of widespread planting of the species north

and west of its natural range. With increasing availability of

genetically superior stock, planting should continue to be the

preferred method of regeneration of slash pine.

Slash pine forests provide forage for domestic livestock,

especially cattle, and food and cover for a variety of wildlife

(10, 25, 38, 49). White-tailed deer is the major big-game

species. Small-game species include bobwhite quail, mourning dove, eastern wild turkey, squirrels, and rabbits. Nongame animals include many species of songbirds, water

birds, small mammals, amphibians, and reptiles. Competition between livestock and deer for food seldom occurs

unless overstocking of cattle causes severe overgrazing,

depleting the browse available for deer (56).

Herbage production may exceed 2,000 pounds per acre

(2240 kg/ha) in sparse stands and newly established plantations.

Production declines markedly as young stands close and may

be no more than about 500 pounds per acre (560 kg/ha) by the

time stands are large enough for a commercial thinning. If

thinned and burned regularly, mature stands should produce

about half as much forage as open, cutover range (26).

Slash pine 9 inches (23 cm) d.b.h. and larger may be

worked for gum naval stores (11, 28). Yields average about 1

pound of gum per inch (179 g/cm) of face width per year.

The most common practice is to work a tree for 4 years (2

years on each of 2 faces) immediately preceding the harvest

cut. Since face widths are made equal to tree d.b.h., a

full-crowned 9-inch (23 cm) tree should yield 36 pounds

(16.3 kg) of gum and a 14-inch (36 cm) tree 56 pounds (25.4

kg) during the 4 years.

Slash pine may be planted to stabilize soil on eroding

slopes and strip mine spoil banks.

Slash pine types provide habitat for several threatened

and endangered species listed in the Endangered Species Act

of 1973 (Public Law 93-205), as amended. The red-cockaded

woodpecker forages extensively in slash pine forests and will

use mature, living slash pines for nesting cavities. The bald

eagle often uses large, dominant slash pines for nest trees,

especially in Florida. The Florida panther ranges over extensive areas that include slash pine flatwoods. The eastern

indigo snake uses a variety of habitats, including flatwoods

of Florida, southern Gerorgia, and Alabama. The red hills

salamander, the pine barrens treefrog, and the Mississippi

sandhill crane are found within the natural range of slash

pine, and are susceptible to habitat loss in areas converted to

slash pine. Endangered plants within the natural range of

slash pine include: Chapman rhododendron {Rhododendron

chapmanii Gray), hairy rattleweed {Baptisia arachnifera

Duncan), Harpers beauty (Harperocallisflava S. McDaniel),

persistent trillium (Trillium persistens Duncan), and green

pitcherplant {Sarracenia oreophila (Keam.) Wherry).

Literature Cited

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slash pine plantations. Bull. 559. Gainesville, FL: Florida Agriculture

Experiment Station, University of Florida; 1955. 23 p.

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11. Clements, Ralph W.; Harrington, T. A. Gum naval stores from

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plantations in the lower coastal plain of Georgia and Florida. In: Fries,

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13. Clutter, Jerome L.; Jones, Earle P., Jr. Prediction of growth after

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14. Coile, T. S. Soil and the growth of forests. Adv. Agron. 4: 329-398;

1952.

15. Coile, T. S.; Schumacher, F. X. Soil-site relationships, stand structure,

and yields of slash and loblolly pine plantations in the United States.

Durham, NC: T. S. Coile, Inc.; 1964. 296 p.

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Engelm. var. elliottii). Stn. Pap. 81. Asheville, NC: U.S. Department

of Agriculture, Forest Service, Southeastern Forest Experiment Station;

1957. 13 p.

17. Dell, T. R.; Feduccia, D. P.; Campbell, T. E.; Mann, W. F., Jr. [and

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West Gulf Region. Res. Pap. SO-147. New Orleans, LA: U.S.

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IB. Derr, Harold J.; Mann, William F., Jr. Direct-seeding pines in the

South. Agrie. Handb. 391. Washington, DC: U.S. Department of

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19. Dormán, Keith W. The genetics and breeding of southern pines. Agrie.

Handb. 471. Washington, DC: U.S. Department of Agriculture; 1976.

407 p.

20. Eyre, F. H., ed. Forest cover types of the United States and Canada.

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21. Feduccia, Donald P. Regenerating slash pine naturally without suppression.

South. J. Appl. For. 2(3): 86-89; 1978,

22. Feduccia, Donald P. Thinning planted slash pine on cutover flatwood

sites in the West Gulf. Res. Pap. SO-158. New Orleans, LA: U.S.

Department of Agriculture, Forest Service, Southern Forest Experiment

Station; 1979. 8 p.

23. Fisher, R. F.; Garbett; W. S. Response of semimature slash and loblolly

pine plantations to fertilization with nitrogen and phosphorus. Soil Sei.

Soc. America J. 44: 850-854; 1980.

24. Fowells, H. A., comp. Silvics of forest trees of the United States.

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25. Grelen, Harold E. Longleaf—slash pine—bluestem range. In: Range

resources of the South. Bull. N.S. 9. Athens, GA: Georgia Agricultural

Experiment Station. University of Georgia College of Agriculture;

1974: 9-12.

26. Grelen, Harold E.; Whitaker, L. B.; Lohrey, Richard E. Herbage

response to precommercial thinning in direct-seeded slash pine. J.

Range Manage. 25(6): 435-437; 1972.

27. Gruschow, George F. Effects of winter burning on growth of slash pine

in the flatwoods. J. For. 50(7): S15-517; 1952.

28. Harrington, T. A. Production of oleoresin from southern pine trees—a

review. Forest Prod. J. 19(6): 31-36; 1969.

29. Hebb, Edwin A.; Bums, Russell M. Slash pine productivity and site

preparation on Florida sandhill sites. Res. Pap. SE-135. Asheville,

NC: U.S. Department of Agriculture, Forest Service, Southeastern

Forest Experiment Station; 1975. 8 p.

30. Hoekstra, P. E.; Mergen, Francois. Experimental induction of female

flowers on young slash pine. J. For. 55(11): 827-831; 1957.

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pine increases volume and monetary returns. Res. Pap. SE-164.

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32. Jones, Earle P., Jr. Slash pine. In: Silvicultural guidelines for forest

owners in Georgia. Georgia Forest Res. Pap. Atlanta, GA: Georgia

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1980.

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37. Lennartz, Michael R.; McMinn, James W. Growth of two varieties of

slash pine on prepared sites in south Florida: 10-year results. Res. Pap.

SE-103. Asheville, NC: U.S. Department of Agriculture, Forest

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regeneration beneath overstories. Res. Note SO-170. New Orleans,

LA; U.S. Department of Agriculture, Forest Service, Southern Forest

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DC: U.S. Department of Agriculture; 1950. 57 p.

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pine. South. J. Appl. For. 5(1): 10-12;* 1981.

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forest vegetation of north central Florida. Am. Midi. Nat. 79: 441 —457;

1968.

48. Osbome, J. G.; Harper, V. L. The effect of seedbed preparation in

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166
Virginia Pine

David L. Branilett

Southeastern Forest Experiment Station

Robert N. Kitchens

Southern Region

Virginia pine (Pinus virginiana Mill.) is widely distributed in the northern Piedmont and the foothills and lower

elevations of the Appalachian and Allegheny Mountains. It is

also found on the western edge of the Coastal Plain in New

Jersey and New York. The range extends from Pennsylvania

southward through the Middle Atlantic States including

Maryland, Delaware, Virginia, West Virginia, the Carolinas,

Georgia, and westward to northern Alabama, eastern Tennessee,

Kentucky, and Ohio.

In the Piedmont of the Carolinas and Virginia, Virginia

pine is a pioneer species that rapidly invades abandoned

agricultural lands or other disturbed sites. The Piedmont soils

are predominantly clays with local variation in sand or loam

content. In the Virginia and Maryland Coastal Plain, Virginia

pine grows in pure or mixed stands on sandy loam soils. Up

to 3,000 feet (915 m) on the low ridges of the Appalachian

and Allegheny Mountains, Virginia pine successfully competes on abandoned fields and on dry ridges with a southern

or western exposure. The upland and ridge sites are typically

shallow soils derived from shales or sandstone and characteristically have low fertility and little organic matter (4).

Virginia pine is a very hardy species and tolerates

weather extremes from -10° to 100° F (-23.3° to 37.7° C).

Average summer temperatures are from 70° to 75° F (21.1° to

23.8° C) and winter temperatures are from 25° to 40° F

(-3.9° to 4.4° C). The growing season changes drastically

from 225 days on the southern and eastern extent of the range

to 160 days in the more mountainous northern and western

portion. Average annual precipitation throughout the range is

35 to 55 inches (890 to 1395 mm) and is well distributed

throughout the year. Seasonal droughts may occur throughout the range and are more severe on the shallow and rocky

soils (10). '

Virginia pine, classified as forest cover type 79 by the

Society of American Foresters (4), is frequently associated

with other conifers including shortleaf {Pinus echinata Mill.),

Table Mountain (P. pungens Lamb.), pitch {P. rigida Mill.),

and loblolly {P. taeda L.) pine, and eastern redcedar {Juniperus

virginiana L.); it is also found with white pine {Pinus strobus

L.) and eastern hemlock {Tsuga canadensis (L.) Carr.).

Commonly associated hardwoods include many oak species—

post oak {Quercus stellata Wangenh.), black oak {Q. velutina

Lam.), northern red oak {Q. rubra L.), scarlet oak {Q.

coccinea Muenchh.), chestnut oak {Q. falcata Michx.), and

blackjack oak {Q. marilandica Muenchh.). Other hardwood

associates are red maple {Acer rubrum L.), hickories {Carya

spp.), blackgum {Nyssa sylvatica Marsh.), sweetgum

{Liquidambar styraciflua L.), yellow-poplar {Liriodendron

tulipifera L.), dogwood {Cornus florida L.), and sourwood

{Oxydendrum arboreum (L.) DC).

Virginia pine is a precocious and prolific seed producer.

Flower and seed production may begin as early as 3 to 4 years

and continue until crown closure. Even dense even-aged

stands normally produce some seed, but abundant production

may be delayed until after dominance is expressed or

mortality opens the stand to sunlight. Large dominant or

open-grown trees are capable of producing over a thousand

cones per year. Virginia pine produces some cones every

year and does not appear to have a well-defined cycle of

seed-producing years (7). Typically, there are good to

excellent years between moderate to poor years. Annual seed

crops of 48,000 to 996,000 seeds per acre (118 600 to

2 461 200/ha) have been observed in Maryland (6). Each

cone has a seed capacity of approximately 90 seeds but this is

normally reduced to about 35 to 45 due to losses from insects

and other causes. Cones of Virginia pine normally are not

serotinous but some trees will have cones that do not open

readily. Normal seed dispersal begins in early November and

continues through February or March; however, most of the

seed is dispersed by the end of December. Germination occurs

in late spring and seedling establishment is greatly enhanced

by exposure of mineral soil.

Virginia pine is shade intolerant (11). The species will

germinate and persist from 1 to 2 years under shaded

conditions but continued shading will result in seedling

mortality. Intolerance to shade and susceptibility to wind,

ice, and snow damage are the most important silvical

characteristics to bear in mind when choosing a management

regime and reproduction method.

Timber production of Virginia pine is greatest on highquality sites with full stocking (1, 8, 9). Yields at site index

of 70 feet (21.3 m) for 30- to 40-year-old natural stands are

from 3,200 to 4,360 cubic feet per acre (224.0 to 305.2

m^/ha) and annual growth is approximately 90 cubic feet per

acre (6.3 m-^/ha) per year (9). The regeneration ability of the

species may result in overstocking and young stands of

40,000 (9) and even up to 100,000 seedlings (3) per acre

(98 840 to 247 100/ha) have been observed. These overly

dense stands may produce a relatively high total cubic-foot

growth but merchantibility may be reduced because the average diameter is very small.

Virginia pine is not long lived. Suggested rotations are

30 to 40 years for pulpwood and 40 to 50 years for

sawtimber. The mean annual growth increment culminates at

about age 35 and is much reduced after 40 to 50 years when

mortality begins to open the stand. By age 70, the stand may

begin to deteriorate and the understory hardwoods to assert

dominance.

Virginia pine is a rather hardy species with relatively

few major pests. Cones and seeds are damaged by insects

including Dioryctria spp., leaffooted pine seed bug Leptoglossus corculus (Say), shieldbacked pine seed bug Tetyra

bipunctata (Herrich-Schaffer), Laspeyresia spp., and Eucosma

spp. Insect pests during seedling growth and establishment include the pales weevil {Hylobius pales (Herbst)), pine webworm {Tetralopha robustella Zeller), and Nantucket pine tip

moth {Rhyacionia frustrana (Comstock)). Although these

insects are prevalent in young stands, the damage rarely

results in economic losses. Virginia pine is a host for the

eastern gall rust {Cronartium quercuum (Berk.) Miy. ex

Shirai f. ^^. fusiforme Burds. & Snow), which causes some

mortality from stem cankers but heavy losses are not common.

167
The most serious insect problem, especially of intermediatesize trees, is the bark beetle, including the southern pine

beetle {Dendroctonus frontalis Zimmermann) and engraver

beetle {Ips spp.)- These insects can cause severe losses and

epidemic years result in mortality of a large number of trees.

Other stress factors, such as drought, poor site, and overly

dense stands, contribute to bark beetle attacks. Another

important insect pest is the Virginia pine sawfly {Neodiprion

pratti pratti (Dyar)). Pitch canker (Fusarium moniliforme

Sheld. emend. Snyd. & Hans. var. subglutinans Wollen. &

Reink.) and annosus root rot {Heterobasidium annosum (fr.)

Bref.) are diseases that may attack Virginia pine stands of

intermediate-size trees. As the stand reaches maturity, the red

heart fungus (Phellinus pini (Thore ex Fr.) A. Ames)

becomes a major disease and can cause serious wood volume

loss.

Because of its silvical characteristics, Virginia pine

should be grown in even-aged stands (11). Also, Virginia

pine has thin bark and is easily damaged or killed by fire (3,

5, 9); therefore, fire normally cannot be used for seedbed

preparation or hardwood control, except at the harvest cut

under even-aged management.

For regenerating Virginia pine stands, clearcutting is

best adapted to this species' silvical characteristics. Clearcutting

allows full sunlight to reach the new trees, produces a stand

of the same age and height that protects the trees from

windthrow, and allows the use of fire in site preparation. The

clearcut area can be planted, seeded, or reproduced by

natural regeneration.

Like the seedlings of other southern pines, Virginia pine

seedlings must be properly handled and planted and all

necessary hardwood control completed (7). Direct seeding

may also be used (12). For natural regeneration, Virginia

pine's prolific seed crop is usually more than adequate and

site preparation and hardwood control will increase regeneration success.

Clearcutting in strips or patches also can be used to

regenerate Virginia pine. (Patch cutting can also be classified

as group selection under uneven-aged management if the

patches are small and cut out of the stand over a period of

many years. Unless these conditions are met, this cutting

method is considered even-aged management.)

In strip cutting, the stand is cut in 100- to 400-foot (30.5

to 121.9 m) wide strips. Slash on these cut areas can be

burned and hardwood control measures applied. Seedbed

preparation using logging equipment or fire is applied to the

harvested strips. Seed is supplied by trees in the adjacent

uncut strips. After 3 to 10 years the uncut areas are harvested.

Regeneration of the uncut strips is more difficult. A light fire

can be used to prepare a seedbed in the uncut strip but

damage to residual trees may negate the benefit of the fire if

mortality results (13).

Thinning uncut stands would stimulate production of

seeds and establishment of advanced regeneration but risks of

windthrow and ice damage would be increased. Perhaps the

best procedure for regeneration of the uncut areas is to time

the harvest cut in the fall or winter following a relatively

good seed crop of the residual stand. Seed shed before

harvest or from cones on logging slash provide seed for

regeneration. Logging equipment provides some seedbed

scarification and exposure of mineral soil to seed in the

surface duff. Hardwood control in the uncut strips may be

difficult, however, and requires weeding to reduce hardwood

competition. Planting or direct seeding could also be used to

ensure regeneration of the residual strips or patches.

Shelterwood or seed-tree cuts are generally not recommended for regenerating Virginia pine. The major reason is

the susceptibility of Virginia pine to ice or windthrow when

released after having been grown under relatively dense

stocking levels.

Single-tree selection is not recommended for Virginia

pine. As the species is shade intolerant, pure pine regeneration in small openings would not be expected but instead a

single-tree cutting would undoubtedly favor hardwood invasion and gradual reduction of the pine-growing stock.

Group selection in the classical sense is also not recommended because the even-age structure of the stand would

deteriorate into a gradual transition to hardwood species. Site

and seedbed preparation, hardwood control, and thinning

would also be difficult to manage.

Hardwood encroachment is a serious problem in the

regeneration of Virginia pine. Virginia pine, as a pioneer

species, achieves its best growth and development in old

abandoned fields. The exposed mineral soil is an ideal

seedbed and the competition from native grasses does not

seriously restrict establishment. Initial stocking is frequently

1,000 to 3,000 stems per acre (2415 to 7415/ha) at age 3 with

gradual reduction to 500 to 400 stems per acre (1235 to

990/ha) at age 40 to 50. Following establishment of Virginia

pine on an old-field site, invasion of hardwood species begins

as the litter depth increases. These associated hardwood

species are relatively tolerant and, although they grow slowly

as understory species, they respond to any openings in forest

canopy. It is therefore important to exert hardwood control at

the time of harvesting. If first-cycle Virginia pine stands are

harvested without hardwood control, the second-rotation

stand will be mixed pine-hardwood and further cutting of the

pine will result in an almost pure hardwood stand.

Regeneration of ridge-top stands or stands that are

growing on droughty, poor sites may not have serious

problems with hardwood competition. These sites can be

maintained by cutting all large hardwoods at the time of the

harvest cut and allowing Virginia pine seedlings to compete

with smaller hardwood sprouts and seedlings. On the very

poorest sites, such as the shale barrens or rocky outcrops,

Virginia pine may be one of the few tree species that survives

the harsh environment. On these sites, Virginia pine serves

primarily to protect the soil, and growth is so poor that the

stands are rarely or never harvested.

Land use patterns throughout most of the Virginia pine

range have recently changed so that agricultural land is rarely

abandoned and allowed to revert to forest growth, and will

probably remain for an extended period in crop or pasture

production. In the Virginia Piedmont, Virginia pine growth

normally exceeds that of shortleaf pine when the two species

are found in mixed natural stands. On the poorer sites and

more mountainous areas, Virginia pine remains the best

suited species. Careful management, hardwood control, and

regeneration strategy will be required to continue production

from Virginia pine as a source of forest and related products.

Vigorous establishment of Virginia pine has severe

limitations on future stand development. Even-age stands of

several thousand trees per acre do not express dominance as

clearly as other species and the major crop trees may appear

as codominants at age 20 to 30 years. Thinning can be used to

regulate stand density and to increase the average diameter of

the stand (2). If thinning is done in Virginia pine stands, it is

recommended that it be completed before age 12 to 15 years.

This may be a precommercial thinning. Later thinnings

apparently do not result in substantial growth increments on

the residual trees. Thus, growth is primarily a function of

basal area stocking and site index. On the better sites,

relatively high basal areas up to 180 square feet per acre

(41.3 m^/ha) have been observed. Thinning these stands

reduces the growing stock and net reductions in total volume

can be expected. Residual trees do show a diameter response

168
but total volume will not equal the unthinned stand (1, 9).

Unless excessive stems per acre are present, no thinning is

recommended for Virginia pine stands that are grown on a

40- to 50-year rotation for small sawlogs and pulpwood on

the better Piedmont sites.

Similarly, improvement cuts after stands reach 30 to 40

years would be unlikely to show an economic gain. Stand

appearance would be improved by partial cutting but the

disadvantages of increased hardwood encroachment and

susceptibility to damage by ice or windthrow probably more

than offset any economic return. Sanitation cuts could

include removal of trees damaged from bark beetles, ice,

etc., but again, most forest managers would normally recommend clearcutting the stand if the damage was severe and

otherwise avoid partial cuts before harvesting fully stocked

stands.

Virginia pine stands provide food, cover, and protection

for native wildlife species during periods of stand establishment,

development, and maturity. During regeneration when stands

are clearcut,, the full sunlight required for pine establishment

and development is very beneficial to small game species

such as quail, rabbits, and numerous nongame birds and

mammals. As the tree crown closes, light is reduced on the

forest floor and food and ground cover species are crowded

out. Even so, the dense stands of Virginia pine provide

winter cover and protection for wildlife species such as deer.

When understory plants such as honeysuckle (Lonicera spp.)

are also present, deer frequently use Virginia pine stands

during winter months. As stands mature, mortality may

expose the forest floor once again and the Virginia pine

gradually reverts to an oak-hickory forest. The mixed pinehardwood forest is a favorable environment for numerous

wildlife species.

The characteristic limby, dense growth of Virginia pine

does not produce visually appealing parklike stands or much

depth of vision. However, its bushy open-grown quality

makes it esthetically desirable for some plantings, especially

where early screening is desired.

Virginia pine is perhaps the best Christmas tree species

to grow in the warmer areas of the South. Proper Christmas

tree plantation management, including shearing, produces a

desirable tree in 4 to 6 years. This use is increasing rapidly.

The aggressive pioneer characteristics of the species

provide considerable protection to barren or exposed sites.

The species is also frequently selected to reclaim mining

areas, spoil banks, borrow pits, or other severely disturbed

sites. Establishment of Virginia pine on these areas reduces

erosion and further deterioration of the site.

Literature Cited

1. Belanger, Roger P.; Bramlett, David L. The growth and yield of

Virginia pine. In: Proceedings of symposium for management of pines

of the Interior South; 1978 November 7-8; Knoxville, TN. Tech. Pub.

SA-TR2. Atlanta, GA: U.S. Department of Agriculture, Forest Service,

Southeastern Area, State and Private Forestry; 1979: 108-118.

2. Carvell, Kenneth L. The effect of stand density on the development of

Virginia pine in the Ohio River area of West Virginia. Curr. Rep. 46.

Morgantown, WV: West Virginia University Agriculture Experiment

Station; 1966. 13 p.

3. Carvell, Kenneth L. Virginia pine management. In: Proceedings of

symposium for the management of pines of the Interior South; 1978

November 7-8; Knoxville, TN. Tech. Pub. SA-TP2. Atlanta, GA:

U.S. Department of Agriculture, Forest Service, Southeastern Area,

State and Private Forestry; 1979: 104-107.

4. Eyre, F. H., ed. Forest cover types of the United States and Canada.

Washington, DC: Society of American Foresters; 1980. 148 p.

5. Fenton, Richard H. Seven years later: effects of wildfire in a young

stand of Virginia pine and hardwoods. For. Res. Notes 100. Broomall,

PA: U.S. Department of Agriculture, Forest Service, Northeastern

Forest Experiment Station; 1960. 4 p.

6. Fenton, Richard H.; Bond, Adna R. The silvics and silviculture of

Virginia pine in southern Maryland. Res. Pap. NE-27. Broomall, PA:

U.S. Department of Agriculture, Forest Service, Northeastern Forest

Experiment Station; 1964. 37 p.

7. Kundt, John. Virginia pine regeneration. In: Proceedings of symposium

for the management of pine of the Interior South; 1978 November 7-8;

Knoxville, TN. Tech. Pub. SA-TP2. Atlanta, GA: U.S. Department of

Agriculture, Forest Service, Southeastern Area, State and Private

Forestry; 1979: 101-103.

8. Nelson, T. C; Clutter, J. L.; Chaiken, L. E. Yield of Virginia pine.

Stn. Pap. 124. Asheville, NC: U.S. Department of Agriculture, Forest

Service, Southeastern Forest Experiment Station; 1961. 11 p.

9. Slocum, G. K.; Miller, W. D. Virginia pine: reproduction, growth, and

management on the Hill Demonstration Forest, Durham County, NC.

Tech. Bull. 100. Raleigh, NC: North Carolina Agricultural Experiment

Station; 1953. 52 p.

10. Snow, Albert G., Jr. Silvical characteristics of Virginia pine {Pinus

virginiam). Stn. Pap. 131. Broomall, PA: U.S. Department of Agriculmre,

Forest Service, Northeastern Forest Experiment Station; 1960. 22 p.

11. Sowers, David W., Jr. Some factors affecting management of conifers

in the Allegheny region. J. For. 54(9): 563-567; 1956.

12. Sowers, David W., Jr. Suggested guidelines for direct seeding Virginia

pine in West Virginia. North. Logger 12: 12-13; 36-39; 1964.

13. Sucoff, Edward I. Regenerating the last strips in strip-cuttings in

Virginia pine. Stn. Pap. 119. Broomall, PA: U.S. Department of

Agriculture, Forest Service, Northeastern Forest Experiment Station;

1961. 6 p.

169
Sand Pine

Kenneth W. Outcalt

Southeastern Forest Experiment Station

William E. Balmer

Southeastern Area

Sand pine (Pinus clausa (Chapm. ex Engelm.) Vasey ex

Sarg.) is native to the droughty, acid, infertile, marine

deposited sandhills of Florida and Baldwin County, Alabama.

The largest concentration of the Ocala variety {Pinus clausa

var. clausa D. B. Ward) is in the center of Florida on an area

of rolling sandhills known as the Central Highlands. The

Choctawhatchee variety {P. clausa var. immuginata D. B.

Ward) is found along the Gulf Coast of northwest Florida

from the Apalachicola River westward into Alabama (15).

Both of these areas have similar climates with hot, humid

summers, somewhat dry winters, and a long growing season

of 269 to 312 days. Precipitation is abundant, 53 to 60 inches

per year (1345 to 1525 mm), and fairly well distributed;

however, because of the low moisture-holding capacity of the

soils, drought conditions can exist within 2 weeks of a heavy

rainfall. Surface temperatures of exposed soils may reach

140° F (60° C) on summer days (6).

Sand pine is the dominant species of the Society of

American Foresters forest cover type 69 (9) on approximately

3 million acres in Florida and shows promise for converting

much of the 8 million acres of scrub-hardwood dominated

sandhill land to pine in the Southeastern States. It occurs as a

minor component of type 70, Longleaf Pine, type 71,

Longleaf Pine-Scrub Oak, and type 84, Slash Pine. The

understory in Ocala stands is primarily evergreen shrubs 6 to

10 feet (1.83 to 3.05 m) tall with very little herbaceous

ground cover (13). Typical understory species are sand live

oak (Quercus virginiana var. geminata (Small) Sarg.), myrtle oak (ß. myrtifolia Willd.), Chapman oak {Q. chapmanii

Sarg.), and palmetto (Sabal spp.). The understory of

Choctawhatchee stands is primarily décidons shrubs with

some herbaceous ground cover. Turkey oak (Quercus laevis

Walt.), bluejack oak (ß. incana Bartr.), sand post oak {Q.

stellata var. margaretta (Ashe) Sarg.), and pineland threeawn

{Artistida stricta Michx.), commonly called wiregrass, are

the major understory species (6).

Considerable differences exist between Ocala and

Choctawhatchee seed production and cone characteristics.

Although both commonly produce cones at an early age,

about 5 years, Ocala trees have abundant annual cone crops

while Choctawhatchee trees produce heavy crops only every

4 to 6 years with smaller crops between (1). Ocala cones are

predominately serotinous and persist on the tree for many

years. Most of the Choctawhatchee variety cones open in the

fall when they reach maturity.

Although rated as moderately intolerant, sand pine is

quite tolerant of shade and competition when young. Both

varieties will survive underplanting among the scrub

oak—wiregrass vegetation found on northwest Florida sandhills.

Eventually they will overtop the competition and dominate

the site (12). Once established, sand pine can endure considerable drought.

Trees on average sites, site index 60, are 10 to 12 inches

(25 to 30 cm) in diameter at breast height (d.b.h.) and

average 60 feet (18.3 m) tall at 50 years. Well-stocked

natural stands of the Ocala variety will yield 900, 1,350, and

1,800 cubic feet per acre (63.0, 94.5, and 126.0 m^/ha) on

poor, average, and good sites, respectively, on a 40- to

45-year rotation (20). On a pulpwood rotation of 25 to 30

years, Choctawhatchee plantations are expected to yield

1,800, 2,700, and 3,600 cubic feet per acre (126.0, 189.0,

and 252.0 m%a) on poor, average, and good sites, respectively.

Insects, disease, and fire play a significant part in the

development and management of sand pine. Bark beetles,

primarily Ips (Ips calligraphus (Germar) and /. grandicollis

(Eichhoff)), can be a problem after thinnings or partial

cuttings. Ocala sand pine, especially in plantations outside its

natural range (19) and natural stands over age 40, frequently

suffer considerable mortality from mushroom root rot

{Armillariella tabescens (Scop, ex Fr.) Sing.). Thus, the

Ocala variety should not be planted outside its natural range

and, within its native range, a maximum rotation age of 40

years is best. The Choctawhatchee variety is quite resistant to

the root rot, except when planted off site on poorly drained

soils, and can be managed for sawtimber production with

rotations as long as 50 years. On private ownerships, both

varieties should probably be managed for pulpwood with

rotations of 25 to 35 years (4).

Because of its thin bark, sand pine is relatively susceptible to fire-caused damage and mortality. The Choctawhatchee

variety, however, with its typical sparse understory can be

prescribed burned under proper conditions (2). The evergreen

shrub understory of Ocala stands is usually dense enough to

shade out grass and low herbaceous cover. Because of this

lack of low base fuels, headfires are necessary to bum the

understory, but these are too explosive to use without high

risk of losing the entire stand. Thus, prescribed burning is

impractical in the Ocala type (7).

Most natural stands of Ocala sand pine have originated

from seed released by its serotinous cones following wildfires.

Although the effects of fire regenerate the stand, it is

undesirable because most of the original timber is lost. Some

kind of disturbance is needed, however, to maintain the type;

otherwise, these stands would gradually be taken over by the

more tolerant scrub oaks.

Sand pine is best suited to even-aged management. Both

form and branch pruning are considerably improved when

trees are grown in dense, even-aged stands. Under natural

conditions, stands are typically dense, pure, and singlestoried, although uneven-aged stands do develop during the

initial invasion stage of scrub-oak sites (2).

Choctawhatchee sand pine can be successfully regenerated by either seed-tree or shelterwood systems (2). In both

methods of regeneration an initial cut is made to stimulate

seed production, followed by a final harvest after adequate

regeneration is obtained, normally 5 to 10 years. Disadvantages are the possible loss of trees from Ips beetle attacks

after the initial cutting and damage to regeneration during the

final cut. Density control can also be a problem with natural

regeneration systems.

Because of its serotinous cones, the seed-tree and

shelterwood systems are not suitable for regeneration of

170
Ocala sand pine. Attempts have been made to get natural

regeneration by using the heat from the sun to open cones in

logging slash, but stocking has been below acceptable levels

(18). Burning logging slash to release seeds has also been

tried but it gave poor results because available cones (and

logging slash) were unevenly distributed and fire destroyed

the seeds (8).

The most successful system for regenerating Ocala sand

pine is clearcutting, site preparation, and direct seeding (18).

Double chopping with a heavy, duplex brush chopper is the

preferred method of site preparation because it gives good

control of competition and adequate exposure of mineral soil.

A prescribed burn may be applied between chops if slash is

especially heavy. Broadcast seeding at a rate of 0.5 to 1.0

pound per acre (0.6 to 1.1 kg/ha) should be done from

October through November when soil temperatures are the

most favorable for seedling establishment. Some method of

covering the seed with a layer of soil 0.25 to 0.75 inches (0.6

to 1.9 cm) thick should be used to reduce seed prédation and

increase germination. Ocala sand pine can also be planted,

but due to its lack of dormancy, survival is generally poor

(about 60 percent) and variable (6, 12).

Unlike Ocala, the Choctawhatchee variety is easily

planted with high and consistant survival rates even on sites

outside its natural range (3). Growth and survival on sandhill

sites in Georgia and South Carolina indicate that sand pine

will outperform other pine species normally planted on these

deep sands (16, 17). Deep planting is recommended, with

seedlings set to a depth that results in the lower branches

remaining covered after the soil settles (4). Recommended

planting densities for 25- to 35-year rotations are 500 to 550

seedlings per acre (1235 to 1360/ha) if no thinning is

planned, and 725 to 775 per acre (1790 to 1915/ha) if an

intermediate thinning at about age 20 is anticipated.

Overstocked stands of sand pine can result from regeneration by seed-tree, shelterwood, or direct seeding. Such stands

should receive a precommercial thinning to prevent stagnation and growth loss. Mechanically thinning seedling-or

small sapling-sized stands in strips using drum choppers or

rotary mowers is the most practical method of reducing their

density. Trees in older stands and plantations will respond to

thinning (5). Thinning in the traditional manner can be used

in older stands for regulation of product size. This is more

applicable to the Choctawhatchee variety which has better

form, smaller branches, and higher wood density, and thus is

better suited to sawlog production than is the Ocala variety.

Thinning should be done during the dormant season to lessen

the risk of bark beetle attacks.

Many of the sites where sand pine currently is being

established are scrub oak—wiregrass areas with no existing

seed source. These sites can be converted by underplanting

sand pine among the existing vegetation. Growth of seedlings

can be substantially increased by release soon after establishment (3). This is an economically attractive strategy for

landowners with small holdings who may not be able or

inclined to make a large investment in stand conversion. On

larger areas, double chopping followed by direct seeding or

planting is more practical. Because spacing can be controlled,

plantation establishment by planting the Choctawhatchee

variety is the preferred procedure.

Site preparation for conversion of scrub oak-wiregrass

sites reduces available wildlife foods. Some useful seedproducing species will invade and grow on these sites for a

few years after chopping, but they soon give way to grasses

(11). Undisturbed strips of scrub vegetation can be left in

larger plantations to increase wildlife use (6). In some cases

these can be provided along natural drainages. Even dense

stands of Ocala sand pine contain many understory shrubs

that provide mast and forage for wildlife. Production can be

increased by clearcutting or thinning (10). Prescribed burning

every 3 to 4 years will improve the quantity and quality of

forage under Choctawhatchee stands (14).

Literature Cited

1. Bamett, J. P.; McLemore, B. F. Cone and seed characteristics of sand

pine. Res. Pap. SO-19. New Orleans, LA: U.S. Department of

Agriculture, Forest Service, Southern Forest Experiment Station; 1965.

13 p.

2. Britt, Robert W. Management of natural stands of Choctawhatchee sand

pine. In: Proceedings, Sand Pine Symposium; 1972 December 5-7;

Panama City Beach, FL. Gen. Tech. Rep. SE-2. Asheville, NC: U.S.

Department of Agriculture, Forest Service, Southeastern Forest Experiment Station; 1973: 135-143.

3. Bums, Russell M. Comparative growth of planted pines in the sandhills

of Florida, Georgia, and South Carolina. In: Proceedings, Sand Pine

Symposium; 1972 December 5-7; Panama City Beach, FL. Gen. Tech.

Rep. SE-2. Asheville, NC: U.S. Department of Agriculture, Forest

Service, Southeastern Forest Experiment Station; 1973: 124-134.

4. Bums, Russell M. Management of sand pine plantations. In: Proceedings,

Sand Pine Symposium; 1972 December 5-7; Panama City Beach, FL.

Gen. Tech. Rep. SE-2. Asheville, NC: U.S. Department of Agriculture,

Forest Service, Southeastem Forest Experiment Station; 1973: 153—163.

5. Bums, Russell M.; Brendemuehl, Raymond H. Sand pine: Early

responses to row thinning. Res. Note SE-262. Asheville, NC: U.S.

Department of Agriculture, Forest Service, Southeastem Forest Experiment Station; 1978. 8 p.

6. Bums, Russell M.; Hebb, Edwin A. Site preparation and reforestation

of droughty, acid sands. Agrie. Handb. 426. Washington, DC: U.S.

Department of Agriculture; 1972. 61 p.

7. Cooper, Robert W. Fire and sand pine. In: Proceedings, Sand Pine

Symposium; 1972 December 5-7; Panama City Beach, FL. Gen. Tech.

Rep. SE-2. Asheville, NC: U.S. Department of Agriculture, Forest

Service, Southeastem Forest Experiment Station; 1973: 207-212.

8. Cooper, Robert W.; Schopmeyer, Clifford S.; McGregor, William H.

D. Sand pine regeneration on the Ocala National Forest. Prod. Res.

Rep. 30. Washington, DC: U.S. Department of Agriculture; 1959. 37 p.

9. Eyre, F. H., ed. Forest cover types of the United States and Canada.

Washington, DC: Society of American Foresters; 1980. 148 p.

10. Harlow, R. F.; Sanders, B. A.; Whelan, J. B.; Chappel, L. C. Deer

habitat on the Ocala National Forest: Improvement through forest

management. South. J. Appl. For. 4(2): 98-102; 1980.

11. Hebb, Edwin A. Site preparation decreases game food plants in Florida

sandhills. J. Wildl. Manage. 35(1): 155-162; 1971.

12. Hebb, Edwin A.; Bums, Russell M. Methods and goals in preparing

sand pine sites. In: Proceedings, Sand Pine Symposium; 1972 December 5-7; Panama City Beach, FL. Gen. Tech. Rep. SE-2. Asheville,

NC: U.S. Department of Agriculture, Forest Service, Southeastem

Forest Experiment Station; 1973: 82-92.

13. Laessle, Albert M. The origin and successional relationship of sandhill

vegetation and sand pine scmb. Ecol. Monogr. 28(4): 361-387; 1958.

14. Lewis, Clifford E. Understory vegetation, wildlife, and recreation in

sand pine forests. In: Proceedings, Sand -Pine Symposium; 1972

December 5-7; Panama City Beach, FL. Gen. Tech. Rep. SE-2.

Asheville, NC: U.S. Department of Agriculture, Forest Service, Southeastem Forest Experiment Station; 1973: 180-192.

15. Little, Elbert L., Jr. Checklist of United States trees (native and

naturalized). Agrie. Handb. 541. Washington, DC: U.S. Department of

Agriculture; 1979. 375 p.

16. McNab, W. Henry; Carter, Allen R. Sand pine performance on South

Carolina sandhills. South. J. Appl. For. 5(2): 84-88; 1981.

17. Preston, Dmid N.; Price, Terry S. Sand pine in Georgia. Ga. For. Res.

Pap. 5. Macon, GA: Georgia Forestry Commission; 1979. 13 p.

18. Price, Murphy B. Management of natural stands of Ocala sand pine. In:

Proceedings, Sand Pine Symposium; 1972 December 5-7; Panama

City Beach, FL. Gen. Tech. Rep. SE-2. Asheville, NC: U.S.

Department of Agriculture, Forest Service, Southeastem Forest Experiment Station; 1973: 144-152.

19. Ross, Eldon W. Sand pine root rot—pathogen: Clitocybe tabescens. J.

For. 68(3): 156-158; 1970.

20. Schumacher, F. X.; Coile, T. S. Growth and yields of natural stands of

southem pines. Durham, NC: T. S. Coile, Inc.; 1960. 115 p.

171
Oak-Pine

David L. Graney

Southern Forest Experiment Station

Robert N. Kitchens

Southern Region

The oak—pine type includes some 35 million acres of

predominantly upland sites in the Southern and Eastern

United States (33). Its range extends from southern New

York and New Jersey to Pennsylvania, southern Ohio,

Kentucky, southwestern Illinois and southern Missouri, south

through Arkansas to eastern Oklahoma and east to northern

Florida and north through the Atlantic Coast States to

Delaware (6, 12, 14).

The several pine and oak species that comprise the

oak-pine type are adaptable to a great variety of site and

soil conditions. The type is found on all topographic positions from dry rocky ridges and steep slopes of the Appalachians and Ozarks to the gently rolling or flat terrain of the

Piedmont or Atlantic and Gulf Coastal Plains. Ultisols are the

dominant soils throughout the oak-pine range. Soils are

derived from a wide variety of parent materials, including

sedimentary and metamorphic rocks, marine terrace, and

loess, and range from clays to sandy loams. The type is much

less common on soils with high pH values or high calcium

content (14).

The oak-pine type occurs at elevations as low as 10

feet (3 m) in southern New Jersey to 3,000 feet (915 m) in the

Appalachians, although the type is most common at elevations of from 150 feet (45 m) in the Coastal Plain to about

1,500 to 2,000 feet (455 to 610 m) in the Piedmont and

mountainous regions (14).

Climatic conditions vary widely throughout the oak—pine

range. Annual precipitation averages 37 to 40 inches (940 to

1015 mm) in the northeastern and western portions of the

range and 60 inches (1525 mm) along the Gulf Coast (31).

Mean annual temperatures vary from 48° to 70° F (8.9° to

21.1° C), and the frost-free period ranges from 160 days in

the north to about 250 days on the Gulf Coast.

The oak—pine type is composed of forests in which

upland oaks and other hardwoods comprise 50 to 75 percent

of the stocking and southern pines constitute the remainder

(32). It encompasses the major pine—hardwood forest cover

types as classified by the Society of American Foresters (12)

including: Shortleaf Pine-Oak (type 76), Virginia Pine-Oak

(type 78), and upland portions of Loblolly Pine—Hardwood

(type 82). Pitch pine-oak variants of the Pitch Pine type

(type 45) are common in the northeast and on poorer sites in

the Appalachians, while Longleaf Pine-Scrub Oak (type 71)

is common on the Atlantic and Gulf Coastal Plains. The

oak-pine type is closely associated with and is most

common within the geographic range of the Shortleaf Pine

(type 75) and Loblolly Pine-Shortleaf Pine (type 80) forest

types. Major oak species include white (Quercus alba L.),

post (Q. stellata Wangenh.), black {Q. velutina Lam.),

scarlet {Q. coccínea Muenchh.), northern red (ß. rubra L.),

southern red {Q. falcata Michx. var. falcata), and chestnut

(Q. prinus L.). Associated hardwoods include hickories

(Carya spp.), yellow-poplar (Liriodendron tulipifera L.),

sweetgum {Liquidambar styraciflua L.), black gum (Nyssa

sylvatica Marsh.), and red maple {Acer rubrum L,). Major

pine species are shortleaf (Pinus echinata Mill.), loblolly {P.

taeda L.), Virginia {P. virginiana Mill.), and, to a lesser

extent, pitch (P. rígida Mill.) (21).

Oak-pine represents a transitional stage of the successional pattern from an essentially pine-dominated forest to

the climax forest types dominated by oaks and other hardwoods (25, 26). When farmlands are abandoned, southern

pines become established on the open lands. Tolerant hardwood species invade the understory of pine stands and

gradually increase in numbers, height, and basal area. Under

heavy overstory shade, pine reproduction cannot compete

successfully with the hardwoods for light and moisture, and

few survive (18, 19, 35). Harvesting of large pines and losses

by windthrow, insects, and disease create small openings in

pine forests which are quickly occupied by oaks and other

hardwoods already present in the understory. Over time, the

pine-dominated stands are transformed to oak-pine stands,

which in turn will be replaced by oak and other hardwooddominated stands. Unless followed by adequate cultural

treatments, repeated cuttings in pine stands will increase the

amount of hardwoods and hasten the succession to oak-pine

and then to oak-hickory (3, 4, 5, 34). By 1973, more than

70 million acres (28.3 million ha) of pine site lands were

occupied by oak-pine or hardwood types (24), and the

acreage has continued to increase through 1979 (3, 4).

Yield of oak-pine stands will vary with the amount of

pine, but on upland sites yield will be intermediate between

pine and oak-hickory types. For natural stands on upland

sites in North Carolina and eastern Virginia, oak-pine yields

at age 50 averaged about 2,600 cubic feet and 9,400 board

feet (fbm) (International !/4-inch) per acre (182.0 and 131.6

m%a, respectively)' on good sites and about 1,600 cubic

feet and 2,700 fbm per acre (112.0 and 37.8 m^/ha, respectively)

on poor sites. Board foot volumes averaged about 50 percent

less on both sites while cubic foot volumes were 25 percent

less on good sites but were approximately the same as pure

loblolly pine stands on poor sites. Upland hardwoods,

primarily oak—hickory, produced the lowest average yields

on all sites (16). Across the southern region, average loss in

yield resulting from hardwood competition in natural pine

stands has been estimated at 25 percent (13).

On better sites, oaks and associated species produce

desirable stems and the succession from oak—pine to oak and

other hardwood types should be encouraged. Also, hardwood

species are aggressive on better sites and control is difficult

and expensive. On medium to poor sites, the silvicultural

objective for timber production in the oak—pine type is to

increase the pine and reduce the hardwood components.

Pines are favored over hardwoods because of the greater

demand for pine products and because of faster growth,

greater yields, and high quality and value of pines on most

upland sites. On poorer sites, pine will produce moderate

' Cubic foot and metric conversions of measurements expressed in board

feet should be viewed as estimates because of the assumptions involved in

the conversion process.

172
yields of merchantable material while associated hardwoods

are usually of poor quality, grow slowly, and produce lower

yields.

The several pine species of the oak-pine type are

intolerant of shade (14) and are best suited to an even-aged

system of management. To obtain maximum pine stocking in

future stands, harvest cuttings must be accompanied by

intensive hardwood control methods such as prescribed

burning, chemicals, or mechanical site preparation (7, 36,

37). Natural pine regeneration can be obtained with shelterwood,

seed-tree, and patch or strip clearcut systems, providing

suitable seedbed preparation and competition control measures are achieved (7, 20). Pure stands of pines (particularly

loblolly) of excessive densities frequently become established by natural or broadcast seeding on well-prepared sites.

Dense natural stands of southern pines usually respond well

to prôcommercial thinning. To insure best volume gains,

stocking should be reduced to 5(X) to 700 stems per acre

(1240 to 1730/ha) by age 5 (15, 22).

Clearcutting followed by site preparation, hardwood

control, and seeding or planting has been the most effective

and desirable system to regenerate southern pines. This

system results in more uniform stocking and spacing, permits

introduction of superior planting stock or insect and disease

resistant strains, and allows more flexibility in selecting the

pine species most suitable to a particular planting site.

Loblolly pine should be favored over shortleaf on sites where

littleleaf disease (Phytophthora cinnamomi Rands) hazard is

high (8). Planting or seeding also permits replacing loblolly

with shortleaf in the northern part of the range where loblolly

is susceptible to ice and snow damage and in the southern

areas where loblolly is vulnerable to fusiform rust {Cronartium

quercuum (Berk.) Miy. ex Shirai f. sp. fusiforme Burds. &

Snow)(10).

Even-aged management with intensive site preparation

and hardwood control measures will inevitably result in

conversion of oak-pine to the pine forest types. Conversion

measures are expensive and costs increase with the amount

and size of the hardwood component (1). Such measures are

feasible under a management system where timber production is the primary objective. However, nearly 70 percent of

the oak-pine type is controlled by nonindustrial private

owners whose management objectives for their forest land

are varied and generally not oriented toward maximum

timber production. Most nonindustrial landowners, for a

variety of social and economical reasons, passively permit

the more tolerant hardwoods to increase after the harvest of

pines (4). Consequently, a high percentage of the oak—pine

forest is in poor condition and has low stocking in trees that

could be featured in management (17).

Although even-aged methods are preferred as the best

timber management, the use of uneven-aged management

with group selection cutting and natural regeneration can be

used as an alternative to increase productivity over the

exploitive cutting common to most nonindustrial private

forest lands. Uneven-aged management can be effective on

small ownerships and is adapted to both understocked and

well-stocked stand conditions (38), and has been successfully

applied to a limited extent in pine (7, 27) and hardwood

forests (23). A combination of silvicultural practices—cleaning,

improvement, liberation, and salvage cuts and thinnings

when combined with group selection cutting—can effectively

rehabilitate depleted oak-pine stands (30). Where better

quality hardwoods occur on suitable sites, they should be

favored. Yellow-poplar, like the southern pines, is intolerant

of heavy shade and requires the same degree of overstory

release and understory control as the pines for successful

xegeneration. Although intermediate in tolerance, desirable

oak species also attain optimum growth under relatively open

conditions, and openings of Vi acre (0.2 ha) or more are

recommended. Adequate oak reproduction, as advance reproduction already established on the site or expected from

stump sprouting, must be assured before the harvest cut (28).

Feasibility of the more intensive rehabilitation treatments

have been enhanced in the eastern portion of the oak—pine

range by expanded markets for low value hardwoods and the

increased use of whole-tree chippers. If a pine seed source is

absent following a clean harvest operation, a mixed

pine-hardwood stand can be established by planting pine.

Establishment costs would be relatively low and the pine

component can be increased with follow-up release (29).

Mixed uneven-aged oak—pine forests are esthetically

pleasing and provide a diversity of habitat for many game and

nongame wildlife species (9, 11). Mixed stands also have a

lower incidence of attack by insects such as the southern pine

beetle {Dendroctonusfrontalis Zimmermann) (2). However,

without some hardwood control in regeneration openings, the

group selection system favors tolerant noncommercial hardwood species. Fire cannot be used for seedbed preparation,

since seedlings in nearby regeneration openings would be

killed. Group selection openings are generally too small for

machine operation and sites must be prepared by scarification

incidental with logging. If desirable reproduction is not

obtained promptly, more expensive hand methods will be

needed to control undesirable hardwoods that usually dominate the small openings.

Single tree selection cutting is not recommended for

management in the oak-pine type because it discriminates

sharply against the more light-demanding species. Openings

created by removal of individual trees are usually too small to

insure adequate reproduction of southern pines, yellowpoplar, and most upland oak species that dominate the

oak-pine type. Successful regeneration of these species

requires forest openings of at least 0.3 acre (0.1 ha) but

preferably larger (14, 23, 28, 38).

Oak-pine stands with their diversity of species offer a

variety of spring-flowering and fall coloration which are

esthetically pleasing to forest visitors and recreationists.

Regeneration cuttings in even-aged management and group

selection cuttings in uneven-aged management, through the

openings they create, provide abundant food and shelter for a

variety of wildlife species. For rare and endangered species,

silvicultural operations must provide the special habitat

requirements that will ensure their continued existence.

Impacts of well-planned silvicultural operations are minimal

on water quality.

Literature Cited

1. Anderson, Walter C. An economist's view of the pine-site hardwood

problem. For. Prod. J. 24(4): 14-16; 1974.

2. Belanger, Roger P.; Porterfield, Richard L.; Rowell, Charles E.

Development and validation of systems for rating the susceptibility of

natural stands in the Piedmont of Georgia to attack by the southern pine

beetle. In: Hazard-rating systems in forest insect management: Symposium Proceedings; 1980 July 31—August 1; Athens, GA. Gen. Tech.

Rep. WO-27. Washington, DC: U.S. Department of Agriculture,

Forest Service; 1981: 79-86.

3. Boyce, Stephen G.; Knight, Herbert A. Prospective ingrowth of

southern pine beyond 1980. Res. Pap. SE-200. Asheville, NC: U.S.

Department of Agriculture, Forest Service, Southeastern Forest Experiment Station; 1979. 48 p.

4. Boyce, Stephen G.; Knight, Herbert A. Prospective ingrowth of

southern hardwoods beyond 1980. Res. Pap. SE-203. Asheville, NC:

U.S. Department of Agriculture, Forest Service, Southeastern Forest

Experiment Station; 1980. 33 p.

5. Boyce, Stephen G.; McClure, Joe P. How to keep one-third of Georgia

in pine. Res. Pap. SE-144. Asheville, NC: U.S. Department of

Agriculture, Forest Service, Southeastern Forest Experiment Station;

1975. 23 p.

173
10

Braun, E. Lucy. Deciduous forests of eastern North America. Philadelphia:

The Blakiston Company; 1950. 596 p.

Brender, Ernest V. Silviculture of loblolly pine in the Georgia Piedmont.

Report No. 33. Macon, GA: Georgia Forest Research Councile; 1973.

74 p.

Campbell, W. A.; Copeland, Otis L., Jr. Littleleaf disease of shortleaf

and loblolly pines. Circ. No. 940. Washington, DC: U.S. Department

of Agriculture; 1954. 41 p.

Crawford, Hewlette S.; Whelan, James B.; Harlow, Richard P.; Skeen,

John E. Deer range potential in selective and clearcut oak-pine stands in

southwestern Virginia. Res. Pap. SE-134. Asheville, NC: U.S.

Department of Agriculture, Forest Service, Southeastern Forest Experiment Station; 1975. 12 p.

Czabator, Felix J. Fusiform rust of southern pines—a critical review.

Res. Pap. SO-65. New Orleans, LA: U.S. Department of Agriculture,

Forest Service, Southern Forest Experiment Station; 1971. 39 p.

11. Evans, Keith E. Oak-pine and oak-hickory forest bird communities

and management options. In: Proceedings of the workshop: Management of southern forests for nongame birds; 1978 January 24-26;

Atlanta, GA. Gen. Tech. Rep. SE-14. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southeastern Forest Experiment

Station; 1978: 76-89.

12. Eyre, F. H., ed. Forest cover types of the United States and Canada.

Washington, DC: Society of American Foresters; 1980. 148 p.

Fitzgerald, Charles H.; Peevy, Fred A.; Fender, Darwin E. The

southern region. J. For. 71(3): 148-153; 1973.

Fowells, H. A., comp. Silvics of forest trees of the United States.

Agrie. Handb. 271. Washington, DC: U.S. Department of Agriculture;

1965. 762 p.

Jones, Earle P., Jr. Precommercial thinning for slash and loblolly pines.

In: Proceedings, Symposium on management of young pines. 1974

October 22-24; Alexandria, LA; 1974 December 3-5; Charleston,

SC. Atlanta, GA: U.S. Department of Agriculture, Forest Service,

Southeastern Area, State and Private Forestry, Southern and Southeastem Forest Experiment Stations; 1974: 229-233.

Knight, Herbert A. Average timber characteristics of the better stocked,

natural stands in North Carolina and eastern Virginia. Res. Note

SE-257. Asheville, NC: U.S. Department of Agriculture, Forest

Service, Southeastern Forest Experiment Station; 1978. 10 p.

Knight, Herbert A.; McClure, Joe P. Opportunities for increasing

timber supplies in the Southeast. Resour. Bull. SE-28. Asheville, NC:

U.S. Department of Agriculture, Forest Service, Southeastern Forest

Experiment Station; 1974. 16 p.

Kozlowski, Theodore T. Light and water in relation to growth and

competition of Piedmont forest tree species. Ecol. Monogr. 19(3):

207-231; 1949.

Kramer, P. J.; Oosting, H. J.; Korstian, C. F. Survival of pine and

hardwood seedlings in forest and open. Ecol. 33(3): 427-430; 1952.

20. Lawson, Edwin R. Natural regeneration ofshortleaf pine. In: Proceedings,

Symposium for the management of pines in the interior South; 1978

November 7-8; Knoxville, TN. Tech. Pub. SA-TP2. Atlanta, GA: U.

S. Department of Agriculture, Forest Service, Southeastern Area, State

and Private Forestry; 1979: 1-6.

13

14

15

16

17

18

19

21. Little, Elbert L., Jr. Checklist of United States trees (native and

naturalized). Agrie. Handb. 541. Washington, DC: U.S. Department of

Agriculture; 1979. 375 p.

22. Mann, W. F., Jr.; Lohrey, R. E..Precommercial thinning of southern

pines. J. For. 72(9): 557-560; 1974.

23. Minckler, Leon S. Woodland ecology. Environmental forestry for the

small owner. Syracuse, NY: Syracuse Univ. Press; 1975. 241 p.

24. Murphy, Paul A.; Knight, Herbert A. Hardwood resources on southern

pine sites. For. Prod. J. 24(7): 13-16; 1974.

25. Oosting, Henry J. An ecological analysis of the plant communities of

Piedmont, North Carolina. Am. Midi. Natur. 28(1): 1-126; 1942.

26. Quarterman, Elsie; Keever, Catherine. Southern mixed hardwood

forest: climax in the southeastern Coastal Plain: U.S.A. Ecol. Monogr.

32:167-185; 1962.

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the Crossett Experimental Forest. Res. Pap. SO-40. New Orleans, LA:

U. S. Department of Agriculture, Forest Service, Southern Forest

Experiment Station; 1969. 19 p.

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Agriculture, Forest Service, North Central Forest Experiment Station;

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Alabama following improvement cuttings. Res. Pap. SO-100. New

Orleans, LA: U.S. Department of Agriculture, Forest Service, Southern

Foresî Experiment Station; 1974. 9 p.

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agriculture 1941. Washington, DC: U.S. Department of Agriculture;

1941. 1248 p.

32. U. S. Department of Agriculture, Forest Service. A forest atlas of the

South. New Orleans, LA and Asheville, NC: U.S. Department of

Agriculture, Forest Service, Southern Forest Experiment Station and

Southeastern Forest Experiment Station; 1969. 27 p.

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DC: U.S. Department of Agriculture, Forest Service; 1977. 243 p.

34. Wahlenberg, W. G. Forest succession in the southern Piedmont region.

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35. Wahlenberg, W. G. Loblolly pine. Its use, ecology, regeneration,

protection, growth and management. Durham, NC: School of Forestry,

Duke University; 1960. 603 p.

36. Walstad, J. D. Weed control for better southern pine management.

Weyerhaeuser For. Pap. No. 15. Hot Springs, AR: Southern Forestry

Research Center; 1976. 44 p.

37. Wenger, Karl F.; Trousdell, Kenneth B. Natural regeneration of

loblolly pine in the South Atlantic Coastal Plain. Prod. Res. Rep. No.

13. Washington, DC: U.S. Department of Agriculture, Forest Service;

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174
Bottomland Hardwoods

R. L. Johnson

Southern Forest Experiment Station

F. W. Shropshire

Southern Region

Bottomland hardwood forests encompass 19 forest cover

types as described by the Society of American Foresters (5).

They are scattered over 52 million acres (21.0 million ha) in

37 States (31). This area is bounded on the east by the

Atlantic Ocean, on the south by the Gulf of Mexico, and on

the north by Canada. The western boundary butts against the

States of Montana, Wyoming, Colorado, and New Mexico.

Floodplains of rivers and streams, backwater and headwater swamps, and minor drainages all support bottomland

hardwoods. Elevations are low, ranging from near sea level

in coastal swamps to about 800 feet (245 m) above sea level

in northern interior drainages. Annual precipitation ranges

from about 30 inches (760 mm) in the western part of the

range to 64 inches (1625 mm) along the Gulf Coast. Growing

season varies from near 100 days in the North to 300 days

along the Gulf Coast. A growing season of between 150 and

270 days is common for most bottomland forests. Temperature extremes range from -40° F (-40.0° C) in the far North

to 110° F (43.3°C) in the deep South.

Bottomland forests include at least 70 different commercial species (28) that, for simplicity, will be discussed in

three major groupings: cottonwood-willow, cypress-túpelo,

and mixed hardwoods. The cottonwood-willow and cypresstúpelo groups are fairly specific with regard to species; the

mixed hardwoods group is quite variable.

Cottonwood — Willow

Eastern cottonwood (Populas deltoides Bartr. ex Marsh.)

and black willow (Salix nigra Marsh.), described as types 63

and 95 of the forest cover types of the Society of American

Foresters (5), grow as pioneer species on recent alluvium,

most extensively along major rivers such as the Mississippi,

Ohio, and Missouri. Both species are very intolerant of shade

and require bare mineral soil to become established (24).

They are also intolerant of weed and vine competition.

Natural stands are even-aged, nearly pure, and very dense.

Eastern cottonwood grows on the higher, well-drained,

coarser-textured soils, usually sandy loam or silt loam; black

willow dominates on fine-textured, low lying soils subject to

more frequent overflow. Both species will survive periodic

growing season flooding and sediment, but black willow will

tolerate more flooding and sediment than eastern cottonwood.

Eastern cottonwood is the fastest growing bottomland

species, and black willow is second. Through a pulpwood

rotation in the southern part of the range, annual diameter and

height growth of crop trees should average 0.8 inch (2 cm)

and 6 feet (1.8 m) for eastern cottonwood and 0.6 inch (2 cm)

and 5 feet (1.5 m) for black willow. Mean annual increment

in unmanaged stands peaks for both species at about 20

years—eastern cottonwood at about 250 cubic feet per acre

(17.5 m%a) and black willow at about 200 cubic feet per

acre (14.0 m^/ha) (33). The better unthinned eastern cottonwood stands produce about 27,000 board feet (fbm) (Doyle

log rule) or 5,400 cubic feet^ per acre (378 m^/ha) in 35 years

with codominant trees averaging 23 inches (58 cm) diameter

at breast height (d.b.h.) and 134 feet (40.8 m) tall. Thinned

stands have produced 32,000 fbm or 6,400 cubic feet per acre

(448.0 m^/ha) in 50 years; residuals averaged 34 inches (86

cm) d.b.h. and 146 feet (44.5 m) tall (14). Unthinned black

willow stands produce about one-half the sawtimber volume

of unthinned eastern cottonwood at 35 years (15). But the

species only reaches sawtimber size along the Mississippi

River and its tributaries.

When practical, light thinnings at 5- to 10-year intervals

beginning at age 5 are recommended for natural stands.

Mortality is forestalled, site utilization is more nearly complete,

and total growth is distributed over fewer trees. Commercial

thinnings usually begin when stands are 15 to 20 years old.

After thinning, minimum basal areas where sawtimber is the

objective should range from 40 square feet per acre (9.2

m^/ha) in pulpwood stands to 90 square feet per acre (20.7

m%a) in sawtimber stands.

Although eastern cottonwood on the best sites will

remain healthy and have rapid growth for at least 75 years,

when codominant trees will be 40 to 45 inches (102 to 114

cm) d.b.h. and approximately 150 feet (45.7 m) tall, most

stands are harvested by age 50. Black willow is short lived

and usually begins to deteriorate by age 35; final harvest

should be complete by age 50.

Neither species provides dense shade, and therefore

species more shade tolerant than cottonwood or willow

become established in the understory. Because of their

establishment requirements, neither species will succeed

itself naturally. Mechanical site preparation has favored

reestablishment of natural eastern cottonwood, but the system is highly dependent upon surface soil moisture (11). If

advance reproduction other than eastern cottonwood or black

willow is present and desirable, group selection, patch

cutting, or clearcutting are the best regeneration systems.

Successional species commonly following eastern cottonwood are hackberry (Celtis occidentalis L.), sugarberry (C.

laevigata Willd.), American elm (Ulmus americana L.),

green ash {Fraxinus pennsylvanica Marsh.), boxelder {Acer

negundo L.), silver maple (A. saccharinum L.), sweet pecan

{Garya illinoensis (Wangenh.) K. Koch), and occasionally

sycamore (Platanus occidentalis L.), sweetgum (Liquidambar

styraciflua L.), and Ohio buckeye (Aesculus glabra Willd.).

Black willow stands normally succeed to sugarberry, American elm, green ash, overcup oak {Quercus lyrata Walt.),

water hickory (Garya aquatica (Michx. f.) Nutt.), and

sometimes noncommercial swamp-privet (Forestiera acuminata

(Michx.) Poir.) (24).

Due to channel straightening and bank stabilization

along major rivers, fewer new stands of eastern cottonwood

and black willow are becoming established. Both can be

successfully planted by cuttings or seedlings. Total site

preparation and at least 1 year of intensive weed control is

necessary to assure success (23).

' Cubic foot and metric conversions of measurements expressed in board

feet should be viewed as estimates because of the assumptions involved in

the conversion process.

175
Plantations of eastern cottonwood have yielded about

3,500 cubic feet per acre (245.0 m^/ha) in 10 years and 5,500

fbm (Doyle) or 1,100 cubic feet per acre (77.0 m^/ha) in 15

years (18). They have also provided excellent wildlife habitat

for a number of game and nongame birds and animals (32).

Eastern cottonwood is frequently attacked by insect

borers and defoliators as well as fungus stem cankers and leaf

spots; damage has been most notable in monoculture plantings (26). Well-managed, vigorous stands are the least

susceptible to injury from insects and diseases.

Cypress -Tupelo

Baldcypress (Taxodium distichum (L.) Rich.) and water

túpelo (Nyssa aquatica L.) constitute the major species in

types 100, 101, 102, 103, and 104 ofthe forest cover types of

the Society of American Foresters. These two species dominate coastal swamps of several mid-southern States and in

deep swamps of "red" and ''black" water rivers (so called

because of the sediment load they carry from their place of

origin in the Piedmont and mountains and in the coastal

plain) in the Southeast. Both species normally grow in pure,

even-aged, densely stocked stands. Baldcypress is only

moderately tolerant of shade; water túpelo is intolerant.

Consequently, advance reproduction is sparse. Although

both species may grow in mixture with other species, neither

will tolerate overtopping competition. They will stagnate in

dense stands but will respond to release. Both species are

extremely tolerant of flooding. Baldcypress seed production

is usually adequate; water túpelo produces good seed crops

most years, with an occasional bumper crop and a few

failures (6). The buoyant baldcypress and water túpelo seeds

are dispersed by flood waters, and scattered by birds and

animals. Both species may sprout from stumps, but sprouting

is erratic and, for water túpelo, may be related to depth and

duration of water, stump diameter and height, and tree

vigor. ^

In nonalluvial headwater swamps of the Southeast,

swamp túpelo (A^. sylvatica var. biflora (Walt.) Sarg.) is

much more prevalent than water túpelo. Common associates

of swamp túpelo and baldcypress include water túpelo, red

maple {Acer rubrum L.), sweetbay {Magnolia virginiana L.),

redbay {Persea borbonia (L.) Spreng.), Carolina ash {Franxinus

caroliniana Mill.), and green ash. Seed crops of swamp

túpelo are generally good to excellent, but the seeds do not

float. Swamp túpelo is a fair stump sprouter. Sprouts may

produce viable seeds in the second year (27).

Cypress—túpelo mixtures seem to thrive on watersaturated soils (17). Basal areas from 250 to 350 square feet

per acre (57.4 to 80.4 m^/ha) are common. Volumes of 6,100

cubic feet per acre (427.0 m-^/ha) have been reported for

70-year-old water túpelo stands (22). Annual volume production for water túpelo may be 90 to 100 cubic feet per acre (6.3

to 7.0 m^/ha). Annual growth of 0.3 inch (0.8 cm) in

diameter and 2 feet (0.6 m) in height may be expected from

crop trees.

Unthinned baldcypress stands can produce 70,000 fbm

(International !/4-inch) or 14,000 cubic feet per acre (980.0

m^/ha) in 100 years. One such stand contained 303 square

feet per acre (69.6 m^/ha) of basal area; crop trees averaged

21.1 inches (53.6 cm) d.b.h. and 119 feet (36.3 m) tall (34).

Baldcypress crop trees should have an annual growth of

between 0.2 and 0.3 inch (0.5 and 0.8 cm) in diameter and

^ Kennedy, Harvey E., Jr. Growth and survival of water túpelo coppice

regeneration after six growing seasons. Unpublished draft supplied to author

by Harvey E. Kennedy, Jr., U.S. Department of Agriculture, Forest Service,

Stoneville, MS. 1981.

about 2 feet (0.6 m) in height during the first 50 years.

Baldcypress will live for hundreds of years, far beyond a

practical rotation age. However, the present practice is to

harvest baldcypress and túpelos before they are 100 years

old. For most stands, thinnings should begin between ages 20

and 30 at intervals of about 15 years. After thinning basal

area should be between 80 and 100 square feet per acre (18.4

and 23.0 m^/ha) (34).

Cypress—túpelo stands on very wet sites may be difficult to quickly regenerate under any silvicultural system.

Seedling establishment requires that portions of a swamp be

dry sometime during the growing season to allow for germination of seeds that may have been submerged for up to 2 years.

Seedlings can be killed by 4 or 5 weeks of total submergence

during the growing season, so a swamp should be essentially

dry for 1 or 2 years following seedling establishment. The

only way to assure a dry cycle is to control water levels—

something that has seldom been done. Stump sprouts may

provide some regeneration but seldom enough.

Since existing swamp stands are even-aged and support

relatively shade intolerant species, an even-aged silvicultural

system is required. Where there has been a drying trend,

cypress-túpelo swamps usually support advance reproduction of mixed bottomland hardwoods. Also, where swamp

túpelo stands are approaching rotation age and are less than

fully stocked, advance reproduction of the species is likely

present in adequate numbers. In either situation, patch

cutting or clearcutting, coupled with brush control, is the

recommended regeneration system.

In the absence of advance reproduction, a shelterwood

of 30 to 40 trees per acre (75 to 100 trees/ha) will favor

regeneration of swamp túpelo. However, harvesting under

the shelterwood system is difficult and costly; strip clearcutting

may offer a viable alternative. Another option, leaving 8 to

10 seed trees per acre (20 to 25/ha) may insure an adequate

seed source to regenerate baldcypress and water túpelo.

Established seedlings will resprout if they are broken during

removal of seed- or shelterwood trees (8).

Cypress-túpelo swamps provide good habitat for fish

and wildlife and therefore, good areas for recreation, as well

as income from fishing and trapping. Commercial crawfish

production is also important in many cypress— túpelo swamps,

especially in southern Louisiana (4).

The forest tent caterpillar {Malacosoma disstria Hubner)

is a major insect enemy to the túpelos and defoliates

thousands of acres annually. Although repeated defoliations

can kill trees, the main effect has been a significant reduction

in growth and a loss of seeds (25).

Mixed Hardwoods

Most bottomland hardwood stands, scattered over types

39, 61, 62, 65, 87, 88, 91, 92, 93, 94, 96, and 108 of the

forest cover types as described by the Society of American

Foresters (5), are of mixed species that are site specific (7).

Discounting the direct influence on the forest by humans,

moisture is the key site factor to separation of species. While

cypress and túpelo are extremely water tolerant, some hardwood species that grow on bottomlands are not water tolerant

during the growing season and may survive less than 1 month

of flooding. During the dormant season, however, all typical

bottomland species can survive extended flooding.

Only a few bottomland species can survive and develop

on either very wet or very dry areas, but most can grow

satisfactorily on moist, well-drained sites. Thus, the best

bottomland sites naturally support a variety of species that

can be manipulated individually to maintain favored species.

Many species that are not present can be introduced on such

176
sites by planting. Although good sites present the greatest

challenge, they also offer the broadest range of silivicultural

opportunities for those with the expertise to handle such

complex communities.

Most desirable bottomland hardwoods are intolerant or

moderately tolerant of shade. Some exceptions are hickories,

American beech (Fagus grandifolia Ehrh.), elms, hackberry,

sugarberry, red maple, and boxelder (10). Even moderately

tolerant trees establish and develop slowly in small openings;

they may become understory trees when the crowns of

overstory trees close. Trees of tolerant and sometimes moderately tolerant species will respond to overhead release at ages

greater than 20 years. Those of moderately tolerant species

that start from seed in dense shade will usually die within 3

years if not released. Seedlings of intolerant species seldom

occur in the understory; those that do will not survive the first

year.

Differences in growth rates and growth patterns among

species of the same stand are exemplified by fast and slow

growers. Sycamore, river birch (Betula nigra L.), and silver

maple are among the fast early growers. Sweetgum and green

ash are characterized by intermediate growth; but like other

hardwoods, sprouts of the two species grow rapidly the first 3

or 4 years. Oaks and hickories usually grow slowly until

about age 10 or 15, then begin more rapid growth, especially

in diameter. In 10 years, tree heights will vary by species

from 10 to 50 feet (3.0 to 15.2 m) tall and from about 1 to 5

inches (3 to 13 cm) in diameter at breast height (d.b.h.). Over

50 years, crop trees should average between 0.2 and 0.5 inch

(0.5 and 1.3 cm) diameter growth and from 1.5 to 2.5 feet

(0.5 to 0.8 m) in height growth, depending on species and

site (1).

Mixed bottomland hardwood stands seldom exceed 150

square feet of basal area per acre (34.4 m^/ha) and most are

between 110 and 130 square feet per acre (25.3 and 29.8

m^/ha). Fully stocked stands of quality timber should yield

between 15,000 and 20,000 board feet (fbm) (Doyle) or

3,000 and 4,000 cubic feet per acre (210.0 and 280.0 m^/ha)

at 60 to 80 years, depending on species mix and site (28).

Some of the bottomland species—sweetgum, sycamore,

silver maple, green ash, and American elm—produce an

abundance of lightweight seeds in most years. Light seeds are

moved mainly by wind for 200 feet (61.0 m) or more, and

sometimes for many miles by water. Oaks and hickories

produce heavy seeds and have good crops about 1 year in 3 or

4. Heavy seeds are dispersed for only a few feet beyond the

crown of the parent tree by gravity and for longer distances

by birds, animals, and sometimes water. Light seeds require

a seedbed relatively free of herbaceous plants and particularly

sod; moist, bare soil is best. Most new seedlings in regeneration areas originate from light seeds. Of the heavy seeds,

ones most likely to produce seedlings are found 1 to 2 inches

(3 to 5 cm) deep in the soil. Good germination also occurs on

moist surface soil when acorns are covered by leaves. A high

proportion of both light and heavy seeds are lost to birds and

animals each year.

Mixed stands were essentially even-aged and predominantly of the faster growing, light-demanding species before

cutting practices and natural mortality modified stand structure and composition. Thus, even-aged management is recommended for maximum timber production. If adequate advance reproduction is present and if sprouting will be

adequate, as it often is, clearcutting or patch cutting, the two

systems found most favorable for fast development of desirable species, can be used to release the regeneration. Full

release is essential; trees of commercial species greater than 2

inches (5 cm) d.b.h. should be cut, sheared, or otherwise

brought back to ground level. Choppers have been successfully used, but the giant machines can destroy root systems.

Deadening trees of unwanted species is recommended, but

they may also be cut; stump sprouts will have rapid early

growth, but trees of more desirable species will ultimately

become dominant in the stand.

Where advance reproduction is inadequate, special attention should be given to stump sprouting. A high proportion of

trees under 8 inches (20 cm) d.b.h. will produce satisfactory

stump sprouts. Many species may produce sprouts from even

larger stumps. Sweetgum stands alone as a prolific root

sprouter (9). A general rule-of-thumb is that the poorer the

site quality, the better the sprouting; best sprouting follows a

November to March harvesting, but acceptable levels are

usually obtained from growing season cuts (16).

The conditions likely to be found under dense stands of

large trees would favor germination of light seeds in a

situation where new seedlings are most needed. Some of

these seeds may already be lying dormant and will germinate

when the overstory is removed (3). Still, complete dependence on seed regeneration is a gamble.

The alternative to clearcutting and patch cutting in

stands where regeneration may be a problem is a light

shelterwood cut about 10 years before final harvest. Seedlings of moderately shade tolerant species, such as the oaks,

can remain alive with only 2 or 3 hours of full daily sunlight.

Thus, evenly dispersed openings that approximate the size

following group selection should be adequate for establishment of the shelterwood. If openings are too large, boles of

leave trees will develop epicormic branches. Removal of

shelterwood trees, which should be done within 5 years after

adequate reproduction is established, should pose no serious

problems, since broken seedlings will resprout.

Under all regeneration systems, the reproduction of

most mixed stands will be composed of the same species as

those in the overstory, but proportions will differ. Within a

few years, however, shade intolerant species, which are

usually the most commercially desirable, will die unless steps

are taken to provide ample sunlight. Small openings created

through single tree selection will thus ultimately result in a

stand of more shade tolerant species unless openings are

enlarged within 10 years. Development of reproduction in

openings of less than half an acre (0.2 ha) is generally much

slower than in openings of 2 acres (0.8 ha) or more. Group

selection is a suitable compromise system, but only the

interior of openings will favor more shade intolerant species

with a tree development rate near to that in clearcuts. The

seed-tree method is seldom successful because of the conditions required to establish new seedlings.

Where possible, smaller trees should be left around the

perimeter of regeneration cuts to shade the boles of surrounding crop trees and thus reduce epicormic branching. Openings of a size that will allow tree development in bottomland

forests are quickly covered by lush vegetation. Vines will not

prevent well-stocked reproduction stands from developing,

but they do tend to equalize development rates of all species.

When natural regeneration appears unsatisfactory, planting is a viable alternative. There are commercial plantings of

sweetgum, sycamore, green ash, Nuttall oak {Quercus nuttallii

Palmer), water oak {Q. nigra L.), cherrybark oak (Q.falcata

var. pagodifolia Ell.), and willow oak (Q. phellos L.) in

bottomlands of the Southern and Southeastern United States.

At least six other commercially important species have been

established in test plantings. A disadvantage to hardwood

plantations is the high cost, due to the necessity of 1 to 5

years of intensive competition control (12).

Another possible option for artificially regenerating

bottomland hardwoods is direct seeding. But, with one

exception, guidelines are unavailable. Nuttall oak has been

177
successfully direct seeded in 3-acre (1.2-ha) site-prepared

openings in a natural forest (13). As for the future, oaks seem

to offer the best potential for direct seeding.

There is. little opportunity for improvement cuts in many

mixed bottomland hardwood stands. A history of stand abuse

resulting from high grading has left little to improve among

residual trees. Reducing the stand to ground level to favor

seedling and sprout regeneration or to convert to a better

species composition through planting is often the course to

follow. No cutting at all is usually better than premature

harvest of a large component of desirable growing stock.

Stands where improvement cutting may help are those with

scattered overmature, damaged, and dying trees of marketable size and quality (24). Even in these stands some

growing-stock trees may have to be harvested to make

openings for regeneration and to provide enough timber to

entice buyers. After an improvement cut, large culls and trees

of undesirable species should be killed to enlarge openings

for reproduction. Unmerchantable trees of desirable species

up to 8 inches (20 cm) d.b.h. should be cut rather than

deadened to stimulate stump and root sprouting. This will

also reduce disease loss in the stand.

Wider spacing between trees and control of competitors

has increased diameter growth in plantation research (29).

Thus, one precommercial thinning and weeding in developing natural stands seems warranted. However, guidelines for

such treatments are unavailable, as are associated economics.

The first treatment of even-aged groups or stands is

usually a commercial thinning when codominant trees average 8 to 10 inches (20 to 25 cm) d.b.h. Thinning removes

diseased trees and those of low vigor and should leave

approximately 60 to 70 square feet per acre (13.8 to 16.1

m /ha) of basal area. At least two or three more thinnings are

recommended at intervals between 7 and 15 years, depending

on species and site. After thinning, basal areas will gradually

increase as trees grow larger. At final harvest, most stands

should not exceed 120 to 130 square feet per acre (27.6 to

29.8 m^/ha).

Of all bottomland hardwoods, those of low vigor are

most susceptible to injury from insects such as wood borers

and defoliators. Practices that promote tree vigor help to

minimize losses (30). Canker diseases cause defects, allow

decay, and can kill trees (21). Dutch elm disease (Ceratocystus

ulmi (Buism.) C. Mor.) and elm phloem necrosis {Morsus

ulmi Holmes) have killed most elms in the northern and

central parts of the range. Oak wilt {Ceratocystus Fagacearum

(Bretz) Hunt) is serious in some areas (20). Fire has been

detrimental to bottomland hardwoods and has had no favorable role in their management (28). Beavers kill trees by

girdling and, according to recent surveys, have impounded

water on 532,384 acres (215 450 ha) in six southern States.^

This is detrimental, since 1 to 4 years of continuous flooding

will kill trees of most bottomland hardwood species (2). Even

first-year plantings have been destroyed by beavers (19).

Some of the most productive and valuable fish and

wildlife habitats in the United States are found in bottomland

hardwood stands. Food and cover are provided for a number

of game and nongame birds and animals. Uncommon wildlife species that dwell in the bottomlands are the swallowtailed kite, river sturgeon, southern black bear, ringed

sawback turtle, and American bald eagle.

Stands absorb much of the pressure of river floods,

reducing damage to populated areas and croplands. The

^ Amer, Dale H.; DuBose, Jay S. The impact of beaver on the environment and economics in the Southeastern United States. UnpubHshed draft

supplied to author by Dale H. Amer, Department of Wildlife and Fisheries,

Mississippi State University, MS. 1981.

ecosystem may also absorb and process pesticides and other

chemicals (4).

Literature Cited

1. Broadfoot, Walter M. Hardwood suitability for and properties of

important Midsouth soils. Res. Pap. SO-127. New Orleans, LA: U.S.

Department of Agriculture, Forest Service, Southern Forest Experiment

Station; 1976. 84 p.

2. Broadfoot, W. M.; Williston, H. L. Flooding effects on southern

forests. J. For. 71(9): 584-587; 1973.

3. Clark, F. Bryan. White ash, hackberry, and yellow-poplar seed remain

viable when stored in the forest litter. Indiana Academy of Sciences

Proceedings. 72: 112-114; 1963.

4. Environmental Law Institute. Bottomland hardwoods: their functions,

values and status. Washington, DC: National Wetlands Newsletter 2(1):

6-8; 1980.

5. Eyre, F. H., ed. Forest cover types of the United States and Canada.

Washington, DC: Society of American Foresters; 1980. 148 p.

6. Fowells, H. A., comp. Silvics of forest trees of the United States.

Agrie. Handb. 271. Washington, DC: U.S. Department of Agriculture;

1965. 762 p.

7. Hodges, John D.; Switzer, G. L. Some aspects of the ecology of

southern bottomland hardwoods. In: North America's forests; gateway

to opportunity: 1978 Joint Convention of Society of American Foresters

and Canadian Institute of Forestry; 1978 October 22-25; St. Louis,

MO. Washington, DC: Society of American Foresters; 1979: 360-365.

8. Hook, D. D.; DeBell, D. S. Factors influencing stump sprouting of

swamp and water túpelo seedlings. Res. Pap. SE-57. Asheville, NC:

U.S. Department of Agriculture, Forest Service, Southeastern Forest

Experiment Station; 1970. 9 p.

9. Hook, D. D.; Kormanik, P. P.; Brown, C. L. Early development of

sweetgum root sprouts in coastal South Carolina. Res. Pap. SE-62.

Asheville, NC: U.S. Department of Agriculture, Forest Service, Southeastern Forest Experiment Station; 1970. 6 p.

10. Illinois Technical Forestry Association, Inc. Recommended silviculture

and management practices for Illinois hardwood forest types. Springfield,

IL: Illinois Technical Forestry Association, Inc.; 1972. 35 p.

11. Johnson, Robert L. Regenerating cottonwood from natural seedfall. J.

For. 63(1): 33-36; 1965.

12. Johnson, R. L. Hardwood culture in the eastern United States. In:

Proceedings of a Symposium, Utilization and Management of Alder;

1977 April 25-27; Ocean Shores, WA. Gen. Tech. Rep. PNW-70.

Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific

Northwest Forest and Range Experiment Station; 1978: 55-59.

13. Johnson, R. L. Oak seeding—it can work. South. J. Appl. For. 5(1):

28-33; 1981.

14. Johnson, R. L.; Burkhardt, E. C. Natural cottonwood stands—past

management and implications for plantations. In: Proceedings, Symposium on eastern cottonwood and related species; 1976 September

28-October 2; Greenville, MS. Baton Rouge, LA: Louisiana State

Univ., Division of Continuing Education; 1976: 20-30.

15. Johnson, R. L.; McKnight, J. S. Benefits from thinning black willow.

Res. Note SO-89. New Orleans, LA: U.S. Department of Agriculture,

Forest Service, Southern Forest Experiment Station; 1969. 6 p.

16. Kellison, R. C; Frederick, D. J.; Gardner, W. E. A guide for

regenerating and managing natural stands of southern hardwoods. Bull.

463. Raleigh, NC: School of Forest Resources, North Carolina State

University; 1981. 24 p.

17. Klawitter, R. A. Water túpelos like it wet. South. Lumberman 290(2609):

108-109; 1964.

18. Krinard, R. M.; Johnson, R. L. Fifteen years of cottonwood plantation

growth and yield. South J. Appl. For. 4(4): 180-185; 1980.

19. Krinard, R. M.; Johnson, R. L. Flooding, beavers, and hardwood

seedling survival. Res. Note SO-270. New Orleans, LA: U.S. Department of Agriculture, Forest Service, Southern Forest Experiment

Station; 1981. 6 p.

20. Lewis, Robert, Jr. Control of live oak decline in Texas with lignasan

and arbotect. In: Proceedings, Symposium on systemic chemical treatments in tree culture; 1978 October 9-11; East Lansing, MI. East

Lansing, MI: Michigan State Univ., Kellogg Center for Continuing

Education; 1979: 240- 246.

178
21. McCracken, F. I. Canker diseases of southern hardwoods and their

control. In: Proceedings, second symposium on southeastern hardwoods;

1977 April 20-22; Dothan, AL. Atlanta, GA: U.S. Department of

Agriculture, Forest Service, Southeastern Area, State and Private

Forestry; 1978: 101-106.

22. McGariity, R. W. Ten-year results of thinning and clearcutting in a

muck swamp timber type. Tech. Note 38. Natchez, MS: International

Paper Co., Natchez Forest Research Center; 1977. 5 p.

23. McKnight, J. S. Planting cottonwood cuttings for timber production in

the South. Res. Pap. SO-60. New Orleans, LA: U.S. Department of

Agriculture, Forest Service, Southern Forest Experiment Station; 1970.

17 p.

24. McKnight, J. S.; Johnson, R. L. Hardwood management in southern

bottomlands. For. Farmer 39(5): 31-39; 1980.

25. Morris, R. C. Tree-eaters in the túpelo swamps. Forests and People

25(1): 22-24; 1975.

26. Morris, R. C; Filer, T. H.; Solomon, J. D. [and others]. Insects and

diseases of cottonwood. Gen. Tech. Rep. SO-8. New Orleans, LA:

U.S. Department of Agriculture, Forest Service, Southern Forest

Experiment Station and Southeastern Area, State and Private Forestry;

1975. 37 p.

27. Priester, David S. Stump sprouts of swamp and water túpelo produce

viable seeds. South. J. Appl. For. 3(4): 149-151; 1979.

28. Putnam, John A.; Fumival, George M.; McKnight, J. S. Management

and inventory of southern hardwoods. Agrie. Handb. 181. Washington,

DC: U.S. Department of Agriculture; 1960. 102 p.

29. Schlaegel, Bryce E. Sycamore plantation growth: 10-year results of

spacing trials. In: Proceedings, first biennial southern silivicultural

research conference; 1980 November 6-7; Atlanta, GA. Gen. Tech.

Rep. SO-34. New Orleans, LA: U.S. Department of Agriculture,

Forest Service, Southern Forest Experiment Station; 1981: 149-155.

30. Solomon, J. D.; Swords, David. Minimizing borer-caused losses in

hardwoods. South. Lumberman 237(2944): 67-68; 1978.

31. U.S. Department of Agriculture, Forest Service. Forest statistics of the

U.S., 1977. Washington, DC: U.S. Department of Agriculture; 1978.

133 p.

32. Wesley, David E.; Perkins, Carroll J.; Sullivan, Alfred D. Wildlife in

cottonwood plantations. South. J. Appl. For. 5(1): 37-42; 1981.

33. Williamson, A. W. Cottonwood in the Mississippi Valley. Agrie. Bull.

24. Washington, DC: U.S. Department of Agriculture; 1913. 62 p.

34. Williston, H. L.; Shropshire, F. W.; Balmer, W. E. Cypress management:

a forgotten opportunity. For. Rep. SA-FR 8. Atlanta, GA: U.S.

Department of Agriculture, Southeastern Area, State and Private Forestry;

1980. 8 p.

179
Yellow-Poplar

Donald E. Beck

Southeastern Forest Experiment Station

Daniel H. Sims

Southern Region

Yellow-poplar (Liriodendron tulipifera L.) grows throughout the Eastern United States from southern New England,

west through southern Ontario and Michigan, south to

Louisiana, then east to north-central Florida. It is most

abundant in the valley of the Ohio River Basin and on the

mountain slopes of North Carolina, Tennessee, Kentucky,

and West Virginia.

Because of its wide geographic distribution, yellow-poplar

grows under a variety of climatic conditions. Low temperature extremes vary from severe winters in southern New

England and upper New York with a mean January temperature of 19° F (-7.2° C) to almost frost-free winters in central

Florida with a mean January temperature of61°F(16.rC).

Average July temperature varies from 69° F (20.6° C) in the

northern part of the range to 81° F (27.2° C) in the southern.

Rainfall varies from 30 inches (760 mm) to more than 80

inches (2030 mm) in some areas ofthe southern Appalachians.

Average number of frost-free days varies from 150 to over

310 days within the north-to-south range of yellow-poplar.

Effects of temperature and moisture extremes are tempered somewhat by local topography. At the northern end of

its range, yellow-poplar is usually found in valleys and

stream bottoms at elevations below 1,000 feet (305 m). In the

southern Appalachians, it may grow on a variety of sites,

including stream bottoms and coves, and moist slopes up to

an elevation of about 4,500 feet (1370 m). Toward the

southern edge of the range, where high temperatures and soil

moisture probably become limiting, the species is usually

confined to moist, but well-drained stream bottoms. Optimum development of yellow-poplar occurs where rainfall is

well distributed over a long growing season. The best growth

usually occurs on north and east aspects, on lower slopes, in

sheltered coves, and on gentle, concave slopes.

Yellow-poplar thrives on many soil types varying widely

in physical properties, chemical composition, and parent

material. Exceptionally good growth has been observed on

alluvial soils bordering streams, on loam soils of mountain

coves, on talus slopes below cliffs and bluffs, and on

well-watered, gravelly soils (15). In general, where yellowpoplar occurs naturally and grows well, the soils are moderately moist, well drained, and loose textured; it rarely does

well in poorly drained, or very dry situations. It is a vigorous

competitor on the most productive sites in eastern North

America.

Yellow-poplar is a major species in four Society of

American Foresters forest cover types (12): Yellow-poplar

(type 57), Yellow-poplar-Eastem Hemlock (type 58), Yellowpoplar-White Oak-Northern Red Oak (type 59), and

Sweetgum-Yellow-poplar (type 87); it is also found as a

minor species in 11 other cover types.

On bottom lands and better drained soils of the Coastal

Plain, yellow-poplar occurs in mixture with baldcypress

(Taxodiüm distichum (L.) Rich. var. distichum), oaks (Quercus

ssp.), red maple {Acer rubrum L.), sweetgum {Liquidambar

styraciflua L.), and loblolly pine {Pinus taeda L.). In bay

heads and branch bottoms of the Coastal Plain, an ecotype of

yellow-poplar is associated with swamp black túpelo (Nyssa

sylvatica var. biflora (Walt.) Sarg.), green ash (Fraxinus

pennsylvanica Marsh.), sweetbay {Magnolia virginiana L.),

and baldcypress. In the Piedmont, associated species include

oaks, sweetgum, blackgum (Nyssa sylvatica Marsh.), red

maple, loblolly pine, shortleaf pine (Pinus echinata Mill.),

Virginia pine (Pinus virginiana Mill.), hickories (Carya

spp.), flowering dogwood (Cornus florida L.), sourwood

(Oxydendrum arboreum (L.) DC), and eastern redcedar

(Juniperus virginiana L.).

At lower elevations in the Appalachian Mountains,

yellow-popular is found with black locust (Robinia pseudoacacia

L.), eastern white pine (Pinus strobus L.), eastern hemlock

(Tsuga canadensis (L.) Carr.), hickories, oaks, black walnut

(Juglans nigra L.), shortleaf, Virginia, and pitch (Pinus

rigida Mill.) pines, flowering dogwood, sourwood, sweet

birch (Betula lenta L.), American basswood (Tilia americana

L.), and Carolina silverbell (Halesia Carolina L.). At higher

elevations, associated species include northern red oak (Quercus

rubra L.), white ash (Fraxinus americana L.), black cherry

(Prunus serótina Ehrh.), cucumbertree (Magnolia acuminata

L.), yellow buckeye (Aesculus octandra Marsh.), American

beech (Fagus grandifolia Ehrh.), sugar maple (Acer saccharum

Marsh.), and yellow birch (Betula alleghaniensis Britton).

Trees associated with yellow-poplar in non-mountainous

areas of the North and Midwest include white oak, black oak

(Quercus velutina Lam.), northern red oak, white ash, beech,

sugar maple, blackgum, flowering dogwood, and hickories.

The successful regeneration of yellow-poplar by natural

means requires adequate seed, a seedbed of exposed mineral

soil, and direct sunlight (17), or trees capable of producing

stump sprouts.

The first requirement, adequate seed, is seldom a

problem on sites capable of growing yellow-poplar where

even a few seed-producing trees are available. Large seed

crops of up to 1.5 million seeds per acre (607 030/ha) are

produced annually in yellow-poplar stands (17). Viable seed

is disseminated from mid-October to mid-March; the percentage of viability, which ranges from 5 to 20 percent, is about

equal throughout the seedfall period. The individual winged

samaras may be scattered by the wind to distances equal to

four or five times the height of the seed-bearing tree.

Distribution of seed is usually satisfactory up to 3 chains (198

ft, 60 m) from a good seed tree in the direction of the

prevailing wind and 1.5 chains (99 ft, 30 m) in all other

directions (29). In addition, seed may be stored in the forest

floor for up to 8 years and germinate and grow when proper

conditions of light and moisture are created (8).

Scarification and fire, which puts seed in contact with

mineral soil, significantly increases the number of seedlings

as compared to an undisturbed forest floor (11, 14, 21, 29).

However, under normal conditions, the site disturbance

caused by harvesting a mature stand is the only seedbed

preparation needed to provide enough yellow-poplar seed180
lings for a new stand. The amount of regeneration obtained

increases directly as the intensity of the harvest cut, with

complete stand removal yielding the highest stocking.

After germination, several critical years follow. Although rated intolerant of shade, yellow-poplar seedlings

reach maximum or near-maximum photosynthetic efficiency

at relatively low-light intensities (17, 18). During the establishment period, protection from dying, frost heaving, and

flooding may be more important than light requirements.-

After the first few growing seasons, vegetative competition

may become the most important factor affecting survival and

growth.

Prolific sprouting from stumps adds considerably to the

ability of yellow-poplar to reproduce. Percentage of stumps

sprouting and the number of sprouts per stump decreases with

increasing age and size of stump. However, trees of the age

and size being harvested in second-growth stands can be

expected to produce at least one stem that is of low origin,

well anchored, vigorous, and capable of producing a highquality tree (1, 26, 27, 28).

Because of its seed-production characteristics and its

sprouting ability, yellow-poplar is readily regenerated by

natural means (15). Growth characteristics of yellow-poplar

indicate that it can best be grown under even-aged stand

conditions although there is considerable leeway in choosing

regeneration methods (5). On suitable sites where yellowpoplar is present, harvest of the mature stand by clearcutting,

small patch cuts, group selections, or shelterwood cuts will

usually ensure establishment of yellow-poplar regeneration.

The minimum-size opening that can be used to establish

yellow-poplar seedlings is fairly small. Research has shown

little difference in number of seedlings per acre in openings

ranging from 0.125 to 5 acres (0.1 to 2.0 ha) in size (20).

However, opening size has a significant effect on growth of

seedlings after establishment. Both diameter and height were

found to be significantly smaller in openings less than 0.5

acre (0.20 ha) in size than in larger openings (22, 23). All

openings, regardless of size, are bordered by a zone where

growth of reproduction is retarded; this zone may extend

from 10 to 30 feet (3.0 to 9.1 m) from boles of surrounding

trees. Thus, the percentage of the area in the restrictive zone

increases greatly for openings smaller than about 0.5 acre

(0.2 ha).

Although the shelterwood cut can be used to establish

yellow-poplar, height growth is severely limited by the

remaining overstory (16, 20). Rapid height growth does not

begin until the overwood is removed, and the removal of

overwood should probably be made within 5 years of

seedling establishment.

The seed-tree method can be used to regenerate yellowpoplar; however, the method has little to recommend it.

Plentiful seed are usually present on the site or blown in from

surrounding stands. The seed trees afford limited protection

to the site and provide uneconomical logging conditions for

tree removal. Regeneration cutting by single-tree selection is

not a suitable method for regenerating yellow-poplar. Although some reproduction will become established, it will

not develop satisfactorily under fully stocked stands.

Treatment of stems left after commercial logging is

essential to successful development of yellow-poplar reproduction. Some stands that have carried high stocking up to

the time of the final harvest cut may have relatively few

unmerchantable stems left after logging where a good pulpwood market is available. But, in the typical case, there will

be numerous stems of the more tolerant understory species

such as dogwood, red maple, and hornbeam (Carpinus L.)

left after commercial logging. This residual material can

significantly reduce growth of yellow-poplar (30).

Cull and nonmerchantable stems may be controlled

before, during, or after the commercial logging operations. A

wide range of techniques is available that may vary from

simple felling nonmerchantable stems with saws, chemical

control by injection or basal spray, and mechanically knocking down leftover material with bulldozers. Burning is also a

viable option. Complete elimination of competition is not

necessary. Cutting back, or top-kill, is usually sufficient to

allow yellow-poplar seedlings to get ahead of the competition.

Where yellow-poplar sprouts are abundant, less competition

control is needed.

Although yellow-poplar has not been planted on a

large-scale, commercial basis, it is biologically and technically feasible to do so with procedures widely used for other

species (19). Key requirements for planting yellow-poplar

are: selection of suitable sites; adequate control of competing

vegetation; and use of the best planting technology, including

high-quality seedlings, careful stock handling, and choice of

appropriate seasons and methods of planting.

Yellow-poplar expresses dominance well and seldom, if

ever, stagnates because of excessive stand density. It prunes

very well in closed stands, and while it will produce

epicormic sprouts when the bole is exposed, this is a minor

problem compared with many hardwood species. The problem of epicormic sprouts can be further minimized by

favoring vigorous trees that show little tendency toward

epicormic development before thinning. Because of these

growth charactertistics, yellow-poplar stands can develop

and produce considerable quantities of large, high-quality

products with no intermediate stand management (2).

In the seedling-sapling stage, dominant and codominant

trees are little affected by thinning or cleaning (13, 24).

Intermediate or overtopped trees of good vigor will respond

to release in both diameter and height growth (30). However,

cultural treatment of seedling-sapling stands is seldom needed

or justified except for removal of vines where they are a

problem (9, 25).

By the time stands reach pole size at 20 to 30 years of

age, the peak rates of growth and mortality are past and the

crown canopy is closed. Crown size on surviving trees is

reduced and diameter growth is considerably slowed. Thinnings done to salvage or prevent mortality, increase the

growth of residual trees, shorten rotations based upon tree

size, and increase the yield of high-value timber products are

practical cultural operations in intermediate stand management.

The net result of numerous thinning experiments is that

residual yellow-poplar trees rapidly utilize space and accelerate diameter increment (3, 4, 6, 17). Response will occur

across a wide range of sites and stand ages, even in stands as

old as 80 years that have never been thinned. Total cubicvolume growth is greatest at the highest densities and cubic

yields would be maximized by very light, frequent thinnings

that salvage anticipated mortality. Mean annual increment in

total cubic volume ranges from 75 to 165 cubic feet per acre

(5.2 to 11.5 m%a) on sites 82 to 115 feet (25.0 to 35.1 m)

respectively, at culmination of approximately 70 years. On

the other hand, board-foot volume growth is maximum at

densities well below those that maximize cubic-foot volume

growth.

Board-foot growth is near maximum over a wide range

of densities. Thus, there is considerable leeway to manipulate

stocking levels to achieve diameter growth and quality goals

without sacrificing volume growth of the high-value products

(5).

There are numerous insects and disease organisms that

can damage or kill yellow-poplar throughout its lifespan.

However, except in rare instances, they are of insufficient

importance to appreciably alter management practices. Fire

181
and vines are particularly damaging to young stands and may

require special protection measures and treatment (24). Glaze

damage occurs in many areas and may alter management

practices in zones where glaze storms are prevalent (7).

Yellow-poplar has nominal value as a source of wildlife

food when compared to many of the species with which it is

associated. Its seeds are eaten by a variety of animals and

birds but it is not considered a critical food supply for any of

them. Deer will browse yellow-poplar but it is not a highly

preferred species (10), however, it has distinctive value as a

source of nectar for honey bees. Yellow-poplar is an excellent ornamental for parks and for landscape plantings where

there is adequate space to accommodate its large size. Its

green leaves and distinctive flowers and seed clusters complement its statuesque appearance.

Literature Cited

1. Beck, Donald E. Growth and development of thinned versus unthinned

yellow-poplar sprout clumps. Res. Pap. SE-173. Asheville, NC: U.S.

Department of Agriculture, Forest Service, Southeastern Forest Experiment Station; 1977. 11 p.

2. Beck, Donald E.; Della-Bianca, Lino. Yield of unthinned yellowpoplar. Res. Pap. SE-58. Asheville, NC: U.S. Department of Agriculture,

Forest Service, Southeastern Forest Experiment Station; 1970. 20 p.

3. Beck, Donald E.; Della-Bianca, Lino. Growth and yield of thinned

yellow-poplar. Res. Pap. SE-101. Asheville, NC: U.S. Department of

Agriculture, Forest Service, Southeastern Forest Experiment Station;

1972. 10 p.

4. Beck, Donald E.; Della-Bianca, Lino. Board-foot and diameter growth

of yellow-poplar after thinning. Res. Pap. SE-123. Asheville, NC:

U.S. Department of Agriculture, Forest Service, Southeastern Forest

Experiment Station; 1975. 20 p.

5. Beck, Donald E.; Della-Bianca, Lino. Yellow-poplar: characteristics

and management. Agriculture Handbook 583. Washington, DC: U.S.

Department of Agriculture; 1981. 246 p.

6. Carvell, Kenneth L. Improvement cutting in immature hardwood stands

yield income while increasing future sawtimber values. Bull. 492.

Morgantown, WV: West Virginia University Agricultural Experiment

Station; 1964. 17 p.

7. Carvell, K. L.; Tryon, E. H.; True, R. P. Effects of glaze on the

development of Appalachian hardwoods. J. For. 55(2): 130-132;

1957.

8. Clark, F. Bryan; Boyce, Stephen G. Yellow-poplar seed remains viable

in the forest litter. J. For. 62(8): 564-567; 1964.

9. Della-Bianca, Lino. Frothingham's hardwood cleaning at LookingGlass Rock. J. For. 69(2): 100-102; 1971.

10. Della-Bianca, Lino; Johnson, Frank M. Effect of intensive cleaning on

deer-browse production in the southern Appalachians. J. Wildl. Manage.

29(4): 729-733; 1965.

11. Engle, Lamont G.; Williams, Robert D. Scarifying seedbed boosts

yellow-poplar germination. Stn. Note 11.0. Columbus, OH: U.S.

Department of Agriculture, Forest Service, Central States Forest Experiment Station; 1957. 2 p. Available from: North Central Forest Experiment Station, St. Paul, MN.

12. Eyre, F. H., ed. Forest cover types of the United States and Canada.

Washington, DC: Society of American Foresters; 1980. 148 p.

13. Lamson, Neil L; Smith, H. Clay. Response to crop tree release: sugar

maple, red oak, black cherry, and yellow-poplar saplings in a 9-year-old

stand. Res. Pap. NE-394. Broomall, PA: U.S. Department of Agriculture,

Forest Service, Northeastern Forest Experiment Station; 1976. 4 p.

14. Little, Silas. Treatments needed to regenerate yellow-poplar in New

Jersey and Maryland. Res. Note NE—58. Broomall, PA: U.S. Department of Agriculture, Forest Service, Northeastern Forest Experiment

Station; 1967. 8 p.

15. McCarthy, E. F. Yellow-poplar characteristics, growth, and management.

Tech. Bull. 356. Washington, DC: U.S. Department of Agriculture;

1933. 58 p.

16. McGee, Charles E. Regeneration alternatives in mixed oak stands. Res.

Pap. SE-125. Asheville, NC: U.S. Department of Agriculture, Forest

Service, Southeastern Forest Experiment Station; 1975. 8 p.

17. Olson, David F., Jr. Silvical characteristics of yellow-poplar {Liriodendron

tulipifera L.). Res. Pap. SE-48. Asheville, NC: U.S. Department of

Agriculture, Forest Service, Southeastern Forest Experiment Station;

1969. 16 p.

18. Renshaw, James F.; Doolittle, Warren T. Silvical characteristics of

yellow-poplar. Res. Pap. 89. Asheville, NC: U.S. Department of

Agriculature, Forest Service, Southeastern Forest Experiment Station;

1958. 18 p.

19. Russell, T. E. Planting yellow-poplar—where we stand today. Gen.

Tech. Rep. SO-17. New Orleans, LA: U.S. Department of Agriculture,

Forest Service, Southern Forest Experiment Station; 1977. 8 p.

20. Sander, Ivan L.; Clark, F. Bryan. Reproduction of upland hardwood

forests in the Central States. Agrie. Handb. 405. Washington, DC: U.S.

Department of Agriculture; 1971. 25 p.

21. Sims, I. H. Establishment and survival of yellow-poplar following a

clear cutting in the southern Appalachians. J. For. 30(4): 409-414;

1932.

22. Smith, H. Clay. Height of tallest saplings in 10-year-old Appalachian

hardwood clearcuts. Res. Pap. NE-381. Broomall, PA: U.S. Department of Agriculture, Forest Service, Northeastern Forest Experiment

Station; 1977. 6 p.

23. Smith, Henry W. Establishment of yellow-poplar {Liriodendron tulipifera

L.) in canopy openings. New Haven, CT: Yale Univ.; 1963. 1976 p.

Dissertation.

24. Trimble, G. R., Jr. Response to crop-tree release by 7-year-old stems of

yellow-poplar and black cherry. Res. Pap. NE-253. Broomall, PA:

U.S. Department of Agriculture, Forest Service, Northeastern Forest

Experiment Station; 1973. 14 p.

25. Trimble, G. R., Jr.; Tryon, E. H. Grapevines a serious obstacle to

timber production on good hardwood sites in Appalachia. North.

Logger and Timber Process. 23(5): 22-23, 44; 1974.

26. True, R. P. Studies on sprout reproduction of yellow poplar as related to

decay. Rep. 3. Morgantown, WV: West Virginia University Agricultural Experiment Station; 1953. 4 p.

27. True, R. P.; Tryon, E. H. Butt decay in yellow-poplar sprouts in West

Virginia. Stn. Bull. 54IT. Morgantown, WV: West Virginia University

Agricultural Experiment Station; 1966. 67 p.

28. Wendel, G. W. Stump sprout growth and quality ofseveral Appalachian

hardwood species after clearcutting. Res. Pap. NE-329. Broomall,

PA: U.S. Department of Agriculture, Forest Service, Northeastern

Forest Experiment Station; 1975. 9 p.

29. Whipple, Sherman D. Yellow poplar regeneration after seed tree cutting

and site preparation. Stn. Bull. 384. Auburn, AL: Auburn University

Agricultural Experiment Station; 1968. 15 p.

30. Williams, Robert D. Release accelerates growth of yellow-poplar—an

18-year look. Res. Note NC-202. St. Paul, MN: U.S. Department of

Agriculture, Forest Service, North Central Forest Experiment Station;

1976. 4 p.

182
Glossary

Definitions contained in this glossary are based on those

that appear in the 1971 edition of Terminology of Forest

Science, Technology, Practice and Products, published by

the Society of American Foresters and prepared in conjunction with the Joint Food and Agriculture Organization/

International Union of Forestry Research Organizations Committee on Forestry Bibliography and Terminology.' In rare

instances where definitions were not available from Terminology

of Forest Science, Technology, Practice and Products,

composites were prepared from other sources.

A silvicultural system is sometimes confused with the

regeneration cutting after which it is named. The following

excerpt explains why this confusion is so prevalent in the

literature, regulations, and legislation concerning silvicultural practices.^

'The main—but not the only—treatments making

up silvicultural systems, involve the cutting or

felling of trees. Cuttings are commonly divided

into those that help to reproduce forest stands

(reproduction or harvest cuttings) and those that

maintain vigor and desired composition and structure of the stands in terms of tree species, ages, and

size classes (intermediate cuttings).

Reproduction cuttings have such a great influence

on the character and management of the new

stand—and the forest as a whole—that silvicultural

systems are generally named after them. The major

systems used in the United States are clearcutting,

seed-tree, shelterwood, single-tree selection, and

group selection. Each system includes reproduction

cuttings to establish seedlings and intermediate

treatments to culture the developing stand."

Advance growth—Young trees that have become established naturally before regeneration cuttings are begun, or a

clearcutting is made.

All-aged—A condition of a forest or stand that contains trees

of all, or almost all, age classes.

Area regulation—An indirect method of controlling (and

roughly determining) the amount of forest produce to be

harvested periodically on the basis of stocked area.

Basal area—^The area of the cross-section of a tree inclusive

of bark at breast height (4.5 feet or 1.37 meters above the

ground) most commonly expressed as square feet per acre or

' Sœiety of American Foresters. Terminology of Forest Science, Technology,

Practice and Products. Washington, DC: Society of American Foresters;

1971. 349 p.

^ Society of American Foresters. Choices in Silviculture for American

Forests. Washington, DC: Society of American Foresters; 1981: 2-3.

square meters per hectare. For a stand, basal area is computed from all living trees.

Biomass—The total quantity, at a given time, of living

organisms of one or more species usually expressed in weight

per unit area.

Cleaning—Elimination or suppression of competing vegetation from stands not past the sapling stage (2 to 4 inches (5 to

10 centimeters) in diameter as measured 4.5 feet or 1.37

meters above the ground); specifically, removal of (a) weeds,

climbers, or sod-forming grasses, as in plantations or (b)

trees of similar age or of less desirable species or form than

the crop trees which they are, or may soon be, overtopping.

Clearcutting—The cutting method that describes the silvicultural system in which the old crop is cleared over a

considerable area at one time. Regeneration then occurs from

(a) natural seeding from adjacent stands, (b) seed contained

in the slash or logging debris, (c) advance growth, or (d)

planting or direct seeding. An even-aged forest usually

results.

Climax forest—A plant community that represents for its

locality and its environment the culminating stage of a natural

succession. When the culminating stage is influenced by

topography, it is termed a topographic climax and when

maintained by regular fires, it is termed a fire climax.

Co-dominant—A tree wkh its crown in the upper forest

canopy but less free than the dominant trees and freer and

taller than the intermediates and suppressed trees. A crown

class.

Composition—The representation of tree species in a forest

stand, expressed quantitatively as percent by volume or basal

area of each species, or as percent by number only in seedling

stands.

Coppice—A regeneration method in which standing trees are

cut and subsequent crops originate mainly from adventitious

or dormant buds on living stumps but also as suckers from

roots and rhizomes.

Crop—^The major woody growth on a forested area.

Crop tree—A tree that forms, or is selected to form, a

component of the final crop, specifically, one selected to be

carried through to maturity. Also known as a final crop tree

or growing stock tree.

Crown class—Any class into which trees of a stand may be

divided based on both their crown development and crown

position relative to crowns of adjacent trees. Commonly used

crown classes are dominant, co-dominant, intermediate, and

suppressed.

183
Culmination of mean annual increment—For a tree or

stand of trees, the age at which the average annual increment

is greatest. It coincides precisely with the age at which the

current annual increment just equals the mean annual increment of the stand and thereby defines the rotation of a fully

stocked stand that yields the maximum volume growth.

Cutting method—Describes cuttings used either to help

reproduce forest stands (reproduction or harvest cuttings) or

to maintain their vigor and desired composition and structure

in terms of tree species, ages, and size classes (intermediate

cuttings).

Dominant—A tree with its largely free-growing crown in the

uppermost layers of the forest canopy. A crown class.

Epicormic—A type of branch or shoot arising from an

adventitious or dormant bud on a stem or branch of a woody

plant. Also called an epicormic branch, epicormic shoot, or

water sprout.

Even-aged management—The application of a combination

of actions that results in the creation of stands in which trees

of essentially the same age grow together. The difference in

age between trees forming the main canopy level of a stand

usually does not exceed 20 percent of the age of the stand at

maturity. Regeneration in a particular stand is obtained

during a short period at or near the time that a stand has

reached the desired age or size for regeneration, and is

harvested. Cutting methods producing even-aged stands are

clearcut, shelterwood, or seed-tree.

Even-aged—The condition of a forest or stand composed of

trees having no, or relatively small, differences in age,

although differences of as much as 30 percent are admissable

in rotations greater than 100 years of age.

Fire climax—(See climax forest.)

Group selection—The cutting method which describes the

silvicultural system in which trees are removed periodically

in small groups resulting in openings that do not exceed an

acre or two in size. This leads to the formation of an

uneven-aged stand in the form of a mosaic of age-class

groups in the same forest.

Growing stock—All the trees growing in a forest or in a

specified part of it, generally expressed in terms of number or

volume.

Habitat type—The aggregate of all areas that support or can

support the same primary vegetation at climax.

Habitat type series—All plant associations having the same

potential dominant plant species at climax. Under forested

conditions, trees are the dominant vegetation.

Harvest cutting—The felling of the final crop of trees either

in a single cutting or in a series of regeneration cuttings.

Generally, the removal of financially or physically mature

trees, in contrast to cuttings that remove immature trees. Also

referred to as main felling and major harvest.

Improvement cutting—The elimination or suppression of

less valuable trees in favor of more valuable trees, typically

in a mixed, uneven-aged forest.

Individual (single) tree selection—The cutting method that

describes the silvicultural system in which trees are removed

individually, here and there, each year over an entire forest or

stand. The resultant stand usually regenerates naturally and

becomes all-aged.

Intermediate—A tree of the middle canopy dominated by

others in the dominant and co-dominant crown classes. A

crown class.

Intermediate cutting—Any removal of trees from a stand

between the time of its formation or establishment and the

harvest cut. Generally taken to include cleaning, thinning,

liberation and improvement cuttings, increment felling, and

sometimes even salvage and sanitation cuttings.

Intolerance—Trees unable to survive or grow satisfactorily

under specific conditions, most commonly used with respect

to their sensitivity to shade but also to conditions such as

wind, drought, salt, and flooding.

Mean annual increment—The total increment of trees in a

stand up to a given age divided by that age, usually expressed

in annual cubic feet of growth per acre (cubic meters of

growth per hectare).

Nurse crop—A crop of trees, shrubs, or other plants

naturally occurring or artifically introduced to foster another,

and generally more important crop, during its youth by

protecting it from frost, insolation, or wind.

Overstory—The trees in a forest of more than one story that

form the upper or uppermost canopy layer.

Pioneer—A plant capable of invading bare sites (that is, a

newly exposed soil surface) and persisting there until supplanted

by successor species. A species planted to prepare a site for

such successor species and therefore, a nurse crop.

Preparatory cutting—The removal of trees near the end of a

rotation, which permanently opens the canopy and enables

the crowns of seed bearers to enlarge, to improve conditions

for seed production and natural regeneration. Typically done

in the shelterwood system.

Progressive clear-strip cutting—A shelterwood system with

clearcutting in strips (usually not wider than the height of

adjoining trees) generally progressing against the prevailing

wind.

Quadrat—A small, clearly demarcated, sample area of

known size (usually a square decimeter, a square meter, or a

milacre (43.56 ft^ or 4.05 m^) on which ecological observations are made.

Regeneration—The renewal of a tree crop whether by

natural or artificial means. Also the young crop itself which

commonly is referred to as reproduction.

Regeneration cutting—Any removal of trees intended to

assist regeneration already present or to make regeneration

possible.

Release—Freeing a tree or group of trees from competition

by cutting or otherwise eliminating growth that is overtopping or closely surrounding them.

184
Salvage cutting—The exploitation of trees that are dead,

dying, or deteriorating (e.g., because they are overmature or

have been materially damaged by fire, wind, insects, fungi,

or other injurious agencies) before their timber becomes

worthless.

Sanitation cutting—The removal of dead, damaged, or

susceptible trees done primarily to prevent the spread of pests

or pathogens and so promote forest hygiene.

Scarifícation—Loosening of the topsoil of open areas, or

breaking up the forest floor, in preparation for regenerating

by direct seeding or natural seedfall.

Seed cutting—Removal of trees in a mature stand to effect

permanent openings in the canopy (if not done in a preparatory cutting) and thereby provide conditions for securing

regeneration from the seed of trees retained for this purpose.

Also the first of the shelterwood cuttings.

Seed-tree—The cutting method that describes the silvicultural system in which the dominant feature is the removal of

all trees in one cut except for a small number of seed bearers

left singly or in small groups, usually 8 to 10 per acre (20 to

25 per hectare). The seed trees generally are harvested when

regeneration is established. An even-aged stand results.

Selection—(See group selection and individual (single)

tree selection.)

Serotinous—A term applied to plant species or individuals

that flower or fruit late in the season and to fruit or cones that

remain on the tree without opening for one or more years (as

the serotinous cones of jack pine, lodgepole pine, and the

Ocala variety of sand pine).

Shelterwood—The cutting method that describes the silvicultural system in which, in order to provide a source of seed

and/or protection for regeneration, the old crop (the shelterwood)

is removed in two or more successive shelterwood cuttings.

The first cutting is ordinarily the seed cutting, though it may

be preceded by a preparatory cutting, and the last is the final

cutting. Any intervening cutting is termed removal cutting.

An even-aged stand results.

Silvicultural system—A process whereby forests are tended,

harvested, and replaced, resulting in a forest of distinctive

form. Systems are classified according to the method of

carrying out the fellings that remove the mature crop with a

view to regeneration and according to the type of forest

thereby produced.

Single tree selection—(See individual tree selection.)

Site—An area considered in terms of its environment as

determined by the type and quality of the vegetation it can

carry.

Site class—A measure of the relative productive capacity of

a site based upon the volume or height (dominant, codominant, or mean) or the maximum mean annual increment

of a stand that is attained or attainable at a given age.

Site index—A measure of site class based upon the height of

the dominant trees in a stand at an arbitrarily chosen age,

most commonly at 50 years in the East and 100 years in the

West.

Stand—A community of naturally or artificially established

trees of any age sufficientíy uniform in composition, constitution,

age, spatial arrangement, or condition to be distinguishable

from adjacent communities thereby forming a silvicultural or

management entity.

Stand density—A measure of the degree of crowding of

trees within stocked areas, commonly expressed by various

growing-space ratios such as crown length to tree height,

crown diameter to diameter at breast height (4.5 feet or 1.37

meters above the ground), or crown diameter to tree height,

or of stem (triangular) spacing to tree height.

Stocking—A measure of the proportion of the area in a stand

actually occupied by trees expressed in terms of stocked

quadrats or percent of canopy closure (as distinct from their

stand density).

Structure—Of a forest, crop, or stand, the distribution and

representation of age and/or size (particularly diameter)

classes, and of crown and other tree classes.

Succession—The gradual supplanting of one community of

plants by another.

Suppressed—One of the four main crown classes. Very

slowly growing trees with crowns in the lower layer of the

canopy and leading shoots not free. Suppressed trees are

subordinate to dominant, co-dominant, and intermediates in

the crown canopy.

Thinning—A felling made in an immature stand primarily to

maintain or accelerate diameter increment and also to improve the average form of the remaining trees without

permanently breaking the canopy. An intermediate cutting.

Thinning from above—A thinning that favors the most

promising (not necessarily the dominant) stems, with due

regard to even distribution over the stand, by removing those

trees that interfere with them.

Thinning from below—A thinning that favors the dominants

or selected dominants more or less evenly distributed over the

stand by removing a varying proportion of the other trees.

Topographic climax—(See climax forest.)

Understory—Trees and woody species growing under an

overstory.

Uneven-aged management—The application of a combination of actions needed to simultaneously maintain continuous

high-forest cover, recurring regeneration of desirable species,

and the orderly growth and development of trees through a

range of diameter or age classes. Cutting methods that

develop and maintain uneven-aged stands are single tree

selection and group selection.

Uneven-aged—The condition of a forest, crop, or stand

composed of intermingling trees that differ markedly in age.

In practice a minimum age difference of 25 percent of the

length of the rotation usually is used.

Volume regulation—A direct method of controlling and

determining the amount of timber to be periodically cut by

calculations based upon growing stock volume and increment,

disregarding area.

Yield—The amount of forest produce that may be harvested

periodically from a specified area over a stated period in

accordance with the objectives of management.

185
English to Metric Conversion Factors

English Unit X Conversio

inch (in) 25.4000

2.5400

foot (ft) 0.3048

yard (yd) 0.9144

mile (mi) 1.6093

ounce (avdp) (oz) 28.3495

pound (avdp) (lb) 453.5924

0.4536

ton (ton) 0.9072

ounce (fluid) (oz) 0.0296

pint (pt) 0.4732

quart (qt) 0.9464

gallon (gal) 3.7854

square inch (in') 6.4516

square foot (ft') 929.0341

0.0929

square yard (yd') 0.8361

acre (acre) 0.4047

cubic inch (in3 16.3871

cubic foot (ft') 0.0283

square feet per acre (ft^/acre) 0.2296

board feet per acre (fbm/acre) 0.0140

cord per acre (cord/acre) 6.2975

(cord = 90ft^)

cubic feet per acre (ft^/acre) 0.0700

pound per square inch (Ib/in^) 70.3067

pound per square foot (Ib/ft^) 4.8824

pound per cubic foot (lb/ft-') 16.0185

pound per cubic yard (Ib/yd^) 3.9543

pound per acre (lb/acre) 1.1208

= Metric Unit

millimeter (mm)

centimeter (cm)

meter (m)

meter (m)

kilometer (km)

gram (g)

gram (g)

kilogram (kg)

tonne (t)

liter (1)

liter (1)

liter (1)

liter ^^K

square centimeter (cm^)

square centimeter (cm^)

square meter (m^)

square meter (m^)

hectare (ha)

cubic centimeter (cm')

cubic meter (stere) (m^)

square meter per

hectare (m^/ha)

cubic meter per

hectare (m^/ha)

cubic meter per

hectare (m^/ha)

cubic meter per

hectare (m^/ha)

gram per square

centimeter (g/cm2)

kilogram per square

meter (kg/m^)

kilogram per cubic

meter (kg/m^)

kilogram per cubic

meter (kg/m^)

kilogram per hectare (kg/ha)

186
Lists of Common and Scientifíc Names

Birds*

Common Name

(American) bald eagle

(American) osprey

American Swallow-tailed kite

American woodcock

Bachman's sparrow

Bay-breasted warbler

Black-and-white warbler

Black-backed woodpecker

Black-throated green warbler

Blackbumian warbler

Bobwhite

Brown-headed nuthatch

Cape May warbler

Chickadee

Chipping sparrow

Clark's nutcracker

Common yellowthroat

Common redpoll

Crossbill

Ducks

Great gray owl

Kinglet

Kirtland's warbler

Magnolia warbler

Merriam's turkey

(Mississippi) sandhill crane

Mourning dove

Nashville warbler

Northern parula warbler

Peregrine falcon

Pheasant

Pileated woodpecker

Pine grosbeak

Pine siskin

Pine warbler

Red-breasted nuthatch

Red-cockaded woodpecker

Ruby-crowned kinglet

Ruffed grouse

Song sparrow

Spruce grouse

Turkey

Veery

Waxwing

White-throated sparrow

Yellow-bellied sapsucker

Scientific Name

Haliaeetus leucocephalus (Linnaeus)

Pandion haliaetus (Linnaeus)

Elanoidesforficatusforficatus

(Linnaeus)

Scolopax minor (Gmelin)

Aimophila aestivalis (Lichtenstein)

Dendroica castanea (Wilson)

Mniotilta varia (Linnaeus)

Picoides árcticas (Swainson)

Dendroica virens (Gmelin)

Dendroica fusca (Muller)

Colinus virginianus (Linnaeus)

Sitta pusilla (Latham)

Dendroica tigrina (Gmelin)

Parus species (Linnaeus)

Spizella passerina (Bechstein)

Nucifraga columbiana (Wilson)

Geothlypis tricha (Linnaeus)

Carduelisflammea (Linnaeus)

Loxia species (Linnaeus)

Anas species (Linnaeus)

Strix nebulosa (Forster)

Regulus species (Cuvier)

Dendroica kirtlandii (Baird)

Dendroica magnolia (Wilson)

Meleagris gallopavo merriami

(Nelson)

Grus canadensis pratensis (Meyer)

Zenaida macroura (Linnaeus)

Verminvora ruficapilla (Wilson)

Parula americana (Linnaeus)

Falco peregrinus (Tunstall)

Phasianus colchicus (Linnaeus)

Dryocopus pileatus (Linnaeus)

Pinícola enucleator (Linnaeus)

Carduelis pinus (Wilson)

Dendroica pinus (Wilson)

Sitta canadensis (Linnaeus)

Picoides borealis (Vieillot)

Regulus calendula (Linnaeus)

Bonasa umbellus (Linnaeus)

Melospiza melodia (Wilson)

Dendrogapus canadensis (Linnaeus)

Meleagris gallopavo (Linnaeus)

Catharusfuscescens (Stephens)

Bombycilla species (Vieillot)

Zonotrichia albicollis (Gmelin)

Sphyrapicus varius (Linnaeus)

' Sources: American Ornithologists' Union. Checklist of North American Birds. Fifth edition. Lawrence, KS: American Ornithologist Union; 1957. 691 p. and

Association of Systematics Collections. Checklist of Birds of the United States and the U.S. Territories. (Prepared for the U.S. Department of the Interior, Fish

and Wildlife Service, Office of Biological Services.) Lawrence, KS: Association of Systematics Collections. 31 p.

187
Animals

Common Name

Abert's squirrel

Antelope (pronghom)

Beaver

Black bear

Canadian lynx

Chipmunk

Coyote

Deer mouse

Elk

Fisher

Florida panther (puma)

Fox

Fox squirrel

Gray squirrel

Gray wolf

Grizzly bear

Hare, snowshoe

Kaibab squirrel

Marten

Meadow vole

Moose

Mountain beaver

Mule deer

Opossum

Pine marten

Pocket gopher

Porcupine

Rabbit

Racoon

Red squirrel

Red-backed vole

Rocky Mountain elk

Skunk

Squirrel

Timber wolf

Tree squirrels

White-footed mouse

White-tailed deer

Wild horse

Woodrat

Scientific Name

Sciurus aberti aherti (Woodhouse)

Antilocapra americana (Ord)

Castor canadensis (Kuhl)

Ursus americanas (Pallas)

Lynx canadensis (Kerr)

Tamias striatus (Linnaeus)

Canis latrans (Say)

Peromyscus maniculatus (Wagner)

Cervus species (Linnaeus)

Martes pennanti (Erxleben)

Felis concolor coryi (Bangs)

Urocyon species (Baird) or Vulpes

species (Bowdich)

Sciurus niger (Linnaeus)

Sciurus carolinensis (Gmelin)

Canis lupus (Linnaeus)

Ursus arctos (Linnaeus)

Lepus americanus (Erxleben)

Sciurus aberti (Woodhouse)

Martes americana (Turton)

Microtus pennsylvanicus (Ord)

Alces alces (Linnaeus)

Aplodontia rufa (Rafinesque)

Odocoileus hemionus hemionus

(Rafinesque)

Didelphis virginiana (Kerr)

Martes americana (Turton)

Thomomys species (Wied)

Erethizon dorsatum (Linnaeus)

Sylvilagus species (Gray)

Procyon lotor (Linnaeus)

Tamiasciurus hudsonicus (Erxleben)

Clethrionomys gapperi (Vigors)

Cervus elaphus (Linnaeus)

Mephitis species (E. Geoffrey St.

Hilaire and G. Cuvier) or

Spilogale species (Gray)

Sciurus species (Linnaeus)

Canis lupis (Linnaeus)

Sciurus species (Linnaeus)

Peromyscus leucopus (Rafinesque)

Odocoileus virginianus (Zimmerman)

Equus species (Linnaeus)

Neotoma species (Say and Ord)

^ Sources: Hall, E. Raymond. Mammals of North America. New York, NY: John E. Wiley and Sons. 1981. 1,175 p. and Association of Systematics

Collections. Checklist of Mammals of the United States and the U.S. Territories. (Prepared for the U.S. Department of the Interior, Fish and Wildlife Service,

'office of Biological Services.) Lawrence, KS: Association of Systematics Collections; 1982. 31 p.

188
Amphibians and Reptiles

Common Name Scientific Name

Eastern Indigo snake Drymarchon coráis couperi

(Holbrook)

Pine Barrens treefrog Hyla andersoni (Baird)

Red Hills salamander Phaeognathus hubrichti (Highton)

Ringed sawback turtle Graptemys oculifera (Baur)

Fishes^

Common Name Scientific Name

Arizona or Apache trout Salmo apache (Miller)

Gila trout Salmo gilae (Miller)

Lake sturgeon Acipenserfulvescens (Rafinesque)

Trout Salmo species and/or Salvelinus

species

^ Sources: Collins, J. T.; Huheey, J. E.; Knight, J. L.; Smith, H. M. Standard Common and Scientific Names for North American Amphibians and Reptiles.

Lawrence, KS: Society for the Study of Amphibians and Reptiles. 1978. 36 p. and Association of Systematics Collections. Checklist of Reptiles and Amphibians

of the United States and the U.S. Territories. (Prepared for U.S. Department of the Interior, Fish and Wildlife Service, Office of Biological Services.) Lawrence,

KS: Association of Systematics Collections; 1982. 33 p.

^ Source: American Fisheries Society. A List of Common and Scientific Names. Names of Fishes from the United States and Canada. Fourth Edition. Special

Publ. No. 12. Bethesda, MD: American Fisheries Society; 1980. 174 p.

189
Index of Forest Cover Types

Page

Appalachian Mixed Hardwoods 141

Aspen 113

Balsam Fir 102

Black Spruce 96

Bottomland Hardwoods* 175

Cherry-Maple 137

Eastern Redcedar 109

Eastern Spruce-Fir 128

Eastern White Pine Including Eastern Hemlock 131

Engelmann Spruce-Subalpine Fir 59

Grand Fir, Douglas-Fir, and Associated Species 19

Interior Alaska White Spruce-Hardwoods 33

Interior Ponderosa Pine in the Black Hills 80

Jack Pine 92

Loblolly Pine 148

Lodgepole Pine 63

Longleaf Pine 153

Mixed Conifers of Southwestern Oregon 23

MixedConifers, Western White Pine, and Western Redcedar 67

Northern Hardwoods 121

Northern White-Cedar 105

Northwestern Ponderosa Pine and Associated Species . 16

Oak-Hickory 116

Oak-Pine 172

Page

Pacific Douglas-Fir 9

Pacific Ponderosa Pine 48

Paper Birch 145

Pinyon-Juniper 84

Pitch Pine 135

Ponderosa Pine and Rocky Mountain Douglas-Fir .... 53

Red Alder 26

Red Fir and White Fir 41

Red Pine 89

Redwood 37

Rocky Mountain Aspen 77

Sand Pine 170

Shortleaf Pine . .157

Sierra Nevada Mixed Conifers 44

Slash Pine 162

Southwestern Mixed Conifers 73

Southwestern Oregon-Northern California Hardwoods . . 29

Southwestern Ponderosa Pine 70

Tamarack 99

True Fir—Hemlock 13

Virginia Pine 167

Western Hemlock-Sitka Spruce 5

Western Larch 56

Yellow-Poplar 180

190
Index of Authors

Page

Alexander, RobertR59,63,80

Argyle, Dean33

Atzet, Tom29

Baker, JamesB148

Balmer, WilliamE148,170

Barrett, JamesW16

Bassett, RichardL84

Beck, DonaldE180

Beebe, Tom19

Benzie, JohnW89,102,128

Blum, BartonM128

Boldt, CharlesE80

Booker, RobertG105

Boyer, WilliamD153

Bramlett, DavidL167

Brittain, RobertE99

Cutler, Dick121

Day, KennethG116

DeBeil, DeanS26

Della-Bianca, Lino131,141

Emmingham, William13

Engelby, Orville59,77

Fiske, JohnN37,41,44,48

Fleming, Harvey135,141

Frank, RobertM102

Franklin, JerryF13

Garrett, PeterW135

Gearhart, Porter137

Gottfried, GeraldJ73

Graham, RussellT67

Graney, DavidL172

Harris, A.S5

Jacobs, RodneyD121,145

Jaszkowski, Ralph13

Johnson, DavidL5

Johnson, R.L175

Johnston, WilliamF96,99,105

Kingsley, Duane23

Kitchens, RobertN157,167,172

Laacke, RobertJ41,44

Lancaster, KennethF131

Larson, MiloJ63,80

Law, JayR109

Lawson, EdwinR109,157

Losensky, Jack53

Page

Lotan, JamesE63

Marquis, DavidA137

Martin, RobertE16

McCumber, JamesE89

McDonald, PhilipM29

McGee, CharlesE116

Meeuwig, Richard084

Merski, Edward128

Minore, Don23,29

Naumann, JohnR56

Oliver, WilliamW48

Olson, David F., Jr37

Outcalt, KennethW170

Parham, Glenn162

Perala, DonaldA113

Peterson, DonaldW153

Powers, RobertF48

Ready, Kenneth L.70

Ronco, Frank, Jr70,73

Rudolph, ThomasD92

Russell, James113,131

Ryker, RussellA53

Safford, L.0145

Sander, IvanL116

Schmidt, WymanC56

Seidel, K.W19

Shaffer, Richard73

Shearer, RaymondC56

Shepperd, WayneD77

Shoulders, Eugene162

Shropshire, F.W175

Sims, DanielH180

Smith, H. Clay141

Smith, ThomasM96, 102

Tubbs, CarlH121

Turpin, Thomas C. . 26

Twombly, AsaD9

Volland, LeonardA63

Ward, Roger67

Wellner, CharlesA67

Wendel, G.W131

Willard, RalphE116

Williamson, RichardL9

Wood, DonaldC16

Zasada, JohnC33

191