Ecology, Silviculture, and

Management of Black Hills

Ponderosa Pine

Wayne D. Shepperd and Michael A. Battaglia

United States

Department

of Agriculture

Forest Service

Rocky Mountain

Research Station

General Technical

Report RMRS-GTR-97

September 2002
Shepperd, Wayne D.; Battaglia, Michael A. 2002. Ecology, siliviculture, and management of Black Hills

ponderosa pine. Gen. Tech. Rep. RMRS-GTR-97. Fort Collins, CO: U.S. Department of Agriculture, Forest

Service, Rocky Mountain Research Station. 112 p.

Abstract

This paper presents a broad-based synthesis of the general ecology of the ponderosa pine ecosystem in the

Black Hills. This synthesis contains information and results of research on ponderosa pine from numerous

sources within the Black Hills ecosystem. We discuss the silvical characteristics of ponderosa pine, natural

disturbances that govern ecosystem processes, wildlife habitat and management, various silvicultural methods

to manage ponderosa pine forests, and watershed management of the Black Hills.

Keywords: Black Hills, silviculture, ecology, ponderosa pine, even-aged management, uneven-aged

management, reforestation, wildlife habitat, natural disturbance, snags, insects, disease, fire history

Authors

Wayne D. Shepperd is a Research Silviculturist, at the U.S. Forest Service Rocky Mountain Research Station

in Fort Collins, CO. He is also administrator of the Manitou Experimental Forest, near Woodland Park,

Colorado. He holds a B.S. in Outdoor Recreation, and M.S. and Ph.D. degrees in Silviculture from Colorado

State University. A Colorado native, Dr. Shepperd has been with the Forest Service since 1969. The author

of over 70 research publications, he is a recognized expert on the ecology, growth, and management of

Rocky Mountain Forests. His current research includes fire, fuels, vegetation, and management studies in

the Colorado Front Range, North Kaibab Plateau in Arizona, and the Black Hills of South Dakota.

Michael A. Battaglia is a research associate with METI Corporation contracted to the Rocky Mountain Research

Station in Fort Collins, CO. He completed a B.S. degree in Biology at the University of South Carolina and an

M.S. degree in Forestry at Virginia Polytechnic Institute and State University.

Acknowledgments

This publication was completed under the sponsorship of the Black Hills National Forest. The authors are

grateful for the insightful and helpful reviews of the manuscript from Lance Asherin, Terrie Jain, Linda Joyce,

Steve Mata, Mark Rumble, Jon Schmid, Blaine Cook, and members of the Black Hills National Forest. We

are thankful for Bob Hamre’s editing of the manuscript. The authors are grateful to Joyce VanDeWater for

creating the cover page and illustrations throughout the manuscript.

You may order additional copies of this publication by sending your mailing information in label form through one of

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series number.

Fort Collins Service Center

Telephone (970) 498-1392

FAX (970) 498-1396

E-mail rschneider@fs.fed.us

Web Site http://www.fs.fed.us/rm

Mailing Address Publications Distribution

Rocky Mountain Research Station

240 West Prospect Road

Fort Collins, CO 80526
Ecology, Silviculture, and

Management of Black Hills

Ponderosa Pine

Wayne D. Shepperd

Michael A. Battaglia

Rocky Mountain Research Station

USDA Forest Service

Sustaining Alpine and Forest Ecosystems

Under Atmospheric and Terrestrial Disturbances

240 West Prospect Road

Fort Collins, CO 80526

USDA Forest Service

General Technical Report RMRS-GTR-97 September 2002
Contents

Background and Scope .............................................................................................................. 1

Physical Characteristics ............................................................................................................. 1

Physiography and Geology .................................................................................................... 1

Climate ................................................................................................................................... 3

Soils ........................................................................................................................................ 6

Vegetation............................................................................................................................... 6

Ponderosa pine (Pinus ponderosa) series .......................................................................... 8

Aspen (Populus tremuloides) series ................................................................................. 12

Bur oak (Quercus macrocarpa) series .............................................................................. 14

White spruce (Picea glauca) series .................................................................................. 15

Natural Disturbances................................................................................................................ 17

Insects .................................................................................................................................. 17

Mountain pine beetle (Dendroctonus ponderosae)........................................................... 17

Pine engraver (Ips pini)..................................................................................................... 23

Red turpentine beetle (Dendroctonus valens) .................................................................. 25

Pine tip moth (Rhyacionia spp.) ........................................................................................ 27

Diseases ............................................................................................................................... 28

Armillaria root disease (Armillaria ostoyae) ...................................................................... 28

Red rot (Dichomitus squalens).......................................................................................... 31

Western gall rust (Peridermium harknessii) ...................................................................... 33

Needle cast (Elytroderma deformans) .............................................................................. 34

Diplodia tip blight (Spheropsis sapinea)............................................................................ 35

Fire ....................................................................................................................................... 36

Wind ..................................................................................................................................... 41

Snow..................................................................................................................................... 42

Overstory-Understory Relationships ........................................................................................ 43

Background .......................................................................................................................... 43

Influence of Soil Type ........................................................................................................... 43

Understory Production .......................................................................................................... 44

Overstory Influence on Functional Groups ........................................................................... 45

Snags and Coarse Woody Debris ............................................................................................ 46

Snag Utilization..................................................................................................................... 46

Snag Population Dynamics .................................................................................................. 47

Coarse Woody Debris .......................................................................................................... 48

Management of Snags and Coarse Woody Debris .............................................................. 49

Major Wildlife Species .............................................................................................................. 49

Habitat Capability Models (HABCAP)................................................................................... 49

Rocky Mountain Elk (Cervus elaphus nelsoni) ..................................................................... 50

Habitat requirements......................................................................................................... 51

Management guidelines .................................................................................................... 52

White-Tailed Deer (Odocoileus virginianus dakotensis) ....................................................... 53

Habitat requirements......................................................................................................... 53

Management guidelines .................................................................................................... 54

Mule Deer (Odocoileus hemionus) ....................................................................................... 55

Habitat requirements......................................................................................................... 55

Management guidelines .................................................................................................... 56

Merriam’s Turkey (Meleagris gallopavo merriami)................................................................ 56

Habitat requirements......................................................................................................... 56

Management guidelines .................................................................................................... 57

Northern Goshawk (Accipiter gentiles atricapillus) ............................................................... 58

Habitat requirements......................................................................................................... 59

Management guidelines .................................................................................................... 60

ii
Nongame Birds ..................................................................................................................... 60

Ground nesters ................................................................................................................. 61

Foliage nesters ................................................................................................................. 63

Cavity nesters ................................................................................................................... 64

Others ............................................................................................................................... 67

Management guidelines .................................................................................................... 67

Silviculture of Ponderosa Pine in the Black Hills ...................................................................... 68

Silvics of Black Hills Ponderosa Pine ................................................................................... 68

Regeneration Cuts: Even-aged ............................................................................................ 68

Two-cut shelterwood ......................................................................................................... 68

Three-cut shelterwood ...................................................................................................... 70

Seed-tree method ............................................................................................................. 71

Clearcut method................................................................................................................ 72

Regeneration Cuttings: Uneven-Aged Silviculture ............................................................... 72

Stocking control ................................................................................................................ 73

Single-tree versus group selection.................................................................................... 76

Layout, marking, and utilization under uneven-aged systems .......................................... 77

Hybrid Systems: Two-Aged/Three Aged............................................................................... 77

Intermediate Operations ....................................................................................................... 78

Precommercial thinning .................................................................................................... 78

Commercial thinning ......................................................................................................... 78

Maximization of merchantable board foot yield................................................................. 81

Prescribed burning ............................................................................................................ 81

Artifical Reforestation ............................................................................................................... 82

Principles .............................................................................................................................. 82

Tree Improvement Program ................................................................................................. 82

Site Preparation .................................................................................................................... 83

Seeding ................................................................................................................................ 84

Seed collection.................................................................................................................. 84

Seed storage..................................................................................................................... 84

Germination treatment ...................................................................................................... 84

Sowing techniques ............................................................................................................ 84

Seed protection ................................................................................................................. 85

Planting................................................................................................................................. 86

Bare-root seedlings ........................................................................................................... 86

Containerized seedlings.................................................................................................... 88

Planting techniques........................................................................................................... 89

Mycorrhizal inoculation of seedlings ................................................................................. 90

Management of Associated Species ........................................................................................ 91

White Spruce ........................................................................................................................ 91

Aspen ................................................................................................................................... 92

Bur Oak ................................................................................................................................ 94

Watershed Management .......................................................................................................... 94

Black Hills Hydrology ............................................................................................................ 94

Timber/Water Yield Relationships......................................................................................... 95

References ............................................................................................................................... 96

Appendix A: Common and scientific names of species listed .................................................110

iii
USDA Forest Service General Technical Report RMRS-GTR-97. 2002 1

Background and Scope

In 1974, Rocky Mountain Station scientists Charles

Boldt and James Van Deusen produced Forest Service

Research Paper RM-124, which summarized available

knowledge about the silviculture and management of

ponderosa pine (Pinus ponderosa) in the Black Hills

of western South Dakota and northeastern Wyoming

(Boldt and Van Deusen 1974). The paper, intended as

a guide for professional foresters, described the growth

environment in the Black Hills, presented the silvical

characteristics of ponderosa pine growing there, discussed

pests, diseases, and damaging agents affecting growth,

and described silviculture techniques that could be used

to manage ponderosa pine for wood fiber production.

Our intent in this paper is to build upon the foundation laid by Boldt and Van Deusen. Not only have we

updated the discussion to include research published

since the earlier report, we have expanded the scope to

include a broad-based synthesis of the general ecology of ponderosa pine in the Black Hills. Rather than

emphasize management for wood production, as was

the focus of the earlier paper, we broadened the discussion of silviculture techniques to include management alternatives for wildlife habitat, esthetics, ecosystem restoration, and biodiversity.

In keeping with current ecosystem-based management philosophy, we synthesized information and results of research on ponderosa pine from numerous

sources both within and outside the Black Hills ecosystem. Both even- and uneven-aged silviculture systems are described, and management alternatives are

presented that can be used to produce and maintain

desired growth and stocking conditions for a variety

of natural resource objectives.

Physical Characteristics

Physiography and Geology

The Black Hills is a forested refuge on the Missouri

Plateau of the Great Plains Province (Hoffman and

Alexander 1987). This refuge spans 125 miles (200

km) from north to south and 60 miles (100 km) from

east to west (Fenneman 1931). The total land base is

nearly 6,000 square miles (15,540 km2

), with two-thirds

of the area in southwest South Dakota and one third in

northeast Wyoming (Froiland 1990).

The Black Hills and neighboring Bear Lodge Mountains to the west (hereafter collectively referred to as

the Black Hills) were formed by a regional uplift of

the Earth’s surface during the Laramide mountainbuilding episodes that produced most of the ranges of

the Rocky Mountains several million years ago. Granites pushing up beneath overlying sedimentary formations formed this maturely dissected domal uplift (Orr

1975). The uplift is elliptical in shape, with a crystalline core, which occupies about 20 percent of the Black

Hills area. The core is encircled by steeply dipping

sedimentary deposits. As a general rule, the closer a

formation is to the center of the Black Hills, the older

its age (Raventon 1994). These distinct differences in

geology across the Black Hills affect vegetation distribution and growth. Consequently, managers must be

aware of these differences.

Both the Black Hills and Bear Lodge Mountains are

similar in geologic makeup and response to erosion.

There are four recognizable geomorphologic features

in the Black Hills (fig. 1): (1) Dakota Hogback ridge;

(2) Red Valley; (3) Limestone Plateau and Minnelusa

Foothills; and (4) Central Crystalline Core (Boldt and

Van Deusen 1974; Froiland 1990). Each of the first

three geomorphological features encircles the Central

Crystalline Core, with the western side of the features

wider than the eastern. These features are elevated

1,000 to 4,000 feet (305 to 1,219 m) above the surrounding plains.

The Dakota Hogback ridge rises several hundred feet

above the surrounding plains and is on the outer rim of

the Black Hills uplift (fig. 1) (Gries 1996). The outer

slope of the formation consists of limestone covered

by several hundred to a thousand feet of shale (Froiland

1990). The main component of the Hogback ridge is

sandstone of the Lakota formation. The eastern edge

of the Hogback dips steeply and is narrow, whereas

Ecology, Silviculture, and Management of

Black Hills Ponderosa Pine

Wayne D. Shepperd and Michael A. Battaglia
2 USDA Forest Service General Technical Report RMRS-GTR-97. 2002

the western edge (side that faces the Red Valley) has a

gentle dip that forms a ridge of an outward slope, dissected plateau extending up to 10 miles (16 km)

(Fenneman 1931). The ridges are covered with ponderosa pine with intermingled open grassy areas

(Radeke and Westin 1963). The potential for mass

movement of soil is greatest in this region due to the

tilt and thinly bedded sedimentary rocks. Available

water capacity is low and permeability is moderate,

with a large potential for runoff (Ensz 1990). The stability of the slopes is especially sensitive to roadcuts

and excavations (Cattermole 1969). Elevations in this

region range from 3,800 feet (1,158 m) in the Rapid

City area to 4,900 feet (1,494 m) in the Elk Mountain

area of the southwest portion of the Black Hills.

The Red Valley extends entirely around the Black

Hills encircling the Limestone Plateau and is in turn

surrounded by the Dakota Hogback (fig. 1) (Gries

1996). This geomorpological feature varies in width

from 0.5 mile (0.8 km) wide near Rapid City to 5 miles

(8 km) wide southwest of Custer. This feature consists of sandstones, sandy clay, and shales of the

Sundance and Spearfish formations (Froiland 1990).

The Red Valley gets its name from the sedimentary rocks

that have oxidized iron particles. The vegetation in this

region is typically grass with some clumpy pines and

Figure 1: Generalized geologic map of the Black Hills

(adapted from Larson and Johnson 1999).
USDA Forest Service General Technical Report RMRS-GTR-97. 2002 3

junipers (Radeke and Westin 1963), most likely a product

of the dry conditions and high concentrations of salts in

the soil (Froiland 1990). The topography of this region is

nearly level to strongly rolling with elevations ranging

from 3,300 to 3,500 feet (1,006 to 1,067 m).

Precipitation is lower in both the Dakota Hogback

and Red Valley features. Therefore, ponderosa pine in

these regions is harder to establish and grows more

slowly than elsewhere in the Black Hills.

The Limestone Plateau and Minnelusa Foothills

(hereas referred to as the limestone plateau) surrounds

the Central Crystalline Core of the Black Hills (fig. 1).

The main rock component of the plateau is limestone,

but sandstone, shale, siltstone, and dolomite are also

present (Gries 1996). On the eastern edge, the plateau

is a narrow 2 miles (3.2 km) wide band (Froiland 1990)

with an elevation of around 4,000 feet (1,219 m)

(Radeke and Westin 1963). This eastern side contains

steep escarpments that rise up to 800 feet (244 m) above

the Central Crystalline Area (Fenneman 1931). Many

large springs that are the headwaters for major streams

of the Black Hills arise along the foot of the east-facing escarpments (Gries 1996). On the western part of

the Limestone Plateau, elevations range from 6,000 to

7,100 feet (1,829 to 2,164 m), and the area can be as

wide as 15 miles (24 km) (Froiland 1990). The summit along the western edge of the plateau is considered the main divide for the Black Hills (USDA Forest

Service 1996a). West of this divide, the rocks of the

plateau are younger and the slopes are gentle. These

slopes are covered with extensive ponderosa pine and

white spruce (Picea glauca) forests and fertile soils.

Precipitation is also higher, which makes the western

Limestone Plateau a productive area for tree growth.

The Central Crystalline Core of the Black Hills consists of divided ridges and mountains scattered among

large valleys. The valleys have canyons that extend

out with a variety of igneous and sedimentary rocks

such as silica-rich schists, slates, and quartizites in different stages of metamorphosis. The major topographic

feature of the core is the great masses of granite and

pegmatites (Froiland 1990). Several eroded outcrops,

such as Harney Peak, the Needles, Cathedral Spires,

Bear Mountain, and Mt. Rushmore, are found in this

area (fig. 1). Elevations in the core range from 4,300

to 6,000 feet (1,311 to 1,829 m), with the tallest, Harney

Peak, reaching elevations of 7,242 feet (2,207 m). The

granitic region is not susceptible to mass soil movement, although soil slumps do occasionally occur on

hillsides if soil water content is high (Ensz 1990). In

the metamorphic regions, mass soil movement can

occur if steep slopes are disturbed. Throughout the

Central Core are many rocky, forested slopes and

ridges, intermingled in the western portion with small

parklike valleys (USDA Forest Service 1996a). The

Central Core is one of the most productive areas for

ponderosa pine timber in the Black Hills (Boldt and

Van Deusen 1974).

Scattered throughout the northern part of the Black

Hills are Tertiary igneous intrusive areas and volcanic

features known collectively as the Laccolith Mountains

(Fenneman 1931). These intrusive magmas were

formed during the uplift of the Black Hills region. The

Laccolith Mountains range in diameter from less than

a mile to as much as 10 miles (16 km), with the Missouri Butte as the most western intrusion and Bear Butte

as the most eastern intrusion. Other prominent intrusions

include: Devils Tower, Inyan Kara Mountain, Sundance

Mountain, and Terry Peak (fig. 1). Terry Peak is the highest of the intrusions with an elevation of 7,071 feet (2,155

m), while the majority of the other intrusions range between 5,000 to 6,500 feet (1,525 to 1,981 m).

Climate

The climate of the Black Hills differs from the surrounding plains due to the influence of the regional

uplift. The Black Hills microclimate is a Continental

type, cold in winter and hot in summer (Johnson 1949).

The increased elevation results in an orographically

induced microclimate that increases precipitation and

decreases temperatures at the higher elevations

(Driscoll and others 2000). The uplift also moderates

the variations in air temperature and lowers the wind

velocities compared to the surrounding Great Plains

(Froiland 1990).

The precipitation patterns in the Black Hills differ

along elevational and latitudal gradients (fig. 2). In

general, northern locations and higher elevations receive more precipitation than southern locations and

lower elevations. Precipitation patterns are influenced

by such factors as wind direction, topography, season,

and storm type. In areas upslope of the wind direction, precipitation occurs more frequently (Hjelmfelt

and others 1994). The uplift of air due to topography

can enhance convective showers and thunderstorms,

increasing precipitation at higher elevations at the expense of lower precipitation at lower elevations

(Trimarchi 1997).

Average annual precipitation ranges from approximately 29 inches (74 cm) in the northern Black Hills

near Lead and Deadwood to about 16 inches (41 cm)

in the southern Black Hills near Hot Springs toward

the Plains (fig. 2) (Driscoll and others 2000). Within

the Black Hills, precipitation averages over 20 inches

(51 cm) at the higher elevations.
4 USDA Forest Service General Technical Report RMRS-GTR-97. 2002

Figure 2: Isohyetal map of the distribution of average annual

precipitation in the South Dakota Black Hills region for water

years 1961 to 1990 (map adapted from Driscoll and others

2000).
USDA Forest Service General Technical Report RMRS-GTR-97. 2002 5

November through February are the least likely

months for precipitation with an average of 12.4 percent of annual precipitation (Driscoll and others 2000).

Precipitation is higher in places where upslope flow

from the northwest and north enhance precipitation,

such as in Lawrence County where 17 percent of the

annual precipitation occurs during these months

(Driscoll and others 2000). On average, there are two

to three snowstorms every year with blizzards occurring on average every 2 to 3 years (Trimarchi 1997).

The Black Hills is subjected to three storm types:

Northern Pacific, Rocky Mountain, and the Colorado

type. Each storm type influences the amount of moisture received by the area. Northern Pacific storm types

bring cold and blustery conditions with small amounts

of precipitation. Rocky Mountain storm types also

bring cold and blustery conditions with small amounts

of precipitation, but move quickly over the area. Colorado type storms are strong systems that move slowly

east and northeasterly out of the Rockies and bring

heavy amounts of precipitation (Johnson 1949).

The months from April to July have the highest probability of precipitation due to the warmer, moister air

from the south combining with the colder, drier air of

the north. On average, May and June are the wettest

months of the year, with an average of 33 percent of

total annual precipitation (Driscoll and others 2000).

June and July are prime times for convective thunderstorms, which usually occur in the afternoon and evenings, especially in the central portion of the Black

Hills, and typically move eastward (Trimarchi 1997).

These storms can be severe with strong, gusty winds,

heavy rain, and hail. For example, on July 5 and 6,

1996, a hailstorm carved a 75-mile (120-km) path of

destruction in Meade and Butte Counties; hail was baseball sized and winds were reported as high as 111 mph

(50 m/s) (Klimowski 1997). Flash floods are also common during these months (Trimarchi 1997). The convective activity diminishes by August, and precipitation from August to November decreases substantially

(Driscoll and others 2000).

Mean annual temperature is also influenced by latitude and elevation. Stations in the northern Black Hills

are generally cooler than those at similar elevations in

the southern Black Hills (Froiland 1990). Mean annual temperatures range from 48.1  ̊F (9  ̊C) at Hot

Springs to 37.2  ̊F (2.9  ̊C) at Deerfield. Mean annual

high temperatures range from 63  ̊F (17.2  ̊C) at Hot

Springs to 52.5  ̊F (11.4  ̊C) at Deerfield (Trimarchi

1997). Mean annual low temperatures range from 35.8

 ̊F to 21.9  ̊F (2.1  ̊C to –5.6  ̊C), although the 35.8

value may be biased due to the location of the sensor

on a rocky surface (Trimarchi 1997).

Temperatures in the winter are less severe than the

typical temperatures found in the surrounding plains

due to temperature inversions (Trimarchi 1997). These

inversions occur because of shallow, arctic air masses

that stretch across the Northern Great Plains and

downslope warming of air at night. November through

March are the coldest months, with the lowest temperatures occurring in areas where the temperature inversions reach the ground less frequently, or in the highest elevations when inversions are lacking and snow is

present (Trimarchi 1997). Mean high temperatures in

January range from 29.3  ̊F (–1 to 2  ̊C) in the northern

Black Hills to the upper 30s ( ̊F) (2 to 4  ̊C) in the

southern Black Hills. Mean low temperatures in January range from single digits  ̊F (–16 to –12  ̊C) in most

of the higher locations to the lower teens  ̊F at lower

elevations (Trimarchi 1997).

Temperatures in the summer are generally cooler as

the elevation increases. July is the warmest month in

the Black Hills. Mean high temperatures range from

the upper 70s ( ̊F) (24 to 26  ̊C) in the higher elevations to the upper 80s ( ̊F) (29 to 32  ̊C) on the surrounding plains (Trimarchi 1997). Mean low temperatures range from the upper 40s ( ̊F) (7 to 10  ̊C) in the

higher elevations to the upper 50s ( ̊F) (13 to 15  ̊C) on

the plains.

The growing season in the Black Hills ranges from

154 days at Rapid City to a minimum of 100 days in

the higher northern locations (Orr 1975). The average

last spring freeze occurs in early to mid May along the

perimeter of the Hills and late May to early June in the

higher elevations (Trimarchi 1997). The first fall freeze

typically occurs in September and is variable due to

the elevation.

Wind velocities in the Black Hills are much lower

than those found in the surrounding plains. The prevailing wind direction in most of the Black Hills is

from the northwest. However, on the southeastern side

of the Black Hills, near Hermosa, the prevailing

winds are from the north, and on the northwestern

side of the Black Hills, near Sundance, the winds

are from the southwest (Johnson 1949). Furthermore, the velocity of winds in the foothill areas are

more variable than those found in the interior of the

Black Hills.

Chinooks commonly occur in the Black Hills. These

warm, dry, downslope winds cause rapid warming of

the lower elevations in the colder months of the year

(Trimarchi 1997). When winds are strong, temperatures can increase 10 to 20  ̊F (6 to 11  ̊C) and then

drop when the winds cease. Chinooks are commonly

found on the east, northeast, and northern slopes

(Johnson 1949).
6 USDA Forest Service General Technical Report RMRS-GTR-97. 2002

Soils

The Black Hills National Forest encompasses five

counties in South Dakota (Custer, Falls, Lawrence,

Meade, and Pennington) and two in Wyoming (Crook

and Weston). Soil inventories for each county have

been completed by the National Resources Conservation Service (NRCS, previously SCS) over the past 25

years. Unfortunately, the soil associations are not consistently named with the same name across county

borders. Furthermore, there are 107 soil series within

the seven counties. To describe each of the associations and soil series is beyond the scope of this publication. In general, soils in the Central Crystalline Core

are Alfisols with the major soils consisting of Stovho,

Trebor, Virkula, Mocmont, rock outcrops, Pactola, and

Buska (Bryce and others 1998). Soils found in the

Limestone Plateau and Minnelusa Foothills are

Alfisols, Mollisols, and Inceptisols. Common soil series in this region include Citadel, Vanocker, Grizzly

Buska, Mocmont, Pactola, and Paunsaugunt. The Red

Valley and Hogback regions consist of Entisols and

Mollisols. Common soil series in these regions include

Butche, Canon, Enning, Nevee, Spearfish, Grummit,

Tilford, Vale, and Rekop (Bryce and others 1998).

Detailed information for each soil series can be found

in the NRCS soil survey, and we suggest that the manager utilize the survey specific to the site where the

management activity will occur. These surveys have

maps at the 1:24000 scale, with soil series boundaries

delineated.

Descriptions and variables associated with soil productivity within the Central Crystalline Core and Limestone Plateau were developed by Myers and Van

Deusen (1960). Equations for estimating ponderosa

pine site index in these areas were based on (1) soil

depth to top of the C horizon, (2) slope position (distance up the slope as a percentage of total slope length),

(3) slope percent, and (4) aspect. In the Central Crystalline Core area where soil is derived from metamorphic or igneous rocks, all four variables are required.

The equation for the Central Crystalline Core is: Y =

1.64660 – 0.10315*X1 – 0.01895*X2 – 0.09042*X3

 +

0.13330*X4

; (r2 = 0.83). In the Limestone Plateau area

where soils are derived from mostly limestone, only

soil depth and slope position are needed. The equation for the Limestone Plateau is: Y = 1.54200 –

0.11819*X3 + 0.20821*X4

; (r2 = 0.78). For each equation, Y = Logarithm of site index, X1 = Grade or percent of slope, as a decimal, X2

 = Aspect as the sine of

the azimuth clockwise from southeast, plus one, X3

 =

Distance of plot center up the slope as a percentage of

total slope length, expressed as a decimal, and X4

 =

Logarithm of soil depth in inches to top of C horizon

(Myers and Van Deusen 1960).

Vegetation

The Black Hills is a refuge for plant species that

occur in four of the North American biomes: Cordilleran Forest, Grassland, Eastern Deciduous Forest, and

Northern Coniferous Forest (Marriott and others 1999).

This mixture of vegetation is a result of the varied topography, geology, and climates found within the Black Hills.

There have been several surveys of Black Hills vegetation since Europeans first visited the region. Each

survey described the vegetation with different classification schemes. Graves (1899) inventoried timber resources and forest conditions, and classified stands by

age class. McIntosh (1930, 1931) described vegetation types based on successional status, and listed plant

species for various habitats. Thilenius (1972) surveyed

vegetation that occurred in deer habitats and classified

them into habitat units using cluster analysis. Hoffman

and Alexander (1987) performed one of the most extensive classifications of habitat types for the Black

Hills, in which habitat types were defined based upon

quantitative data and Daubenmire methodology1

. Habitat type refers to the potential climax natural vegetation. Johnston (1987) reported plant associations for

the Rocky Mountain Region (Region 2), which includes

the Black Hills National Forest. Within this survey,

Johnston relates classifications from other surveys (for

example, Thilenius habitat units and Hoffman and

Alexander habitat types) to his plant associations.

Recently, The Nature Conservancy completed the

Black Hills Community Inventory report, which classified and described vegetation within the region using the U.S. National Vegetation Classification System (Marriott and others 1999).

Relationships for the information of the three most

recent vegetative descriptions of ponderosa pine habitats (Hoffman and Alexander 1987; Johnston 1987;

Marriott and others 1999) are shown in table 1.

Hoffman and Alexander listed only eight ponderosa

1 Plant association is a kind of plant community represented by

stands occurring in places where environments are so closely

similar that there is a high degree of floristic uniformity in all

layers (Daubenmire 1968). Not only is vegetational uniformity

important in the classification, but also the abiotic (landform and

soils) components must be similar (Johnston 1987). A habitat

type is a collective term for all parts of the land surface supporting or capable of supporting the same kind of climax plant association (Daubenmire 1968). Plant association should be used

for the climax plant community (the taxonomic unit), and habitat

type should be used for the land unit (map unit) to which each

plant association corresponds (Johnston 1987).
USDA Forest Service General Technical Report RMRS-GTR-97. 2002 7

Table 1: Cross-reference of different habitat vegetative surveys of ponderosa pine habitats in the Black Hills.

U.S. National Vegetation

Habitat type Plant association code Classification System (USNVC)a

Hoffman and Alexander (1987) Johnston (1987) Marriott and others (1999)

Pinus ponderosa/Arctostaphylos uva-ursi Pipo/Arad Pinus ponderosa/Arctostaphylos uva-ursi

Woodland

(CEGL000844)

Pinus ponderosa/Carex heliophila Pipo/Cahel Pinus ponderosa/ Carex inops spp.heliophila

Woodland

(CEGL000849)

Pinus ponderosa/Juniperus scopulorum Pipo/Bocu Pinus ponderosa/Juniperus scopulorum

Woodland

(CEGL000861)

Pinus ponderosa/Juniperus communis Pipo/Juco; Pipo/Juco-Syal Pinus ponderosa/Juniperus communis

Woodland

(CEGL000859)

Pinus ponderosa/ Symphoricarpos albus Pipo/Syal Pinus ponderosa/ Symphoricarpos albus

Forest

(CEGL000203)

Pinus ponderosa/ Symphoricarpos albus Pipo/Spbe N/A

Phase: Balsamorhiza sagittata

Pinus ponderosa/ Symphoricarpos albus Pipo/Syal phase 2 Pinus ponderosa/Oryzopsis asperifolia

Phase: Oryzopsis asperifolia Woodland

(CEGL002123)

Pinus ponderosa/Physocarpus monogynus Pipo/Phmo Pinus ponderosa/Physocarpus monogynus

Forest

(CEGL000190)

Pinus ponderosa/Prunus virginiana Pipo/Pavi Pinus ponderosa/Prunus virginiana

Forest

(CEGL000192)

Pinus ponderosa/Quercus macrocarpa Pipo/Quma Pinus ponderosa/Quercus macrocarpa

Woodland

(CEGL000873)

Not discussed Pipo/Rosp Pinus ponderosa/ Pseudoroegneria spicata b

Woodland

(CEGL000865)

Not discussed Pipo/Scsc-Elsm Pinus ponderosa/Schizachyrium scoparium

Woodland

(CEGL000201)

Pinus ponderosa/Pascopyrum smithii c

Woodland

(CEGL000188)

Not discussed Pipo/Pavi phase 4 Pinus ponderosa/Mahonia repens d

Forest

(CEGL000187)

Not discussed Not discussed Pinus ponderosa

Limestone Cliff Sparse Vegetation

(CEGL002055)

Not discussed Not discussed Pinus ponderosa

Scree Woodland

(CEGLK000878)

a Global code used in the Biological and Conservation Database maintained by The Nature Conservancy and its Natural Heritage

Program Partners. b Also known as Agropyron spicatum. c Also known as Agropyron smithii. d Also known as Berberis repens.
8 USDA Forest Service General Technical Report RMRS-GTR-97. 2002

pine habitat types, while Marriott and others listed 15

different ponderosa pine community types. Some of

these 15 community types corresponded to Johnston’s

plant association descriptions. Recently, the Black Hills

National Forest adopted the use of the U.S. National

Vegetation Classification System used by The Nature

Conservancy (Marriott and others 1999). Our descriptions in the following section will refer to the Hoffman

and Alexander (1987) classification unless otherwise

noted.

Ponderosa pine (Pinus ponderosa) series

Ponderosa pine is the most dominant tree in the

Black Hills. It occurs at all elevations, on all soil types,

and on all aspects. Ponderosa pine is considered to be

the climax species over much of the Black Hills due to

fire disturbance and insect outbreaks.

Many of the ponderosa pine vegetation habitat types

at lower elevations can be classified as Dry Coniferous Forest and Woodlands (Marriott and others 1999).

The ponderosa pine/bearberry (Pinus ponderosa/Arctostaphylos uva-ursi) habitat type (fig. 3) is widespread

in the Central Core region (fig. 1) in areas of granite

outcrops and calcareous soils (Hoffman and Alexander

1987; Marriott and others 1999). This habitat type

occurs at elevations from 5,080 to 6,700 feet (1,548 to

2,042 m) but is restricted to the more xeric sites at

higher elevations (Marriott and others 1999). Soil textures range from sandy loam to clay loam (Hoffman

and Alexander 1987), and soil depth is moderately deep

to lithic and well drained (Johnston 1987). Soil pH ranges

from 4.7 to 6.7, with organic matter ranging from 2 to

10.3 percent (Hoffman and Alexander 1987). Understory

species associated with this habitat type include: prickly

rose (Rosa acicularis), white coralberry (Symphoricarpos

albus), rough-leaved ricegrass (Oryzopsis asperifolia),

yarrow (Achillea millefolium), wild strawberry (Fragaria

virginiana), cream peavine (Lathyrus ochroleucus), and

wild spirea (Spiraea betulifolia) (Hoffman and Alexander

1987; Johnston 1987).

The ponderosa pine/sun sedge (Pinus ponderosa/

Carex heliophila) habitat type (fig. 4) is most dominant at lower elevations along the foothills on borders

and hogback ridges (fig. 1) in the plains (Johnston 1987;

Marriott and others 1999), although it can be found at

higher elevations (Marriott and others 1999). This

habitat type occurs at elevations from 4,500 to 5,170

feet (1,372 to 1,576 m) (Hoffman and Alexander 1987;

Johnston 1987). Soil texture ranges from sandy loam

to loam with organic matter ranging from 1.5 to 4.7

percent (Hoffman and Alexander 1987). Reported values for pH differ, ranging from 4.8 to 5.8 (Hoffman

and Alexander 1987) or 5.8 to 6.9 (Johnston 1987).

Graminoids comprise 67 to 90 percent of the total

Figure 3: Ponderosa pine/bearberry (Pinus ponderosa/Arctostaphylos uva-ursi) habitat type

on the Black Hills Experimental Forest. Note the complete

development of the understory.
USDA Forest Service General Technical Report RMRS-GTR-97. 2002 9

undergrowth coverage, with the most important being

sun sedge, poverty oatgrass (Danthonia spicata), and

Kentucky bluegrass (Poa pratensis) (Hoffman and

Alexander 1987). In some areas, bur oak (Quercus

macrocarpa) can be found in the understory.

Although not discussed by Hoffman and Alexander

(1987), the ponderosa pine/little bluestem (Pinus ponderosa/Andropogon scopanis) and ponderosa pine/

western wheatgrass (Pinus ponderosa/Agropyron

smithii) habitat types have been described by Johnston

(1987), Marriott and others (1999), and Thilenius

(1972). These habitat types dominate the lower elevations of the foothills and Hogback Rim in the southwestern part of the Black Hills (fig. 1). Elevations range

from 4,800 to 5,500 feet (1,463 to 1,676 m) (Johnston

1987; Thilenius 1972). Soils are often deep and derived from limestone, with pH ranging from 7.2 to 8.0

(Johnston 1987; Thilenius 1972). Common understory

species include: Rocky Mountain juniper (Juniperus

scopulorum), woods rose (Rosa woodsii), and white

coralberry (Thilenius 1972). Herbaceous species such

as star lily (Leucocrinum montanum) and leafy phlox

(Phlox alyssifolia) indicate the affinity to the prairie

herb stratum (Thilenius 1972).

Located in the outer Hogback Rim and Red Valley

on the dry southern parts of the Black Hills (fig. 1) is

the ponderosa pine/Rocky Mountain juniper (Pinus

ponderosa/Juniperus scopulorum) habitat type (fig. 5)

(Hoffman and Alexander 1987; Marriott and others

1999). This habitat type is usually found on steep,

rocky slopes on sandy loam soils at an elevation of

about 3,900 feet (1,200 m) (Hoffman and Alexander

1987; Johnston 1987). Soil pH is around 7.3 with organic matter content approximately 6.9 percent

(Hoffman and Alexander 1987). Understory growth is

poorly defined and unevenly dispersed, and includes

species such as sideoats grama (Bouteloua

curtipendula), littleseed ricegrass (Oryzopsis

micrantha), pasqueflower (Anemone patens), fringed

sagewort (Artemisia frigida), and bluebell (Campanula

rotundifolia) (Hoffman and Alexander 1987).

Many of the ponderosa pine vegetation habitat types

at higher elevations and mesic sites at lower elevations

can be classified as Mesic Coniferous Forest and Woodlands (Marriott and others 1999). The ponderosa pine/

common juniper (Pinus ponderosa/Juniperus communis) habitat type (fig. 6) is widely distributed on the

Limestone Plateau in the northwestern and western part

of the Black Hills (fig.1) at higher elevations on cool,

moist sites (Hoffman and Alexander 1987; Johnston

1987; Thilenius 1972). Elevations range from 5,670

to 6,780 feet (1,384 to 1,989 m). Soils are typically

derived from limestone, but the habitat type has also

been found on soils derived from igneous rock

Figure 4: Ponderosa pine/sun

sedge (Pinus ponderosa/

Carex heliophila) habitat type

in the southwestern Black Hills.

Note the abundance of

graminoids covering the forest

floor.
10 USDA Forest Service General Technical Report RMRS-GTR-97. 2002

Figure 6: Ponderosa pine/common juniper (Pinus ponderosa/

Juniperus communis) habitat

type.

Figure 5: Ponderosa pine/Rocky

Mountain juniper (Pinus ponderosa/Juniperus scopulorum)

habitat type in the southern

Black Hills.

(Hoffman and Alexander 1987). Soil texture has been

characterized as sandy loam to clay loam with pH ranging from 5.1 to 6.5 and organic matter ranging from

4.6 to 9.7 percent (Hoffman and Alexander 1987).

Vegetation in this habitat type is diverse and even includes an occasional paper birch (Betula papyrifera)

or white spruce in the overstory. Vegetation in the

understory includes various shrubs and herbaceous

species. The shrub layer is the most important undergrowth lifeform in this habitat type (Hoffman and

Alexander 1987), with common juniper (Juniperus

communis) as the most prevalent shrub reaching heights

up to 3 feet (0.9 m) (Thilenius 1972). Other shrubs in

the understory include bearberry, Oregon grape (Berberis repens), prickly rose, wild spirea, and white coralberry. Herbaceous species include smooth brome

(Bromus inermis), yarrow, wild strawberry, and silvery

lupine (Lupinus argenteus) (Hoffman and Alexander

1987). This habitat type has an understory similar to

ponderosa pine/bearberry but is distinguished by the

presence of common juniper, Oregon grape, and silvery lupine and the absence of cream peavine and

rough-leaved ricegrass.

The most common ponderosa pine dominated habitat type in the Black Hills is ponderosa pine/white coralberry (Pinus ponderosa/Symphoricarpos albus)
USDA Forest Service General Technical Report RMRS-GTR-97. 2002 11

(fig. 7) (Hoffman and Alexander 1987; Johnston 1987;

Thilenius 1972). This habitat type is typically found

on moderately steep slopes on southern aspects in the

northern Black Hills, on northern aspects in the southern Black Hills, and along stream bottoms throughout

the area (USDA Forest Service and others 1982). Elevations range from approximately 3,700 to 6,100 feet

(1,127 to 1,860 m) on sandy loam to silty loam soils.

Soil pH ranges from 5.1 to 7.0 with organic matter

content 3.5 to 16.6 percent (Hoffman and Alexander

1987). Aspen (Populus tremuloides), paper birch, and

bur oak are occasional components of the overstory

(Thilenius 1972). The understory is dominated by the

open growing low shrub, white coralberry, but other

important shrubs include western serviceberry

(Amelanchier alnifolia), Woods rose, common juniper,

and russet buffaloberry (Shepherdia canadensis)

(Hoffman and Alexander 1987; Thilenius 1972). The

herbaceous layer is highly diverse with ricegrass

(Oryzopsis spp.), yarrow, pasqueflower, pussytoes

(Antennaria spp.), arrowleaf balsamroot (Balsamorhiza

sagittata), bluebell, timber oatgrass (Danthonia

intermedia), low northern sedge (Carex concinna), and

bearberry. This habitat type is quite easily identified

where past management activities have left a variety

of size classes and gaps in the overstory, which favors

understory development of these species. The habitat

type ponderosa pine/white coralberry has two recognized

phases in the Black Hills. The arrowleaf balsamroot phase

is restricted to the western edge of the Black Hills and

is separated based on its codominance with white coralberry in the understory (Hoffman and Alexander

1987). The rough-leaved ricegrass phase is usually

found in the Central Core region on more acidic, sandy

loam soils (Hoffman and Alexander 1987; Johnston

1987). Rough-leaved ricegrass is prominent along with

white coralberry and bearberry.

The habitat type ponderosa pine/ninebark (Pinus

ponderosa/Physocarpus monogynus) (fig. 8) is found

scattered throughout the central and southern Black

Hills on north to northwest facing slopes at elevations

ranging from 5,140 to 5,700 feet (1,567 to 1,737 m)

(Hoffman and Alexander 1987; Marriott and others

1999). Soil texture is typically loamy with pH ranging

from 6.5 to 7.1 and organic matter content 4.5 to 11.3

percent (Hoffman and Alexander 1987). Vegetation in

the understory consists of several species including

ninebark (Physocarpus monogynus), chokecherry

(Prunus virginiana), prickly rose, white coralberry,

slender wheatgrass (Agropyron caninum), pasqueflower (Anemone patens), northern bedstraw (Galium

boreale), and mosses and lichens. Some stands are

ecotonal between ponderosa pine dominated forests and

true mountain mahogany (Cercocarpus montanus)

dominated shrub-steppe. If a fire occurs in these stands,

a stage of true mountain mahogany will occur and will

Figure 7: Ponderosa pine/white

coralberry (Pinus ponderosa/

Symphoricarpos albus) habitat

type. This habitat type is the

most common ponderosa pine

dominated habitat in the Black

Hills.
12 USDA Forest Service General Technical Report RMRS-GTR-97. 2002

be eventually shaded out by ponderosa pine (Hoffman

and Alexander 1987).

Although only discussed briefly by Hoffman and

Alexander (1987), the ponderosa pine/chokecherry

(Pinus ponderosa/Prunus virginiana) habitat type

has been described by Johnston (1987), Marriott and

others (1999) and Thilenius (1972). This habitat type

is scattered throughout the central and southern

Black Hills, but limited to a few locations in the

northern Black Hills. Elevations range from 5,125

to 5,440 feet (1,562 to 1,658 m). The habitat type is

found on calcareous or noncalcareous gravelly silt

loam to silty soil with pH ranging from 6.0 to 9.0

(Johnston 1987). The understory vegetation includes

chokecherry and western serviceberry (Hoffman and

Alexander 1987). Other important understory plants

include Oregon grape, wild spirea, and spreading

dogbane (Apocynum androsaemifolium). This habitat type might be another phase of the ponderosa

pine/white coralberry habitat type (Hoffman and

Alexander 1987).

The ponderosa pine/bur oak (Pinus ponderosa/

Quercus macrocarpa) habitat type (fig. 9) is found

in the northern Black Hills, but is most common in

the Bear Lodge Mountain area (fig. 1) (Hoffman and

Alexander 1987). It is found at elevations ranging

from 4,120 to 5,300 feet (1,256 to 1,615 m) on calcareous soils and soils derived from igneous rocks.

Soil texture is sandy loam to clay loam with pH ranging from 5.3 to 6.9 and organic matter of 4.6 to 9.5

percent. The most important shrub in this habitat is

bur oak, but other shrubs observed include western

serviceberry, Oregon grape, chokecherry, and wild

spirea (Hoffman and Alexander 1987). Both

graminoids such as dryspike sedge (Carex foenea)

and rough-leaved ricegrass, as well as the forbs

Lindley’s aster (Aster ciliolatus), northern bedstraw,

silvery lupine, and starry false Solomon’s seal

(Smilacina stellata) are found in the understory

(Hoffman and Alexander 1987).

Aspen (Populus tremuloides) series

Severson and Thilenius (1976) analyzed aspen in

the Black Hills using a synecological classification

approach, which produced nine different aspen vegetation associations. Marriott and other (1999) listed

four different aspen community types. Hoffman and

Alexander (1987) characterized aspen habitats based

on quantitative data and Daubenmire methodology, and

classified only one aspen habitat type, with two phases.

Hoffman and Alexander’s associations are included

here for consistency with the ponderosa pine habitat

types already reported.

The aspen/beaked hazelnut (Populus tremuloides/

Corylus cornuta) habitat type (fig. 10) is typically found

at higher elevations in the Bear Lodge Mountains and

in the northern limestone plateau of the Black Hills

(fig. 1) (Hoffman and Alexander 1987). This habitat

type occurs at elevations from 4,000 to 6,240 feet

(1,219 to 1902 m) (Hoffman and Alexander 1987). Soil

textures range from sandy loam to silty loam with soil

pH ranging from 5.5 to 6.2. Organic matter ranges

from 2.2 to 8.7 percent. Both beaked hazelnut and

paper birch are tree species found in the understory as

undergrowth. Stands in the central Black Hills will

frequently have bur oak in the understory as well. This

Figure 8: Ponderosa pine/

ninebark (Pinus ponderosa/

Physocarpus monogynus)

habitat type in the southern

and southwestern Black Hills.
USDA Forest Service General Technical Report RMRS-GTR-97. 2002 13

species rich habitat type has several shrubs and herbaceous species. Frequent shrubs found in the understory include: western serviceberry, Oregon grape, wild

honeysuckle (Lonicera dioica), chokecherry, pink shinleaf (Pyrola asarifolia), prickly rose, red raspberry

(Rubus idaeus), wild spirea, and white coralberry. Frequent herbaceous species found in the understory include: baneberry (Actaea rubra), wild sarsaparilla

(Aralia nudicaulis), Lindley’s aster, wild strawberry,

sweet-scented bedstraw (Galium triflorum), cream

peavine, wild lily-of-the-valley (Maianthemum canadense), sweetroot (Osmorhiza spp.), bracken fern

(Pteridium aquilinum), Maryland sanicle (Sanicula

marilandica), starry false Solomon’s seal, purple

meadowrue (Thalictrum dasycarpum), Canada violet

(Viola canadensis), and rough-leaved ricegrass. The

Figure 9: Ponderosa pine/bur oak

(Pinus ponderosa/Quercus

macrocarpa) habitat type found

in the northern Black Hills and

the Bear Lodge Mountains.

Figure 10: Aspen/beaked hazelnut (Populus tremuloides/

Corylus cornuta) habitat type.
14 USDA Forest Service General Technical Report RMRS-GTR-97. 2002

habitat type aspen/beaked hazelnut has two recognized phases in the Black Hills: bracken fern and

wild sarsaparilla.

The bracken fern phase (fig. 11) is distinguished by

several features. First, the abundance of bracken fern

under the beaked hazelnut is at least 23 to 33 percent coverage and the frequency is greater than 50 percent. Second, some stands of aspen/bracken fern are over 100 years

old, with the bracken fern still growing vigorously and

remaining dominant. Third, the soils in this phase are

distinct from those of the parent habitat type as well as

the wild sarsaparilla phase; more exchangeable Ca and

Mg are found in the upper 4 inches (10 cm) of the soil,

indicating a higher cation-exchange capacity and more

organic matter (Hoffman and Alexander 1987).

The wild sarsaparilla phase is distinguished by the

dominance of wild sarsaparilla in the understory. Other

prominent understory species include: Lindley’s aster,

spurred gentian (Halenia deflexa), Maryland sanicle, and

poison ivy (Toxicodendron rydbergii). Grasses, such as

Kentucky bluegrass and timothy (Phleum pratense), are

also abundant in the understory, and tend to increase with

grazing pressure (Hoffman and Alexander 1987).

Bur oak (Quercus macrocarpa) series

Bur oak communites occupy the upland areas of the

Black Hills. Marriott and others (1999) recognized

three bur oak community types, while Hoffman and

Alexander (1987) reported only two. Hoffman and

Alexander’s associations are included here for consistency

with the ponderosa pine habitat types already reported.

The bur oak/ironwood (Quercus macrocarpa/

Ostrya virginiana) habitat type is typically found in

the drier and lower elevations of the northern Black

Hills (Hoffman and Alexander 1987). Stands can be

found around elevations ranging from 3,500 to 4,200

feet (1067 to 1280 m). Soil textures range from sandy

loam to clay loam with soil pH ranging from 5.6 to

7.4. Organic matter ranges from 3.6 to 8.5 percent. Vegetation in this habitat type is distinguished with abundant ironwood (Ostrya virginiana) in the shrub layer.

Other tree species such as green ash (Fraxinus

pennsylvanica), American elm (Ulmus americana),

paper birch, and ponderosa pine occur in the understory; however, only ponderosa pine persists beyond

the seedling stage. Other understory species include:

Oregon grape, chokecherry, currant (Ribes spp.), western snowberry (Symphoricarpos occidentalis), dryspike

sedge, fairybells (Disporum trachycarpum), starry false

Solomon’s seal, and mountain cliff fern (Woodsia

scopulina).

The bur oak/western snowberry (Quercus

macrocarpa/Symphoricarpos occidentalis) habitat type

(fig. 12) occurs along the northern periphery of the

Figure 11: Aspen/beaked hazelnut (Populus tremuloides/

Corylus cornuta) habitat type

bracken fern (Pteridium

aquilinum) phase found in the

Bear Lodge Mountains.

Bracken ferns are abundant in

the understory.
USDA Forest Service General Technical Report RMRS-GTR-97. 2002 15

Black Hills with the best-developed stands occurring

in the foothills between Sundance, WY, and Whitewood, SD (fig. 1) (Hoffman and Alexander 1987). This

habitat type is typically drier than the bur oak/ironwood habitat type. Most of these stands are heavily

grazed, but Hoffman and Alexander (1987) did report

on one intact stand located around 4,200 feet (1,280

m) in elevation. Soil texture was loamy and pH was

6.0 with 7.2 percent organic matter. Vegetation in this

habitat type is distinguished with abundant western

snowberry in the understory. Other shrubs found in

this habitat type include: western snowberry, Oregon

grape, chokecherry, red raspberry, and poison ivy. Important herbaceous species include dryspike sedge,

Kentucky bluegrass, and bedstraw (Gallium spp.).

White spruce (Picea glauca) series

The Black Hills is home to the furthest western white

spruce (Picea glauca) population in the United States.

White spruce forests constitute the high-elevation coniferous forests of the Black Hills (fig.13) where temperatures are cooler and precipitation is greatest (fig. 2).

These forests grow on soils derived from both igneous

and limestone parent material. The common seral species in these forests include: ponderosa pine, aspen,

and paper birch (Hoffman and Alexander 1987).

Marriott and others (1999) recognized three white

spruce community types, while Hoffman and Alexander

(1987) reported only two. Hoffman and Alexander’s

associations are included here for consistency with the

ponderosa pine habitat types already reported.

Figure 12: Bur oak/western snowberry (Quercus macrocarpa/

Symphoricarpos occidentalis)

habitat type with chokecherry

(Prunus virginiana) in understory.

Figure 13: White spruce (Picea

glauca) forest in the northern

Black Hills.
16 USDA Forest Service General Technical Report RMRS-GTR-97. 2002

The white spruce forests in the Black Hills are important habitats for wildlife. Big game species, such

as deer and elk, utilize the white spruce forest for summer-fall range and thermal and hiding cover. Nongame

animals also use these forests for habitat. Since these

forests have limited distribution in the Black Hills, their

contribution to the ecosystem is very important

(Hoffman and Alexander 1987).

The white spruce/twinflower (Picea glauca/Linnaea

borealis) habitat type (fig. 14) is found in the higher

elevations and wetter areas of the Black Hills. This

habitat is usually found on northwest to northeast aspects and is distinguished from other types by the abundance of twinflower (Linnaea borealis) and the absence

of grouseberry (Vaccinium scoparium) in the understory. Stands are typically found at elevations ranging

from 5,800 to 6,423 feet (1,768 to 1,958 m). Soil

texture is loamy with pH ranging from 5.4 to 7.3 and

organic matter ranging from 2.7 to 10.5 percent. Other

important shrubs in the understory include: bearberry,

common juniper, prickly rose, russet buffaloberry, and

white coralberry. Major grasses include Kentucky bluegrass and rough-leaved ricegrass. Forbs, such as wild

strawberry, sweet-scented bedstraw, American sweetvetch

(Hedysarum alpinum), and longspur violet (Viola adunca),

are also in abundance. Mosses and lichens are also prevalent (Hoffman and Alexander 1987).

The white spruce/grouseberry (Picea glauca/

Vaccinium scoparium) habitat type (fig. 15) is found

in the cooler, moist, high elevations of the Black Hills.

This habitat is distinguished from other types by the

presence of grouseberry in the understory, although its

coverage can be variable. Stands are typically found

at elevations ranging from 5,697 to 6,693 feet (1,737

Figure 14: White spruce/twinflower (Picea glauca/Linnaea

borealis) habitat type.

Figure 15: White spruce/

grouseberry (Picea glauca/

Vaccinium scoparium) habitat

type.
USDA Forest Service General Technical Report RMRS-GTR-97. 2002 17

to 2,040 m). Soil texture is loam to silty clay loam with

pH ranging from 4.9 to 6.9 and organic matter ranging

from 2.3 to 7.7 percent. Other important shrubs in the

understory include: bearberry, Oregon grape, common

juniper, prickly rose, wild spirea, and white coralberry.

Herbaceous species found in the understory include:

yarrow, pussytoes, rough-leaved ricegrass, and Kentucky bluegrass (Hoffman and Alexander 1987).

Natural Disturbances

The ponderosa pine ecosystem of the Black Hills

has been subjected to several natural disturbances

throughout its history, and these disturbances are an

integral part of the ecological processes of the system.

Disturbances produce heterogeneity in forest structure

that affects timber volume, wildlife habitat, biodiversity, nutrient cycling, and other ecological processes. Disturbances identified include wind, hail,

lightning, fire, bark beetles, root rot, neighboring tree

fall, weak parasites and pathogens, and ice and snow

buildup (Lundquist 1995a, b). Two or more disturbance agents will often interact to kill trees (Lundquist

1995a). Understanding these disturbances and how

they shape forest structure and influence ecological

processes could allow foresters to better manage their

forests by integrating disturbance history into informed

management decisions.

Insects

Mountain pine beetle

(Dendroctonus ponderosae)

The mountain pine beetle is a native insect that plays

an important role in the natural disturbance regime in

the Black Hills (Lessard 1984; Schmid and others

1994). Each year, various stress factors weaken a few

trees in a stand and lower their defenses to mountain

pine beetle infestation. Mountain pine beetles carry

spores of blue-staining fungus (Ceratocystis montia)

into the sapwood of the tree (Amman and others 1989a).

The fungus develops and spreads throughout the sapwood and interrupts the flow of water to the crown

and reduces the tree’s sap flow. Endemic population

levels of mountain pine beetles, defined as tree mortality of less than 1 tree per acre per year, reproduce in

these stressed trees (McMillin and Allen 1999). The

combination of the fungus and the beetles cause tree

death (Amman and others 1989a).

Periodic mountain pine beetle outbreaks influence

both forest structure and growth (Berryman 1986). The

mountain pine beetle improves growth rates of trees

adjacent to beetle-killed trees by thinning the stand,

thereby reducing competition for light, water, and nutrients. In addition, canopy gaps created by mountain

pine beetle epicenters allow regeneration to occur.

Even-aged stands tend to convert to irregular unevenaged stands due to mortality of mid-range diameters

(Lessard 1982). Furthermore, mountain pine beetles

create snag trees and downed logs for wildlife habitat,

but contribute to the fuel load for fires. Coarse woody

debris not consumed by fire contributes to microfauna

diversity and favors nitrogen-fixing mycorrhizal fungi

(Graham and others 1994).

Stress agents such as drought can lower the resistance of a stand and increase mountain pine beetle

populations to highly destructive epidemic levels

(Schmid and others 1991). Epidemics typically have

an 11- to 20-year cycle (Lessard 1984; Pasek and

Schaupp 1992) with an outbreak lasting from 2 to 14

years (McMillin and Allen 1999; Schmid and Mata

1992a). From 1895 to 1910, the mountain pine beetle

was estimated to have killed trees containing up to 2

billion board feet of lumber in the Black Hills (Boldt

and Van Deusen 1974). Outbreaks continued to plague

the Black Hills throughout the 1930s, 1940s, 1960s,

and 1970s (McMillin and Allen 1999). Tree mortality

exceeded 250,000 trees per year for several years during the 1960s and 1970s (Thompson 1975). From 1988

to 1990, 50,000 trees on less than 11,000 acres

(4,451 ha) were killed by mountain pine beetle (Pasek

and Schaupp 1992). By the mid-1990s, tree mortality

by mountain pine beetle was light and scattered

throughout the Hills (McMillin and Allen 1999), but

aerial surveys in the late 1990s indicated a sharp increase in mountain pine beetle populations with over

25,000 trees killed in 1999 (McMillin and Allen 1999).

In an epidemic, both stressed and healthy ponderosa pine trees are attacked and killed (Lessard 1982).

Even-aged densely stocked forests are more conducive

to widespread outbreaks than the irregularly spaced

uneven-aged forests. Typically trees more than 8 inches

(>20 cm) d.b.h. are attacked, but in an epidemic, mountain pine beetles may attack saplings less than 8 inches

(<20 cm) d.b.h. if they are intermixed with larger trees

(Sartwell and Stevens 1975; Schmid and Mata 1992a).

This widespread mortality alters the forest ecosystem

in several ways. Forested areas can be converted to

grasslands and shrub systems, thus changing the distribution of hiding and thermal cover for wildlife

(Amman and others 1989a). The increase in tree mortality will increase water yields in streams for several

years following an infestation (Amman and others

1989a; Shepperd and others 1992). Timber stocking

levels are decreased, and the dead trees become fuel
18 USDA Forest Service General Technical Report RMRS-GTR-97. 2002

for high-intensity fires (Amman and others 1989a;

Schmid and others 1985). Understory diversity and

biomass also increase following a mountain pine beetle

epidemic (Kovacic and others 1985; McCambridge and

others 1982).

Life cycle—The majority of the 1-year life cycle of

the mountain pine beetle occurs under the bark of the

ponderosa pine tree (fig. 16) (Amman and others

1989a). Female mountain pine beetles lay eggs in long,

straight, vertical egg galleries in the phloem adjoining

the cambial interface. These galleries range from 4 to

48 inches (10 to 122 cm) long, but typically average

around 10 inches (25 cm). The small, white eggs are

located along the sides of the galleries. The eggs are

laid in summer and early fall and hatch within 10 to 14

days.

In August, the eggs hatch and the larvae, white with

brown heads, feed on phloem. The larval stage may

last until the following June. Short-term temperatures

of 0  ̊F (–18  ̊C) and below in October or April decrease brood survival more than if they were to occur

in December (Schmid and others 1993). In fact, air temperatures less than –20 ̊F (–29  ̊C) must occur continuously for at least 7 days in December to decrease the

larval population (Schmid and others 1993).

Once the larvae mature, they excavate oval cells and

develop into pupae (fig. 16). Formation of pupae is a

function of time and temperature (Schmid and others

1993). By July, the pupae change into adults (fig. 16),

which feed within the phloem before they emerge to

attack nearby trees (Amman and others 1989a). The

emergence of the adult mountain pine beetles is also a

function of time and temperature (Schmid and others

1993).

Mountain pine beetle emergence in the Black Hills

usually occurs in the last days of July, with peak emergence around August 15 (Schmid 1972). The female

mountain pine beetle is the first to emerge, from an

exit hole about 0.09 inch (2.4 mm) in diameter (Amman

and others 1989a). Daily emergence is affected by air

temperature. When maximum temperatures are below

55  ̊F (12.7  ̊C) beetles will not emerge (Schmid 1972).

Optimal temperature range for emergence is between

60  ̊F (15.5  ̊C) and 80  ̊F (26.7  ̊C) and appears to be

influenced by factors such as humidity, cloud cover,

and bark temperature (Schmid 1972; Schmid and others 1991).

Mountain pine beetle attacks show a pattern of reduced frequency during midday and increased frequency around 6:00 p.m. (McCambridge 1967). The

decrease in attacks at midday corresponds with the

period of highest temperatures in the forest understory

where bark temperatures can exceed 90  ̊ F (32  ̊C)

(Schmid and others 1991). The increased frequency

of attack around 6:00 p.m. coincides with a period when

bark temperatures are decreasing but the air temperature is still above the emergence temperature threshold (Schmid and others 1991).

The process of a mass attack of a susceptible tree is

a complex sequence of chemical interactions. The

study of pheromone chemistry in ponderosa pine ecosystems is limited; therefore, the following discussion

on the sequence of chemical interactions was obtained

from research performed in lodgepole pine (Pinus

contorta) ecosystems. Although ponderosa pine and

lodgepole pine are different tree species, the same species of mountain pine beetle attacks both types of trees

with similar patterns. The pioneer female is attracted

to a susceptible tree emitting monoterpenes such as

alpha-pinene (Lindgren and Borden 1989), myrcene

(Billings and others 1976; Borden and others 1983),

and delta-3-Carene (Miller and Borden 2000). Once a

Figure 16: Mountain pine beetle brood at various stages of

development in an infested ponderosa pine tree (photo

courtesy of Stephen Mata, Rocky Mountain Research

Station).
USDA Forest Service General Technical Report RMRS-GTR-97. 2002 19

pioneer beetle attacks, this tree becomes a focal point

for subsequent attacks from other mountain pine beetles

(Eckberg and others 1994) because the unmated female pioneer mountain pine beetle releases an aggregating pheromone, trans-verbenol, which mixes with

the tree’s monoterpenes to initiate a mass attack by male

and female mountain pine beetles (Lindgren and

Borden 1989). Males joining the attacking females

release low levels of exo-brevicomin (Lindgren and

Borden 1989), which attracts mainly females. As the

tree becomes occupied by beetles establishing brood

galleries, increasing concentrations of exo-brevicomin

and frontalin from males and decreasing concentrations

of trans-verbenol from females reduce the attractiveness of the tree and act as anti-aggregation pheromones

(Lindgren and Borden 1989). Furthermore, autoxidation of cis- and trans- verbenol to verbenone produce a

strong anti-aggregation message to prevent overcrowding (Lindgren and Borden 1989). As the focus tree,

which is usually a tree under stress, reaches the carrying capacity, subsequent arriving mountain pine beetles

attack adjacent healthy trees, which then become focus trees (McCambridge 1967).

Detection—Mountain pine beetle attacks are usually evident on the lower 15 feet (4.4 m) of the tree

bole (Amman and others 1989a). In response to an

attack by mountain pine beetles, a tree will attempt to

produce enough resin to “pitch out” the beetles as they

bore into the bole (fig. 17). Unsuccessful attacks will

have large pitch tubes (0.75 to 1 inch [19 to 25 mm] in

diameter) widely scattered on the trunk. The pitch tubes

are often white in color and may have an embedded

adult beetle. Successful beetle attacks produce pitch

tubes about 1/4 to 1/2 inch (0.64 to 1.27 cm) in diameter with cream to dark-red masses of resin mixed with

boring dust. Reddish boring dust at the base and in the

bark crevices of the tree is also good indicator of a

successful beetle attack. In years of severe drought,

pitch tubes may not be evident because trees produce

little pitch. A later indication of infestation is the blue

staining of the sapwood caused by the fungus carried

by the beetle (Boldt and Van Deusen 1974). Several

months after the infestation, usually late spring, the

tree needles will start to fade from green to yellowish

green to sorrel to red and then finally rusty brown. The

fading begins in the lower crown and progresses upward (Amman and others 1989a).

Stand susceptibility—Because of the devastating

economic impacts that mountain pine beetles can generate, a variety of research studies have been carried

out to determine how best to avoid outbreaks and control infestations (Lessard and others 1986). One of the

best methods of prevention is to maintain unsusceptible

stands. Mountain pine beetles generally infest ponderosa pine trees that are between 8 and 12 inches (20 to

30.5 cm) in diameter (Sartwell and Stevens 1975), although trees larger than 20 inches (51 cm) have been

attacked (Obedzinski and others 1999; Olsen and others 1996). Typically, stands with average stem diameters less than 6 inches (15 cm) do not sustain outbreaks because the phloem thickness is inadequate to

sustain a large mountain pine beetle population

(Sartwell and Stevens 1975).

Stand density is the driving factor of a potential

outbreak of mountain pine beetle. Stands with basal

areas between 140 and 260 ft2 per acre (32 to 60 m2 per

hectare) are highly susceptible to beetle attack (Olsen

and others 1996; Sartwell and Stevens 1975). Schmid

and Mata (1992b) suggested stands over 120 ft2 per

acre (27 m2 per hectare) were highly susceptible. In

their study, they noted an absence of tree mortality in

stands with Growing Stock Levels (GSL2

) of 60, 80,

and 116, even though the average diameters were in

the susceptible-size category of greater than 8 inches

(>20 cm). Several studies have attempted to explain

this trend with empirical data.

As stand density increases, the amount of competition between trees within the stand increases. This intensive competition in high-density stands lowers a

tree’s resistance to beetle attack and represents a key

feature in mountain pine beetle outbreaks (Sartwell and

Stevens 1975). For instance, Sartwell (1971) examined the radial growth of 666 beetle-killed trees and

reported that only three had grown over 1 inch in

Figure 17: Pitch tubes on a ponderosa pine tree resulting

from attack by mountain pine beetle.

2 Growing Stock Levels (GSL) are defined as the residual square

feet of basal area when average diameter is > 10 inches

(Alexander and Edminster 1981).
20 USDA Forest Service General Technical Report RMRS-GTR-97. 2002

diameter in the previous 10 years, and 435 trees had

not grown an inch in the previous 20 years. Even in

managed stands with increased spacing and decreased

competition, some individual trees will grow slowly

and will be less resistant to mountain pine beetle attack (Obedzinski and others 1999).

Larsson and others (1983) suggested that susceptibility to damage was closely related to tree vigor, which

has been demonstrated to respond to stocking levels.

In their study, the number of trees attacked per plot

decreased as average tree vigor increased. Average

tree vigor decreased with denser tree spacing and larger

leaf area index. They noted a threshold response in

which plots with vigor of less than 100 g m-2 yr-1 (based

on amount of stem wood produced per square meter of

leaf area) had significantly higher average percentage

of trees attacked.

The ability of a tree to resist a mountain pine beetle

attack has been linked to the amount of carbohydrates

that can be utilized directly for defensive wound reactions (Christiansen and others 1987). Environmental

factors that restrict the size of a canopy or its photosynthetic efficiency weaken tree resistance. Drought

can affect the carbon balance of a tree by halting photosynthesis, which depletes carbon reserves for defensive compounds and eventually reduces the size of the

canopy. Tree vigor also decreases when live crown ratio decreases to 30 percent (Smith and others 1997).

For instance, Sartwell (1971) examined nearly 4,000

beetle-killed trees and reported that 91 percent had foliage-bearing branches on less than one-third of the

stem height.

Based on several studies performed in the Black

Hills, Schmid and others (1994) developed a hazardrating guide based on mean stand diameter, stand density, and spacing for even-aged ponderosa pine stands

(fig. 18). Schmid and Mata (1992b) suggested that the

critical threshold for mountain pine beetle infestation

in Black Hills ponderosa pine stands might be in a stand

of GSL 120, instead of an earlier level of GSL 150

proposed by Sartwell and Stevens (1975). Stands with

GSLs between 80 and 120 are considered moderately

hazardous, while stands with GSLs less than 80 are

considered to be at low risk for infestation (Schmid

and others 1994). Growth potential of a partially cut

stand should be considered because a GSL 80 stand

can grow into a high-hazard stand within 10 to 20 years

depending on its growth rate (Schmid 1987). It should

be emphasized that the hazard rating was developed

for relatively homogeneous even-aged stands, and that

the method needs modification for locations where

stands are composed of low-density but uniformly

spaced even-aged trees intermixed with clumps of high

density trees or where stands are uneven aged (Schmid

and others 1994).

Semiochemical control—Semiochemicals are naturally occurring compounds that an individual of a species creates to produce a behavioral response in other

individuals of the same or different species (Lindgren

and Borden 1989). These compounds have shown

promise in managing insect populations (Schmid and

others 1989). Several methods have been tested with

mixed results, including mass trapping, tree baiting,

and repellants.

Mass trapping uses funnel traps to suppress the

mountain pine beetle population (Amman and Lindgren

1995). The funnel traps are baited with pheromones

to attract the mountain pine beetle, but beetles attracted

to the traps frequently attack nearby trees. On an operational level, mass trapping probably has little or no

potential for mountain pine beetle control (Amman and

Lindgren 1995). The technique is commonly used to

detect the presence or absence of mountain pine beetle

populations, however (Schmid and others 1989).

Tree baiting is an operational procedure adopted

by the British Columbia Ministry of Forests to manage mountain pine beetle populations in lodgepole

pine forests (Amman and Lindgren 1995). In contrast to mass trapping where the objective is to reduce populations, tree baiting manipulates the beetle

into attacking selected trees (Borden and others

1983). For instance, lodgepole pine trees baited with

myrcene, trans-verbenol, and exo-brevicomin had

higher attack densities than unbaited trees. In the

Figure 18: Hazard levels of mountain pine beetle infestation of even-aged ponderosa pine stands in the Black

Hills (graph adapted from Schmid and others 1994).
USDA Forest Service General Technical Report RMRS-GTR-97. 2002 21

study, 59.8 percent of all attacked trees and 68.1

percent of mass attacked trees (attack density of 336

per ft2

; 31.25 per m2) were either baited trees or trees

surrounding the baited trees (Borden and others

1983). In theory, by concentrating the beetle attacks

into a defined area, the newly infested trees could

easily be located and cut. Although tree baiting does

not directly control insect populations, used in conjunction with silvicultural techniques it can be very

effective (Amman and Lindgren 1995). However,

absence of harvesting or other followup control treatments can intensify the infestation problem since

both attack densities and tree mortality are increased

where baits are used (Amman and Lindgren 1995).

Tree baiting has been successfully tested in ponderosa pine forests in the Black Hills. Beetle baits of

trans-verbenol (Phero Tech) were placed on two

uninfested green trees immediately adjacent to 11 infested areas (defined as 1 to 13 infested trees) (Schmid

and others 1989). Attack densities were significantly

higher on baited trees than on unbaited trees. Furthermore, 82 percent of the newly infested trees developed

within a 55-foot (17-m) radius of the baited trees. Because tree baits have a limited range of effectiveness,

baited trees should be no more than 300 feet (91 m)

and probably only 100 to 150 feet (30 to 46 m) from

the source of mountain pine beetles. The effective distance is also influenced by wind direction (Schmid and

others 1989). To improve containment, the bait should

be placed on a tree in the densest stand adjacent to the

existing infestation. Trees should be baited before

beetle emergence, preferably in early July, with baits

placed on the north side of susceptible trees as high as

the applicator can reach (Amman and Lindgren 1995;

Schmid and others 1989). This strategy is particularly

appropriate in the beginning of an outbreak when small

group infestations are evident (Schmid and others

1989). Tree baiting might also be useful in groups of

susceptible trees scheduled for removal under group

selection management, providing the baited trees can

be removed before adults fly the next year.

The use of anti-aggregating pheromones has been

shown to reduce attack densities of mountain pine

beetles on several pine species (Amman and others

1989b; Lindgren and Borden 1989). Verbenone is produced by the autoxidation of cis- and trans-verbenol, a

pheromone produced by mountain pine beetle

(Lindgren and Borden 1989). In British Columbia, field

tests of commercially produced verbenone in the presence of mountain pine beetle bait inhibited both the

attraction of male and female mountain pine beetles to

funnel traps (Borden and others 1987). The presence

of verbenone baits reduces attacks, but does not

prevent tree mortality (Amman and others 1989b;

Lindgren and Borden 1989; Lindgren and others 1989).

In the Black Hills, two studies have investigated the

use of verbenone to decrease the number of trees attacked by mountain pine beetles (Bentz and others

1989; Lister and others 1990). Verbenone levels tested

were 0, 10, 20, 40, and 68 capsules per acre (0, 25, 49,

100, 169 capsules per hectare) at a release rate of 5 mg

per day per capsule (Bentz and others 1989; Lister and

others 1990). In both studies, there was a downward

trend in attacked trees with increased numbers of

verbenone capsules, but due to the high variation and

low number of replicates, significant treatment differences could not be detected (Bentz and others 1989;

Lister and others 1990). Current studies in the Black

Hills are investigating this further. Even though mortality is not eliminated with the use of verbenone, it

may be feasible in areas where some mortality can be

tolerated (Lindgren and Borden 1993).

The use of anti-aggregation pheromones cannot be

recommended on an operational basis due to the inconsistent results. The effect of verbenone on beetle

attacks may depend on whether the infestation is endemic or epidemic. Lindgren and Borden (1993) found

an increase in the percentage of lightly attacked trees

in verbenone treated subplots in a lodgepole pine study.

The authors suggest that the verbenone interfered with

the ability of pioneer beetles to attract large numbers

of additional beetles to initiate the mass aggregation

necessary to overcome tree defenses. They expect that

verbenone would work best at endemic levels, but at

epidemic levels, multiple pioneer beetles attacking the

same tree may release enough aggregating pheromone

to negate the effect of verbenone.

Chemical control—Insecticides offer temporary

management of mountain pine beetles by slowing infestation (Amman and others 1989a). These agents also

affect nontarget species, however, and use in forested

ecosystems is less desirable (McCambridge 1982). In

areas with high-value trees, such as campgrounds and

on private property, preventative spraying may be necessary. Spraying individual trees may provide effective protection if applied correctly, but it does not address the cause of the outbreak (McMillin and Allen

1999). Furthermore, it does not guarantee protection

and the application must be thorough. To be effective,

the insecticide must be applied directly to the boles of

individual trees with a high-pressure sprayer, prior to

beetle flight, forcing the insecticide into crevices in

the bark. The entire bole must be treated to a top diameter of 6 inches (15 cm) or less. Annual treatments

are necessary for as long as the outbreak is occurring

(McMillin and Allen 1999).
22 USDA Forest Service General Technical Report RMRS-GTR-97. 2002

If the use of insecticides is the chosen method, trees

must be treated before the beetles emerge (McMillin

and Allen 1999). Carbaryl (tradename Sevin) has been

shown to be effective in protecting test trees from mass

attack (Shea 1989). It is most effective in concentrations ranging from 0.5 to 2.0 percent and with water

used for dilution having a pH of 6 (Leatherman 2001a).

Carbaryl at concentrations greater than 2 percent did

not increase protection success (McCambridge 1982).

Carbaryl may be effective for up to 2 years. Permethrin

(trade names: Astro or Dragnet), a synthetic form of

pyrethrin, was shown to prevent beetle attacks in California, Montana, and the South (Leatherman 2001a),

and preliminary results indicate that it provides one

year of protection in the Black Hills.

Silvicultural control—Several silvicultural activities can be used to minimize the chance that endemic

mountain pine beetle populations may become epidemic. Options include thinning, salvage/sanitiation

harvesting, and treating infested logs. If the manager

takes the stance that beetle-caused mortality and the

impacts associated with this mortality are part of the

natural process, then the best option would be to do

nothing (McMillin and Allen 1999). Some advantages

of doing nothing are no mechanical site disturbance,

increase in light and enhancement of understory species and regeneration, and enhancement of habitat for

some wildlife from the formation of snags and decreased crown closure. A risk of this decision is that

beetle populations may spread to adjacent land. If timber productivity is a primary objective, there will be a

loss of timber revenues as well as an increase in fire

hazard (McMillin and Allen 1999).

Some management practices can help impede mountain pine beetle population explosions. One key to inhibiting epidemic mountain pine beetle populations is

to maintain a healthy population of trees that can resist

mountain pine beetle attack. Active forest management with traditional thinnings is crucial for reducing

competition, sustaining healthy trees with good growth

rates, and minimizing mountain pine beetle-caused tree

mortality (Olsen and others 1996). Without a thinning

program, stands will eventually grow into dense, unhealthy conditions and again be susceptible to mountain pine beetle attack.

For instance, basal area growth rates of 1.3 ft2 per

acre (0.298 m2 per hectare) or more are possible in

partially cut stands (Obedzinski and others 1999). If

150 ft2 per acre (34.43 m2 per hectare) is considered

the threshold level for epidemic mountain pine beetle

populations (Sartwell and Stevens 1975), stands that

increase 1.5 ft2 per year (0.14 m2 per year) need to be

thinned about every 20 years (Obedzinski and others

1999). For GSL greater than 120 growing at 1.5 ft2 per

year (0.14 m2 per year), the threshold would be reached

before the 20 years and would need to be thinned earlier. For stands of GSL less than 120 and greater than

80, the threshold may be exceeded between the first

and second entry and should be cut (Obedzniski and

others 1999). If 120 ft2 per acre (27.55 m2 per hectare)

is considered the threshold level (Schmid and Mata

1992b), then GSLs greater than 100 would reach the

susceptible level before 20 years, while reentry in a

GSL 80 might be necessary halfway between the first

and second reentry (Obedzinski and others 1999).

A problem arises when trying to apply even-aged

principles and susceptibility thresholds to uneven-aged

forest structures. The susceptibility thresholds in terms

of average d.b.h. and basal area are probably different

for even-aged and uneven-aged forests (Olsen and others 1996). Mean stand density, a common descriptor

of even-aged forest stand structure, does not provide a

useful description of tree groups within an uneven-aged

forest. In some uneven-aged stands, particularly susceptible groups of trees may exist unintentionally due

to management practices (Olsen and others 1996).

Furthermore, delaying scheduled thinnings in unevenaged stands might increase the chance of increased

group densities and lack of detection in average stand

density estimates. Large groups containing densely

spaced trees in susceptible diameter classes are certainly more at risk of attack. Smaller clumps might be

less so, due to increased vigor from edge effect, but no

empirical data are available. Conversely, managed uneven-aged stands might be at somewhat less risk to

mountain pine beetle outbreaks because the portion of

total basal area in susceptible d.b.h. classes would be

below threshold limits. If uneven-aged stands were

managed with clumped or grouped spacings as called

for under current Northern Goshawk (Accipiter gentiles atricapillus) habitat guidelines (Reynolds and others 1992), individual clumps of trees might be susceptible to mountain pine beetle, but the discontinuity of

suitable host trees might slow or prevent large-scale

mountain pine beetle outbreaks. Further research is

needed to assess this situation and for guidance in defining threshold limits for uneven-aged forest stands.

Managers should monitor mountain pine beetle activity in stands managed under irregularly spaced unevenaged prescriptions to test these hypotheses.

Salvage and sanitation harvesting may be appropriate when it is desirable to reduce mountain pine beetle

populations and recover timber resource value. Salvage harvest removes the dead trees, while a sanitation harvest removes infested pines before the beetles

mature and leave to infest new trees (McMillin and
USDA Forest Service General Technical Report RMRS-GTR-97. 2002 23

Allen 1999). Sanitation harvest can also remove trees

that are susceptible to infestation. Sanitation harvesting can be used in conjunction with semiochemical tree

baiting. An advantage of salvage and sanitation harvesting is that beetle populations can be reduced in a

localized area, especially when tree baits are used to

concentrate the population (McMillin and Allen 1999).

More advantages include recovered timber value, fuel

hazard reduction, and regeneration enhancement by

overstory removal and site disturbance. A major disadvantage is the short execution time and the possibility of spreading the infestation to other areas during

transportation of the cut wood. The infested areas must

be marked, cut, and processed before the beetles

emerge. In addition, success on a landscape level will

need to incorporate the sanitation of infested stands as

well as thinning of susceptible stands to decrease the

chance of infestation, since sanitation cuts are only

effective on a stand level (McMillin and Allen 1999).

A spinoff of the salvage/sanitation harvesting

method is the fell and treat method. Beetle populations are reduced or eliminated from the treated area

and site disturbance is typically less than in conventional harvest. As with any overstory removal process, regeneration is enhanced and crown fire hazard

is reduced (McMillin and Allen 1999). However, execution time is short and the treatment must be applied

after newly infested trees are located and before beetle

emergence. Furthermore, treatment only reduces the

beetle pressure on a stand level and does not address

the stand conditions that lead to the infestation

(McMillin and Allen 1999).

Infested trees can be felled and exposed to solar radiation to kill mountain pine beetles. The premise of

this technique is that increased bark temperature creates lethal temperatures within the phloem that kill the

mountain pine beetle larvae (Negron and others 2001).

Furthermore, increased humidity levels encourage

mold growth beneath the bark, which minimize normal beetle development (Leatherman 2001b). Beetle

mortality of 80 to 90 percent is realistic when maximum bark temperatures exceed 104 oF (40 oC). Treatments should be initiated in late May/early June with a

duration of at least 6 weeks. There are two different

approaches for this technique: with clear plastic or

without plastic (Negron and others 2001).

When using the solar radiation technique with plastic, the main objective is to increase the temperature

and humidity of the felled logs to inhibit the development of the mountain pine beetle. Logs should be cut

into 4-foot (1.2-m) sections, moistened with water, and

covered with clear plastic. When using plastic, logs

can be oriented in one or two layers, but stacks more

than two layers high may not increase temperatures

enough to reduce mountain pine beetle populations

(Negron and others 2001). Logs should be placed in

an area that receives direct solar radiation. After the

logs are covered with plastic, the edges of the plastic

should be covered with surrounding soil. Treat the logs

for at least 2 months to kill mountain pine beetles. After

the treatment is complete, remove and dispose of the

plastic sheeting. The wood can then be safely stored

or used without infecting live trees (Leatherman

2001b).

The solar radiation technique without plastic involves using sunlight to heat the felled trees to lethal

temperatures. Infested trees should be cut into 4-foot

(1.2-m) long logs and delimbed. Logs need to be placed

in a sunny location, preferably on southern slopes.

Arrange the logs side by side and do not stack them

because the bark surfaces need direct sunlight to reach

lethal temperatures. Logs need to be rolled at least

three times during the treatment period to ensure all

sides have been exposed to direct sunlight. If logs are

not rotated, then the north aspect of the log should face

the sun to ensure a decrease in brood populations

(Negron and others 2001). The survival status of the

beetles should be checked by the end of June

(Leatherman 2001b). If beetles are still alive, logs

should be covered with plastic, or stripped of bark to

prevent beetle escape.

Pine engraver (Ips pini)

The pine engraver is a native beetle in the Black

Hills. In general, pine engraver beetles are

nonaggressive and breed in windthrown ponderosa pine

trees, trees damaged by wind and snow, and logging

slash greater than 2 inches (5 cm) in diameter (Boldt

and Van Deusen 1974; Kegley and others 1997). However, if populations become larger than the surrounding slash can absorb, the beetle may attack nearby live

trees. Pine engravers have the potential to cause damage to surviving trees after a wildfire (Kegley and others

1997). Fire scorched trees that still have suitable phloem

are frequently attacked, and there is a chance for green

stands surrounding a burned area to be attacked if the pine

engraver population reaches high levels.

In the event that pine engravers do attack live trees,

risk is highest for trees 2 to 8 inches (5 cm to 20 cm) in

diameter (Boldt and Van Deusen 1974). Although not

as aggressive as the mountain pine beetle, pine engravers have been reported to kill up to 500 trees in an

unthinned young stand (Kegley and others 1997).

Large trees that are attacked are often top killed by the

pine engravers, while the lower bole is infested by other

insects (Kegley and others 1997).
24 USDA Forest Service General Technical Report RMRS-GTR-97. 2002

Outbreaks of pine engravers are linked to the amount

of precipitation from April through July (Kegley and

others 1997). If precipitation is 75 percent of normal

or less, moderate to heavy tree mortality can be expected in overstocked, second-growth ponderosa pine

stands. Typically, these outbreaks only last one season, but in cases of extreme drought, damage can continue for 2 or 3 years.

Life cycle—The pine engraver life cycle from egg

to adult is approximately 40 to 55 days long (Kegley

and others 1997). Because of this short life cycle, pine

engravers can produce 2 to 3 generations from April

through late September (Kegley and others 1997). The

flight of the first generation occurs in April or May

when the daily maximum temperature reaches 60 to

70  ̊F (15.5 to 21  ̊C) (Kegley and others 1997). The

attack is pioneered by the male beetle, which is attracted

to a stressed tree releasing monoterpenes. The male

bores through the outer bark into the phloem and excavates a nuptial chamber. Once the chamber is ready,

he releases an aggregation pheromone, Ipsdienol, to

attract several females and males (Kegley and others

1997; Raffa and Dahlsten 1995). An attacked tree is

indicated by reddish-orange boring dust in small

mounds on the bark surface at the point of entry (Kegley

and others 1997).

One male will mate with 3 or 4 females, and once

mating has occurred, each female constructs a 4- to 7-

inch-long (10 to 18 cm) egg gallery in the phloem layer

(Kegley and others 1997). Several galleries radiate

from the nuptial chamber, often forming a Y or H pattern aligned with the grain of the wood (fig. 19). Once

the egg gallery is formed, the female lays 30 to 60 oval,

pearly white eggs along the sides. The eggs hatch into

larvae within 4 to 14 days.

The larvae are creamy-white, legless grubs with

brown heads and about 0.2 inch (0.5 cm) long (Kegley

and others 1997). The larvae mine laterally up to 1 to

2 inches (2.5 to 5 cm) from the egg gallery and feed

for 2 to 4 weeks. At the end of this time, each larva

excavates an oval chamber at the end of the tunnel to

pupate. The pupae stage typically lasts for 12 days.

The adult pine engraver beetle is cylindrical, about

0.125 to 0.2 inch (0.3 to 0.5 cm) long, and has four

small spines on each side of its lower posterior (Kegley

and others 1997). If it is still early in the year, the

adult beetle will emerge and reproduce, otherwise, it

will spend the winter in the adult stage under the bark

of an infested tree, slash, or in the duff and litter on the

forest floor.

Control—Several management practices can minimize infestation by the pine engraver beetle. The most

important practice is to maintain a vigorous growing

forest. Stands with basal areas of 80 to 100 ft2 per acre

(18.37 to 22.96 m2 per hectare) have been shown to be

less susceptible to pine engraver beetle attack (Kegley

and others 1997).

Since pine engraver breed in slash, two methods

have been proposed to control their population: (1) provide enough slash for endemic populations; or

(2) promptly dispose of slash to minimize populations.

If enough slash is provided, the pine engraver beetle

may ignore the green trees surrounding the slash piles.

This technique calls for providing a continuous supply

of fresh slash throughout the flight period of emerging

adults (Kegley and others 1997). New slash should be

produced at the pupal stage, and a large slash pile should

be created prior to the first beetle emergence in the

spring. The piles should be large enough (20 feet [6m]

wide and 10 feet [3m] deep) to keep the interior pieces

moist enough to support beetle reproduction. When

the adults emerge, they will go deeper into the pile and

stay away from the standing green trees (Kegley and

others 1997). There are some potential problems with

this method, however. First, to create sizable slash

piles, there is need for constant timber operations,

which is not always feasible. Second, this method has

the potential to increase the pine engraver population

Figure 19: Pine engraver breeding gallery in ponderosa pine (photo source: Kegley and others

1997).
USDA Forest Service General Technical Report RMRS-GTR-97. 2002 25

to an epidemic level and increase the probability of

attack on green trees.

Promptly disposing of slash is the other method to

help minimize a population explosion (Kegley and others 1997). Removal of slash is especially important

when slash is created from early winter through late

spring because it provides a large amount of breeding

material (Gara and others 1999; Kegley and others

1997). If logging does occur during this time, burning

the slash can destroy potential brood sites, but workers must be careful not to scorch the residual trees.

The optimal time to log is late summer to early winter

because this allows time for the phloem in the slash to

dry out and become unsuitable pine engraver habitat.

If the slash is covered by early snows, however, it may

maintain enough phloem moisture to attract beetles in

the spring. Therefore, scattering the slash material

around the site and exposing it to direct sunlight can

minimize possible pine engraver habitat (Kegley and

others 1997). Gara and others (1999) reported that drying host material and predation by natural enemies

helped regulate endemic pine engraver populations in

southeastern Montana.

Several insects and birds play a role in lowering pine

engraver populations, although they are not known to

prevent outbreaks (Kegley and others 1997). Wasps and

nematodes are parasitic, while woodborer larvae (family Cerambycidae) can unintentionally munch on pine

engraver broods as they feed indiscriminately through

the galleries. Predators such as woodpeckers and several beetle species can consume large numbers of pine

engravers. Because the predator beetles blackbellied

clerid (Enoclerus lecontei), redbellied clerid (Enoclerus

sphegeus), and trogositid beetle (Temnochila chlorodia)

emerge at different times from April to August, competition among them is low, and predation is constant

throughout most of the pine engraver emergence. The

predator beetles all respond to pine engraver pheromones (Gara and others 1999).

Semiochemicals—Competition among developing

pine engraver broods as well as with other bark beetles

and woodborers can reduce pine engraver populations.

Mountain pine beetles and pine engravers often coexist in the same tree but in separate areas of the bole

(Furniss and Carolin 1977). In lodgepole pine forests

in British Columbia, Rankin and Borden (1991) reported that extensive pine engraver attacks before

mountain pine beetle could establish gallery systems

exerted a major negative effect on mountain pine beetle

offspring. However, pine engraver beetles and mountain pine beetles can coexist within the same tree if

populations are low due to the mutual exclusion created by the semiochemicals produced by both beetles

(Rankin and Borden 1991). The mutual exclusion occurs because the mountain pine beetles produce

verbenone, a repellent to pine engravers (Miller 1991),

while the pine engraver produces Ipsdienol, a repellent to mountain pine beetle (Hunt and Borden 1988).

Pine engraver attraction to Ipsdienol was significantly

reduced in the presence of trans-verbenol and exobrevicomin, two pheromones produced by mountain

pine beetles (Hunt and Borden 1988).

The chemical (+)-Ipsenol has been shown to reduce

pine engraver attacks of ponderosa pine by 68 percent

at release doses of 2 mg per day (Furniss and Livingston

1979). Borden and others (1992) reported a mixture

of verbenone and ipsenol dramatically reduced pine

engraver attack density and lowered the number of

emergent brood on felled and standing lodgepole pine

in British Columbia. When ipsenol was applied alone,

however, there was not a protective effect (Birch and

Light 1977; Borden and others 1992).

Lanierone is another male-produced aggregation

pheromone for some populations of pine engravers

(Teale and others 1991). The attraction of pine engravers to ipsdienol is synergized by lanierone. However, this response has only been documented among

eastern and midwestern populations of pine engravers

(Miller and others 1997; Teale and others 1991).

Among western populations, Miller and others (1997)

showed only a weak significance in Montana and British Columbia, while populations in California showed

no response (Miller and others 1997; Seybold and others 1992). Ipsdienol enantiomers have a high degree

of geographic variation (Raffa and Dahlsten 1995),

which might be the case for lanierone (Miller and others 1997). Miller and others (1997) suggested that specific mixtures of pheromones might be specific to a

region due to other species utilizing the same pheromones. For instance, the blackbellied clerid predator

beetle can detect the lanierone pheromone. In California, however, pine engravers were found not to respond to lanierone, suggesting that pine engraver

beetles that utilized lanierone would have a greater

selection pressure toward them.

Utilizing pheromones to control pine engraver populations is still in its infancy. Furthermore, no studies

have been performed in the Black Hills to determine if

pine engravers will respond to lanierone, or which enantiomers of ipsdienol or ipsenol attract or repel the Black

Hills pine engraver population.

Red turpentine beetle (Dendroctonus valens)

The red turpentine beetle is a native bark beetle of

the Black Hills. In contrast to the mountain pine beetle,

the red turpentine beetle is not aggressive. Red turpentine
26 USDA Forest Service General Technical Report RMRS-GTR-97. 2002

beetles are not usually a primary cause of ponderosa

pine mortality in the Black Hills; instead, they are a

secondary cause of mortality. Red turpentine beetles

typically attack trees already weakened by drought, fire,

insects, lightning (Boldt and Van Deusen 1974) or logging damage (Smith 1971). Occasionally, red turpentine beetless will be the primary attacker of a tree and

cause the tree to be attacked by other insects or diseases (Boldt and Van Deusen 1974).

Trees greater than 1 inch (2.5 cm) in diameter are

subject to red turpentine beetle attack (Boldt and Van

Deusen 1974). Weakened trees are often attacked, but

trees close to freshly cut stumps or green logs are also

susceptible (Boldt and Van Deusen 1974; Smith 1971).

Schmid and Mata (1991) reported that the percentage

of red turpentine beetle-attacked trees in a Black Hills

ponderosa pine stand was greater in stands that were

located near recently logged areas. Furthermore, all

red turpentine beetle attacked trees were attacked within

the first year after logging. Although these trees were

attacked, red turpentine beetles did not appear to be a

significant mortality factor in either uncut or partially

cut stands.

Red turpentine beetles can increase tree mortality

in areas that have been disturbed by fire (Smith 1971).

Eckberg and others (1994) reported that red turpentine

beetle attacks were evident on fire-scorched trees in

the Black Hills. This raises some concerns for the firedependent ponderosa pine ecosystem of this region,

especially in the aftermath of wildfires. For example,

trees that survived but were damaged by the catastrophic Jasper Fire in the southern Black Hills in 2000

might be subjected to red turpentine beetle attack, and

the population of red turpentine beetles might build up

enough to attack nearby green trees (USDA Forest

Service 2001a). Current and future monitoring of the

Jasper Fire area will aid in determing mortality caused

by red turpentine beetles.

Life cycle—There is typically one generation of red

turpentine beetles per year (Smith 1971). Pupae and

eggs rarely overwinter (Smith 1971), but adults and

larvae do overwinter (Furniss and Carolin 1977). The

distinctive large (0.5 to 1 inch wide) longitudinal (vertical) egg galleries of red turpentine beetles differ from

other bark beetles (Boldt and Van Deusen 1974). The

eggs, which are shiny, opaque white, ovoid cylindrical, and approximately 0.04 inch (1 mm) in length, are

laid in an elongated mass along the side of the egg

gallery and can number from a few to more than 100

(Smith 1971).

The eggs hatch into larvae within 1 to 3 weeks after

being laid (Boldt and Van Deusen 1974; Smith 1971)

and look grublike, legless, and white, except for a

brown head capsule and a small brown area at the hind

end. As the larvae grow, a row of small, pale-brown

tubercles develop along each side of the body (Smith

1971). Larvae are typically 0.39 to 0.47 inch (10 to

12 mm) long when fully grown. The larvae feed on

the inner bark tissue between the outer dry bark and

the wood. As the larvae grow, they feed constantly and

form a fan-shaped cavity with an irregular margin, a

characteristic feature of red turpentine beetle infestation (Boldt and Van Deusen 1974; Smith 1971).

Once the larvae are ready to pupate, they create separate cells and transform into adults (Boldt and Van

Deusen 1974). The pupae are slightly shorter than the

larvae, but are still white (Smith 1971). Close examination of the pupae shows the wings, legs, and antennae being held against the body. An adult beetle, 0.24

to 0.39 inches (6 to 10 mm) in length and quite stout,

finally emerges from the pupal cells by boring through

the bark (Boldt and Van Deusen 1974) in the spring. A

distinguishing feature of a red turpentine beetle adult

is that they are reddish brown and large (up to 0.375

inch; 0.95 cm), while the mountain pine beetle adult is

black and smaller (0.125 to 0.33 inch; 0.3 to 0.85 cm).

A red turpentine beetle may fly up to several miles

to attack a new host (Boldt and Van Deusen 1974).

The female red turpentine beetle is the first to attack a

weakened tree, and bores into the bark to reach the

surface of the wood (Smith 1971). The male follows

shortly afterward (Boldt and Van Deusen 1974) and an

egg gallery is excavated. Typically, only one pair of

beetles is found per gallery (Smith 1971).

Generally, red turpentine beetles concentrate their

attack in the lower 6 feet (1.8 m) of the tree, but can

reach up to 12 feet (3.7 m) (Boldt and Van Deusen

1974; Smith 1971). Trees attacked by red turpentine

beetles usually show pitch tubes on the outer surface

of the bark and boring particles (reddish frass) either

in bark crevices or on the ground at the base of the tree

(fig. 20) (Boldt and Van Deusen 1974; Smith 1971).

Pitch tubes are large (up to 1.5 inches [3.8 cm] in diameter) and reddish white in color. Mountain pine

beetle pitch tubes are sometimes confused with red

turpentine beetle pitch tubes. Successful mountain pine

beetle attacks produce pitch tubes that are smaller (0.25

to 0.5 inch [0.64 to 1.27 cm] in diameter) and are cream

to dark red in color. Unsuccessful mountain pine beetle

attacks produce pitch tubes that are to 1 inch (1.9 to

2.5 cm) in diameter.

Fading needles indicate the infestation was successful and the tree is dying. The needles will fade in a

progression from yellowish green to yellow to sorrel

and finally red (Smith 1971). In addition, examination

of the phloem and sapwood around the galleries might
USDA Forest Service General Technical Report RMRS-GTR-97. 2002 27

show a blue stain because of a fungus brought in by

the beetle (Boldt and Van Deusen 1974).

Control—As with any insect or pathogen, the best

defense against attack is to keep the trees growing vigorously. Limiting root or stem injuries will aid in protecting the trees from red turpentine beetle attack (Boldt

and Van Deusen 1974). In addition, minimizing logging activities in stands adjacent to recently cut stands,

which might harbor red turpentine beetles, can limit

the number of red turpentine beetle attacks (Schmid

and Mata 1991). Finally, avoid piling green logs or

timber near live trees since this might attract red turpentine beetles and other insects to the standing trees

(Boldt and Van Deusen 1974).

The use of semiochemicals to control red turpentine beetles is in its infancy. Red turpentine beetles

are known to be attracted to three chiral monoterpenes, (S)-(-)-beta-pinene, (S)-(+)-3-carene, and (R)-(+)-

alpha-pinene, emitted by stressed ponderosa pine trees

(Hobson and others 1993). To date, no evident aggregation pheromone has been identified for red turpentine

beetles, and it has been suggested that red turpentine

beetles rely solely on the tree’s monoterpenes (Borden

1982; Hobson and others 1993).

Other modes of protection include chemical and biological agents. The chemicals 4 percent carbaryl

(Sevimol 4), and 2 percent carbaryl (Sevin XLR) were

shown to be effective in protecting trees from red turpentine beetles (Hall 1984). Chlorpyriphos and

permethrin were shown not to be effective in protecting trees from red turpentine beetles (Hall 1984). Biological control of red turpentine beetles occurs via competition with other beetles and from woodpecker predation (Smith 1971).

Pine tip moth (Rhyacionia spp.)

Two species of pine tip moth reside in the Black

Hills, the western pine tip moth (Rhyacionia bushnelli)

and the southwestern pine tip moth (Rhyacionia

neomexicana) (Furniss and Carolin 1977). Both moths

attack small trees (less than 10 feet [<3 m] tall) and are

not considered serious pests (Boldt and Van Deusen

1974). However, repeated attacks on regeneration can

seriously slow down a revegetation project.

Adult western pine tip adult moths have yellowish

gray to reddish brown wings that span 0.39 to 0.59

inch (1 to 1.5 cm) and have gray scales covering the

head, body, and appendages (Furniss and Carloin 1977).

The moths fly in late May and early June to lay eggs

on pine needles, buds, and shoots of ponderosa pine

seedlings. The larvae of the western pine tip moth,

which are yellow with black heads and about 0.35 to

0.47 inch (0.9 to 1.2 cm) long, feed on the tissues during June and July (Furniss and Carolin 1977). The

moth pupates over the winter in the litter or soil.

The southwestern pine tip moth is larger than the

western pine tip moth, with a wingspan of 0.79 to 1

inch (2.0 to 2.5 cm) (Furniss and Carolin 1977). This

moth has front wings that are dark gray with the outer

third having a reddish-orange color with two horizontal black lines. The moths fly in late May and early

June (Furniss and Carolin 1977).

Peak flight activity occurs at night when males are

attracted to females by a sex pheromone (Jennings and

Stevens 1982). The southwestern pine tip moth lays

eggs on 1-year-old needles in the upper three whorls

of the foliage. The eggs are light greenish yellow and

as they develop change to yellowish orange and then

to bright reddish orange. The larvae have five instar

stages and when fully developed are 0.47 to 0.63 inch

(1.2 to 1.6 cm) long (Jennings and Stevens 1982).

Through the instar stages, the larvae change from orange to yellowish orange to reddish orange. The pupal stage starts in July and early August, and the pupae

Figure 20: Pitch tubes on ponderosa pine resulting from

attack by red turpentine beetle.
28 USDA Forest Service General Technical Report RMRS-GTR-97. 2002

overwinter in bark crevices on the base of the tree below the litter (Furniss and Carolin 1977).

Ponderosa pine seedlings less than 6 to 8 feet (less

than 1.8 to 2.4 m) tall are most susceptible (Jennings

and Stevens 1982). In an Arizona study, ponderosa

pine trees greater than 20 years old or taller than 13 feet

(4 m) were not attacked by the moths; instead, attacks

were highest in the 5- to 7-year age class (Spiegel and

Price 1996). Both species of moths bore into new expanding shoots and feed on the tender tissues of the

needles (Dix and Jennings 1982; Jennings and Stevens

1982). An early indication of infestation is the shiny

pitch “tents” formed by the larvae in May and June

(Jennings and Stevens 1982). By midsummer, infested

shoots turn a reddish brown and become dry and brittle.

Both terminal and lateral shoots are attacked (Jennings

and Stevens 1982; Lessard and Jennings 1976), but

damage is usually greatest on the terminal bud (Dix

and Jennings 1982). New buds form below the damaged terminal bud, resulting in multiple stems,

crooks, forks, spiketops, and a bushy appearance

(Jennings and Stevens 1982; Lessard and Jennings

1976). Although trees are seldom killed by tip

moths, repeated infestations can jeopardize the survival and growth of young planted seedlings

(Jennings and Stevens 1982).

Special care should be taken when revegetating a

site after a large-scale fire. Lessard and Jennings

(1976) reported that small trees in large, open areas

seem most vulnerable to persistent infestations. For

instance, after a 1956 fire in the Apache-Sitgreaves

National Forest, several large areas were naturally

reseeded or replanted with seedlings; after 10 years,

38 percent of the seedlings were damaged by tip

moths. By 1969, 82 percent of the seedlings were

damaged.

Control—Although growth loss is not considered

serious enough to justify the cost of direct control,

several methods can be used to mitigate pine tip moth

damage. First, silvicultural treatments that promote

rapid tree growth, such as thinning overstocked

“dog-hair” stands, may help reduce pine tip moth

damage (Jennings and Stevens 1982). Although not

practical for large areas, clipping infested shoots

before the larvae leave the shoots can reduce pine

tip moth populations. Finally, relying on natural

predators such as mites, ants, spiders, lizards, birds,

mice, and parasitic wasps can help control the pine

tip moth population (Jennings and Stevens 1982).

Hand spraying of commercial insecticides labeled

for shoot moth control can be effective in landscape

plantings of ponderosa pine if applied during shoot

elongation and 2 to 3 weeks later.

Diseases

Armillaria root disease (Armillaria ostoyae)

Armillaria root disease is a native pathogen in the

Black Hills (Boldt and Van Deusen 1974; Holah 1993;

Lundquist 1991). Until the late 1970s, it was assumed

that Armillaria root disease was caused by a single

polymorphic species, Armillaria mellea (Vayl. Ex Fr.)

Kummer, but now several species are recognized within

the genus (Watling and others 1991). In the previous

edition of this publication, Boldt and Van Deusen

(1974) described the shoestring root rot, which they

identified as Armillaria mellea. It is now known that

only Armillaria ostoyae exists in the Black Hills (Kallas

1997; Wu and others 1996).

As a natural component of the forest, the fungus

causes mortality, wood decay, and growth reduction.

Armillaria root disease infects both healthy and stressed

trees, and kills the trees either directly or indirectly by

predisposing the trees to attacks by other pathogens or

insects (Williams and others 1986). This parasitic fungus attacks the roots and root crown of trees of all ages,

killing the cambium and inner bark and causing decay

of both sapwood and heartwood (Smith 1993). Direct

mortality in ponderosa pine seems to occur by the combination of destruction of living root cambial tissue by

the fungus and girdling resinous lesions produced by

the tree (Holah 1993).

Armillaria root disease has been reported as a potentially important disease of ponderosa pine in the

Black Hills since the 1930s (Boldt and Van Deusen

1974; Holah 1993; Lundquist 1991). Several studies

(Hinds and others 1984; Holah 1993; Kallas 1997;

Lessard and others 1985; Lundquist 1991) have reported a wide distribution of armillaria root disease

throughout the Black Hills. In general, the incidence

of armillaria root disease is greater in the northern Black

Hills than in the southern Black Hills (Holah 1993;

Lessard and others 1985; Lundquist 1991). Several

hypotheses have been proposed for this difference in

distribution: different soil types, higher frequency of

fire in the southern hills, differences in tree physiology, and historically sparser forests in the southern hills

prohibiting the spread of the fungus (Holah 1993).

Areas affected by armillaria root disease are characterized by patchy openings containing fallen trees,

patches of dead and dying trees that are broken at the

root collar, and trees with poor crown conditions (Holah

1993; Williams and others 1986). Armillaria root disease kills trees in a pattern of gradually expanding disease centers (Williams and others 1986). These centers can occur in managed or unmanaged areas and vary

in size from several trees up to 1,000 acres (404.7 ha).
USDA Forest Service General Technical Report RMRS-GTR-97. 2002 29

Armillaria root disease centers can be detected from

aerial photographs by searching for openings in the

forest canopy that have dead or nearly dead standing

trees on the margins, or by looking for snags and

windthrown conifers (Williams and Leaphart 1978).

These centers are sometimes large enough to appear

as circular openings surrounded by green timber (Roth

and others 1980).

The crown condition of a tree may suggest armillaria

root disease infection. Typical characteristic symptoms

include red or chlorotic needles (Lundquist 2000; Williams and others 1986), stunted internodal growth of

recent lateral and terminal shoots, reduced growth of

shoot and foliage on older trees (Williams and others

1986), distressed crop of cones (Lundquist 2000), and

branch dieback (Williams and others 1986). On large,

lightly infected or vigorous trees, crown symptoms

typically occur over a number of years (Williams and

others 1986). However, on small, extensively infected

or low-vigor trees, the crown symptoms develop rapidly and the tree often dies within a year. It should be

noted, however, that the crown symptoms reported for

armillaria root disease infection are similar to symptoms caused by drought, bark beetles, and other fungi.

For this reason, further verification will be needed to

correctly diagnosis the problem.

Examination of the lower stem can aid in the correct diagnosis of armillaria root disease. Infected areas of the lower stem are typically enlarged and secrete large amounts of resin (Lundquist 2000; Williams and others 1986). Mycelial mats and rhizomorphs

are usually present beneath the bark. Mycelial mats

are white, irregular, fanlike striations that decompose

the inner bark (fig. 21) and leave resin-impregnated

impressions (Williams and others 1986). These impressions can occur for several years after the fans disappear (Morrison and others 1991). Rhizomorphs are

flat, black to reddish brown rootlike features that are

up to 0.2 inch (0.5 cm) wide (Williams and others

1986).

Diagnosis by examining the soil is more difficult.

Rhizomorphs do occur in the soil, but are half as wide

as those found in the bark (Williams and others 1986).

Mushrooms, the reproductive stage of armillaria root

disease, usually occur in clusters around the base of

the infected tree or stumps, but are typically short lived.

The mushrooms are sporadic in late summer and

autumn and are most abundant in moist periods (Williams and others 1986).

The majority of armillaria root disease infection in

green trees occurs via rhizomorphs and not spores, thus

limiting its ability to infect large areas quickly (Roth

and others 1980). Infection typically occurs when

rhizomorphs in the soil encounter uninfected roots, or

when uninfected roots are exposed to infected roots

(Williams and others 1986). Rhizomorphs can grow

up to 10 feet (3 m) through the upper soil layers (Williams and others 1986), but Armillaria ostoyae typically forms fewer rhizomorphs and spreads more via

root contacts (Redfern and Filip 1991). Root contact

infections are quite common in dense stands where root

contact is frequent (Williams and others 1986).

Armillaria root disease has a long life span. The

inoculum of armillaria root disease can survive for several decades in both broad-leaved and conifer stumps

(Redfern and Filip 1991) and coarse woody debris

(Williams and others 1986). Shaw (1975) reported that

wood cut from 30-year-old ponderosa pine stumps

contained viable armillaria root disease. Roth and others (1980) reported the occurrence of armillaria root

disease in large, old growth stumps that were over 35

years old.

The ability of armillaria root disease inoculum to

reside in stumps for several decades increases the

opportunity for infection under silvicultural treatments

such as clear felling, selective cutting, and thinning

(Morrison and others 2001; Shaw and others 1976).

Several studies show an increase in the frequency of

armillaria root disease and mortality in managed stands

compared to undisturbed stands (Filip 1977; Hagle

and Goheen 1988; Shaw and others 1976). Physical

disturbance of soil by logging or scarifying may split

rhizomorphs, causing them to initiate new growing tips

Figure 21: Characteristic Armillaria white mycelial fan under the bark of an infected ponderosa pine tree (source:

Williams and others 1986).
30 USDA Forest Service General Technical Report RMRS-GTR-97. 2002

and increase likelihood of new infections (Redfern

1973). Kile and others (1991) noted that the spread of

armillaria root disease was more dependent on the frequency of cutting than the intensity of the operation.

On the Northern Hills Ranger District (Spearfish/Nemo

Ranger District) in the Black Hills, Holah (1993) noted

that stands with more recent harvest activity had over

twice as much acreage (10 percent versus 5 percent)

occupied by armillaria root disease as stands that had

not been logged for at least 5 years, although the number of root disease centers was similar. Thus, management activities that create stumps might increase the

potential for armillaria root disease to spread, but may

not necessarily increase mortality.

A major concern that managers should be aware of

is the risk that natural regeneration, which does not

have the vigor to resist the infection, might become

infected by the residual inoculum. Stumps are food

bases for armillaria root disease (Wargo and Harrington

1991) and can limit the ability for a site to revegetate

due to reinfection. Shaw and others (1976) reported

that mortality of small trees was first noticed around

stumps at a dry site 4 to 6 years after harvest.

Trees with reduced vigor are most susceptible to

armillaria root disease (Wargo and Harrington 1991).

Thinning operations increase the growth and vigor of

residual trees, thus lowering the susceptibility to disease. Vigorous trees can limit armillaria root disease

in localized lesions and curtail the spread of the disease by secreting resin and forming callus tissues (Williams and others 1986). However, trees are typically

stressed upon the initial release and might become infected before the trees can respond to the benefits of

the release (Wargo and Harrington 1991). Yet, in central Oregon, Filip and others (1989) reported that an

early precommerical thinning on a moderately poor

ponderosa pine site did not increase armillaria root disease infection.

Several studies have suggested an association between armillaria root disease and mountain pine beetle

(Cobb 1989; Cobb and others 1974; Eckberg and others 1994; Hinds and others 1984; Lessard and others

1985). Hinds and others (1984) surveyed over 115 trees

on 40 plots in the northern Black Hills and found 28

percent of trees infested with mountain pine beetle were

also infected with armillaria root disease. In addition,

75 percent of the dead trees were infected with

armillaria root disease, while none of the vigorous trees

showed signs of infection. Holah (1993) reported a

high probability (67 to 78 percent) of being in or near

an armillaria root disease center when an area of mountain pine beetle was located. Furthermore, the probability of finding a beetle-killed tree or pitch-out tree

when armillaria root disease was present was 43 to 48

percent. Her survey data suggest that many armillaria

root disease centers are not associated with mountain

pine beetle, but most areas with mountain pine beetle

contain root disease (Holah 1993).

Several hypotheses have been suggested for the association of armillaria root disease and mountain pine

beetle. First, armillaria root disease stresses a tree and

predisposes it to beetle attack, colonization, and death

(Cobb 1989; Cobb and others 1974; Hinds and others

1984; Lessard and others 1985). Eckberg and others

(1994) suggest that when armillaria root disease is

present in stands without an established root disease

center, it infects the roots of a small percentage of the

trees within the stand. These trees then become primary focus trees for the mountain pine beetle. If the

mountain pine beetle population is large enough, trees

surrounding the primary focus tree are also attacked

and an added stress is placed on the trees without

armillaria root disease. Once these trees start combating the mountain pine beetle, defenses against

armillaria root disease infection decrease and the probability of infection increases (Eckberg and others

1994).

Holah (1993) made an excellent point when discussing the association of mountain pine beetle and

armillaria root disease: “Areas impacted by Armillaria

appear to have been frequently confused with areas

infested by mountain pine beetle, probably because they

often occur in the same area and patches of Armillariacaused mortality can look like beetle-caused mortality

to the untrained eye.” However, it is extremely important to recognize beetle frass, pitch tubes, and fungal

mycelium or fruiting bodies to distinguish the two because management activities will affect the two agents

differently. Furthermore, managers should be aware

that Armillaria is a persistent agent that will kill trees

over extended periods of time, whereas beetle-caused

mortality is generally concentrated over short periods

of time.

Control—Eradication of armillaria root disease is

not a realistic option, but management that limits the

buildup of the disease and reduces its impact is feasible (Williams and others 1986). As with any

disease, maintaining vigorous tree growth and minimizing stresses such as wounding the tree bole can limit

the development of armillaria root disease.

Another effective technique is to reduce the food

source available to armillaria root disease by uprooting infected or susceptible root systems and stumps

(Williams and others 1986). However, we do not

recommond removal of all stumps because of the risk

of reducing soil biota and site productivity (Graham
USDA Forest Service General Technical Report RMRS-GTR-97. 2002 31

and others 1994). The health of young trees within a

stand is also a useful indicator of armillaria root disease (Roth and others 1980). If there are groups of

dead trees of pole size or larger located around old

stumps, then armillaria root disease is present in the

stand (Roth and others 1980). Removal of old stumps

in armillaria disease epicenters can reduce infection.

Instead of removing all old stumps in an area, creation of root-free zones between diseased and healthy

stands can be an effective method to contain armillaria

root disease (Roth and others 1977). The mode of action differs depending on the type of infected stand.

Armillaria root disease typically advances sporadically

in waves along short fronts outward from infected

stumps at an average rate of 3 feet (0.9 m) per year. In

dense stands of young trees where old-growth stumps

are common, establishment of a root-free area to serve

as a barrier can be effective (Roth and others 1977).

Keep in mind that treatment of the actual infected area

by uprooting maybe expensive, determental to soil productivity, and ineffective.

Stands that have scattered infections require a different approach to contain armillaria root disease. If

the mortality in dense stands is limited to small trees

of low vigor and the stand is free of old stumps, then

treatment is not required because the armillaria root

disease is in an endemic state (Roth and others 1977).

However, poorly stocked stands with infected old

stumps do require some sanitation treatment to maintain the crop trees. Stumps and roots should be removed in an area extending no less than 33 feet (10 m)

past the obvious boundary of the disease center because the root systems are most likely infected (Roth and

others 1980; Williams and others 1986). Refer to Roth

and others (1977) for marking and removal methods.

Prescribed fire may directly affect armillaria root

disease activity in forests through the destruction of

inoculum or indirectly through stress effects on the

fungal mycelium (Reaves and others 1993). Kile and

others (1991) suggested that high-intensity fires could

directly destroy inoculum present in stumps as well as

reduce rhizomorphs. However, Filip and Yang-Erve

(1997) reported that armillaria root disease was significantly reduced following a fall burn in Oregon only

at soil depths up to 3.2 inches (8 cm), but not at

11.8 inches (30 cm). This poses a problem because

most of the woody roots that are naturally infected with

armillaria root disease are at depths greater than

3.2 inches (8 cm). The authors suggest, however, that

if the fire was intense enough or more penetrating, it

could decrease armillaria root disease infection (Filip

and Yang-Erve 1997). Probably the best use of prescribed fire to control armillaria root disease is to use

fire to increase the vigor of the trees instead of trying

to destroy the fungus.

The use of chemicals to control armillaria root disease is only recommended in situations where highvalue trees, such as in campgrounds, need protection.

Chemical fumigants such as chloropicrin, methyl bromide, and carbon disulfide can reduce infection levels

(Williams and others 1986). These fumigants should

be applied around the base of the infected stem or

placed in holes where trees have been uprooted to prevent the spread of armillaria root disease. Filip and

Roth (1987) list several chemicals that failed to protect ponderosa pine from armillaria root disease in central Washington.

As with any native pathogen that attacks ponderosa

pine in the Black Hills, managers need to realize that

this is a natural process and part of the checks and balances of the ecosystem. The presence of armillaria

root disease in the Black Hills does have some benefits. For instance, large-scale gaps formed in the forest create a variety of new habitats. The structural complexity of this landscape created by armillaria root disease and other disturbance factors provides a variety

of plants that benefit wildlife. Furthermore, habitats

for cavity-nesting birds are created as well as coarse

woody debris habitat for small animals. In addition,

since armillaria root disease has a low pathogenicity

in hardwoods (Kallas 1997), regeneration of these trees

is encouraged (Holah 1993), increasing the diversity

of the landscape.

Red rot (Dichomitus squalens)

Red rot is caused by the fungus Dichomitus squalens,

which produces a white-pocket rot in ponderosa pine.

It is one of the major causes for loss of sound wood in

commercial stands (Andrews 1971; Boldt and Van

Deusen 1974). It has been estimated that up to onefifth of the gross volume cut in virgin sawtimber in the

Black Hills has been culled due to red rot (Andrews

1971). Red rot can infect pines of all age classes except seedlings and small saplings, thus it is problematic in second-growth stands because once it infects a

young tree, it has several decades, depending on the rotation age, to develop and cause damage (Andrews 1971).

The life cycle of the red rot fungus starts on decaying dead material that is in close contact with the ground

(Andrews 1971). The fruits are flat and white and typically appear 4 years after the material is infected. For

the next 6 years, the sporophores develop annually on the

decaying material during the summer rainy season. The

combination of summer high temperatures and moist conditions favor fruiting, spore germination, and vegetative

development of the red rot fungus (Andrews 1971).
32 USDA Forest Service General Technical Report RMRS-GTR-97. 2002

The spores of the red rot fungus are wind disseminated and become established in living trees through

the dead wood on branches or insect holes (Andrews

1971; Boldt and Van Deusen 1974). If the moisture

regime is favorable, the spores will germinate immediately and develop a white, feltlike mycelial pad between the bark and wood. From the mycelial pad the

fungus invades the wood of the branches and starts

growing toward the bole through both wood and pith

of the branch (Andrews 1971; Boldt and Van Deusen

1974). The red rot eventually will reach the heartwood

of the trunk and cause the most damage.

Red rot fungus has two distinct stages: incipient and

advanced (Andrews 1971). Both of these stages can

be viewed in a board sawed from a decayed log. The

incipient stage is identified by the reddish-brown discoloration of the infected wood, but with no change in

structural integrity (fig. 22a). At the end of an infected

log, incipient decay is often fan shaped or radiates out

from the center of the log like spokes on a wagon wheel

(fig. 22b) (Andrews 1971).

In the advanced stages of decay, the incipient stage

typically surrounds the more decayed areas of the

wood. The advanced stage is often poorly defined

white pockets of discolored wood (fig. 22c). The

strength and structural integrity of the wood are reduced, and long axes parallel to the grain appear to be

filled with lintlike material (Andrews 1971). As the

decay advances, the white pockets become more abundant until they join and give the infected wood the appearance of a fibrous white mass. In the end stages of

decay, the white lintlike substance disappears and a

bleached, grayish-brown, stringy decayed wood is left.

Eventually, the stringy decayed wood will fall away

and create a cavity in the wood (Andrews 1971).

Red rot is most damaging in wood products that are

sawn into boards, where rotten portions of logs have

to be discarded. It is less of a problem when logs are

utilized for whole fiber products such as chips, particle board, or tongue-and-groove products. In these

cases rot can effectively be removed in the manufacturing process. Utilization of red-rot-infested

trees is limited by the economics of harvesting and

transporting heavily infested trees with little recovery

potential.

Red rot has some positive effects on forest ecosystems. The formation of cavities in the wood provides

excellent habitat for the many cavity-nesting birds in

the Black Hills. Furthermore, the presence of red rot

in a forest adds structural heterogeneity in the form of

small gaps within the forested landscape. Rot contributes to breakdown of woody debris, reduction of fuel

loadings, and provides habitat for soil flora and fauna.

Red rot in mature standing trees is often difficult to

detect because the saprophytes rarely develop on living trees. In mature trees over 60 years old, examination of bark-covered branch stubs and branch debris

on the ground at the base of the tree can give vital

information on the extent of the infection (Andrews

1971). A branch must be pruned to determine if the

fungus has reached the heartwood.

To determine if an immature tree is infected with

red rot, try to break a branch close to the trunk (Andrews

1971). If the branch resists breakage or breaks with a

crack, then the tree probably is not infected. If there is

little resistance, however, and the branch breaks as if

water logged, then decay is in an advanced stage. To

determine if the red rot has reached the heartwood,

prune the branch flush to the trunk and look for the

decay.

Branches that have deadwood and retain their bark

are primary infection vectors (Andrews 1971; Boldt

and Van Deusen 1974). Trees that have large, dead,

bark-covered branches are likely candidates for red rot

Figure 22: Example of various stages of red rot in ponderosa pine. (A) incipient decay at the end of a saw log; (B)

advanced decay at the end of a saw log; (C) advanced

decay bordered by incipient decay in the heartwood of a

board (photo source: Andrews 1971).
USDA Forest Service General Technical Report RMRS-GTR-97. 2002 33

infection (Boldt and Van Deusen 1974). Infections in

trees less than 20 years old are rare because few of

these trees have dead branches large enough to be susceptible (Andrews 1971). Typically, infections are

more related to the size of a dead branch than to the

age of a tree. Since older trees typically have more

dead branches, infections are usually more prevalent

in older trees.

Control—There is no chemical control for red rot.

The best method of controlling red rot in a forested

stand is through silvicultural treatments. Precommerical thinnings should avoid small-branched

trees and cut large-branched trees that are already infected or at risk for infection (Andrews 1971). In addition, intermediate cuts to improve volume growth

rates should focus on the large-branched trees that are

already infected or have the potential for infection

(Boldt and Van Deusen 1974).

One of the best cultural treatments is to prune stands

where average diameter is still small (less than 7 inches;

<18 cm) (Boldt and Van Deusen 1974). Pruning eliminates future entrance points and branch infections, and

can actually inactivate the red rot fungus in the decay

columns (Andrews 1971). Removal of all branches

on the butt log at the same time is desirable, but pruning may need to be conducted over several operations

(Andrews 1971; Boldt and Van Deusen 1974). The

earlier pruning is performed, the greater the protection

from red rot infection (Boldt and Van Deusen 1974).

Furthermore, pruning stubs are not subject to red rot

infection and can increase the value of timber.

Western gall rust (Peridermium harknessii)

Western gall rust is caused by a fungus that forms

galls on branches and stems of ponderosa pines in the

Black Hills. Historically, the western gall rust was

designated the scientific name Endocronartium

harknessii, but recent studies have found Endocronartium to be incorrect and Peridermium harknessii

is the accepted designation (Johnson 2000). Western

gall rust is the second most troublesome disease of

ponderosa pines (Boldt and Van Deusen 1974). Unlike other rusts, this fungus spreads directly from pine

to pine without an alternate host (Johnson 2000). The

fungus reduces tree growth, affects tree form, and

causes tree mortality. It infects trees of all ages and

sizes, but rarely kills an entire stand (Boldt and Van

Deusen 1974; Johnson 2000).

Seedlings are quite susceptible to the gall rust because it girdles the stem with galls and can kill within

a few years (Johnson 2000). Moreover, infections are

most serious in plantations where mortality of young

trees is common (Boldt and Van Deusen 1974). Unlike

most diseases that kill the weakest of the population,

the gall rust infects vigorous trees more readily. The

greater surface area of new shoots on the faster growing trees provides greater chance of infection (Boldt

and Van Deusen 1974).

Western gall rust is an obligate parasite that grows

perennially in the inner bark and xylem of the ponderosa pine host. This parasite reproduces using two types

of spores, spermatia, which are rarely seen, and aeciospores (Johnson 2000). Aeciospores are produced

under bark scales in whitish sacs called peridia in late

spring or early summer the second or third year after

infection. New spores are produced annually until the

pine tissue dies, which can be up to 200 years. During

periods of high humidity, the peridia rupture and expose masses of orange powdery spores, which are then

dispersed by wind. Once the spores land on susceptible tissue, they need rainfall to germinate and cause a

new infection (Johnson 2000).

Infections occur on twigs of the current year,

branches, and stems (Boldt and Van Deusen 1974). It

is difficult to determine if a tree has been infected during the first growing season of exposure. However,

during the summer of the second year of infection, galls

will develop on the infected area (fig. 23) and spores

will be produced from the galls the following spring

(Johnson 2000). Once the rust invades the pine bark,

the cambial cells begin to divide rapidly resulting in a

woody gall. The gall is soft at first, but as resins solidify, the gall becomes harder and decay resistant

(Boldt and Van Deusen 1974).

The formation of galls on tree stems is the most damaging impact of western gall rust. This type of gall is

often referred to as a canker (fig. 24) and can result in

growth loss and cull. Cankers not only form weak

points in the tree stem and increase the probability of

wind breakage, but also create opportunities for other

decay fungi to enter the tree stem (Johnson 2000). Stem

cankers result in loss of merchantable length and mechanical weakness of lumber (Boldt and Van Deusen

1974). Gall formation on branches of mature trees is

typically of slight importance, although it can girdle

and kill a branch (Johnson 2000). Up to 100 galls may

form on susceptible trees and reduce growth of the tree

(Johnson 2000).

Control—There is no chemical control for western

gall rust. Removal of infected trees during stand entries for thinning, timber stand improvement, and sanitation is the only practical method of reducing gall rust

damage (Johnson 2000). Although pruning has been

suggested to reduce western gall rust (Boldt and Van

Deusen 1974), it does not seem practical (Johnson

2000). The presence of a few branch galls is not
34 USDA Forest Service General Technical Report RMRS-GTR-97. 2002

Figure 23: Western gall rust canker on a branch in a ponderosa

pine plantation in the Black

Hills Experimental Forest.

Figure 24: Western gall rust canker on the bole of ponderosa pine in the Black Hills.

sufficient to cut a tree, but if a tree has a stem canker

or branch gall within a few inches of the main stem it

should be felled (Johnson 2000). If a main-stem canker encircles more than one-third of the circumference

of a tree in a high-use recreational area, the tree should

be removed to avoid potential injury (Johnson 2000).

If the infected tree is located in a timber production

area, compensation for future losses can be achieved

by leaving a surplus of trees of precommerical thinning age. However, doing so on a large scale can potentially affect future growth and susceptibility to other

pathogens.

Needle cast (Elytroderma deformans)

Needle cast is a fungus that defoliates ponderosa

pine trees (Boldt and Van Deusen 1974). The fungus

is widespread in the Black Hills, and the damage intensity varies among locations (Lundquist 1991).

Needle cast typically occurs in areas where moisture

is higher due to heavy dews and frequent fogs such as

bottoms of draws and edges of meadows (Childs and

others 1971). Infections are usually more severe in

shaded thickets of reproduction, interiors of pole-sized

stands, and lower crowns of pole-sized and larger trees

on north to northwest slopes (Boldt and Van Deusen

1974; Childs and others 1971).

The needle cast fungus infects the needles, branches,

and bark of ponderosa pine (Childs and others 1971).

Infected needles appear red brown in the spring. The

infection starts on the needles with long, dark, slender

fruiting bodies appearing on the outer surfaces of red

needles. The fruiting bodies appear as faint lines on
USDA Forest Service General Technical Report RMRS-GTR-97. 2002 35

the outer surfaces of the needles and are visible by late

spring or early summer. In late summer to early fall,

the spores mature and are disseminated when the

needles are wet and the temperature is favorable (Childs

and others 1971).

The infection of branches and bark is perennial because the fungus can live in the inner bark and does

not require the favorable weather conditions for spore

infections needed for needle infection (Childs and others 1971). Infected branches form globular witches’

brooms which are more dense and round than those

caused by dwarf mistletoe (Arceuthobium campylopodum). Infected bark typically has visible lesions

on the surface (Childs and others 1971).

The damage caused by needle cast is not as severe

as other diseases, but it does weaken a tree’s defense

against other agents such as bark beetles or root rot

(Childs and others 1971). Needle cast fungus is most

damaging to trees with poor crowns. If the infection

of a mature tree is moderately severe, the crown will

gradually become thin, ragged, or short and the vigor

of the tree will decrease (Childs and others 1971).

Damage inflicted by the fungus is classified on the

amount of area diseased. If one-fourth of the needles

on a twig are infected then it is considered little or no

injury (Childs and others 1971). If one-fourth to threefourth of the twig has needle infection then the tree is

considered stressed and is likely to be killed by another agent such as bark beetles. If more than threefourth of the needles are infected, then the tree will

most likely die due to defoliation.

Control—Maintaining a healthy, vigorous stand is

the best defense against the needle cast fungus, since

fungicides are shown not to protect ponderosa pine

from infection (Lightle 1955). Surveys for needle cast

infections should be made in spring or early summer.

If needle cast is detected in a stand, no immediate

action is necessary because serious damage will not

occur for several years (Childs and others 1971). If

the stand is due for a thinning, thin the trees with trunk

infections and trees that are within 6 feet (1.8 m) of a

flagged tree. If mature trees are infected, salvage them

when mortality rates or bark beetle populations start

to increase in the stand. If a stand is lightly infected,

remove only the trees with more than one-fourth of

the crown flagged or killed. If the stand is moderately

to heavily infected, cut the stand drastically and only

leave trees with very good crowns (Childs and others

1971).

Diplodia tip blight (Sphaeropsis sapinea)

Diplodia tip blight (Sphaeropsis sapinea), once

known as Diplodia pinea, attacks ponderosa pine trees

in the Black Hills. The spores of the diplodia tip blight

fungus develop in small, black fruiting bodies known

as pycnidia (Peterson 1981). Pycnidia form on fascicle sheaths and bark, but are most numerous on the

base of needles and on scales of second-year cones.

Pycnidia can be easily identified by looking for the

ashen-gray needles of previous year infections. The

spores of this fungus are disseminated from March to

October during rainy periods (Peterson 1981). To germinate and penetrate the needles and shoots, the spores

need high relative humidities (Peterson 1981). If it is

a dry year, infection levels are usually very low.

Infection of ponderosa pine trees develops on both

the shoots and second-year cones (Peterson 1981). One

of the first indicators of infection on shoots is the presence of resin droplets; another is brown, stunted new

shoots still encased in fascicle sheaths. Entire shoots

can be killed rapidly by the fungus and infection on

major branches can vary. Damage generally occurs

first in the lower crown and can be detected in late

May. The extent of the damage can be assessed by late

June or July (Peterson 1981).

Infections that occur on ponderosa pine cones typically happen in late May and are limited to secondyear cones (Peterson 1981). Infections occur on both

healthy and stressed ponderosa pine trees. On older

pines, numerous fruiting bodies develop on the cones

first before the new shoots are infested. This build up

on the cones leads to greater damage on older trees

(Peterson 1981).

Although trees of all ages are susceptible to diplodia

tip blight, mature trees are most susceptible due to the

greater surface area of the cones (Peterson 1981). In

fact, open-grown trees and trees along the edges of

stands are most susceptible due to the abundance of

cones typically found on these trees (Johnson and others 1983, 1985). Susceptibility is also increased if

tissues are wounded by insects or hail, especially during May or June when vulnerability is highest (Peterson

1981). New shoots are susceptible during a 2-week

period starting when buds begin to open until about

mid-June (Peterson 1981). Repeated infections of

diplodia tip blight can reduce growth, deform trees,

and eventually kill the tree (Peterson 1981). Johnson

and others (1983) reported that trees that were infected

for 5 years showed a 20 percent reduction in growth.

Control—Since stressed and weakened trees are

most susceptible to diplodia tip blight, maintaining tree

vigor is important to prevent infection. Fungicides can

reduce infection of new shoots during the 2-week period that shoots are highly susceptible, however, it does

not prevent infection of seed cones. Peterson (1981)

suggests two applications of 4-4-50 Bordeaux mixture
36 USDA Forest Service General Technical Report RMRS-GTR-97. 2002

(4 lb. (1.8 kg) copper sulfate, 4 lb. (1.8 kg) hydrated

lime, and 50 gallons (189 liter) of water each week for

the 2-week period. The pruning of infected branches

will probably not reduce the spread of the disease

(Peterson 1981).

Fire

Historically, fire was a keystone ecological process

that shaped the composition and structure of plant communities in the Black Hills. Over the past 100 years,

however, fire has been suppressed in the Black Hills

due to a combination of circumstance and a misunderstanding of the significance of fire. Forest density has

changed markedly in many Black Hills landscapes over

the past 120 years (fig. 25) as a result of fire suppression. No longer should fire be viewed solely as a destructive force, but instead as another tool managers

can use to manage a healthy forest. To use this tool

effectively, however, we must first understand the historical frequency and intensity of these fires.

Ponderosa pine is a fire-adapted species. It has

evolved to coexist and flourish with fire, particularly

frequent, low-intensity underburns. The thick, wellinsulated bark of large trees enables them to resist damage from these fires (aside from the occasional basal

scars that leave a record of the fire, which allows reconstruction of the fire history). In the past, periodic

low-intensity fires consumed small seedlings, pruned

lower branches from large trees, and consumed concentrations of woody fuels on the forest floor; continuous fuels did not exist to allow such fires to burn completely through a forest. The result was a mosaic of

conditions ranging from openings to groups of young

seedlings to clumps and groups of older trees, including large orange-barked patriarchs. If (or when) large

crown fires did occur, they probably did not completely

consume all trees within a landscape, but left sources

of seed for the eventual recolonization of the burned

areas.

All over the Western United States, numerous studies are documenting historical fire regimes within ponderosa pine forests using dendrochronological methods. Most of these studies have been performed in the

Southwest, where presettlement fires were relatively

low-intensity surface fires that occurred on average

Figure 25: Increased density in ponderosa pine forests of the Black Hills region can be seen with this paired photograph

taken by W. H. Illingworth in 1874 during Custer’s Expedition and Paul Horsted in 2000. ©Paul Horsted/custertrail.com.

Permission to use this photograph “Camp in Castle Creek Valley, 1874-2000” was graciously granted by Paul Horsted.

The photograph is from a forthcoming book entitled “Exploring with Custer: The 1874 Black Hills Expedition,” by Ernest

Grafe and Paul Horsted, published by Golden Valley Press, Custer, SD, June 2002.
USDA Forest Service General Technical Report RMRS-GTR-97. 2002 37

every 3 to 20 years (Brown and Sieg 1996). While

understanding the historical fire regime in southwestern ponderosa pine forests is important, knowledge

gained there must be adapted carefully to the Black

Hills ecosystem.

To date, five studies have documented the historical fire regime of different regions within the Black

Hills (fig. 26). Several factors influence fire regimes

in forests, including: climate, elevation, topography,

and fuel loads (Brown and others 2000). Therefore, it

is important to look at fire regimes across the different

regions. Most of these studies have taken place in National Monuments, National Parks, or wilderness areas within the Black Hills due to the availability of

older trees for the dendrochronological analysis.

The study at the Devils Tower National Monument

is representative of an area of open ponderosa pine

forest and savanna with expansive areas of prairie

northwest of the Black Hills proper (Fisher and others

1987). Annual average precipitation is 17.25 inches

(43.8 cm) and elevation is 4,200 feet. (1280 m).

Presettlement fire intervals were reported to be 27 years

before 1770 and on average every 14 years between

1770 and 1900. After 1900, the frequency dropped to

an average of 42 years due to fire suppression efforts

and livestock grazing. The last reported area-wide fire

for the Devils Towers area was in 1937 (Fisher and

others 1987).

Three types of fires occurred at Devils Tower: spot

fires, local fires, and area-wide fires. Spot fires, caused

by lightning, were the most common and typically affected a single tree to a few trees. Low fuel loads or

extinguishments by rainfall probably kept these fires

from spreading (Fisher and others 1987). Lightning

combined with conditions favoring the spread of fire

probably ignited local fires. These fires covered a

sizeable area and usually were extinguished by

weather or low fuel loads (Fisher and others 1987).

The largest fires were the area-wide fires, which typically burned throughout the area. The presettlement

mosaic of fire frequency and different sized fires

allowed the savanna-prairie boundary to remain in

equilibrium. With the advent of fire suppression, however, dense forests have increased and prairie has decreased (Fisher and others 1987).

The study at the Jewel Cave National Monument

in the south-central Black Hills is representative of

the interior ponderosa pine forest (Brown and Sieg

1996). Elevations range from 5,200 to 5,800 feet

(1,585 to 1,768 m) (Brown and Sieg 1996) with average annual precipitation approximately 18 to 19

inches (45.7 to 48.3 cm) (Driscoll and others 2000).

Mean fire intervals in this area, calculated for the

years between 1388 and 1900 ranged from 20 to 24

years (fig. 26; table 2). These ranges are consistent

with the mean fire intervals found by Fisher and others (1987) in their study of Devils Tower and with

fire frequency data reported for ponderosa pine forests in the Northern Rocky Mountains (Arno 1976;

Barrett and Arno 1982; Wright and Bailey 1982).

Brown and Sieg (1996) also determined that the

majority of fires were late growing season fires (July

to August). These late-season fires coincide with

the results from a study of historic lightning-ignited

fires on the Northern Great Plains grasslands and

pine savanna (Higgins 1984). Higgins also found that

the majority (73 percent) of the 294 fires started by

lightning occurred in July and August. The last recorded fire in the Jewel Cave area was a large-scale

fire in 2000 due to arson (USDA Forest Service

2001a), but the previous fire was over 100 years ago

in 1900 (table 2) (Brown and Sieg 1996).

The study at the Wind Cave National Park in the

southeastern foothills of the Black Hills is representative of the ponderosa pine forest Northern Great Plains

mixed-grass prairie ecotone (Brown and Sieg 1999).

Elevations range from 3,600 to 5,020 feet (1,100 to

1,530 m) (Brown and Sieg 1999) and average annual

precipitation is approximately 17 inches (43.2 cm)

(Driscoll and others 2000). Season of fire was consistent with the Jewel Cave study, with fire scars indicating fires occurring later in the growing season or in the

dormant season (Brown and Sieg 1999). However,

mean fire intervals at Wind Cave sites ranged from 10

to 12 years (table 2), and were roughly twice as frequent as in the interior ponderosa pine stands of Jewel

Cave (fig. 26; table 2). The authors suggest that the

higher frequency of fire may be due to the lower elevation and warmer and drier environment of the Wind

Cave area. This comparison of Wind Cave and Jewel

Cave shows how differences in abiotic factors such as

elevation and moisture can change a fire regime. The

last extensive fire recorded in this area was over

90 years ago in 1910 (Brown and Sieg 1999).

The study at the Black Elk Wilderness Area in Upper Pine Creek Basin (Brown and others 2000) is representative of the high elevation (6,000 to 6,900 feet;

1,829 to 2,103 m) and rugged environment of the central Black Hills. The area is dominated by undisturbed

forests of ponderosa pine, mixed with white spruce and

aspen (Ryan and others 1994). Average annual precipitation is 20.8 inches (52.9 cm) (Ryan and others 1994).

From 1580 to 1890, median fire interval was 22 to 23

years with a range 11 to 74 years for the area (fig. 26;

table 2). The last fire recorded in this area was over

100 years ago in 1890 (Brown and others 2000).
38 USDA Forest Service General Technical Report RMRS-GTR-97. 2002

Figure 26: Locations and corresponding fire chronologies complied from published fire histories of the Black Hills (Brown

and Sieg 1996, 1999; Brown and others 2000; Wienk 2001). GPA = South Dakota game production area; PCA = Pine

Creek Area; JC = Jewel Cave area; WCN = Wind Cave; PIG = Pigtail Bridge; GOB = Gobbler Ridge. Horizontal lines

represent life span of individual trees. Fire scars are signified by triangles at the dates they were recorded. Open

triangles are other injuries or questionable fire scars recorded within the ring series.

1350 1500 1550 1650 1750 1850 1950 2000 1450 1450 1600 1700 1800 1900

Legend

Fire scar

Other injury

Pith date

Inner date

Outer date

Bark date

Recorder years

Null years

South Dakota game production area, Spearfish, SD Upper Pine

Creek

Middle Pine

Creek

GOB

WCN

PIG

PCA

JC

GPA
USDA Forest Service General Technical Report RMRS-GTR-97. 2002 39

1350 1500 1550 1650 1750 1850 1950 2000 1450 1450 1600 1700 1800 1900

Legend

Fire scar

Other injury

Pith date

Inner date

Outer date

Bark date

Recorder years

Null years

Bridge

Pigtail Wind Cave

North

Jewel Cave

North

Jewel Cave

Central

Jewel Cave

East

Jewel Cave

South

Gobbler

Ridge
40 USDA Forest Service General Technical Report RMRS-GTR-97. 2002

The most recent study was performed in the northern Black Hills in Lawrence County, on the South Dakota Game, Fish and Parks Badger Game Production

Area (GPA) west of Spearfish (Wienk 2001). Elevation of the site is 4,003 to 4,200 feet (1,220 to 1,280 m)

and average annual precipitation is approximately

24 inches (61.0 cm) (Wienk 2001). The dominant vegetation is ponderosa pine. The majority of the fire scars

were either late season or dormant season, which is

consistent with the Jewel Cave and Wind Cave studies

(Brown and Sieg 1996; 1999). Wienk’s analysis of

fire intervals from 1450 to 1998 yielded a mean fire

interval of 13 years with a range of 1 to 43 years

(table 2). This mean fire interval is similar to the interval reported for the foothills ponderosa pine stands of

the Wind Cave study (fig. 26; table 2) (Brown and Sieg

1999). The last fire reported in the Badger GPA area

was over 120 years ago in 1879 (Wienk 2001).

Examination of the dendrochronological data from

these five sites within the Black Hills indicates that

some fires were recorded on scarred trees within the

same year (fig. 26), but it is impossible to ascertain if

these fires were part of the same event or were separate events. Nevertheless, the evidence of fire acting

as part of the natural disturbance regime in the Black

Hills is overwhelming. Shinneman and Baker (1997)

proposed that both low-intensity and stand-replacing

fires were significant components of this disturbance

regime. Determining which type of fire occurred historically is not easy because fire scars detected by dendrochronology indicate only that a tree survived a fire.

Whether the surviving tree was on the edge of a highintensity fire or in the middle of a low-intensity ground

fire is difficult to ascertain.

Inferences can be made about the occurrence of

large-scale, stand-replacing fires by examining

historical descriptions of early expeditions in the Black

Hills, and by surveying the landscape for large areas

of even-aged trees that have not been logged. Since

the majority of the Black Hills has been logged within

the past 100 years, we can only rely on historical descriptions. Shinneman and Baker (1997) examined

several historical reports of the Black Hills and reported

that many fires ranged from 7,500 to 22,000 acres

(3,000 to 9,000 ha) in size, with a possibility of a very

large fire of 50,000 acres (20,000 ha). Several observations by H. S. Graves in the 1899 forest inventory

survey report indicate large-scale stand-replacing fires.

Table 2: Fire frequency, intervals, range, and time since last fire for 10 ponderosa pine sites in the Black Hills. Data

compiled from published fire histories of the Black Hills (Brown and Sieg 1996, 1999; Brown and others 2000; Wienk

2001).

Number of Mean fire Range of

Period of fire intervals interval fire intervals Year since

Location analysis (years) (+ SD) (years) last fire _ 1

Jewel Cave National Monumenta

Jewel Cave North 1576 to 1890 16 19.6 + 13.5 4 to 45 104 (1890 to 1994)2

Jewel Cave Central 1388 to 1890 22 22.8 + 17.6 1 to 63 104 (1890 to 1994)2

Jewel Cave East 1591 to 1890 13 23.0 + 22.0 1 to 77 104 (1890 to 1994)2

Jewel Cave South 1591 to 1900 13 23.8 + 23.1 7 to 93 94 (1900 to 1994)2

Wind Cave National Parkb

Wind Cave North 1564 to 1896 27 12.3 + 6.9 3 to 32 102 (1896 to 1998)

Pigtail Bridge 1528 to 1912 38 10.1 + 5.8 2 to 23 86 (1912 to 1998)

Gobbler Ridge 1652 to 1910 21 12.3 + 7.2 3 to 34 88 (1910 to 1998)

Black Elk Wilderness Areac

Upper Pine Creek 1580 to 1887 9 233 11 to 74 110 (1887 to 1997)

Middle Pine Creek 1668 to 1890 7 223 13 to 72 107 (1890 to 1997)

South Dakota Game, Fish, and Parks Area, Spearfish SDd

Badger GPA 1450 to 1998 26 13 + 10 1 to 43 119 (1879 to 1998)

1 When studied was performed.

2 Site was within the Jasper fire that occurred in 2000.

3 Median fire interval.

a Brown and Sieg (1996).

b Brown and Sieg (1999).

c Brown and others (2000).

d Wienk (2001).
USDA Forest Service General Technical Report RMRS-GTR-97. 2002 41

For instance, Graves described a large forested patch

of second-growth even-aged ponderosa pine approximately 100 years old on the limestone plateau (Graves

1899). In addition, Graves noted that patches of forest

100 to 110 years old could be found everywhere in the

Black Hills. These stands could be a result of the 1785

fires recorded in the dendrochronological record (fig.

26) (Brown and Sieg 1996,1999; Brown and others

2000; Wienk 2001). Another even-aged forest stand

around 190 to 200 years old documented by the Forest

Service in the 1940s (USDA Forest Service 1948) can

be traced to originate after a severe fire in the central

Black Hills around 1730 to 1740 (fig.26) (Graves 1899;

Progulske 1974; Raventon 1994). Evidence of a largescale fire in 1842 (fig. 26) was confirmed by accounts

reported by Native Americans that the “entire Black

Hills were ablaze” around that time, and the presence

of several clusters of 150-year-old trees in the northern Hills (Graves 1899; Raventon 1994; Shinneman

and Baker 1997; USDA Forest Service 1948).

Within the past 100 years or so, large stand-replacing fires have occurred due to human and natural

causes. In the 1890s, a severe 20,000-acre (8,100-ha)

fire near Deadwood and Lead was thought to be started

by settlers, and in 1898, a 20,000-acre (8,100-ha) fire

near Crow Peak was caused by lightning (Progulske

1974). Throughout the 20th century (fig. 27), several

fires burned areas from 7,400 to 22,000 acres (3,000

to 8,900 ha) (Raventon 1994). The most recent fire,

known as the Jasper Fire, occurred in 2000 with approximately 83,500 acres (33,800 ha) burning in less

than 6 days (USDA Forest Service 2001a). The intensity of this fire varied throughout the burned area,

leaving pockets of living trees, which will certainly

record this large-scale fire event for future generations.

Wind

Wind damage, common in the Black Hills

(Lundquist 1995a; Raventon 1994), can range from

a single tree to thousands of acres. Historical accounts of wind damage in the Black Hills indicate

that tornados and chinooks can cause severe damage (USDA Forest Service 1948). Graves (1899)

reported a large-scale windfall event in the late 19th

century around Grizzly Creek. In May 1933, a tornado destroyed over 7,000 acres (2,800 ha) with a

loss of 9 million board feet around the Rapid Creek

area (USDA Forest Service 1948). In 1943, a chinook in the Black Hills region caused severe damage

over an area 25 miles (40.2 km) long and 2 miles

Figure 27: Some wildfires that

have occurred in the Black Hills

National Forest within the past

62 years. Data obtained from

USDA Black Hills National Forest OnlineLinkage: FTP://

www.fs.fed.us/incoming/r2/

bhnf/Core_Coverages/

fire_history.zip
42 USDA Forest Service General Technical Report RMRS-GTR-97. 2002

(3.2 km) wide (USDA Forest Service 1948). These

events are only a few recorded instances within the

past 100 years. More often, wind damage is restricted to individual stands or a small number of

trees. Localized damage typically occurs in large

pole and small sawtimber-sized stands (Boldt and

Van Deusen 1974) and in mature to overmature

stands during windstorms associated with heavy precipitation events (Alexander 1987a).

Wind damage on a smaller scale typically happens when a tree is already stressed by a predisposing agent such as suppression, fire, or shallow soil

(Lundquist 1995a). The combination of the predisposing agent and the strong wind can result in a fallen

tree, a broken stem (fig. 28), or an uprooted tree

(Lundquist 1995a). Although tree mortality because

of wind damage is not usually desired, each of these

treefalls plays a role in ecosystem processes. A fallen

tree creates coarse woody debris, which can provide

wildlife habitat, insect habitat that also produces

forage for birds, and will eventually decompose and

return nutrients to the soil. A broken stem can provide a snag for cavity nesters. Uprooted trees create

pit and mound microsites (Stephens 1956). Pit soils

are often shallow and are high in organic matter,

while mound soils are deep with buried soil horizons present (Norton 1989). These microsites can

influence plant distribution and productivity.

There are several things to keep in mind if minimizing wind damage is an objective. Although ponderosa

pine is considered a wind-firm species (Alexander

1987a), Graves (1899) noted that trees on exposed

ridges of micaceous schist or limestone formations

were typically toppled. Blowdowns typically occur in

higher elevations in exposed stands. Wind damage

most often occurs on hillsides directly exposed to west

winds or at the edge of high clearings where wind can

be funneled down a valley (Raventon 1994).

Ratios of tree height to diameter have been shown

to predict ponderosa pine susceptibility to wind and

snow damage in the Northern Rocky Mountains (Wonn

and O’Hara 2001). Ponderosa pine trees that have

height:diameter ratios greater than 80:1 (units in feet)

are more prone to damage than trees with lower ratios.

Height:diameter ratios below the threshold level can

be maintained with thinnings during early stand development. If stands are older and have borderline

height:diameter ratios, a series of low-intensity

thinnings is preferable to allow greater diameter growth

while maintaining stand stability (Wonn and O’Hara

2001). If the density of a stand is dramatically reduced, then the residual trees will not utilize the

available growing space to the full potential. Furthermore, dense stands typically have high

height:diameter ratios due to competition. These

trees do not have the bole and root systems to withstand the wind when opened up, and many of the

residual trees are likely to be uprooted, broken, or

bent (Boldt and Van Deusen 1974).

Snow

Ponderosa pine is also frequently damaged by snow

in the Black Hills. In 1903, a particularly heavy snowfall downed and killed trees over a wide area (USDA

Forest Service 1948). Snowbend and breakage occur

more often in sapling and small pole-sized trees

(fig. 29) (Boldt and Van Deusen 1974). Small saplings

usually recover from snowbending, but larger saplings

often fail to return to their original form. Pole-sized

trees are in the highest danger of breakage. Early thinning of dense stands will strengthen the residual trees

and prevent losses from heavy snow (Schubert 1974).

Maintaining tree height:diameter ratios of less than 80:1

Figure 28: A ponderosa pine snag toppled by wind. This

snag is still useful as a perch and for cavity nesters for

roosts.
USDA Forest Service General Technical Report RMRS-GTR-97. 2002 43

significantly decreases the susceptibility of snow damage in ponderosa pine trees (Wonn and O’Hara 2001).

Overstory-Understory

Relationships

Background

Historical accounts of the understory vegetation of

ponderosa pine forests in the Black Hills suggest a productive and diverse understory that would be excellent for livestock grazing (Dodge 1965; Graves 1899;

Newton and Jenney 1880; Parrish and others 1996).

With the onset of fire exclusion and forest management a century ago, ponderosa pine forests in the Black

Hills have become more dense and extensive

(McAdams 1995; Parrish and others 1996). Dense

ponderosa pine forests in conjunction with overgrazing in the early part of the century have changed the

herbaceous and shrub communities of the Black Hills.

Different overstory stocking levels result in various levels of competition for light, nutrients, and water, which

influence understory productivity and composition. In

general, as ponderosa pine overstory density increases,

understory plant biomass and species diversity decrease

(Bennett and others 1987; Clary 1988; Pase 1958;

Uresk and Severson 1989,1998; Uresk and others 2000;

Wrage 1994).

Influence of Soil Type

Soil properties in conjunction with overstory density and precipitation influence understory production

in the Black Hills. Bennett and others (1987) developed models using stepwise regressions to predict understory herbage production potential of six predominant forest soils (Pactola, Sawdust, Stovho, Trebor,

Vanocker, and Virkula) in the physiographic areas of

the central crystalline core and limestone plateau in

the Black Hills. They reported that canopy cover was

the most important independent variable for predicting understory production, although, herbage yield did

not respond to canopy coverage equally for different

soils. Soils that produced more herbage at low canopy

coverage had a steeper decline in production under high

canopy coverage. Stovho and Virkula soils had the

highest production potential of 1,600 lb per acre

(1,800 kg per hectare) with no cover and normal May

to June precipitation. However, Stovho soils produced

more graminoids while Virkula produced more forbs.

Sawdust soils had the lowest production with only

490 lb per acre (550 kg per hectare) under similar conditions, with hardly any forbs. The Pactola soil sites

had different understory production and composition

based on aspect. The southern aspects were dominated

by graminoids and had lower production yields than

the northern shrub-dominated aspect. If the objective

were herbage production, the southern aspect would

Figure 29: Snow damage in a

ponderosa pine stand in the

Black Hills.
44 USDA Forest Service General Technical Report RMRS-GTR-97. 2002

have produced higher yields. It was also noted that

graminoids were more negatively sensitive to changes

in precipitation patterns than forbs. The equations produced by Bennett and others (1987) can be used to estimate forage potential on these six forest soils types.

Understory Production

Crown cover effects—Several studies in the Black

Hills have investigated how ponderosa pine crown

cover influences understory production for livestock

and wildlife grazing (Bennett and others 1987; Pase

1958; Wienk 2001; Wrage 1994). Dense ponderosa

pine stands have little or no understory vegetation, but

stands that are more open have varying amounts of

graminoids, forbs, and shrubs depending on site characteristics. Generally, herbage production decreases

with an increase in crown cover in ponderosa pine forests. For instance, total herbage produced in a clearcut

was estimated to be 2,160 lb per acre (2421 kg per

hectare) but only 40 lb per acre (45 kg per hectare)

with 70 percent crown coverage (Pase 1958). Another

study reported total herbage produced for an open stand

(0–20 percent crown coverage) to range from 1428 lb

per acre to 1784 lb per acre (1600 to 2000 kg per hectare), for an intermediate cover class (30–60 percent)

638 lb per acre (715 kg per hectare), and for the dense

canopy cover class (~85 percent crown coverage)

244 lb per acre (273 kg per hectare) (Wrage 1994).

Basal area effects—In 1963, a long-term study was

initiated in the ponderosa pine/bearberry habitat type

within the Black Hills Experimental Forest to determine the effects various growing stock levels (GSL)

and size class of ponderosa pine had on forage production and diversity (Severson and Boldt 1977). The

GSLs were 0, 20, 40, 60, 80, 100, and 120 in units of

ft2 per acre (0, 5, 9, 14, 18, 23, and 28 in units of m2 per

hectare) (Uresk and Severson 1989,1998; Uresk and

others 2000). The unthinned controls had basal areas

of 161 to 174 ft2 per acre (37 to 40 m2 per hectare) for

the pole-sized (6 to 7 inches; 15.2 to 17.9 cm d.b.h.)

stands, and 118 to 144 ft2 per acre (27–33 m2 per hectare) for the sapling-sized (3 to 4 inches; 7.6 to 10.2 cm

d.b.h.) stands. Three replications of each GSL within

each size class were established, and plots were thinned

every 5 years to maintain treatment GSL. Understory

production was measured in 1974, 1976, and 1981, allowing researchers to monitor the relationship of stand

density to understory production and diversity over the

course of several years (Severson and Boldt 1977; Uresk

and Severson 1989,1998; Uresk and others 2000).

The GSL affects the production of herbage in the

understory. Generally, the production of graminoids,

forbs, and shrubs is similar between sapling and pole

stands (fig. 30 and 31) (Uresk and Severson 1989).

Total understory production is highest in the clearcuts

and lowest in the unthinned stands (Uresk and Severson

1989). In years of drought, however, total annual production of understory vegetation was actually higher

in the GSL 20 ft2 per acre (GSL 5 m2 per hectare) plot

and not the clearcut (Severson and Boldt 1977). This

might be due to the shading effect of the overstory lowering the soil temperature and evapotranspiration. In

general, understory production was greatest when density was less than GSL 100 ft2 per acre (GSL 23 m2 per

hectare) in sapling stands and when density was less

Figure 30: Percent of total understory production of different

plant functional groups under

various overstory densities in

sapling-sized (3 to 4 inches [7.6–

10.2 cm]) ponderosa pine

stands in the Black Hills Experimental Forest (data for graph

obtained from Uresk and

Severson 1989).

Basal area (m2/ha)
USDA Forest Service General Technical Report RMRS-GTR-97. 2002 45

than GSL 60 ft2 per acre (GSL 14 m2 per hectare) in

pole stands (Uresk and Severson 1998).

Overstory Influence on Functional

Groups

In general, species richness declines with increasing canopy coverage (Wrage 1994) or basal area (Uresk

and Severson 1989; Wienk 2001). Different densities

of ponderosa pine overstory influence the species composition and abundance of the various functional groups

in the understory (fig. 30 and 31). Uresk and Severson

(1989) observed greater floristic diversity in ponderosa pine stands with low GSL, but suggested that total floral diversity would be greatest if all stocking levels, including clearcuts and unthinned dense stands,

were present. To maximize the benefit to wildlife, these

stands should be distributed across the landscape

(Uresk and Severson 1998). Understanding how individual forage species within each stand respond to

changes in stand density, and relating the response to

the preferred species of fauna, would help the forest

manager provide forage for a range of wildlife and livestock species.

Forbs—Generally, forb production is relatively low

compared to shrub and graminoid production in understories of ponderosa pine forests in the Black Hills

(fig. 30 and 31)(Severson and Boldt 1977; Uresk and

Severson 1989,1998). The production of forbs is negatively affected by overstory canopy coverage (Wrage

1994) and basal area (Uresk and Severson 1989). For

both sapling and pole-sized stands, forb production is

highest where overstory density is low and decreases

substantially as the density increases (Uresk and

Severson 1989). Pase (1958) reported 305 lb per acre

(341.9 kg per hectare) of forb production on clearcuts

compared to only 5 lb per acre (5.6 kg per hectare)

under stands of 70 percent crown coverage. Similar

patterns of forb production were noted by Uresk and

Severson (1989).

Forb diversity is highest in areas without canopy

coverage. Pase (1958) reported 63 species of forbs in

areas with low crown coverage, but found few of the

63 persisting under stands with greater than 40 percent

crown coverage. Forb species diversity was lower in

the Uresk and Severson (1989) study than in the Pase

(1958) study. Clearcuts were the most diverse, with

21 species in the pole stands and 18 species in the

sapling stands. There were significantly fewer forb

species in both pole and sapling stands that exceeded

GSL 60 ft2 per acre (14 m2 per hectare) (Uresk and

Severson 1989).

Graminoids—Graminoids are more sensitive to

changes in canopy coverage and basal area than are

forbs or shrubs (fig. 30 and 31). Several studies report

a sharp decrease in graminoid production with an increase in ponderosa pine canopy coverage (Pase 1958;

Wrage 1994) and basal area (Uresk and Severson 1989).

Pase (1958) reported up to 1,730 lb per acre (1,939 kg

per hectare) of graminoid production in a clearcut compared to 25 lb per acre (28 kg per hectare) under canopy

coverage greater than 70 percent. Production estimates

reported by Uresk and Severson (1989) were slightly

lower in clearcuts than what Pase (1958) reported.

Uresk and Severson also noted that graminoid production of 817 lb per acre (916 kg per hectare) was lower

Figure 31: Percent of total understory production of different

plant functional groups under

various overstory densities in

pole-sized (6 to 7 inches [15.2-

17.9 cm]) ponderosa pine

stands in the Black Hills Experimental Forest (data for

graph obtained from Uresk and

Severson 1989).

Basal area (m2/ha)
46 USDA Forest Service General Technical Report RMRS-GTR-97. 2002

in pole-sized stands than the 1,157 lb per acre (1,297 kg

per hectare) reported for the sapling-sized stands. Furthermore, they reported a significant decrease in the

number of graminoid species in stands that exceeded

GSL 60 ft2 per acre (14 m2 per hectare) for both sapling- and pole-sized stands.

Shrubs—Shrub production is less sensitive to ponderosa pine canopy coverage and basal area. Shrubs

make up 35 to 50 percent of total understory production in clearcuts (fig. 30 and 31) and up to 70 percent

in dense stands. Estimates of shrub production vary

between studies. Pase (1958) reported 10 lb per acre

(11 kg per hectare) under crown coverage greater than

70 percent and 125 lb per acre (140 kg per hectare) in

clearcuts. Shrub productivity differed between poleand sapling-sized stands (Uresk and Severson 1989).

In the sapling-sized stands, shrub productivity of 713

to 834 lb per acre (800 to 935 kg per hectare) was maintained up to a density of GSL 100 ft2 per acre (23 m2

per hectare) and then decreased to 205 lb per acre

(230 kg per hectare) at GSL 118 to 144 ft2 per acre

(GSL 27 to 33 m2 per hectare). Clearcutting maximized

shrub production (1,200 lb per acre [1,344 kg per hectare]) after treatment in pole-sized stands. Similar productivity in the pole-sized stands was reported after saplingsized stands were thinned to GSL 20 ft2

 per acre (GSL 5

m2 per hectare) and 40 ft2 per acre (GSL 9 m2 per hectare), but denser treatments lessened shrub productivity.

There was a significant reduction in shrub species

in pole stands that exceeded GSL 60 ft2 per acre (GSL

14 m2

 per hectare), but no difference in species diversity in the sapling stands (Uresk and Severson 1989).

Shrub diversity under different ponderosa pine densities varied with study site, but in general, within a study

site, diversity did not differ, although dominance did

differ. Uresk and Severson (1998) reported up to 14 different shrub species in the ponderosa pine understory, Pase

(1958) reported 18, and Wrage (1994) counted only six.

Snags and Coarse Woody

Debris

Long viewed as a waste of wood fiber and added

fire hazard, snags and coarse woody debris are now

being recognized for the benefits they provide for wildlife habitat, nutrient cycling (Graham and others 1994;

McComb and Lindenmayer 1999), and forest structural

complexity (Franklin and others 1997). Snags and

coarse woody debris are produced by natural disturbances such as wind, fire, insect and pathogen attacks,

and timber harvesting. The creation of snags and coarse

woody debris depends upon the intensity, frequency,

and pattern of the disturbance. For instance, an epidemic of mountain pine beetles or a large fire can produce large numbers of snags and more coarse woody

debris. Ice or wind can break treetops, resulting in

fungal infections that in turn produce lower amounts

of snags and less coarse woody debris. Thus, depending on the disturbance, various decomposition stages

of snags and coarse woody debris can occur in the forest, providing habitat for several different organisms

(McComb and Lindenmayer 1999).

A snag is defined as a dead or partly dead tree at

least 4 inches (10.2 cm) d.b.h. and at least 6 feet (1.8 m)

tall (Thomas and others 1979). Over time, snag characteristics change from the time the tree dies to when

it falls to the ground (fig. 32). Snags can be either characterized as hard or soft depending on their state of

decomposition. Hard snags have mostly sound wood

on the outside, but may have heart rot decay on the

inside. Snags in an advanced stage of decay and decomposition are commonly referred to as soft snags.

Each stage in the decomposition of a snag has a particular value for certain wildlife. Therefore, the presence of sufficient numbers of snags with a variety of

diameters and decay classes is critical in maintaining

populations of several wildlife species (Raphael and

White 1984; Scott and others 1977; Thomas and others 1979).

Snag utilization

Snags provide habitat for many forms of life. Fungi,

mosses, and lichens use decayed wood as a growth

substrate. Insects often use snags for cover and food

throughout their development. At least 23 birds and 10

mammal species in the Black Hills depend on snags

during a portion of their life history for nest sites, roosts,

perches, dens, and foraging substrate (USDA Forest

Service 1996a).

Animals that excavate their own nest cavity in a snag

are known as primary cavity nesters. Primary cavity

nesters have an important role in forested ecosystems

because most excavate a new cavity each year. The

cavities left behind will subsequently be used by secondary cavity nesters such as chickadees (family

Paridae), wrens (family Troglodytidae), bluebirds (family Muscicapidae), flycatchers (family Tyrannidae), and

swallows (family Hirundinidae), who do not have the

excavating capability (Balda 1975; Cunningham and

others 1980; McComb and Lindenmayer 1999). Mammals, such as the northern flying squirrel (Glaucomys

sabrinus bangsi) and bats (family Vespertilionids), also

utilize these cavities (McComb and Lindenmayer

1999). Some bird species such as the red-breasted
USDA Forest Service General Technical Report RMRS-GTR-97. 2002 47

nuthatch (Sitta canadensis) are opportunistic nesters

that utilize existing cavities or create their own nests

in soft snags (Cunningham and others 1980).

Most cavity nesters in the Black Hills are year-round

residents and make up a large proportion of the winter

bird community (Rumble and others 1999). Cavities

provide protection from predators and winter weather.

The survival of some resident birds may depend solely

on the availability of suitable snags (Sydeman and

Guntert 1983). For instance, pygmy nuthatches (Sitta

pygmaea) roost communally in groups of 10 to 14 birds

(Cunningham and others 1980; Hay and Guntert 1983;

Sydeman and Guntert 1983). Therefore, snags large

enough to accommodate such a large group are required

to aid in the survival of this species.

The availability of suitable snags directly influences

the population levels of primary and secondary cavity

nesters (Cunningham and others 1980; Thomas and

others 1979) as well as species density and diversity

(Raphael and White 1984). Since secondary cavity

nesters rely on primary cavity nesters to provide nest

sites, supplying enough snags for primary cavity nesting pairs is a good strategy. Thomas and others (1979)

suggested up to three snags are needed for each

primary cavity nesting pair because each year a pair

might go through a number of false starts before finally excavating a cavity. Furthermore, since certain

species nesting habitat are positively or negatively effected

when snags are clumped, the spatial arrangement of snags

on the landscape should be diverse with both clumping of snags in small patches as well as even distribution (Thomas and others 1979).

Cavity-nesting species do not randomly pick snags

for cavities; instead, a snag is chosen based on certain

attributes such as tree species, diameter, bark coverage, and decomposition stage (Cunningham and others 1980; Lentile and others 2000; Raphael and White

1984; Thomas and others 1979). In the Black Hills,

evidence of cavity use was highly correlated (r2 = 0.95)

with snag d.b.h. and was only observed in ponderosa

pine, aspen, and paper birch (Lentile and others 2000).

Evidence of forage use in snags greater than 3 inches

(>7.6 cm) d.b.h. was found in ponderosa pine (46 percent), aspen (26 percent), paper birch (49 percent), bur

oak (17 percent), white spruce (19 percent), and Rocky

Mountain juniper (2 percent), although highest forage

use was observed for trees greater than 10 inches d.b.h..

Since 98 percent of the snags greater than 10 inches

(>25 cm) d.b.h. surveyed in the Black Hills are ponderosa pine (Lentile and others 2000), the importance of

maintaining ponderosa pine snags for forage is crucial.

Snag Population Dynamics

Snag density—A survey in the summer of 1999

assessed snag densities across the entire Black Hills

National Forest (Lentile and others 2000). The mean

Figure 32: Various stages of the formation of snags and coarse woody debris (figure adapted from Maser and others

1979).

Stage 1

Live

Log decomposition

class 1

Log decomposition

class 2

Log decomposition

class 3

Log decomposition

class 4

Log decomposition

class 5

Stage 2

Declining

Stage 3

Dead

Stage 4

Loose bark

Stage 5

Clean

Stage 6

Broken

Stage 9

Stump

Stage 8

Down

Material

Stage 7

Decomposed
48 USDA Forest Service General Technical Report RMRS-GTR-97. 2002

density of snags regardless of tree species in areas with

no recent evidence of logging (20 to 30 years) was reported to be 17 snags per acre in trees greater than 3

inches (>7.6 cm) d.b.h., 3.6 snags per acre in snags

greater than 10 inches (>25 cm) d.b.h., and 0.33 snags

per acre in snags greater than 20 inches (>51 cm) d.b.h..

Snag composition of snags > 10 inches (>25 cm) d.b.h.

was predominately (more than 98 percent) ponderosa

pine. Smaller diameter snags were still dominated by

ponderosa pine (81 percent), but 19 percent of the composition was aspen, paper birch, oak, white spruce, and

Rocky Mountain juniper. Ponderosa pine snag density ranged from 5.22 snags per acre in the 4- to 8-

inch (10- to 20-cm)-diameter class to 0.44 snag per

acre in the 20-plus-inch (51-cm)-diameter class. Proposed guidelines for snags in the Black Hills National

Forest’s Phase I Amendment to the Forest Plan call for

an average retention of four ponderosa pine snags per

acre greater than 10 inches (25 cm) d.b.h. (on north- or

east-facing slopes) and two ponderosa pine snags per

acre greater than 10 inches (25 cm) d.b.h. (on southor west-facing slopes), of which 25 percent on all aspects must be greater than 20 inches (51 cm) in diameter (USDA Forest Service 2001b).

Snag persistence—Lentile and others (2000) also

surveyed three randomly selected snag populations in

the southern (Jewel Cave n = 24), central (Black Fox

n = 26), and northern (Thompson’s Gulch n = 27) areas of the Black Hills. Snags at each site were randomly chosen and date of tree death was determined

to estimate the amount of time a snag persisted. Snag

persistence ranged from 8 to 46 years for the southern

site, 9 to 57 years for the central site, and 1 to 17 years

for the northern site. Since the distribution of snag persistence was not uniform, Lentile and others (2000)

calculated the median age of snag longevity, which

would be a better estimate than the mean snag longevity. They reported that the median age of snag longevity (defined as the years since death of a tree that half

of the snags from a particular site have persisted) was

17.5 years for the southern site, 24 years for the central site, and 3 years for the northern site. It should be

noted that stand age of both the southern and central

sites ranged between 150 to 400 years, while the northern site was 60 to 130 years. The lower values of snag

longevity in the northern site were attributed to the age

of the stands, which would contain few older snags.

Age of ponderosa pine at time of death is positively

related to snag longevity in western Montana (Smith

1999a,b). Smith found that trees greater than or equal

to 200 years old had a greater chance of standing for at

least 10 years, while younger trees fell sooner. It should

be noted, however, that these 200-year-old trees were

subjected to frequent, nonlethal underburns that created minor basal scarring and increased pitch flows in

tree boles (Smith 1999a,b).

Coarse Woody Debris

Once a snag falls, it becomes coarse woody debris

and is still valuable for wildlife habitat and forage, as

well as a nutrient pool for the soil (fig. 32). Coarse

woody debris is woody material derived from tree

limbs, boles, and roots in various stages of decay (Graham and others 1994). In general, larger diameter

coarse woody debris offers a broader range of habitats

than smaller pieces. Coarse woody debris greater than

3 inches (7.6 cm) in diameter is suggested as a minimum because this size will still contribute to the forest

floor and soil before completely decaying or being

consumed by fire (Graham and others 1994). Furthermore, many species use the various stages of

decomposition of coarse woody debris for habitat and

forage. Providing many different sizes of coarse woody

debris allows the various stages to occur in a forest.

The ecological role of coarse woody debris is multifaceted. First, coarse woody debris provides habitat

for a variety of organisms, including reptiles, amphibians, birds, small mammals, insects, plants, and fungal

and microbial species (Franklin and others 1997;

Hassinger 1989; Maser and others 1979). Coarse

woody debris also has the potential to hold large

amounts of water that may be important for plants during dry periods, as well as for development of fungi

that serve as forage for several small mammals

(Hassinger 1989). Physically, coarse woody debris

reduces soil erosion by acting as a barrier to soil movement (Franklin and others 1985), provides shade and

disrupts airflow, insulating and protecting new forest

growth, and can protect tree seedlings from livestock

damage (Graham and others 1994).

Coarse woody debris is a long-term source of organic matter and nitrogen (Franklin and others 1997).

As coarse woody debris decomposes or burns, it adds

nutrients such as sulphur, phosphorus, and nitrogen into

the soil (Graham and others 1994). In advanced stages

of decay, it produces humus and buried residue that

are excellent sites for the formation of ectomycorrhizal

root tips (Harvey and others 1981). Ectomycorrhizal

fungi provide a food source for many small rodents

and larger predators, and aid woody plants in obtaining water and nutrients (Maser and others 1986;

Reynolds and others 1992).

Past practices of slash disposal and site preparation

after a logging operation have reduced the coarse

woody debris available in the forest. It is essential
USDA Forest Service General Technical Report RMRS-GTR-97. 2002 49

that managers recognize that coarse woody debris is

not a waste of wood fiber, but a resource that promotes

wildlife habitat, nutrient cycling, and structural complexity.

Management of Snags and Coarse

Woody Debris

Providing enough snags across a range of forested

habitats and in large diameter classes, as well as a commitment to providing a variety of decomposition stages

of coarse woody debris, will take a concentrated effort. Plans for the management of snags and coarse

woody debris must consider numbers, sizes, and dynamics of decay and persistence. Both hard and soft

snags are needed, and new snags must be recruited

periodically to replace those that have fallen. Managers should protect and retain standing dead trees and

coarse woody debris that have occurred naturally. In

stands without snags or coarse woody debris, trees can

be killed in several ways to create snags. Wolfy, dead

top, or deformed trees are excellent candidates for

snags, provided they do not have butt or root rot. A

commercially available power girdler with a rotary

cutting head called the Li’l Beaver girdles trees between 4 and 12 inches (10 cm to 30.5 cm) d.b.h. efficiently, while a chain saw works best for trees larger

than 12 inches (>30.5 cm) d.b.h. (Kilroy and Windell

1999). The disadvantage of girdling is that decay begins in the sapwood before the heartwood, and by the

time the tree is rotten enough for an animal to excavate a cavity, the snag may be ready to fall. Girdling

must be thorough to kill the tree (Bull and Partridge

1986). Herbicides have been used to kill trees, but Bull

and Partridge (1986) reported trees killed in this manner typically fell before girdled trees and were seldom

used for forage or nest habitat.

Bull and Partridge (1986) recommended topping

trees 49 to 82 feet (15 to 25 m) above ground and removing lower limbs as the best technique to create

snags in ponderosa pine. The topping technique is

currently being tested in the Black Hills, but results

(Smith 2001, personal communication) are not yet

available. Another technique involves killing a tree by

injecting a fungicide into the phloem and then inoculating the heartwood with a fungus (Hunt 1990). Although this method has not been tested, Hunt suggests

that this method could prolong the longevity of a snag

by preserving the sapwood while stimulating decay in

the heartwood.

Increasing the decay resistance of a snag has been

suggested as a method to prolong its longevity

(Smith 1999b). Extractives such as terpenoids,

flavenoids, tropolones, and stilbenes, important to

the naval stores industry in the 19th century, are now

being investigated for their decay resistance properties in snags. Both sapwood and heartwood contain extractives (Hillis 1977; Zavarin and Cool

1991). When a tree is wounded, such as in a lowintensity fire, extractives are produced from resin

canals in ponderosa pines (Zavarin and Cool 1991).

Extractives are thought to be toxic to insects and

diseases (Kurth 1952; Scheffer and Cowling 1966),

thus increasing the decay resistance of the heartwood. Smith (1999b) found that pitch content was

no higher in standing ponderosa pine snags than in

broken snags. However, the testing of pitch content

was exploratory, and further study is needed to better understand this relationship. Furthermore, she

suggests that in future studies, sapwood and heartwood samples should be separated for chemical

analysis.

Major Wildlife Species

Habitat Capability Models (HABCAP)

Habitat capability is defined as the capacity of a

given area to meet the needs of a species, either seasonally or year round (Lyon and Christensen 1992)

based on a combination of forage and cover. Habitat

capability (HABCAP) models are frequently used to

assess the consequence of management activities on

the quality of wildlife habitat. These models represent

the ability of an area to support a variety of wildlife

species, but do not represent population levels.

HABCAP models contain coefficients, ranging from 0

to 1.0, that rate the cover and forage capability of structural stages and forest type for each wildlife species.

Coefficients of zero indicate conditions with no value

and coefficients of 1.0 denote optimal conditions for

that species. The Rocky Mountain Region of the USDA

Forest Service has published a user guide for the

HABCAP program (USDA Forest Service [n.d.]).

Initial use of the HABCAP model by the U. S. Forest Service Rocky Mountain Region utilized information from Towry (1984) and Hoover and Wills (1984).

Towry (1984) discussed acreage for minimum viable

populations, and ratings of structural stages within various ecosystems, to meet habitat requirements for numerous mammals and birds of Colorado. The Black

Hills has modified the Rocky Mountain regional

HABCAP model to create a HABCAP model specific

to the Black Hills area. The adjustments were based

on literature reviews, experience with Black Hills habitats and wildlife habitat associations, and empirical data
50 USDA Forest Service General Technical Report RMRS-GTR-97. 2002

(Mills and others 1996; Rumble and Anderson 1995;

Rumble and others 1999). The Black Hills HABCAP

model utilizes ARCINFO, a GIS program, to analyze habitat capability for species based on spatial

data, and has the ability to map habitat capability

results (USDA Forest Service 1996b). The vegetative structural stages described by Buttery and

Gillam (1984) are used for the HABCAP model in

the Black Hills (table 3).

The intended use of HABCAP output is as a planning tool for different management scenarios. The

model is not intended to predict population levels because HABCAP does not include all the factors that

affect population densities. The model only estimates

habitat capability at one point in time and does not

simulate change over time. Spatial distribution of cover

and forage, except for deer and elk, is not incorporated

into the model due to lack of information. Furthermore,

the model assumes snags, down woody material, and

water are well distributed across the analyzed area

(USDA Forest Service 1996b). Neither herbaceous

understory composition nor subdominant tree species in

mixed species forests are included in the model parameters. Topography is ignored and competition for

forage, cover, or space among different animal species

(both wild and domestic) is not addressed. Lastly, the

model permits compensation for poor forage by good

cover, which is not always true (USDA Forest Service

1996b).

Rocky Mountain Elk

(Cervus elaphus nelsoni)

Prior to 1870, the Black Hills was home to the

Manitoban elk (Cervus elaphus manitobensis) but by

1888, overhunting had led to extirpation from the area

(Turner 1974). Between 1912 and 1914, the Rocky

Mountain subspecies of elk (Cervus elaphus nelsoni)

Table 3: Cross-reference of ponderosa pine structural stages categorized by diameter breast height. Numbers in parentheses

denote the numeric structural stage code.

Region 3

D.B.H. Buttery and Gillam Vegetation Structural Region 2 Black Hills NF

(inches) (1984)a,b Stage c,d Structural Stageb Structural Stagee

0 Grass-forb stage (1) Grass/forb/shrub (1) Nonstocked (1) Grass/forb/shrub (1)

0 to 1 Shrub-seedling stage (2) Grass/forb/shrub (1) Established (2) Grass/forb/shrub (1)

1 to 2 Sapling-pole stage (3) Seedling/sapling (2) Small (3) Seedling/sapling (2)

2 to 3 Sapling-pole stage (3) Seedling/sapling (2) Small (3) Seedling/sapling (2)

3 to 4 Sapling-pole stage (3) Seedling/sapling (2) Small (3) Seedling/sapling (2)

4 to 5 Sapling-pole stage (3) Seedling/sapling (2) Small (3) Seedling/sapling (2)

5 to 6 Sapling-pole stage (3) Young forest (3) Medium (3) Young forest (3)

6 to 7 Sapling-pole stage (3) Young forest (3) Medium (3) Young forest (3)

7 to 8 Sapling-pole stage (3) Young forest (3) Medium (3) Young forest (3)

8 to 9 Mature stage (4) Young forest (3) Medium (3) Young forest (3)

9 to 10 Mature stage (4) Young forest (3) Large (4) Mid-aged forest (4)

10 to 11 Mature stage (4) Young forest (3) Large (4) Mid-aged forest (4)

11 to 12 Mature stage (4) Young forest (3) Large (4) Mid-aged forest (4)

12 to 13 Mature stage (4) Mid-aged forest (4) Large (4) Mid-aged forest (4)

13 to 14 Mature stage (4) Mid-aged forest (4) Large (4) Mid-aged forest (4)

14 to 15 Mature stage (4) Mid-aged forest (4) Large (4) Mature forest (5)

15 to 16 Mature stage (4) Mid-aged forest (4) Large (4) Mature forest (5)

16 to 17 Mature stage (4) Mid-aged forest (4) Very large (4) Mature forest (5)

17 to 18 Mature stage (4) Mid-aged forest (4) Very large (4) Mature forest (5)

18 to 19 Mature stage (4) Mature forest (5) Very large (4) Mature forest (5)

19 to 20 Mature stage (4) Mature forest (5) Very large (4) Mature forest (5)

20 to 21 Mature stage (4) Mature forest (5) Very large (4) Old forest (6)

21 to 22 Mature stage (4) Mature forest (5) Very large (4) Old forest (6)

22 to 23 Mature stage (4) Mature forest (5) Very large (4) Old forest (6)

23 to 24 Mature stage (4) Mature forest (5) Very large (4) Old forest (6)

> 24 Old growth (5) Old forest (6) Very large (4) Old forest (6)

a Structural stage classification used for white-tailed deer (USDA Forest Service 1996a) and nongame birds (Mills and others 1996,

2000; Rumble and others 1999). b Overstory canopy coverage: A = 0 to 40 percent; B = 40 to 70 percent; C = more than 70 percent.

c Vegetation structural stages used in the Southwestern Goshawk Guidelines (Reynolds and others 1992). d Overstory canopy coverage: A = 0 to 40 percent; B = 40 to 60 percent; C = more than 60 percent.

e

 Phase I goshawk analysis structural stages for Black Hills National Forest.
USDA Forest Service General Technical Report RMRS-GTR-97. 2002 51

was introduced to the area from Montana and Wyoming (Turner 1974). In 2000, the estimated elk population in the South Dakota section of the Black Hills

was 3,895 (South Dakota Game Report 2000).

An estimate for the Wyoming portion of the Black Hills

in 1996 was approximately 500 elk (USDA Forest Service 1996a). Elk in the Black Hills region have been

studied in Custer State Park (Millspaugh 1995;

Millspaugh and others 1998; Rumble and others 2002),

Wind Cave National Park (Bauman 1998; Wydeven

and Dahlgren 1983), the central Black Hills

(Hippensteel 2000; Rice 1988), and southern Black

Hills (Rice 1988).

Elk in the Black Hills utilize a variety of habitats

for forage, loafing, and escape cover throughout the

year. Although most elk in South Dakota are considered non-migratory, seasonal movement among elk

populations to different habitat types in response to

snow depth (greater than 20 inches; >51 cm) and hunting pressure have been reported (Millspaugh 1995; Rice

1988; Bauman 1998). One issue of concern is the movement of elk from the Black Hills National Forest into

Wind Cave National Park during the hunting season,

which diminishes hunter success in the National

Forest (Rice 1988) and places additional stress on food

sources and competition with other ungulates within

the National Park (Bauman 1998; Wydeven and

Dahlgren 1985). Therefore, providing sufficient forage

and security cover habitat for elk within the Black Hills

National Forest might avoid or lessen this problem.

Habitat requirements

Historically, many wildlife biologists have accepted

the idea that providing dense vegetative cover for thermal cover enhances the survival of wild ungulates by

moderating the effects of harsh weather and minimizing the energy required for thermoregulation. The

majority of studies supporting the thermal cover hypothesis are based on observational studies of habitat

selection. However, a recent study in the Blue Mountains of northeastern Oregon tested the thermal cover

hypothesis by monitoring body mass and composition

of elk subjected to 1 of 4 levels of cover during 4 winter and 2 summer season-long experiments (Cook and

others 1998). They concluded that thermal cover does

not significantly improve the energetic status and productive performance of elk (Cook and others 1998).

Instead, they suggest that observational studies of elk

habitat selection may be more related to other needs

such as forage or security. Furthermore, a test of the

HABCAP model for elk in Custer State Park suggests

that forage is three times more important than cover,

and the modification of the model resulted in a better

fit between elk dispersion patterns and predicted habitat effectiveness (Rumble and others 2002).

Elk diets depend on forage availability and the time

of year (Hippensteel 2000; Kufeld 1973; Wydeven and

Dahlgren 1983). In the Central Black Hills, elk consumed graminoids, shrubs, and ponderosa pine in both

the winter and summer, but consumption of forbs was

very low (0.16 to 2.78 percent) in the winter and ranged

from 4.2 to 24.9 percent in the summer (Hippensteel

2000). The large range in forb consumption between

the summer of 1994 (24.9 percent) and the summer of

1995 (4.2 percent) in the central Black Hills elk herd

was contributed to precipitation and forb availability

(Hippensteel 2000). Elk in the Wind Cave National

Park area were reported to feed primarily on forbs in

the fall and winter and graminoids in the spring and

summer (Wydeven and Dahlgren 1983). Furthermore,

shrubs only contributed 7 to 9 percent of the elk’s diet

(Wydeven and Dahlgren 1983), as opposed to making

up 30 percent of the central Black Hills elk diet

(Hippensteel 2000).

Elk habitat selection throughout the year for forage,

escape cover, and calving indicates the need for a variety of habitat types within the Black Hills. Openings

created or maintained by wildfire and prescribed burns

were extensively used year round as forage habitat

unless disturbance prevented such use (Rice 1988). In

general, annual habitat use patterns of elk showed high

proportional use of meadow/range and fire-killed forests (Bauman 1998; Millspaugh 1995; Rice 1988) most

likely a result of higher forage production and diversity (Uresk and Severson 1989). Openings less than

0.5 acre (0.2 ha) with limited canopy of aspen or bur

oak were also heavily utilized for forage habitat (Rice

1988). In the summer, elk still utilized openings but

increased their use of ponderosa pine forests (Bauman

1998; Millspaugh 1995). This increased use of forests

was most likely due to the increase in human disturbance (for example, tourist activity, vehicles); however, Millspaugh and others (1998) suggest that this

increased use was to provide relief from summer temperatures. Although Cook and others (1998) did not

find any evidence that forest cover enhanced the growth

and condition of elk in their summer experiments, they

did note that elk under dense forest cover required less

water. Whether or not the elk selected the ponderosa

pine forests for summer bed sites based on a cooler

microclimate or for security, the elk selected areas with

canopy closures more than 54 percent, increased basal

area, and more trees per acre than random sites within

Custer State Park (Millspaugh and others 1998).

Elk habitat selection is influenced by several human-caused disturbances such as roads used by
52 USDA Forest Service General Technical Report RMRS-GTR-97. 2002

motorized vehicles (Millspaugh 1995; Rowland and

others 2000; Rumble and others 2002; Ward and Cupal

1979), gunshots (Ward and Cupal 1979), and hunter

activities (Millspaugh and others 2000). Elk that sense

danger respond with increased alertness accompanied

by an increase in heart rate. If the disturbance is deemed

as hazardous to the elk, it will typically run away. This

increase in heart rate in combination with running away

expends large amounts of energy and can negatively

affect the elk’s health, especially in times of physiological stress. Ward and Cupal (1979) reported an increase

in heart rate at distances up to 1,300 feet (400 m) for

gunshots, humans seen on foot, audible car horns, and

stopped vehicles; however, moving high-speed traffic

produced very few heart rate reactions.

Providing hiding cover that enables the elk to feel

safe is considered a critical component of elk habitat

(Millspaugh and others 1998). In Custer State Park,

elk tend to avoid areas with high hunter density and

hide in dense vegetative cover to minimize the disturbance during the fall hunting season. Dense vegetative

cover allows greater space overlap with hunters. In

areas with low vegetative cover, elk and hunter space

overlap is much larger. This was especially noticeable

in the fire-killed areas of the Park, which has lower

vegetative cover (Millspaugh and others 2000). Rice

(1988) observed the use of large openings in early fall

ceased during daylight, and the use of openings less than

5 acres (2 ha) in size and next to dense ponderosa pine

forests increased substantially during hunting season.

The effect of roads on elk movement, distribution,

and habitat use appears to be a function of season and

amount of traffic (Millspaugh 1995; Rowland and others 2000; Rumble, in press; Ward and Cupal 1979).

For instance, proximity to primary roads (more than

35 vehicles per week) in Custer State Park had a negative effect on the dispersion patterns of elk during the

winter, while primitive roads (less than 7 vehicles per

week) did not negatively affect elk (Rumble and others 2002). In northeast Oregon, female elk were reported to select areas away from open roads in both

spring and summer (Rowland and others 2000). Calving elk in Custer State Park typically avoid areas within

660 feet (200 m) of primary and secondary roads

(Millspaugh 1995). Several studies have reported that

the negative effects of roads decline as distance from

the road increases (Rowland and others 2000; Rumble

and others 2002). Negative effects of roads can be minimized by providing greater canopy coverage along

roadsides (Unsworth and others 1998).

The spatial arrangement of forage and cover habitats is an important component to consider in elk

management. Calving habitat typically occurs in

openings less than 1 acre (0.4 ha) in size, with no

overstory more than 5 feet (1.5 m) tall and ground

cover with herbaceous vegetation, shrubs, and some

coarse woody debris. These openings typically have

at least one side adjacent to dense ponderosa pine

stands with high canopy coverage (Rice 1988). Elk

in Custer State Park were found to use forage areas

330 feet or less (100 m) from cover proportionally

more than forage areas more than 660 feet (200 m)

from cover (Rumble, in press). Season also influences how far elk will venture into an opening. Rice

(1988) noticed that during spring, summer, and fall,

elk would rarely feed more than 300 feet (90 m) from

the forest edge, but in winter, elk were observed in

the middle of openings over one-fourth mile (0.4 km)

from the forest edge.

Management guidelines

Providing adequate food sources while maintaining

cover, through a mixture of open meadows and closed

dense forests, will help maintain elk populations in the

Black Hills. This balance of conditions at the stand

scale can be achieved through multiaged management,

either utilizing group selection or even-aged management of two to three age-classes. In either case, silviculture activities should emphasize an irregular spatial distribution of trees to allow canopy openings for

understory production and groups of trees for security.

Understanding how different levels of forest density favor plant functional groups (fig. 30 and 31) will

allow managers to manipulate forest cover to provide

sufficient amounts of the preferred forage at different

times of the year. Tall shrubs such as woods rose, snowberry, and western serviceberry on winter range can

provide forage in years with deep snow. Management

practices that benefit elk summer range should focus

on northern slopes, while winter range should focus on

southern slopes. Maintaining meadow/range areas within

the forest canopy with prescribed fire can help prevent

tree encroachment. Furthermore, prescribed fire has been

shown to increase forage production in Montana

(Koncerak 1996) and should be tested in the Black Hills.

Providing sufficient security cover for elk can help

minimize human-related disturbance. Guidelines for

elk hiding cover call for vegetation that is capable of

hiding 90 percent of a standing adult elk from the view

of a human at a distance of at least 200 feet (61 m)

(Thomas and others 1979). Achieving these requirements could be difficult in mature stands in which only

the boles provide screening. Smith and Long (1987)

demonstrated that, for a mature lodgepole pine stand

to meet the guideline requirements, the stand would

be so dense that it would slow growth, reduce vigor,
USDA Forest Service General Technical Report RMRS-GTR-97. 2002 53

and be susceptible to mountain pine beetle infestation.

However, young stands that have full crowns were

shown to provide hiding cover that met the guidelines.

Therefore, providing patches of young stands and managing these stands with thinning operations that maintain low crowns for extended periods of time can provide suitable security cover.

Security cover should be in close proximity to forage areas. Meadow areas near roads should be concealed by a forested buffer zone of a least 1,300 feet

(400 m) to mitigate the negative effects of roads and to

ensure these areas are utilized by the elk. Known travel

lanes used by elk should be maintained. In areas that

lack cover, travel lanes can be provided with timber

stringers or riparian zones. To remain effective, buffer

zones should be actively managed to retain their desired attributes. Ideally, buffer zones should be irregularly structured forests with groups of trees of all ages

and sizes to ensure their integrity through time. These

conditions are best maintained through use of unevenaged management.

Hunter disturbance can be lessened by controlling

hunter density and access to areas with low vegetative

cover (Millspaugh and others 2000). Retaining areas

of dense vegetation within a landscape that has been

subjected to wildfire will help mitigate hunter

disturbance. In areas of high recreational activity such

as hiking or camping, providing forested buffer zones

will lessen human-caused harassment.

White-Tailed Deer

(Odocoileus virginianus dakotensis)

The white-tailed deer population within the Black

Hills is on the decline. Population estimates from

the early 1990s report approximately 75,000 whitetailed deer lived in the Black Hills. Current estimates

place white-tailed deer populations at 29,000 (South

Dakota Game Report 2000). In the central Black

Hills (Pennington, Lawrence, Crook, and Weston

Counties), white-tailed deer herds are estimated to

be decreasing at a rate of 10 to 15 percent annually

(DePerno 1998; DePerno and others 2000). To effectively manage for white-tailed deer, managers

need information on white-tailed deer habitat requirements in the Black Hills. In response to this

need, several studies have investigated the specific

habitat requirements (DePerno 1998; Kennedy 1992;

Sieg and Severson 1996; Stefanich 1995; Thilenius

1972; USDA Forest Service and others 1982) and

diet (Hill 1946; Hill and Harris 1943; Hippensteel

2000; Schenck and others 1972; Schneeweis and

others 1972; Sieg and Severson 1996; USDA Forest

Service and others 1982) of Black Hills white-tailed

deer populations.

White-tailed deer in the Black Hills migrate between

summer and winter ranges (DePerno 1998). Deer migration from high-elevation summer ranges to low-elevation winter range typically occurs between August

and February. Females typically migrate to summer

ranges in May, about 3 weeks before giving birth

(DePerno 1998). A map of the Black Hills National

Forest with migratory patterns and summer, winter, and

critical winter ranges is provided in the Coordination

Guidelines for Timber Management in Black Hills Deer

Habitat manual (USDA Forest Service and others

1982).

Habitat requirements

White-tailed deer population decline has been

atributed to the deterioration of habitats used for cover

and forage, especially on winter range (DePerno 1998;

DePerno and others 2000; Griffin and others 1992). It

has been suggested that the reduction in forage quality

and availability because of increased ponderosa pine

overstory density has lowered the reproductive potential of white-tailed deer in the Black Hills (Rice 1984).

Although hunting white-tailed deer in the Black Hills

is popular, DePerno and others (2000) reported that 71

percent of female white-tailed deer mortality in the

central Black Hills was natural (malnutrition, predation, and sickness), and over 50 percent of the female

mortality occurred in the spring coinciding with late

spring snowstorms. Females are most susceptible then

because they are typically in the third trimester of pregnancy and nutritionally stressed from poor-quality forage on fall and winter ranges (DePerno and others

2000).

Habitat and forage availability differs between the

northern and central Black Hills, and therefore affects

the habitat selection and diet composition of whitetailed deer populations within each region. Although

ponderosa pine forests dominate both regions, the forested habitats utilized by deer populations in the northern Black Hills have lower basal area, lower average

d. b. h., and lower total canopy coverage than the forested habitats available to central Black Hills deer

populations (Hippensteel 2000). In addition, northern

Black Hills forests have agricultural fields that supplement the natural forage and a prevalence of deciduous

habitats with an understory shrub component, which

contributes to better escape cover and browse (DePerno

1998; Kennedy 1992).

Forage availability and diet quality in the winter

depend on winter severity and duration (Hippensteel

2000; Osborn 1994; Sieg and Severson 1996). In the
54 USDA Forest Service General Technical Report RMRS-GTR-97. 2002

northern Black Hills, low-growing shrubs such as Oregon grape and bearberry are important forage during

mild winters, but in severe winters with deep snow,

ponderosa pine needles, bur oak twigs, and common

juniper are consumed (Hill 1946; Hippensteel 2000;

Schenck and others 1972; Schneeweis and others 1972;

Sieg and Severson 1996). Although the highly nutritious and digestible bur oak acorn has not been identified as an important food source, it is probably consumed when available (Sieg and Severson 1996). In

the central Black Hills, Oregon grape, bearberry, and

common juniper are not present on the deer’s winter

range; instead, deer in this region rely on serviceberry,

western wild rose, and ponderosa pine needles for food

(Hippensteel 2000). In the southern Black Hills, ponderosa pine, true mountain mahogany, common juniper, bearberry, western snowberry, and Rocky Mountain juniper are important browse during winter

(Schenck and others 1972). The winter-spring transition is a critical time for all Black Hills white-tailed

deer. Although spring deer diets increase in graminoids

and new leaves from trees and shrubs (Hill 1946),

spring snowstorms frequently cover the graminoids and

winter browse is still utilized.

Availability of high-quality forage in summer and

fall for fat storage is essential for winter survival

(Mautz 1978). Food sources on summer range are

typically greater in quantity and quality than winter

range. However, availability of plant functional groups

is influenced by precipitation (Bennett and others

1987). Forbs have been reported to dominate the whitetailed deer diet in the Black Hills in the summer

(Schenck and others 1972; Sieg and Severson 1996;

USDA Forest Service and others 1982); however, in

the central Black Hills, Hippensteel (2000) reported

populations ate mostly graminoids and moderate

amounts of shrubs and forbs during the two summers

of her study. She suggests that lower precipitation increased graminoid availability and lowered forb availability.

White-tailed deer utilize a variety of habitat types

and structural stages throughout the year for cover

and forage (DePerno 1998; Kennedy 1992; Stefanich

1995; Uresk and others 1999). High-quality deer

habitat is a function of a variety of habitats within

its home range that provides cover and forage. During winter in the central Black Hills, white-tailed

deer selected dense young ponderosa pine/deciduous mixed forests and open burned ponderosa pine/

grass habitats in greater proportion than available

(DePerno 1998). In addition, young and mid-aged

open ponderosa pine forests, aspen/coniferous forests, and most structural stages of aspen were

utilized, while mid-aged ponderosa pine stands with

moderate to dense canopy coverage and meadow

habitats were avoided (DePerno 1998). In contrast,

white-tailed deer in the northern Black Hills selected

young and mid-aged ponderosa pine stands with high

canopy coverage while avoiding the more open ponderosa pine stands within the same diameter class

(Kennedy 1992).

During summer in the central Black Hills, whitetailed deer selected ponderosa pine/deciduous, aspen,

aspen/coniferous, spruce, and spruce/deciduous habitats, and areas with juniper and shrubs, while avoiding

grass/forb habitats and mid-aged ponderosa pine forests with moderate to dense canopy coverage (DePerno

1998). White-tailed deer in the northern Black Hills

selected agricultural lands, open young ponderosa pine

forests and open aspen/beaked hazelnut habitats while

avoiding mid-aged ponderosa pine forests with moderate canopy coverage and pine/grass-forb stands

(Kennedy 1992).

Fawning habitat requires horizontal and vertical

screening cover to hide young deer from predators.

Sites chosen by fawns typically have more vertical

and horizontal obstruction for screening cover than

those found on randomly selected sites (Uresk and

others 1999). In the northwestern Black Hills, whitetailed deer fawns were observed in ponderosa pine

stands with 45 percent horizontal screening coverage and in aspen/paper birch stands with 63 percent

horizontal coverage (Stefanich 1995). In areas where

aspen habitats are limited, such as the northeastern

Black Hills, fawn beds were found in relatively open

stands of ponderosa pine with a substantial percentage of grass cover and a relatively tall understory

(Uresk and others 1999). Therefore, habitats with

dense tall shrub/saplings, regardless of habitat type,

provide great horizontal cover for fawns (Stefanich

1995).

Management guidelines

Enhancing cover and forage habitats utilized by

white-tailed deer in the Black Hills can increase carrying capacity and aid in the stabilization of population

levels. Maintenance and enhancement of deciduous

forests and coniferous/deciduous mixed forests should

be a major element in deer habitat management in the

Black Hills. Various silvicultural treatments and prescribed burning can be used to create a variety of habitats that will provide forage and cover for white-tailed

deer. Close proximity of forage and cover areas can

reduce energy expenditures for travel and foraging.

USDA Forest Service and others (1982) recommend

that forage areas should be no further than 600 feet
USDA Forest Service General Technical Report RMRS-GTR-97. 2002 55

(183 m) from the edge of the cover habitat for all deer

habitat.

Deciduous habitats are important to white-tailed

deer on both winter and summer range (DePerno

1998; Kennedy 1992). Aspen stands provide horizontal cover for fawning and abundant high-quality

understory forage (DePerno 1998; Kennedy 1992;

Stefanich 1995). Providing a variety of seral aspen

stages will maximize cover and forage diversity

(Severson 1982). Removal of some ponderosa pine

overstory in areas where remnant aspen occur can

increase the deciduous component as well as restore

declining aspen stands. Aspen regeneration should

be closely monitored, however, to insure that declining clones are recovering. Fencing, or other measures may be needed to allow sprouting to introduce

a new age class into the clone before deer are allowed access.

Forage production can be increased through prescribed burning, ponderosa pine stand thinning, and

pine litter reduction (DePerno 1998; Hippensteel

2000; Osborn 1994). Prescribed burning of browse

species such as chokecherry, serviceberry, and aspen can be beneficial since these species are prolific root or crown sprouters (Wright and Bailey

1982). Young succulent sprouts are usually more

nutritious than unburned mature plants (Sieg and

Severson 1996). Thinning ponderosa pine stands

allows more light to reach the forest floor and increases forage production (Uresk and Severson

1998). In mixed oak-pine stands, selective removal

of pine trees may enhance reproduction of oak and

associated shrubs (Sieg and Severson 1996).

Precipitation patterns and plant abundance should

be monitored on deer summer ranges. In years with

lower precipitation, plant functional groups on summer range can change and might have detrimental

effects on white tail deer populations, especially in

areas that are grazed by livestock and other wild

ungulates.

Mule Deer (Odocoileus hemionus)

The current mule deer population for the South Dakota region of the Black Hills is approximately 12,000

(South Dakota Game Report 2000). The majority of

mule deer are found in the southern Black Hills (Sieg

and Severson 1996). Although white-tailed deer, elk,

and mule deer coexist in the Black Hills, they occupy

different ecological niches. Unfortunately, most detailed studies of habitat requirements of ungulate populations in the Black Hills focus on white-tailed deer.

We have therefore attempted to utilize information on

mule deer habitat requirements from other geographical regions and have applied this information to Black

Hills populations.

Habitat requirements

The quality and quantity of food sources on winter

range is usually cited as the limiting factor to mule

deer populations (Natural Resource Conservation

Service 2000; Towry 1984). Mule deer extensively

use higher elevation areas of the Black Hills during

the summer months, but use the entire Black Hills

habitat as year-round range (Wyoming Game and

Fish Department 1985). Winter range is usually below 5,200 feet in elevation and often occurs in winter livestock range (Wyoming Game and Fish Department 1985).

Although habitat requirement studies of mule deer

are limited for the Black Hills (Wydeven and Dahlgren

1985), some general conclusions can be made based

on other geographical studies. Mule deer abundance

is highest in shrubby/brushy land, riparian woodland,

and at the edge of forest and meadow areas where

shrubs are found (Natural Resource Conservation Service 2000). In the Wind Cave National Park, mule

deer were most often observed in the shrubby draws,

while the use of ponderosa pine habitats was low

(Wydeven and Dahlgren 1985). On the Front Range

of northern Colorado, mule deer utilize ponderosa pine

forests with mountain mahogany understory or open

areas where mountain mahogany is dominant (Natural

Resource Conservation Service 2000). In the Missouri

River Breaks study area in Montana, mule deer were

found in ponderosa pine-Rocky Mountain juniper

habitat types throughout the year (Mackie 1970). In

the Badlands National Park in South Dakota, chokecherry habitat and Rocky Mountain juniper habitat

types were used (Steigers 1981). Towry (1984) noted

that aspen stands also provide an abundant source of

forage for mule deer populations in Colorado.

Mule deer browse on a variety of woody plants, but

also graze on forbs and graminoids (Kufeld and others

1973; Towry 1984). Kufeld and others (1973) reported

that mule deer diets varied seasonally and depended

on the availability of forage. Shrubs and trees make

up the majority of mule deer diets throughout the year,

especially in the fall and winter. Grasses are grazed in

the winter and spring when available. Forbs are also

consumed throughout the year, with the highest consumption during the summer and fall when available

(Kufeld and others 1973). In the Wind Cave National

Park, mule deer fed mostly on browse species such as

sumac (Rhus spp.) and western snowberry, but also ate

moderate amounts of forbs. Forbs were more important
56 USDA Forest Service General Technical Report RMRS-GTR-97. 2002

in summer and browse most important in fall and winter (Wydeven and Dahlgren 1985).

Although mule deer cover requirements are not well

understood, current guidelines estimate that 40 percent

of a deer’s use area should be in cover. Hiding cover

for mule deer should be capable of hiding 90 percent

of the standing adult mule deer at a distance of at least

200 feet (61 m). Broken terrain or topographic features are often used as escape cover by mule deer.

Fawning habitat is often found in areas with ground

cover at least 2 to 6 feet (0.6 to 1.8 m) in height. Ground

cover can consist of herbaceous vegetation mixed with

low shrubs or small trees (Towry 1984). In the Badlands National Park in South Dakota, chokecherry habitat was used for fawning sites and early fawn-rearing

activities (Steigers 1981).

Management guidelines

Not all ponderosa pine habitat types in the Black

Hills are suitable mule deer habitat. Mule deer use of

open shrubby habitats, riparian woodlands, aspen forests, and edges of forest and meadow areas indicate

the need to maintain these habitats where they occur

within the Black Hills landscape. Since the majority

of mule deer diet throughout the year comes from

woody plants, enhancement of browse is key to providing sufficient forage. Open habitats and browse

availability can be maintained through prescribed burning. Mule deer seem to prefer foraging in burned areas, most likely due to the increased nutrient content

and palatability of forage. Fire can be used to stimulate browse, creating openings in dense forests, and

create mosaics of forage and cover habitat (Gruell 1986;

USDA Forest Service 2002a). Since mule deer share

winter range with livestock, care should be taken that

these areas are not over grazed and damaged (Wyoming Game and Fish Department 1985).

Providing sufficient security cover for mule deer

can help minimize human related disturbance. Close

proximity of forage and cover areas can reduce energy expenditures for travel and foraging. Mule deer

frequently use draws and riparian zones to travel,

indicating the need for maintenance of these areas

(Wyoming Game and Fish Department 1985). Guidelines for mule deer hiding cover call for vegetation

that is capable of hiding 90 percent of a standing

adult deer from the view of a human at a distance of

at least 200 feet (61 m) (Thomas and others 1979).

Providing patches of young stands and managing

these stands with thinning operations that maintain

low crowns for extended periods of time can provide suitable security cover. Maintenance of areas

with low crowns and ground cover at least 2 to

6 feet (0.6 to 1.8 m) in height will also provide mule

deer fawning habitat.

As with elk habitat, use of irregularly spaced, uneven-aged or multiaged management can maintain and

enhance ponderosa pine forests for mule deer habitat.

The requirement to maintain open stands for shrub production will require the sacrifice of some timber yield,

however.

Merriam’s Turkey

(Meleagris gallopavo merriami)

Merriam’s turkeys are not native to the Black Hills,

but are an important game species. Eight turkeys from

New Mexico were introduced into the Black Hills in

March 1948 for hunting purposes. In 1950, 15 turkeys

from Colorado were released and in 1951, 6 more turkeys from New Mexico were released (Petersen and

Richardson 1975). By 2000, the population of turkeys

in the Black Hills (South Dakota region only) was estimated to be around 16,000 (South Dakota Game Report 2000).

Habitat requirements

Most turkey populations in the Black Hills begin

nesting in late April (Rumble and Hodorff 1993). Nesting attempts are positively related to precipitation from

April to June and turkeys may attempt to nest up to three

times throughout this period. Nest survival generally increases from first attempt to third attempt. An average

turkey clutch size is 9.2 eggs with 86 percent of the eggs

hatching successfully (Rumble and Hodorff 1993).

Because reproductive success is one of the many

important features for population stability, the quality

of nesting habitat can greatly affect the turkey population (Rumble and Hodorff 1993). Successful turkey

nests are generally found on slopes 30 to 40 percent

regardless of aspect in moderately open ponderosa pine

forests with average basal area of 85 ft2 per acre

(19.4 m2 per hectare) and 451 trees per acre (1,116 trees

per hectare) (Rumble and Hodorff 1993). Turkeys show

preference for nesting in areas that have not been cut

or recently thinned (precommerical and commercial)

within the past 2 years. Seed-tree cuts are infrequently

used and clearcuts are never utilized for nesting habitat. Nest overstory coverage is often greater than

77 percent and often consists of shrubs such as common juniper or the combination of western snowberry,

chokecherry, and Wood’s rose. Horizontal cover within

5 feet (1.5 m) of the nest sites should be at least 9 inches

(23 cm) tall. Required horizontal cover decreases rapidly within the first 16 feet (5 m) from the nest to

4 inches (10 cm) high (Rumble and Hodorff 1993).
USDA Forest Service General Technical Report RMRS-GTR-97. 2002 57

Within a few days after eggs hatch, hens often move

the poults up to 2 miles (3.5 km) to brood-rearing habitats, even if suitable habitat is close to the nesting site

(Rumble and Anderson 1993a). Hens with poults less

than 7 weeks old are typically found in natural openings with abundant herbaceous vegetation (Rumble and

Anderson 1993a). Meadows with herbaceous vegetation provide a high abundance of invertebrates (Rumble

1990; Rumble and Anderson 1993a, 1996a), which

provide large amounts of protein required by poults

for proper growth and survival (Robbins 1983). Meadows range in size from 5 to 465 acres (2 to 188 ha) and

are usually within 33 feet (10 m) of a dense (greater

than 100 ft2 per acre; 23 m2 per hectare) forest (Rumble

and Anderson 1993a). Although young poults usually

use western snowberry for hiding cover, older poults

(more than 7 weeks) utilize the dense forested stands

(Rumble and Anderson 1993a, 1996b).

From late spring to summer, turkeys forage in ponderosa pine habitats with low basal areas and large

amounts of understory cover consisting of grasses,

forbs, and shrubs (Rumble and Anderson 1996b). Turkeys are also found in aspen/paper birch habitats, which

contain an abundance of grasses, forbs, and shrubs

(Rumble and Anderson 1993b). From May to September, turkeys consume herbaceous foliage, grass

seed, forb seed, forb flowers, and insects (Rumble and

Anderson 1996a). Smooth brome seeds dominate the

diet from June to September. Peak consumption of forb

seeds and flowers occurs during periods of flowering

in spring and autumn. Insect consumption increases

during early summer and declines after August. In times

of drought, turkeys will increase their consumption of

soft mast and arthropods (Rumble and Anderson

1996a). In years of good bur oak mast production, turkeys can be found in bur oak habitats for 2 to 4 weeks

in September and October.

In early fall, turkeys can still be found in the aspen/

paper birch habitat, as well as open ponderosa pine

habitats (Rumble and Anderson 1993b). By October,

however, turkeys move to dense ponderosa pine habitats with overstory canopy cover greater than 71 percent and basal areas greater than 140 ft2 per acre (32 m2

per hectare). From October to April, ponderosa pine

seed and bearberry seeds, which can be found in great

abundance under dense ponderosa pine habitats, make

up the majority of a turkey’s diet (Rumble and

Anderson 1993b, 1996b). In years of a poor ponderosa pine cone crop, a greater proportion of bearberry

fruit and grass leaves and seeds comprise the turkey

diet throughout the winter (Rumble and Anderson

1996a), and stands with lower basal area and more understory vegetation are preferred.

Roosting trees provide perches and a resting place

for turkeys, and are an important habitat component

for sustaining turkey populations (Hoffman and others

1993; Rumble 1992). In the Black Hills, turkeys select

roost sites that have trees with large d.b.h., low tree

density, and high basal area (Rumble 1992). Roost

trees averaged 13.8 inches (35 cm) d.b.h., but trees

9 inches (23 cm) d.b.h. or greater were used. Average

basal area of roost sites ranged from 82.8 ft2 per acre

to 109 ft2 per acre (19 to 25 m2 per hectare). Trees with

layered horizontal branches spaced at 2- to 3- foot intervals that allow easy access for turkeys were characteristic of roost trees (Hoffman and others 1993;

Rumble 1992). Roosts were usually located near the

tops of slopes or on ridges. Roosts with western and

northern aspects were located on the lower portions of

slopes, while roosts on eastern or southern aspects were

found on upper slopes. Selected roost sites had limited or no recent timber activity within the past 5 years

(Rumble 1992).

Management guidelines

The key to providing Merriam’s turkey habitat is

to have a diversity of structural and stocking conditions within the Black Hills ponderosa pine landscape. Merriam’s turkeys utilize different structural

habitats for nesting, brood rearing, roosting, and

foraging. Broods are reared in open meadows adjacent to dense ponderosa pine forests. Nesting habitat is found in open stands, with an understory component that provides cover. Summer habitats are

found in open ponderosa pine and aspen stands with

low canopy coverage. Winter habitats typically consist of dense, mature ponderosa pine stands with high

canopy coverage. The use of these different habitats

by Merriam’s turkey throughout the year enables

managers to utilize various silvicultural treatments

to manage and create the structural stages needed.

Rumble and Hodorff (1993) suggest that nest site

availability does not appear to limit Merriam’s turkey

populations in the Black Hills, and that specific management to enhance nest site availability is not necessary. However, suitable nesting habitat consisting of

moderately open ponderosa pine forests with average

basal area of 85 ft2 per acre (19.4 m2 per hectare) and a

shrubby understory should be maintained.

Providing suitable habitat for poults is key for maintaining turkey populations. Poults younger than 7

weeks old prefer meadows and openings with large

amounts of herbaceous vegetation. Hoffman and others (1993) suggest that the openings should be long

and narrow with an irregular edge, and not exceed 240

feet (73 m) in width. Dense ponderosa pine stands
58 USDA Forest Service General Technical Report RMRS-GTR-97. 2002

(greater than 100 ft2 per acre or 23 m2 per hectare)

should be left along the meadow edges to provide escape and loafing cover for the hens (Rumble and Anderson 1993a). Trees encroaching into small openings or

natural meadows and slash from a created opening

should be removed promptly to encourage quick herbaceous vegetation recovery. Because poults require

at least 1,200 lb per acre (1,345 kg per hectare) of herbaceous vegetation along forest/meadow edges

(Rumble and Anderson 1996c), grazing by livestock

should be monitored (Rumble and Anderson 1993a).

Grazing should not exceed 50 percent of the herbaceous vegetation, and be prohibited during drought

years. A rest-rotation grazing system is recommended

because moderate grazing does stimulate new herbaceous

growth, but re-entry into a previously rested pasture should

be delayed until July 15 (Hoffman and others 1993).

Summer habitats should have low basal area to maintain high production levels of grasses, forbs, and shrub.

Ponderosa pine stands with basal area around 61 to

78.4 ft2 per acre (14 to 18 m2 per hectare) are consistent with habitats chosen by turkeys without poults

(Rumble and Anderson 1993b). Although the use of

seed-tree regeneration harvests, which typically leave

basal areas less than 39 ft2 per acre (9 m2 per hectare),

should not impact summer habitats (Rumble and Anderson 1996a), care should be taken not to degrade nesting habitat (Rumble and Hodorff 1993).

Most limiting to the turkey population in the Black

Hills is the availability of winter habitat. Winter habitats should be abundant and well distributed at the lower

elevations and on southern aspects because snow depth

limits the turkey’s foraging ability. Ponderosa pine trees

that are greater than 9.8 inches (>25 cm) d.b.h. provide better winter habitat than smaller trees with comparable overstory cover (Rumble and Anderson 1995).

Silvicultural management that reduces stands to basal

areas less than 78 ft2 per acre (18 m2 per hectare) will

decrease the quality of winter habitat (Rumble and

Anderson 1996b). Providing some ponderosa pine

habitat with overstory canopy coverage greater than

70 percent and basal area greater than 139 ft2 per acre

(>32 m2 per hectare) will ensure quality winter habitat

(Rumble and Anderson 1993b). Mature, seed-bearing

ponderosa pine trees should be maintained to provide

winter forage.

Management of roost sites should be based on roost

sites, rather than individual roost trees. Roosting habitat

should be dispersed throughout the forest and can be

located in dense winter habitat (Rumble 1992). Timber management that reduces stands to growing stock

levels of less than 96 ft2 per acre (22 m2 per hectare)

and tree diameters of less than 9.8 inches (<25 cm)

will degrade roosting habitat. Maintaining portions of

the forest with basal areas greater than 91.5 ft2 per acre

(21 m2 per hectare) with tree diameters that average

from 9.8 to 13.8 inches (25 to 35 cm) should be adequate for roosting habitat. Mixed ponderosa pine/

white spruce forests greater than 9.8 inches (>25 cm)

d.b.h. and greater than 40 percent canopy cover also

provide suitable roosting habitat (Rumble and Anderson 1995). Stands managed for roost sites should be

situated on the upper third of a slope with layered horizontal branches (Rumble 1992) and be located on easterly aspects (Hoffman and others 1993).

Enhancement of deciduous tree habitats, such as

aspen and bur oak, is important for nesting habitat,

escape cover, and forage. Mature bur oak stands provide nutritious acorn mast. These bur oak stands should

be maintained at basal areas greater than 35 ft2 per acre

(> 8 m2

 per hectare) and should be adjacent to ponderosa pine stands that have basal areas greater than 80

ft2

 per acre (>18.4 m2 per hectare). Restoration of aspen stands will increase forage and provide sufficient

escape and nesting cover.

High road densities and the frequent use of them by

humans can cause turkeys to abandon some habitats.

Hoffman and others (1993) suggest that roads should

be eliminated from meadows wherever possible, and

necessary new roads placed along the edge of openings to minimize disturbance.

Northern Goshawk

(Accipiter gentiles atricapillus)

The northern goshawk occurs throughout North

America in coniferous and mixed forests. Concern that

the goshawk population may be declining in the Western United States has lead the U.S Forest Service to

designate the goshawk as a sensitive species and

management indicator species for the Black Hills as

well as other areas in the West (Reynolds and others

1992; USDA Forest Service 1996c, 2001b). As a result of this designation, management recommendations

for the northern goshawk were developed for the Southwestern Region of the Forest Service (Arizona, New

Mexico) by a scientific committee (Reynolds and others 1992). These authors identified three critical components of goshawk nesting home range (about 6,000

acres; 2,400 ha): nest area (30 acres; 12 ha), post-fledging family area (420 acres; 170 ha), and foraging area

(5,400 acres; 2,185 ha) (Reynolds and others 1992).

This forage-based habitat management guideline identifies forest structural characteristics for goshawk nesting, post-fledging, and foraging habitats (Reynolds and

others 1992).
USDA Forest Service General Technical Report RMRS-GTR-97. 2002 59

One concern is that the management recommendations for the goshawk in the Southwestern United

States. are applicable only to forests for that region.

Specifically, ponderosa pine in the Southwestern

United States differs from the Black Hills ponderosa

pine forest in structure, disturbance regimes, precipitation patterns, and site productivity. Furthermore, only

two studies have briefly investigated goshawk ecology in the Black Hills (Bartelt 1977; Erickson 1987).

Adaptation of southwestern guidelines to fit the Black

Hills ecosystem is needed as well as further studies on

goshawk ecology in the Black Hills to ensure proper

management.

Habitat requirements

Nesting habitat has been suggested as an important

component of goshawk management (USDA Forest

Service 2000, 2001b). The goshawk nest area is approximately 30 acres (12 ha) and may include more

than one nest (Reynolds and others 1992). Suitable nesting habitat for the goshawk is essential for reproductive success since goshawks have high site fidelity and

may still use lower quality habitat and not produce

young (USDA Forest Service 2000). In addition, all of

the actions and behaviors associated with courtship,

incubation, and the nestling stage occur in the nest area

(Kennedy and others 1994; Reynolds and others 1992).

A number of factors have been identified for goshawk nest site selection in the Black Hills (Bartelt

1977; Erickson 1987). Goshawk nest sites in the

Black Hills have been found in mature ponderosa

pine, white spruce, or near stands of maturing aspen, but only mature ponderosa pine were actually

selected as nest trees (Bartelt 1977; Erickson 1987).

Tree sizes at nest sites ranged from 8 to 20 inches

(20 to 51 cm) d.b.h. with a mean of 16 inches (41

cm) (Bartelt 1977; Erickson 1987). Nest trees ranged

from 12 to 23 inches (31 to 58 cm) and were usually

the largest trees in the stand (Erikson 1987). Nest

site locations contained over 120 ft2 per acre (27.5

m2 per hectare) basal area with average canopy closure of 70 percent. Although nest sites were found

in dense forests, they are often in close proximity to

forest openings or roads. Bartelt (1977) reported

approximately half of the nests he located were

within 33 ft (10 m) of a 0.125 to 0.250 acre (0.05 to

0.10 ha) opening. Most nest sites were on gentle

(less than 15 percent) west to northeast slopes, above

elevations of 5,085 feet (1,550 m), within 0.75 mile

(1.25 km) of open water, and included dead and down

woody material (Bartelt 1977; Erikson 1987).

The impact of human activities such as logging, tourism, and road traffic on nesting habitat in the Black

Hills is unclear. The timing of human activity near

nest sites is likely related to the disturbance of nesting

goshawks. Nest abandonment seems to increase with

an increasing amount of disturbance, and the probability of nest abandonment is greatest just before, during,

or just after incubation (Bartelt 1977). Goshawks establish their nest sites in the Black Hills around midto late March. Eggs are laid around mid- to late April,

and eggs hatch around late May. Young goshawks

fledge in the Black Hills around mid- to late July, sometimes later if a nest was reinitiated because the first

nesting attempt failed (Bartelt 1977).

The largest impact from logging on the nest site

would be from the change in forest structure surrounding the nest area (Bartelt 1977). On the North Kaibab

Plateau of Arizona, Reynolds (USDA Forest Service

2000) stated that goshawk fecundity decreased when

seed-tree cuts were within one-half mile (0.8 km) of a

goshawk nest. The use of large machinery in logging

operations might disturb goshawk nesting success, although a study in northern Arizona reported that logging trucks more than 1,300 feet (>400 m) from a nest

site did not disturb the nesting goshawk (Grubb and

others 1998).

The post-fledging family area (PFA) encompasses

approximately 420 acres (170 ha) surrounding the nest

area (Reynolds and others 1992) and is used by the

goshawk from the time the young leave the nest until

they are not reliant on the parents for food (up to 2

months). The PFA provides hiding cover for goshawk

fledglings while providing habitat for prey and foraging opportunities for the adults. The PFA contains a

diversity of seral stages that provide patches of dense,

large trees intermixed with small trees and shrubby

understories for hiding cover. In addition, the well-developed understory and down woody debris provide

habitat for prey populations. The PFA for Black Hills

goshawks has not yet been determined, so guidelines

from other regions must be used until further studies

can be completed.

The tenet of management for foraging areas is

based on providing habitat for the goshawk’s prey

species. The southwestern goshawk guidelines call

for the foraging area to surround both the nest area

and the PFA, and be approximately 5,400 acres

(2,185 ha) (Reynolds and others 1992). The foraging area comprises a variety of landforms, forest

canopy types, and vegetation structural stages. Goshawks need an open understory to detect and capture prey from their tree perches (Reynolds and others 1992). Snags, downed logs, woody debris, openings, large trees, and herbaceous and shrubby understories are all required to provide critical habitat
60 USDA Forest Service General Technical Report RMRS-GTR-97. 2002

for the various birds, small mammals, and invertebrates eaten by the goshawk (Reynolds and others

1992). Providing habitat for the prey and the goshawk will require a mosaic of interspersed vegetative structural stages over a large area.

In the Black Hills, goshawks have been reported to

eat insects, rodents, rabbits, and birds (Bartelt 1977;

Erickson 1987). Specific prey include: red squirrels

(Tamiasciurus hudsonicus), least chipmunks (Tamias

minimus), thirteen-lined ground squirrels

(Spermophilus tridecemlineatus), bushy-tailed

woodrats (Neotoma cineria), voles (Microtus spp.),

white-tailed jackrabbits (Lepus townsendii), Nuttall’s

cottontails (Sylvilagus nuttallii), ruffed grouse (Bonasa

umbellus), northern flickers (Colaptes auratus), blackbacked woodpeckers (Picoides arcticus), three-toed

woodpeckers (Picoides tridactylus), American robins

(Turdus migratorius), Townsend’s solitaire (Myadestes

townsendi), black-headed grosbeaks (Pheucticus

melanocephalus), evening grosbeaks (Coccothraustes vespertinus), gray jays (Perisoreus canadensis), dark-eyed juncos (Junco hyemalis), and

Merriam’s turkey poults (Bartelt 1977; Erickson 1987;

USDA Forest Service 2000).

Management guidelines

Management guidelines for the goshawk in southwestern ponderosa pine and mixed-species forests are

described in great detail in Reynolds and others (1992).

Included in the guidelines are attributes of stand conditions for nest sites, post-fledging family area, and

foraging area, and how to obtain these features with

silvicultural techniques. Additional guidelines are given

concerning habitat attributes required for several goshawk prey species. Similar assessments are needed for

optimum management of goshawk populations in the

Black Hills. Recommendations for management of

goshawk habitat in the Black Hills are currently under

review (USDA Forest Service 2001b).

A balance of coniferous forest structural stages

across the entire landscape was suggested as a longterm solution for providing prey and goshawk habitat

in the Southwestern United States (Reynolds and others 1992) and for the Black Hills region (USDA Forest

Service 2000). The examination of historic conditions and

the range of natural variability of ponderosa pine distribution can aid in defining this balance of structural stages

for the Black Hills region (USDA Forest Service 2000).

Continuous management will be needed to obtain

and maintain the various structural conditions the goshawk requires for all three of the critical habitat components. Management of large areas of the same structural stage should be avoided. Instead, Reynolds and

Graham (personal communication, 2001) feel that small

groups and clumps of trees are a critical component of

the spatial heterogeneity needed for properly functioning goshawk habitat, regardless of the region. These

patches and clumps should vary in size, shape, and

structural stage to mimic natural vegetative patterns

and patch sizes (USDA Forest Service 2000). Retention of at least one green ponderosa pine tree greater

than 20 inches (>51 cm) d.b.h. per acre will aid in providing snags and large-diameter coarse woody debris

for prey species.

Maintaining small groups of trees in the desired mix

of what Reynolds calls Vegetation Structural Stages

(VSSs) will be especially difficult in the higher structural stages that require high canopy closure (Shepperd

and others 2001). Several issues must be considered:

first, the time needed for a stand to grow from one VSS

class to another will vary depending on stocking levels and site class. Second, trees in open-spaced groups

or widely spaced clumps will grow into larger VSS

classes quicker than those in denser clumps. Also, small

open spaces are conducive to rapid seedling establishment in the Black Hills. These seedlings will create a

dense sapling understory, which is not always desirable for goshawk habitat. Managing ponderosa pine

forests for goshawk habitat will thus take continuous

silvicultural activity to establish and maintain the desired mix of VSSs.

Uneven-aged group and irregularly spaced individual-tree selection systems can be well suited to accomplish and maintain these goals. Uneven-aged silviculture systems offer the flexibility to create and

monitor conditions over large areas while minimizing

the need for delineation and record keeping (Shepperd

and others 2001). Under uneven-aged management,

each goshawk territory could be designated as a site,

or audit unit, for record-keeping purposes. Stocking

growth projections of all VSSs in the unit could be

handled as one stand. However, even-aged management of a diverse goshawk habitat would require breaking each group or VSS into a separate stand. Such

stands might need to be as small as a fraction of an

acre to meet goshawk diversity requirements. Breaking the landscape into many small even-aged stands to

accomplish goshawk management objectives would not

guarantee that stocking over the entire habitat would

be regulated, and would infinitely complicate record

keeping and database management.

Nongame Birds

The Black Hills is host to numerous bird species

that are typically found in the Eastern, Western, and
USDA Forest Service General Technical Report RMRS-GTR-97. 2002 61

Northern United States. The location of the Black Hills

in the Northern Great Plains allows this area to host

over 190 species of birds that are either migrants or

permanent year-round residents (American Bird Association 1994). Haldeman (1980) identified some 111

species of nongame birds in the Black Hills National

Forest, and developed habitat matrices based on vegetation type and successional stages within these types.

Since bird communities are influenced by vegetative

structure, several studies have investigated the effects

of timber harvests on bird populations in the Black Hills

(Dykstra 1996; Dykstra and others 1999; Mills 1994).

These studies have aided in the development of habitat capability models (HABCAP) for the Black Hills

National Forest to help predict consequences of land

management decisions on both resident birds (Mills

and others 1996) and wintering birds (Rumble and others 1999).

Composition and structure of vegetative communities influence bird species richness (in other words, the

number of species). In the Black Hills, bird species

richness is highest in stands of pure aspen and aspen

with limited ponderosa pine (less than 10.5 ft2 per acre;

<2.4 m2 per hectare), while stands of pure ponderosa

and stands dominated by ponderosa pine with some

aspen have slightly lower bird species richness (Mills

1994; Mills and others 2000; Rumble and others 2001).

Although species richness was not shown to differ

significantly among ponderosa pine structural stages,

bird composition does differ among the structural stages

(Dykstra 1996; Dykstra and others 1999; Mills 1994;

Mills and others 2000). Individual bird species are

adapted to specific habitat structures that allow successful foraging and nesting. Timber harvests that reduce the amount of tree foliage within a forest can negatively affect birds that depend on crown vegetation for

nesting and foraging (Szaro and Balda 1979). However, the same process of losing foliage and biomass

to timber harvests can benefit other species of birds

that prefer open or edge habitats. Thus, understanding

how tree density and coverage influence bird abundance will allow land managers to manipulate forested

stands to encourage or discourage the presence of different bird species (Dykstra 1996).

The following species discussions include some representative ground, foliage, and cavity nesters that utilize ponderosa pine, aspen, and mixed ponderosa pine/

aspen habitats within the Black Hills, although some

bird species do use white spruce habitats. Residency

and possible HABCAP coefficient references for the

bird species discussed in the following section are listed

in table 4. Vegetative structural stages listed in the

following bird discussion are based on the Buttery and

Gillam (1984) classification scheme; refer to table 3

for diameters and crown coverage values, as well as a

crosswalk for current structural guidelines now applied

in the Black Hills National Forest and other Forest

Service regions.

Ground nesters

Dark-eyed Junco—The dark-eyed junco (Junco

hyemalis) is found in all structural stages of ponderosa

pine and aspen/paper birch forests throughout the year,

but abundance is highest in open-canopied forests of

ponderosa pine (3A and 4A) and aspen (3A) (Dykstra

and others 1999; Mills 1994; Mills and others 1996,

2000; Rumble and others 2001). Abundance of darkeyed juncos declines in both forested habitats as overstory cover increases (Mills and others 1996, 2000).

During the summer, abundance in the shrub-seedling

(2) stage of aspen/paper birch is high. In the winter,

however, use declines significantly (Rumble and others 1999). Dark-eyed juncos build their nests on the

ground or occasionally up to 8 feet (2.4 m) above

ground in a shrub or tree. Nests on the ground are

often concealed under herbaceous vegetation or largediameter woody debris. Most food is obtained from

the ground and includes some insects, but mostly seeds

(DeGraaf and others 1991).

MacGillivray’s Warbler—The MacGillivray’s

warbler (Oporornis tolmiei) is considered an aspen/

paper birch obligate (Mills and others 2000; Rumble

and others 2001) and prefers open canopied stands

or low- to intermediate-density forests with a shrub

understory (DeGraaf and others 1991). Abundance

is highest in the sapling-pole (3A) aspen/paper birch

habitat, with moderate use of sapling-pole (3B) and

shrub/seedling (2) aspen/paper birch stands (Mills

and others 1996, 2000). This warbler also uses habitats with serviceberry, snowberry, ninebark, wild

spirea, and riparian willows (Salix spp.) and alders

(Alnus spp.) (DeGraaf and others 1991). Ponderosa

pine stands and meadows were not chosen by the

MacGillivray’s warbler (Mills and others 1996). The

MacGillivray’s warbler builds nests 2 to 5 feet (0.6

to 1.5 m) off the ground attached to plant stems in

brushy habitat. It forages close to the ground, eating insects gleaned from vegetation (DeGraaf and

others 1991).

Ovenbird—Ovenbirds (Seiurus aurocapillus) are

found mostly in aspen/paper birch habitats and in ponderosa pine stands with deciduous components

(Dykstra and others 1999; Mills 1994; Mills and

others 2000; Rumble and others 2000b, 2001). In aspen/paper birch habitats, abundance is highest in sapling-pole (3B and 3C) stands with moderate to high
62 USDA Forest Service General Technical Report RMRS-GTR-97. 2002

canopy coverage (Mills 1994; Mills and others 1996,

2000). Ovenbirds are also found in mature (4C) and

multistoried/old growth (5) ponderosa pine stands with

a deciduous component (Dykstra and others 1999; Mills

1994; Mills and others 2000; Rumble and others 2001).

Ovenbirds build nests that look like a Dutch oven.

These nests are often located in a small depression in

the ground near the roots of a tree or by the side of a

fallen log. It gleans insects, small snails, slugs, earthworms, and spiders from the forest floor (DeGraaf and

others 1991).

Virginia’s Warbler—A breeding population of the

Virginia’s warbler (Vermivora virginiae) was recently

found in the southwestern region of the Black Hills.

This population is the most northeasternmost known

breeding population and extends the breeding range

by over 125 miles (200 km). The birds were found in

a pine-juniper-shrub habitat that was relatively dense

with shrubs, steep, and among medium to large ponderosa pine trees (Swanson and others 2000). Virginia’s

warblers are ground nesters, and often conceal the nest

with overhanging vegetation (DeGraaf and others

1991). Insects are foraged on the ground and foliage.

Insects are also caught by hawking, a foraging technique in which a bird attacks from a perch on short

flights to capture flying prey (DeGraaf and others

1991).

Townsend’s Solitaire—Townsend’s solitaires

(Myadestes townsendi) utilize the sapling-pole, mature,

and multistoried/old growth structural stages of

Table 4: Residency and available habitat capability (HABCAP) models for birds found in the Black Hills, South Dakota.

Common name Scientific name Residence HABCAP- summer HABCAP- winter

Ground nesters

Dark-eyed junco Junco hyemalis Permanenta Mills and others 1996 Rumble and others 1999

MacGillivray’s warbler Oporornis tolmiei Neotropicalb Mills and others 1996 n/a

Ovenbird Seiurus aurocapillus Neotropicalb Mills and others 1996 n/a

Virginia’s warbler Vermivora virginiae Neotropicalc Not developed n/a

Townsend’s solitaire Myadestes townsendi Permanenta Mills and others 1996 Rumble and others 1999

Foliage nesters

Gray jay Perisoreus canadensis Permanenta Mills and others 1996 Rumble and others 1999

Yellow-rumped warbler Dendroica coronata Summera Mills and others 1996 n/a

Western tanager Piranga ludoviciana Neotropicala Mills and others 1996 n/a

Chipping sparrow Spizella passerina Summera Mills and others 1996 n/a

Pine siskin Carduelis pinus Permanenta Not developed Not developed

Red crossbill Loxia curvirostra Wintera n/a Rumble and others 1999

Swainson’s thrush Catharus ustulatus Neotropicala Not developed n/a

Ruby-crowned kinglet Regulus calendula Neotropicala Mills and others 1996 n/a

American robin Turdus migratorius Summera Mills and others 1996 n/a

Dusky flycatcher Empidonax oberholseri Neotropicalb Mills and others 1996 n/a

Warbling vireo Vireo gilvus Neotropicala Mills and others 1996 n/a

Cavity nesters

Brown creeper Certhia americana Permanenta Not developed Not developed

Mountain bluebird Sialia currucoides Summera Mills and others 1996 n/a

Black-capped chickadee Parus atricapillus Permanenta Mills and others 1996 Rumble and others 1999

Northern flicker Colaptes auratus Summera Mills and others 1996 n/a

Lewis’ woodpecker Melanerpes lewis Summerc Not developed n/a

Black-backed woodpecker Picoides arcticus Permanenta Not developed Not developed

Downy woodpecker Picoides pubescens Permanenta Not developed Not developed

Three-toed woodpecker Picoides tridactylus Permanenta Not developed Not developed

Hairy woodpecker Picoides villosus Permanenta Mills and others 1996 Rumble and others 1999

Red-naped sapsucker Sphyrapicus nuchalis Summera Mills and others 1996 n/a

Red-breasted nuthatch Sitta canadensis Permanenta Mills and others 1996 Rumble and others 1999

White-breasted nuthatch Sitta carolinensis Permanenta Mills and others 1996 Rumble and others 1999

Pygmy nuthatch Sitta pygmaea Permanentc Not developed Not developed

Others

Brown-headed cowbird Molothrus ater Summera Not developed n/a

a South Dakota Ornithologists’ Union (1991).

b Ehrlich and others (1988).

c DeGraaf and others (1991).
USDA Forest Service General Technical Report RMRS-GTR-97. 2002 63

ponderosa pine forests, but their habitat preference

changes between the summer breeding season and winter (Mills and others 1996; Rumble and others 1999).

During the summer, abundance is greatest in the sapling-pole (3A, 3B, and 3C) stage of ponderosa pine,

moderate in the mature (4A, 4B, and 4C) stands, and

lowest in the multistoried/old growth (5) stage of ponderosa pine (Dykstra and others 1999; Mills and others 1996, 2000). However, in winter, abundance is

greatest in mature (4A and 4B) stands, moderate in

multistoried/old growth (5) and mature (4C) stands,

and low in sapling-pole (3A, 3B, and 3C) ponderosa

pine stands (Rumble and others 1999). Abundance in

aspen stands is low; aspen provides low habitat capability in both summer and winter (Mills and others

1996, 2000; Rumble and others 1999). Townsend’s

solitaires build nests on the ground, often hidden at the

base of a tree or among the roots of a fallen tree. During the summer, the Townsend’s solitaire hawks for

flying insects or gleans food from the ground, foliage,

and fruiting stems. During the winter, juniper berries,

seeds, and other fruits are eaten (DeGraaf and others

1991).

Foliage Nesters

Gray Jay—Gray jays (Perisoreus canadensis) utilize the sapling-pole, mature, and multistoried/old

growth structural stages of ponderosa pine forests, but

their habitat preference changes between the summer

breeding season and winter (Mills and others 1996;

Rumble and others 1999). In the summer, optimal habitat includes mature (4B and 4C) and multistoried/old

growth (5) ponderosa pine (Mills and others 1996,

2000). In the winter, optimal habitat for gray jays is

found in the mature (4C) ponderosa pine stands, although sapling-pole (3C) and mature (4B) ponderosa

pine stands are utilized (Rumble and others 1999).

Nests are typically well concealed under heavy cover

near the trunk about 10 to 30 feet (3 to 9 m) above the

ground (DeGraaf and others 1991). Gray jays are

omnivorous and eat insects, conifer seeds, berries,

young birds, small mammals, lichens, fungi, and carrion (DeGraaf and others 1991).

Yellow-rumped Warbler—Yellow-rumped warblers (Dendroica coronata) are one of the most common species within all ponderosa pine structural stages

(Dykstra and others 1999; Mills 1994; Mills and others 2000), but abundance declines as coniferous tree

density and overstory cover decreases (Mills and others 1996, 2000). Abundance is low in the aspen/paper

birch habitats (Mills and others 1996), although this

habitat is utilized more frequently when a small component of ponderosa pine is present (Rumble and

others 2001). The yellow-rumped warbler builds its

nest away from the tree bole on a horizontal branch

about 15 to 20 feet (4.6 to 6.1 m) off the ground. The

nest is usually screened from above by clumps of

needles. Food is obtained by gleaning insects from

foliage or hawking (Szaro and Balda 1979).

Western Tanager—In the northern Black Hills, the

western tanager (Piranga ludoviciana) is most common in mature (4B and 4C) and multistoried/oldgrowth (5) ponderosa pine forests (Mills and others

2000). In the central Black Hills, they prefer

multistoried (5) ponderosa pine stands, partially due

to the bur oak and aspen/paper birch understory (Mills

and others 2000). Moderate numbers of western tanagers are found in sapling-pole (3B) and mature (4A

and 4B) ponderosa pine stands (Mills and others 1996,

2000). Western tanagers are also found in aspen habitats with a small amount of ponderosa pine (Rumble

and others 2001). Western tanagers are sensitive to fragmentation and are typically absent from stands less than

25 acres (<10 ha) in size (Rumble and others 2000).

Nests are built away from the trunk on a horizontal

branch. Its main diet is insects either gleaned from foliage or caught in the air (DeGraaf and others 1991).

Chipping Sparrow—Chipping sparrows (Spizella

passerina) live in both ponderosa pine and aspen/paper birch habitats (Rumble and others 2001). Abundance is highest in sapling-pole (3A, 3B) and mature

(4A, 4B) ponderosa pine stands and aspen/paper birch

(2, 3A and 3B) habitats (Mills and others 2000). Abundance decreases in habitats with dense canopy coverage (greater than 70 percent) and multistoried/old

growth (5) ponderosa pine stands (Dykstra and others

1999; Mills and others 2000). Nests are typically built

in trees about 3 to 10 feet (0.9 to 3 m) above ground

and are well concealed by the foliage. Chipping sparrows are ground foragers, typically found in open

meadows gleaning insects and seeds (DeGraaf and others 1991).

Pine Siskin—Pine siskins (Carduelis pinus) inhabit

ponderosa pine and mixed ponderosa/aspen forests in

the Black Hills (Rumble and others 2001). Pine siskins

have been observed in sapling-pole (3A and 3B), mature (4B and 4C), and multistoried/old growth (5) ponderosa pine stands (Mills 1994; Dykstra and others

1999). Nests are usually covered with foliage on a

branch about 15 to 35 feet (4.6 to 10.7 m) off the

ground. Pine siskins glean insects and seeds from the

ground, foliage, and off bark (DeGraaf and others

1991).

Red Crossbill — The red crossbill (Loxia curvirostra)

is a short-distance migrant that breeds in the Black Hills

during the winter (late December to March) (South
64 USDA Forest Service General Technical Report RMRS-GTR-97. 2002

Dakota Ornithologists’ Union 1991). The red crossbill relies heavily on ponderosa pine seed for its food.

Although ponderosa pine forests with 71 to 100 percent canopy coverage have greater seed production than

less dense forests (Rumble and Anderson 1996b), habitat suitability was shown to decline slightly as canopy

coverage increases above 40 percent in the saplingpole structural stage (Rumble and others 1999). Mature (4A, 4B, 4C) ponderosa pine forests provide some

suitable habitat. Aspen/paper birch habitats with less

than 70 percent overstory canopy coverage are unsuitable habitats. Moderate habitat capability for the aspen/paper birch habitat, with 71 to 100 percent canopy

coverage, depends on the presence of ponderosa pine

(Rumble and others 1999, 2001). Nests are built on

branches of coniferous trees where suitable seed crops

are available (DeGraaf and others 1991).

Swainson’s Thrush—The Swainson’s thrush

(Catharus ustulatus) is found in both ponderosa pine

and aspen/paper birch habitats of the Black Hills (Mills

and others 2000; Rumble and others 2001). Abundance

is limited to mature (4B) and multistoried/old-growth

(5) ponderosa pine stands and sapling-pole (3A, 3B,

3C) aspen/paper birch stands (Dykstra and others 1999;

Mills and others 2000). Nests are built 2 to 20 feet

(0.61 to 6.1 m) off the ground near the bole of a tree on

a horizontal branch. Its diet consists of insects and small

fruits, which are gleaned from the forest floor, foliage,

and branches (DeGraaf and others 1991).

Ruby-crowned Kinglet — Optimal habitat for the

ruby-crowned kinglet (Regulus calendula) in the Black

Hills occurs in mature (4C) and old-growth ponderosa

pine (5) structural stages. Sapling-pole (3A, 3B, and

3C) ponderosa pine structural stages were found to be

unsuitable habitat (Mills and others 1996). These birds

are also found in aspen/paper birch habitats with moderate to dense canopy cover (Mills and others 1996)

and in aspen/paper birch habitats with a small component of ponderosa pine (Rumble and others 2001).

Nests are usually suspended from a branch 15 to 60 feet

(4.6 to 18.3 m) above the ground. Insects and spiders

are its main source of food, and are obtained by gleaning or hawking (DeGraaf and others 1991).

American Robin—American robins (Turdus

migratorius) live in both ponderosa pine and aspen/

paper birch habitats in the Black Hills (Mills and others 2000; Rumble and others 2001). Sapling-pole (3A

and 3C) aspen, sapling-pole (3B) ponderosa pine, and

mature (4B) ponderosa pine stands are used frequently

(Dykstra and others 1999; Mills and others 2000), but

aspen sapling-pole (3B) stands are considered optimal

habitat (Mills and others 1996, 2000). Although meadows do not provide suitable nest sites, they are used

extensively for feeding (Mills and others 1996). Thus,

the juxtaposition of meadows and suitable nesting sites

is an important factor to consider. Nests are built in

trees or shrubs, and mud is required for nest materials.

American robins are ground foragers that eat both fruits

and insects (DeGraaf and others 1991).

Dusky Flycatcher—The dusky flycatcher (Empidonax

oberholseri) is considered an aspen/paper birch obligate (Mills and others 2000) and prefers open canopied stands or low to intermediate density forests with

a shrub overstory (DeGraaf and others 1991). The

shrub-seedling (2) stage of aspen is considered optimal habitat, although all structural stages of aspen provide suitable habitat (Mills and others 1996, 2000).

Ponderosa pine stands and meadows are unsuitable

habitat for the dusky flycatcher (Mills and others 1996;

Rumble and others 2001). This bird usually nests in

the lower portion of a tree, and eats flying insects

(DeGraaf and others 1991).

Warbling Vireo—This aspen/paper birch obligate

inhabits all aspen structural stages (Mills 1994; Mills

and others 2000). The warbling vireo (Vireo gilvus) is

also observed in all structural stages of ponderosa pine,

but most often when the pine is associated with a small

inclusion of aspen (Mills and others 1996; Rumble and

others 2001). This bird nests and gleans most of its

food (insects) from the mid to upper branches of deciduous trees. Nests are built away from the trunk and

usually over 20 feet (greater than 6.1 m) above ground

(DeGraaf and others 1991).

Cavity nesters

Brown Creeper—The brown creeper (Certhia

americana) is classified as a sensitive species by the

U.S. Forest Service Rocky Mountain Region (USDA

Forest Service 2002b). Brown creepers select stands

that are dense and have large-diameter trees (Dykstra

and others 1999; Mills and others 2000; Rumble and

others 1999, 2000). Even in stands within the same

size category, brown creepers will choose stands with

higher densities of large diameter (greater than

15 inches; >38 cm) ponderosa pine (Rumble and others 2000). In the northern Black Hills, brown creepers occur in high abundance in multistoried/old

growth (5) ponderosa pine stands (Dykstra and others 1999). In the central Black Hills, brown creepers are observed in mature (4A, 4B, 4C) and

multistoried (5) ponderosa pine stands, but abundance is highest in the mature (4B and 4C) ponderosa pine stands (Mills and others 2000). The brown

creeper builds nests between loose bark and the trunk

of a live, dead, or dying tree, but will sometimes

utilize a natural or old woodpecker cavity. Most food
USDA Forest Service General Technical Report RMRS-GTR-97. 2002 65

is obtained by exploring tree trunks and branches

for insects and larvae (DeGraaf and others 1991).

Mountain Bluebird—Optimal habitat for the

mountain bluebird (Sialia currucoides) is found in open

habitats such as sapling-pole (3A) and mature (4A) ponderosa pine stands, as well as shrub-seedling (2) and

sapling-pole (3A and 3B) aspen stands (Mills and others 1996, 2000). Rumble and others (2001) observed

this species most often in pure aspen stands. Mountain bluebirds also feed in wet and dry meadows in the

Black Hills (Mills and others 1996), but their abundance in these habitats is limited by suitable nest sites

in adjacent habitats (Mills and others 1996). The availability of suitable snags for cavities can limit mountain bluebird abundance (Mills and others 1996). As a

secondary cavity nester, it usually nests in old woodpecker holes or natural cavities in dead trees. Artificial nest boxes are also utilized. Insects make up the

majority of the mountain bluebird’s diet, and high

perches are an important habitat requirement for the

capture of these insects (DeGraaf and others 1991).

Black-capped Chickadee—The black-capped

chickadee (Parus atricapillus) is abundant in all structural stages of both the ponderosa pine and aspen/paper birch habitats, but is most abundant in multistoried/

old growth (5) ponderosa pine and sapling-pole (3B)

aspen/paper birch habitats (Mills and others 1996,

2000). The black-capped chickadee is a cavity nester

and will either excavate its own nest in soft decayed

wood or use an old cavity of another bird (DeGraaf

and others 1991). As with most cavity nesters, abundance might be dictated by the amount and quality of

snags or advanced wood decay rather than by vegetative structural stage (Mills and others 1996). In winter, black-capped chickadees require suitable cavities

in snags greater than 6 inches (>15 cm) d.b.h. to maintain thermoregulation for roosting (Balda 1970;

Cunningham and others 1980). Insects, seeds, and

fruits are gleaned from the ground up to the tops of

trees (DeGraaf and others 1991).

Northern Flicker—Northern flickers (Colaptes

auratus) utilize both ponderosa pine and aspen/paper

birch habitats in the Black Hills (Mills and others 2000;

Rumble and others 2001). Northern flickers are most

abundant in the shrub-seedling (2) and sapling-pole

(3A-3C) aspen stands and in open mature (4A) ponderosa pine stands (Mills and others 2000). The use of

the shrub-seedling aspen stands is limited to areas with

suitable snags (Mills and others 1996). Northern flickers are also observed in the sapling-pole (3A and 3C),

mature (4B and 4C), and multistoried/old growth (5)

ponderosa pine stands (Dykstra and others 1999; Mills

and others 2000). The use of a variety of structural

stages and vegetative habitat types suggests that northern flicker abundance is probably determined more by

the density of snags, rather than the age or overstory

coverage of a stand (Mills and others 1996). Northern

flickers excavate a new cavity annually in a dead tree

or near the top of a broken-off live tree. Abandoned nests

are typically reused by secondary cavity nesters. Northern flickers are ground foragers that consume seeds, fruits,

and insects, especially ants (DeGraaf and others 1991).

Lewis’ Woodpecker—The Lewis’ woodpecker

(Melanerpes lewis) is listed as a sensitive species by

the U.S. Forest Service Rocky Mountain Region

(USDA Forest Service 2002c). Open mature (4A and

4B) and multistoried/old growth (5) ponderosa pine

forests and burned, partially logged forests are valuable nesting habitat (Saab and Dudley 1998; Tobalske

1997; USDA Forest Service 2000). Saab and Vierling

(2001) reported that conditions created by stand-replacing wildfire in a southwestern Idaho ponderosa pine

forest appeared to be a potential source habitat of

Lewis’ woodpeckers, whereas unburned ponderosa

pine forests appear to be a sink habitat. Large burned

areas are colonized within a year after fire, and abundance increases for several years (USDA Forest Service 2000). Lewis’ woodpeckers require large snags in

an advanced stage of decay to excavate a nest (Raphael

and White 1984; Tobalske 1997). In southwestern

Idaho, nest trees average 18 inches (46.7 cm) in diameter (Saab and Vierling 2001). Lewis’ woodpeckers will

also use natural cavities and old cavities created by

other woodpeckers (USDA Forest Service 2000). Unlike other woodpeckers that obtain food by drilling into

trees, the Lewis’ woodpecker catches insects by hawking from perches in dead trees or stumps (DeGraaf and

others 1991).

Black-backed Woodpecker—The black-backed

woodpecker (Picoides arcticus) is classified as a sensitive species by the U.S. Forest Service Rocky Mountain Region (USDA Forest Service 2002d). The blackbacked woodpecker is a primary cavity nester and requires snags for nesting, foraging, and roosting. The

management of this bird relies on the maintenance of

forest diseases and other mortality-causing agents that

lead to beetle infestations for food and heart rot for

cavities (Goggans and others 1989; Marshall 1992). In

the Black Hills, the black-backed woodpecker is observed in sapling-pole (3A and 3B), mature (4B and

4C) and multistoried/old growth (5) ponderosa pine

stands (Dykstra and others 1999; USDA Forest Service 2000). The black-backed woodpecker forages on

larvae of bark beetles and pupae of wood-boring insects (Clark and others 1989; Marshall 1992; USDA

Forest Service 2000) from tree boles by scaling or
66 USDA Forest Service General Technical Report RMRS-GTR-97. 2002

flaking bark (Bull and others 1986). Populations are

irruptive and abundance is high in areas where insects

proliferate such as stand-replacement burns and beetlekilled areas (Clark and others 1989; USDA Forest Service 2000). Fire suppression and postfire salvage logging can adversely affect this species (Dixon and Saab

2000). However, retaining 42 to 50 snags per acre (104

to 123 snags per ha) greater than 9 inches (greater than

23 cm) d.b.h. in clumps can minimize the impact of

postfire salvaging (Wisdom and others 2000).

Downy Woodpecker—Abundance of the downy

woodpecker (Picoides pubescens) throughout the

year is similar across structural stages and canopy

coverage of both ponderosa pine and aspen stands

(Mills and others 2000; Rumble and others 1999,

2001). This cavity nester, which rarely reuses an old

cavity or cavities of other birds, will excavate a new

cavity each year near the top of a dead tree, or in a

live tree if heartrot is present. The abundance and

distribution of suitable snags is probably most

important in determining habitat suitability. The majority of its diet is wood-boring larvae, which are

obtained by excavating and drilling into the bark of

trees (DeGraaf and others 1991).

Three-toed Woodpecker—The three-toed woodpecker (Picoides tridactylus) is classified as a sensitive species by the U.S. Forest Service Rocky Mountain Region (USDA Forest Service 2002e). The threetoed woodpecker chooses mature (4) and multistoried/

old growth (5) ponderosa pine and white spruce stands

(USDA Forest Service 2000). Recently burned areas

or areas infested with bark beetles, disease, or heart

rot provide foraging and nesting habitat (Goggans and

others 1989; USDA Forest Service 2002e). This primary cavity nester excavates nests each year in large

diameter (9 to 20 inches; 23 to 51 cm) dead or live

trees that have heartrot (Clark and others 1989;

Goggans and others 1989; Scott 1980). Once the threetoed woodpecker abandons the nest, it is often used by

a variety of secondary cavity-nesting species (Finch

1991). Three-toed woodpeckers forage on wood-boring beetle larvae, and are attracted to areas with high

concentration of beetles (USDA Forest Service 2000;

Villard 1994).

Hairy Woodpecker—Hairy woodpeckers (Picoides

villosus) utilize both ponderosa pine and aspen/paper

birch habitats in the Black Hills throughout the year

(Mills and others 1996, 2000; Rumble and others 1999,

2001). Hairy woodpecker abundance is generally highest in the open to moderate canopy coverage stands of

sapling-pole (3A and 3B) and mature (4A and 4B)

stands of ponderosa pine. In addition, abundance is

high in multistoried/old growth (5) ponderosa pine and

in the moderate to high canopy coverage of saplingpole (3B and 3C) stands of aspen/paper birch (Dykstra

and others 1999; Mills and others 1996, 2000). The

similarities of hairy woodpecker abundance among

vegetation types and canopy coverages is most likely

associated with the availability of suitable snags rather

than the structural stage of the stand (Mills 1994; Mills

and other 1996). For instance, the occurrence of hairy

woodpeckers in the shrub-seedling (2) stage of aspen

was related to the presence of snags (Mills and others

1996). Hairy woodpeckers excavate nests in live or

dead ponderosa pine and aspen trees greater than 10

inches (>25 cm) d.b.h.. Live trees typically have

heartrot present (DeGraaf and others 1991). An important habitat requirement for this species is largediameter woody material for forage (Rumble and others 1999). Its main food source, wood-boring beetles,

is obtained by excavating and drilling holes into the

bark of trees. It also eats nuts, fruits, and other insects

(DeGraaf and others 1991).

Red-naped Sapsucker—This medium-sized

woodpecker (Sphyrapicus nuchalis) is considered an

aspen/paper birch obligate in the Black Hills, although it does utilize ponderosa pine forests (Dykstra

and others 1999; Mills and others 2000; Rumble and

others 2001). The red-naped sapsucker creates nests

in live aspen trees, especially ones that are susceptible to heart rot (Crockett and Hadow 1975). Rednaped sapsucker abundance is related to suitable

snag availability. Mills and others (2000) reported

that structural stages with at least four aspen/paper

birch snags greater than 6 inches (>15 cm) in diameter per acre (11 snags per ha) had a high red-naped

sapsucker abundance. Furthermore, Daily (1993)

suggests that the degree of heart rot is more

important in determining habitat capability than the

vegetative structural stage. In the Black Hills, rednaped sapsucker abundance is highest in sapling-pole

(3B and 3C) aspen stands, although some are found

in the other structural stages of aspen (Mills and others 1996, 2000). Red-naped sapsuckers are also

found in mature (4C) and multistoried/old growth

(5) ponderosa pine stands (Dykstra and others 1999;

Mills and others 1996). Red-naped sapsuckers drill

rows of holes through the outer bark of trees and eat

the tree sap and cambium. They also eat the insects

that are attracted to these holes (DeGraaf and others

1991).

Red-breasted Nuthatch—The red-breasted

nuthatch (Sitta canadensis) is found at higher elevations during summer and in lower elevation ponderosa

pine and deciduous forests during winter (Haldeman

1980; South Dakota Ornithologists’ Union 1991).
USDA Forest Service General Technical Report RMRS-GTR-97. 2002 67

Throughout the year, red-breasted nuthatches are most

abundant in mature (4B and 4C) and multistoried/oldgrowth (5) ponderosa pine stands (Crompton 1994;

Dykstra and others 1999; Mills 1994; Mills and others

2000; Rumble and others 1999). Red-breasted

nuthatches are also found in sapling pole (3) ponderosa pine stands with the highest abundance in areas

with high canopy coverage (Mills 1994; Mills and others 2000). Sapling-pole aspen/paper birch habitats also

provide some habitat, especially in areas with high

canopy coverage and where ponderosa pine is present

(Mills and others 1996; Rumble and others 2001). The

red-breasted nuthatch nests in natural cavities, old

woodpecker cavities, or excavates its own in soft snags

(DeGraaf and others 1991). The high abundance of redbreasted nuthatches in mature and multistoried/old

growth ponderosa pine forests is most likely related to

its diet and need for large-diameter snags for nests

(Mills and others 2000). Ponderosa pine seed makes

up the majority of the red-breasted nuthatch’s diet, and

seed production in ponderosa pine stands is highest in

areas with increased basal area and canopy coverage

(Rumble and Anderson 1996b).

White-breasted Nuthatch — Both coniferous and

mixed coniferous/deciduous forests can provide habitat for the white-breasted nuthatch (Sitta carolinensis)

(Mills and others 1996, 2000; Rumble and others 2001).

Abundance during the summer is greatest in saplingpole (3B) and mature (4B) ponderosa pine stands

(Dykstra and others 1999; Mills 1994; Mills and others 1996, 2000). In winter, multistoried/old growth (5)

and ponderosa pine stands with more than 70 percent

canopy coverage provide moderate quality habitat.

Open bur oak habitats provide the best habitat for whitebreasted nuthatches during the winter (Rumble and

others 1999). White-breasted nuthatches are secondary cavity nesters, and use natural cavities or old woodpecker cavities (DeGraaf and others 1991). Food is

obtained by gleaning insects from the bark of trees and

seeds from the ground. In the fall and winter, acorn

mast is an important food source (DeGraaf and others

1991).

Pygmy Nuthatch—The pygmy nuthatch (Sitta

pygmaea), found in the lower elevations of the southern and eastern sections of the Black Hills, has been

classified by the Rocky Mountain Region of the Forest Service as a sensitive species (USDA Forest Service 1996c). The pygmy nuthatch is associated with

mature (4A and 4B) and old growth (5) ponderosa pine

forests with canopy coverage less than 70 percent

(Clark and others 1989). The pygmy nuthatch is a primary cavity nester and requires soft snags and old trees

over 19 inches (>48 cm) d.b.h. for nesting (Clark and

others 1989; DeGraaf and others 1991). Since pygmy

nuthatches are communal nesters, clumps of snags

would benefit the population. In Arizona, Scott (1979)

reported pygmy nuthatch populations declined in

thinned stands where snags were removed, but were

stable in adjacent thinned stands where snags were

conserved. Clark and others (1989) suggest three to

five snags per acre (8 to 12 snags per ha) that are at

least 19 inches (48 cm) d.b.h. for roost cavities. Insects are its primary food source, but it also consumes

conifer seeds (DeGraaf and others 1991). Food is obtained by gleaning insects from the bark of trees or

hawking insects from the air.

Others

Brown-headed Cowbird—The brown-head cowbird (Molothrus ater) does not build its own nest; instead, it lays its eggs in the nests of other songbirds.

Some authors attribute recent declines in songbird

populations to parasitism of nests by the brown-headed

cowbird (Whitcomb and others 1981). In the Black

Hills, the brown-headed cowbird is less abundant than

most permanent resident species (Mills 1994). Abundance is similar among all structural stages of ponderosa pine and aspen, as well as all the canopy coverage

categories (Dykstra and others 1999; Mills and others

2000; Rumble and others 2001). Brown-headed cowbirds eat insects and seeds gleaned from the ground

(DeGraaf and others 1991).

Management guidelines

Managers concerned with sustaining and increasing Black Hills bird diversity should start by maintaining within- and between-stand structural diversity to

provide for habitat needs of birds during both the breeding season and the winter (DellaSalla and others 1996;

Huff and others 1991; Mills and others 2000). Ponderosa pine forests that have deciduous components such

as bur oak or aspen can provide more habitats for some

wildlife species than are typically found in a monotypic coniferous stand (Dykstra 1996; Glenn-Lewin

1977; Mills and others 2000; Rumble and others 2001).

Cavity nesters comprise 30 percent of the breeding

bird richness in the central Black Hills (Mills and others 2000). Some cavity nesters that require large snags,

such as the pygmy nuthatch and brown creeper, might

be negatively impacted if snag guidelines do not provide for them (Dykstra 1996). Distribution, abundance,

and condition of snags as well as deciduous trees beneath the ponderosa pine canopy should be included

in forest inventories to better quantify habitats for these

birds (Mills and others 2000). Snag data should be

stratified by vegetation structural stage to ensure
68 USDA Forest Service General Technical Report RMRS-GTR-97. 2002

adequate snag density and size across all classes (Mills

and others 2000). The largest snags should be retained

during timber harvests because birds prefer them, the

snags survive longer, and better winter thermal cover

is provided (Cunningham and others 1980). Snags less

than 6 inches (<15 cm) d.b.h. should also be retained

because they are important forage sites for cavity-nesting species (Baker 1973). Firewood gathering should

be monitored carefully in areas of low snag density

because this activity can negatively affect cavity nester

populations.

The importance of postfire forests in conifer-dominated systems of the West should not be ignored. Fire

affects bird nesting and foraging habitat by creating

snags, altering insect communities, reducing foliage,

and altering forest structure (Brown and Smith 2000;

Smith 2000). Kotliar and others [in press] summarized the influence of fire and salvage logging on avian

communities in conifer-dominated forests of the West.

In general, wood drillers (black-backed woodpeckers and

three-toed woodpeckers) and aerial insectivores (mountain bluebirds) were more abundant in early postfire forests, while bird species that occur most often in unburned

forests were usually foliage and bark gleaners.

Postfire salvage logging can be detrimental to cavity nesters that use postfire habitats. Snag reduction

may seriously impact black-backed and three-toed

woodpeckers, which rarely use partially logged postfire

forests (Kotilar and others, in press). This effect can

be ameliorated if proper measures are taken to retain a

diversity of snag sizes in various stages of decay. Furthermore, varying the spatial distribution of snags

within salvaged forest can provide nesting and foraging habitats for both bird species that prefer high densities of snags and bird species that don’t.

Tree density and coverage influence bird species

composition. Harvests of mature and old growth ponderosa pine stands would negatively affect redbreasted nuthatches, western tanagers, gray jays,

brown creepers, and Swainson’s thrush, which require high amounts of overstory canopy coverage

(Mills and others 2000). However, species that require open overstory canopy cover, such as northern flickers, dark-eyed juncos, mountain bluebirds,

and chipping sparrows would benefit from such harvests (Mills 1994; Mills and others 1996, 2000).

Forests are dynamic. Any natural disturbance, management activity, or even ecologic succession will

have both positive and negative effects on the birds

living in them. Maintaining as much diversity as

possible at the landscape scale is likely the best

means of balancing the winners and losers and maintaining optimal bird populations.

Silviculture of Ponderosa Pine

in the Black Hills

Silvics of Black Hills Ponderosa Pine

Several unique characteristics of the Black Hills

make the area well suited for management with different silvicultural techniques. The intermediate

shade tolerance of ponderosa pine allows regeneration under partial shade as well as full sunlight. Pine

seedlings can establish under a variety of overstory

densities, ranging from 0 to 60 ft2 per acre (0 to 14 m2

per hectare) and in some cases above that density

where gaps occur in the forest canopy (fig. 33). Ponderosa pine has large, heavy seeds with relatively

small wings that disperse fairly close to parent trees

(1 to 1.5 tree height). Ponderosa pine seed is produced almost every year, with abundant crops every

2 to 5 years (Boldt and Van Deusen 1974), although

seed production on the Limestone Plateau and some

portions of the Bearlodge Mountains has been sporadic in recent years. In areas with prolific seed production and favorable climate, natural regeneration

of ponderosa pine can be quite successful.

Frequent rain showers throughout the growing

season, which lasts from early March to August, is

the major climatic factor contributing to the prolific

growth and establishment of ponderosa pine. Greenhouse studies (Noble and others 1979) have shown

that seed germination and growth are optimal at temperatures above 50 oF (15 oC) and where rainfall

exceeds 1 inch (2.5 cm) a month. These conditions

are usually met throughout the growing season in

the Black Hills (fig. 34). In contrast, average precipitation from March to July in the Colorado Front

Range and Southwest is insufficient to establish ponderosa pine seedlings (fig. 35). Furthermore, temperatures in the Front Range and Southwest do not

usually reach the 50 oF (15 oC) germination threshold at the same time when rains do occur. Consequently, ponderosa pine regenerates only sporadically in these areas (Shepperd and others, submitted).

Regeneration Cuts: Even-aged

Two-cut shelterwood

The two-cut shelterwood, even-aged method is very

well suited for Black Hills ponderosa pine. This

natural regeneration method has been the most extensively used within the Black Hills, and proven to be

most reliable in managing these forests.
USDA Forest Service General Technical Report RMRS-GTR-97. 2002 69

Figure 34: The average precipitation and average temperature in the Black Hills over an

entire year (Shepperd and others 1983). Dotted arrows indicate the minimum precipitation

and temperature required for

ponderosa pine seed germination (Noble and others 1979).

Shaded gray area indicates

period in the Black Hills where

conditions are optimal for seed

germination.

Figure 35: The average precipitation and average temperature in the Rocky Mountains

and Southwest United States

over an entire year (Shepperd

and others 1983). Dotted arrows indicate the minimum precipitation and temperature required for ponderosa pine seed

germination. Shaded gray area

indicates period in these regions where conditions are

optimal for seed germination.

Figure 33: An even-aged ponderosa pine stand in the Black

Hills Experimental Forest with

an average basal area of 64 ft2

per acre. Note the scattered

ponderosa pine regeneration

in the understory.
70 USDA Forest Service General Technical Report RMRS-GTR-97. 2002

In a two-cut shelterwood, basal areas are generally

reduced below 60 ft2 per acre (14 m2 per hectare) in an

initial seed cut using a marking regime that leaves a

uniform canopy of the biggest and healthiest trees for

a seed source. Abundant natural regeneration is usually produced within 5 to 10 years. Under a classic

shelterwood, all remaining overstory trees are removed

once a new generation of trees is established. The overstory can be harvested anytime after sufficient seedlings are present to establish a new forest. Ideally, the

overstory should be removed while the new trees are

small to minimize damage to them during logging.

In practice, however, the overstory has either not

been completely removed or removal has been delayed until new seedlings have grown to large sapling or pole-size trees. In addition, some residual

overstory trees are also left in Black Hills shelterwood systems for wildlife habitat, snag recruitment,

and other purposes.

A classic two-cut shelterwood allows sufficient

sunlight to reach the forest floor to establish seedlings, yet provides enough shade to ameliorate the

harsh microclimates of full canopy openings. The

residual overstory trees provide an even distribution

of seed from healthy, desirable genotypes. Scarification that occurs with logging is usually adequate

to provide the mineral soil seedbed favored by ponderosa pine. Except for extremely harsh sites, these

factors combine to establish abundant understories

of several thousand seedlings per acre (fig. 36)

(Boldt and Van Deusen 1974).

Three-cut shelterwood

Three-cut shelterwood is primarily recommended

for situations where overstory trees are susceptible to

windthrow, or where additional growth of a portion of

the overstory canopy is desired before the forest is regenerated. Removing too many trees at once in a high

wind risk situation can result in the loss of seed trees

before the new regeneration becomes established. To

lessen this risk, an initial preparation cut is first made

to open the overstory somewhat and allow the residual

trees to develop windfirmness before the seed cut is

made. Usually no more than one-third of the existing

stand basal area is removed under the initial entry of a

three-cut shelterwood. Residual basal areas are kept

above 60 ft2 per acre (14 m2 per hectare) to minimize

regeneration after the initial entry. Following the development of natural windfirmness or the loss of trees

that were susceptible to windthrow (usually 10 to

15 years), a seed cut is then applied to regenerate the

forest as in a two-cut shelterwood system. Areas that

have exhibited unusual amounts of past windthrow, evidenced by many downed trees with large root masses

tipped up, windy ridge tops, saddles in ridges, and other

places susceptible to wind are candidates for the threecut shelterwood system.

Using the shelterwood system for managing Black

Hills ponderosa pine provides a reliable and quick

means to reestablish an even-aged forest. There has

been a long, successful history of shelterwood use in

the Black Hills. Shelterwood management provides the

Figure 36: A ponderosa pine

shelterwood stand with dense

regeneration ready for the removal of the overstory in the

Black Hills National Forest.
USDA Forest Service General Technical Report RMRS-GTR-97. 2002 71

Figure 37: A ponderosa pine

seed-tree cut in the Black Hills.

seedbed treatment, growth environment, and seed

source necessary to successfully reestablish ponderosa

pine. In addition, understory forage for wildlife and

livestock is increased in many habitat associations under a shelterwood system.

Extensive use of both two- and three-cut shelterwood

systems can create uniform forests over large areas of

a landscape, which may not meet diversity requirements

for wildlife habitats and other resource values. Classic shelterwood systems also have the appearance and

environment of regenerated clearcuts following the

overstory removal. Careful layout and scheduling of

cuts is therefore necessary to avoid conflicts with other

resource values.

Three-step shelterwoods have the disadvantage of

the extra expense of the third entry and the extra time

needed to regenerate the forest. The additional entry

may also contribute to soil compaction and erosion,

unless properly executed. However, these factors are

potentially offset by increased growth of the trees remaining after the first cut.

Seed-tree method

The seed-tree method has also been used successfully in the Black Hills. The seed-tree method is

similar to the two-step shelterwood, except only a

few trees per acre are left to provide seed for regeneration (fig. 37). One feature of the seed-tree method

that can be either a potential advantage or disadvantage is that heavy ponderosa pine seed does not get

uniformly distributed throughout the stand. Regeneration may then be spotty and clumpy, especially if

the seed trees themselves are not uniformly spaced .

However, such a structure may actually be desirable

under current holistic management philosophy. If

so, the seed-tree method can provide an open, irregular stand structure. The seed-tree method can

be modified to both regenerate the forest and provide reserve trees for wildlife and snag recruitment

in a single entry by simply never removing the seed

trees.

The low density of residual trees in a seed-tree cut

allows abundant understory forage production for livestock and wildlife. Seed-trees are more susceptible to

windthrow, however, because they are more isolated

and widely separated than trees in the shelterwood system. The seed-tree method should therefore not be used

in high wind risk areas. Seed-trees also look artificial,

especially when regularly spaced and applied to large

areas of the landscape. Nor does the seed-tree method
72 USDA Forest Service General Technical Report RMRS-GTR-97. 2002

provide suitable habitat for closed-forest and canopydependent birds and animals.

Clearcut method

From a natural regeneration standpoint, clearcutting

is the least desirable of any of the even-aged systems

that could be practiced in the Black Hills. The primary

reason is that effective seed fall distance is so short

that only very small clearcuts could be successfully

regenerated. The clearcut method is generally recommended only for ponderosa pine stands that are heavily

infested with dwarf mistletoe, which does not occur in

the Black Hills.

Clearcutting does provide openings for some wildlife species (fig. 38), and can be used to open roadside

vistas within pine forests for a period of time until the

regeneration is established. Clearcutting can certainly

be used in the Black Hills in a patch clearcut mode

where the cuts are small enough to allow seeds from

surrounding stands to reach the opening. The size of

the opening should normally be restricted to about twice

the 250-foot (76 m) dispersal distance of ponderosa

pine seed, if a seed-dispersing stand exists all around

the perimeter (Boldt and others 1983). Strip clearcuts

that are oriented perpendicular to the direction of prevailing winds can also be quite successful, as experience on the Black Hills Experimental Forest has demonstrated (fig. 39).

Clearcuts can look artificial from a distance or from

the air unless the cuts are properly designed and shaped

to blend into the natural character of the landscape.

Geometric shapes should be avoided. Openings should

be irregularly shaped, and be placed in the landscape

to mimic natural disturbance patterns. Production of

grasses and forbs for domestic livestock and wildlife

is maximized in clearcuts, at least for a few years until

the regeneration is established and reaches sapling size.

Clearcuts benefit bird and mammals that prefer openings, such as deer and elk, provided the clearcuts are

not too large (Wallmo and Schoen 1981).

Regeneration Cuttings: Uneven-Aged

Silviculture

Uneven-aged regeneration methods can meet the

requirements for a variety of conditions needed under

today’s management philosophy. Uneven-aged management allows for the creation of forests of various

Figure 38: Structural diversity within the forested landscape created by applying

a patch clearcut in the middle of a dense forest.
USDA Forest Service General Technical Report RMRS-GTR-97. 2002 73

structural and spatial distributions, and allows managers to create conditions that can meet a variety of resource needs, such as wildlife habitat, scenic values,

forage, recreation areas, timber, roadside travel corridors, and so forth. Uneven-aged management mimics

the later stages of succession, primarily the understory

reinitiation stage (Guldin 1996; Oliver and Larson

1996). Basically, the older age cohorts in the overstory

die at the same rate as new age cohorts are established.

This creates a forest of diverse canopy structure that

may be uniformly stocked, or contain numerous gaps

and clumps of trees.

While even-aged silviculture is designed to raise a

crop of trees to maturity and then harvest and replace

them with a new forest, uneven-aged silviculture is

designed to create a desired condition in the forest landscape and then maintain that condition through time

by periodic entries to remove trees of various sizes and

in various patterns. The goal is to eventually attain a

forest comprised of trees of all ages and sizes. While

this diverse structure is probably not achievable initially in any major area in the Black Hills, existing

conditions are such that many areas can be moved toward an uneven-aged structure with one or two entries,

or cutting cycles.

Stocking control

Control of stocking or density under uneven-aged

management is achieved through one of two methods: either the BDQ method, which relies on a basal

area, diameter distribution, and a “Q” ratio, or the

SDI3 (Stand Density Index) method (Long 1995),

which distributes stocking of a forest in a variety of

SDI classes containing trees of various sizes. Both

of these methods require a stocking guideline that is

usually based on basal area as well as upper and

lower diameter limits to achieve the desired stocking goal.

Under the BDQ system, the manager first selects

the “Ds,” or upper and lower target diameters that define the range of tree sizes to be managed. Normally,

the upper diameter limit is dictated by the maximum

tree size the manager wants to retain on the site

(whether it is actually present or not). The lower diameter limit is usually the smallest diameter class tallied in the stand inventory.

The “Q” curve is used to control the distribution of

tree diameters between upper and lower target diameter classes. By definition, the Q factor is the ratio between the number of trees per acre in one diameter

class and those in the next smaller class (Alexander

and Edminster 1987). At values larger than 1.0 its computation always results in a distribution of tree sizes

that follows a negative exponential decay function. In

other words, each diameter class in the target forest

Figure 39:A ponderosa pine strip

clearcut in the Black Hills Experimental Forest.

3 Stand density index (SDI) is a relative measure of stand density

that provides a relationship between stand basal area, trees

per unit area, average stand diameter, and stocking of a forested stand (Reineke 1933). The premise of SDI is that if the

carrying capacity for tree growing space is fully occupied, an

increase in average stand diameter can only occur if there is a

reduction in the number of trees per unit area.
74 USDA Forest Service General Technical Report RMRS-GTR-97. 2002

will always contain greater numbers of trees than the

next larger class. The intent of such a distribution is to

ensure that there will always be sufficient numbers of

smaller trees to grow into each successive larger diameter class, even with normal rates of mortality. Increasing the Q factor will increase the density of smaller

trees in the desired forest. Decreasing the Q factor

will lower the density of smaller trees (fig. 40). Therefore, changing the Q factor can drastically alter the

appearance of the target forest, regardless of the desired residual basal area.

The final factor that controls stocking under the BDQ

method is “B,” or the residual basal area that the

growing stock is reduced to following each cutting

cycle. Raising or lowering the residual basal area

changes the number of trees desired in each diameter

class (and thus the overall stocking), but the Q ratio is

unaffected (fig. 41). Specific methods for calculating

Figure 41: Influence that residual

basal area has on trees per

acre in each diameter class

under identical “Q” factors.

Figure 40: Influence the “Q” factor has on trees per acre in

each diameter class for a stand

with similar basal area.
USDA Forest Service General Technical Report RMRS-GTR-97. 2002 75

desired stocking under the BDQ method are presented

in Guldin (1996) and in Alexander and Edminster

(1987). Desired stocking can easily be calculated with

a computer spreadsheet and rudimentary cruise data.

The SDI method of calculating desired stocking in

an uneven-aged forest also utilizes upper and lower

diameter limits, but apportions stocking in each diameter class according to Stand Density Index, rather than

using a Q factor and residual basal area (Long 1995).

A total residual SDI is first selected (usually about onethird of maximum SDI for the species). This SDI is

then apportioned evenly across all diameter classes in

the target stand, and used to calculate the number of

desired residual stems per acre in each class. The result is a distribution of stems across all diameter classes

not unlike that achieved using the BDQ method, but

without a constant ratio between the number of trees

in each class. Changing the residual target SDI for a

stand will raise or lower the overall stem density, but

will not change the shape of the distribution of trees

among classes (fig. 42). The target SDI can be apportioned differentially rather than evenly among diameter classes to vary the distribution, and avoid dense

understories (Long 1995). However, apportionment

must not result in greater numbers of trees in larger

diameter classes than in smaller classes. Regardless

of how the total SDI is apportioned, overall stocking

for the target stand will remain within the desired SDI

stocking limits.

Another method of allocating growing stock in complex multiaged or multistructured stands is the Multiaged Stocking Assessment Model MASAM (O’Hara

and Valappil 1999). This approach relies on fundamental relationships between leaf area and growing

space to predict the growth response under a specified

allocation of growing stock, and could potentially be

used with many existing Black Hills ponderosa pine

stands.

There are several complicating factors in using the

MASAM as presented in O’Hara and Valappil (1999).

Local allometric relationships must be developed to

estimate leaf area index (LAI) of designated structural

cohorts of the forest canopy. These allometric relationships have not yet been developed for Black Hills

ponderosa pine. Evaluations of alternate prescriptions

require repeated runs of the MASAM and cannot be

done in a spreadsheet as with the BDQ and SDI methods. MASAM does not produce yield or stand tables

that can be utilized to develop timber sale plans or

marking guides. If these limitations can be overcome,

MASAM could potentially be a useful tool in managing complex ponderosa pine stands in the Black Hills.

By manipulating either the target stocking or the

distribution of trees in the various size classes, both

the BDQ and the SDI methods can create forests of

infinitely different structures. Managers must rely on

their knowledge of silvics and common sense to choose a

desired condition that is both attainable and sustainable.

Figure 42: Distributing stocking in

an uneven-aged stand using

the SDI method. A change in

the residual target SDI will

change overall stem density,

but the proportional distribution

of trees among diameter

classes will remain the same.
76 USDA Forest Service General Technical Report RMRS-GTR-97. 2002

For example, a residual stocking target greater than 80

to 100 ft2 (18.3 to 23 m2 per hectare) of basal area per

acre in Black Hills ponderosa pine forests is probably

not sustainable. Such forests would grow slowly and

be highly susceptible to mountain pine beetle attack.

Conversely, selecting a high Q factor (or differentially

apportioning SDI into smaller diameter classes) would

also result in unattainable stocking (not enough light

through the overstory canopy to establish pine regeneration and grow new trees into larger diameter classes).

Such dense understories would also serve as live fuel

ladders, making those forests extremely susceptible to

crown fire.

In practice, the goal of most uneven-aged prescriptions in Black Hills ponderosa pine is to create a relatively open diverse forest that has a lot of structural

and spatial diversity, and is not susceptible to standreplacement fires or catastrophic insect attack. This

can usually be accomplished using residual basal areas under 60 ft2 per acre (13.8 m2 per hectare) with

moderate stocking in the smaller diameter classes,

while retaining some large trees. Cutting cycles of 20

to 30 years are usually appropriate, although initial

applications of uneven-aged management in the Black

Hills indicate that a supplemental pre-commercial thinning may be needed between entries to control excessive regeneration before it gets too large (fig. 43).

Another factor controlling the selection of a residual

target condition for uneven-aged management is the

current stocking of the forest. While it is possible to

eventually convert a strictly even-aged forest to an

uneven-aged condition after several cutting cycles,

uneven-aged management is best suited to forests that

already contain several age classes and have some

structural diversity. In these cases, the desired target

condition should approximate the current diameter distribution as much as possible, removing surpluses from

overstocked classes and leaving understocked classes

to grow. Diameter class distributions of existing forests almost never agree with the Q curve, even in stands

that have previously been placed under uneven-aged

management. Unforeseen mortality, insect and disease

damage, and differences in microsite conditions and

genetics can all be responsible. Therefore, surpluses

and deficits among diameter classes should be balanced

so that the target stocking (basal area or SDI) is maintained. Strictly cutting surplus diameters back to the target stocking will result in an overharvest, or understocked

condition whenever deficit diameter classes exist.

Single-tree versus group selection

Under single-tree selection, trees are managed as

individuals within a population where trees are selected

for harvest or retention on a tree by tree basis in each

entry, or cutting cycle. The ideal result from singletree selection is a uniformly stocked forest containing

trees of a variety of sizes.

Under group selection, the mix of trees of various

ages and sizes in the forest is accomplished by manipulating the trees in groups such that openings,

groups, and clumps of similar sizes are distributed

throughout the landscape. Group selection is not simply creating small holes in the forest, or harvesting

small patch clearcuts from the forest in periodic

Figure 43: Uneven-aged ponderosa pine stand in the Black

Hills Experimental Forest.
USDA Forest Service General Technical Report RMRS-GTR-97. 2002 77

entries. The intervening matrix of forest between harvested groups and clumps of trees is also managed to

insure that overall stocking of the forest is maintained

in the desired distribution of age and size classes.

Regardless of the method used to control stocking,

both group and individual-tree selection systems should

be implemented so that a sustainable (and desired) condition are maintained through time. Either the BDQ

or SDI method can be used to regulate overall stocking under both single-tree and group selection. This

enables a very diverse forested landscape to be created

and maintained using a single set of inventory records.

Uneven-aged silviculture can provide an infinite variety of forest structures and conditions for wildlife habitat guidelines, fiber production, aesthetics, developed

recreation areas homesites, and roadside corridors,

where maintenance of the forest environment through

time is paramount.

Another advantage of uneven-aged management is

that the forest structure itself provides a record of past

disturbance and management activity, so it is easy to

interpret what condition the forest is in, and what additional entries or manipulations are needed to return

it to the desired condition. Unless clear records have

been retained, it is often impossible to tell what the

intentions of previous management entries were under

even-aged systems. This is especially true where residual

overstory trees were retained for other resource uses.

Layout, marking, and utilization under unevenaged systems

Uneven-aged management requires skill on the part

of tree markers, timber inventory personnel, and salelayout and sale-administration personnel to achieve the

desired objectives. Layout of an uneven-aged prescription begins with a well-designed inventory of the

forest. Calculating the desired BDQ or SDI stocking

distributions requires reliable data by diameter classes

in all areas of the stand. Grouped or clumped stands

may require greater numbers of inventory plots to obtain statistically accurate data. The total number of trees

to be removed in the stand can be calculated once target stockings have been selected for each diameter

class. These totals are then used to mark the stand.

Computing a ratio or percentage of trees to mark in

each diameter class can help guide marking personnel

in selecting trees and avoid undermarking or overmarking a particular diameter class.

The above system can be used in marking both group

and individual tree selections by simply tallying all trees

removed in a group (or subtracting the equivalent per

area stocking by diameter class if groups are designated by a painted boundary). Individual trees can also

be removed from the area between harvested openings

to maintain the overall desired stocking goal. Treating

an uneven-aged forest in this manner ensures that stocking is maintained throughout diverse sites, and allows

the entire area to be tracked as a single site record in

inventory databases. Although stocking may vary considerably within a group selection area, and result in

differential growth and susceptibility to insect and disease attack in some portions of the stand, such discrepancies should average out over the site and not

deviate significantly from the growth that would be

expected in a uniformly stocked uneven-aged stand.

Any uneven-aged management harvest entry will

produce a variety of product sizes, which will require

a complete spectrum of wood product utilization to be

economically viable. Typically, an uneven-aged management entry will produce material throughout the

range of diameters within the site. Where natural regeneration is prolific, as in Black Hills ponderosa pine

forests, many small stems will have to be removed in

each entry. Markets or ways of economically disposing of this material will need to be developed. It therefore may be desirable to discourage regeneration by

carrying slightly higher residual stocking, or avoiding

excessive scarification during logging. An additional

pre-commercial thinning entry or prescribed burning

between cutting cycles may also be needed to remove

excessive saplings.

Uneven-aged management also requires careful logging to avoid damage to residual stems, many of which

will be maintained on site for several cutting cycles.

Harvest equipment and techniques need to be configured to handle a variety of log sizes and product classes.

Removing material in two stages may be more efficient to accommodate these needs. Designating permanent skid trails may be a practical way to avoid compacting soil under the 20- to 30-year cutting cycles in

Black Hills uneven-aged ponderosa pine forests.

Hybrid Systems: Two-Aged/Three Aged

Today’s resource demands are such that maintaining stands in two or more even- aged classes is desired. Black Hills ponderosa pine forests lend themselves well to management under two- or three-aged

systems. These hybrid forests are not strictly even-aged

or uneven-aged, but have a canopy that would be two

to three storied in nature, comprised of trees of two or

three distinct age classes (fig. 44). Each of these age

classes would be managed as an even-aged cohort

within these forests. Older age classes would be harvested at some point in time when they mature, and a

new replacement age class would be established under
78 USDA Forest Service General Technical Report RMRS-GTR-97. 2002

the remaining canopy. These systems have the advantage of keeping a forested environment on a site at all

times, and are somewhat less complicated than applying a pure uneven-aged system. A more regimented

forest structure is maintained than in an uneven-aged

system. While these systems theoretically could be

applied in a group or clumped mode with more than

three age classes, a point is reached in which they become indistinguishable from an uneven-aged system

and probably should be treated as such.

Intermediate Operations

One thing unique to the Black Hills ponderosa pine

is the prolific establishment of regeneration under both

even- and uneven-aged management. It is certainly

possible to achieve more regeneration in the understory

than is desired under any of the systems discussed

above. The need for intermediate operations to control density of Black Hills ponderosa pine is easily illustrated by simulating the growth of a typical forest

under a number of even- and uneven-aged scenarios

(fig. 45). Without periodic silvicultural intervention,

most stands will quickly grow into stocking levels that

are either unhealthy, or are undesirable for many resources.

The Black Hills National Forest has an increasing

precommerical thinning backlog that is evident

throughout many of the forests that have been managed or entered in the last 20 or 30 years. Many of

these forests contain dense, very thick understories

containing several thousand stems per acre (fig. 46).

As these stems grow, they are becoming more susceptible to catastrophic wildfire, disease, and insect attacks. Managers should plan for periodic density control to alleviate some of the current overstocking problems and avoid future problems.

Precommercial thinning

Precommercial thinning is an absolute necessity in

the Black Hills under all even- and uneven-aged silviculture regeneration methods to maintain desired density attributes for managed stands. Thinning should be

performed as early as possible from both a biologic

and economic standpoint. As dense young trees increase in size, the cost of cutting and removing them

increases as well as the biomass of fuel loadings created. Early thinning is also the most cost-effective way

to maximize productivity over a rotation in even-aged

management, or between cutting cycles in uneven-aged

stands.

Commercial thinning

Commercial thinning is an intermediate silviculture

entry into an even-aged forest that removes sufficient

trees of marketable size to cover the direct costs of

harvest (Ford-Robertson 1971). Commercial thinning

is intended to improve the health, vigor, and future

growth capacity of a forest that is not yet ready to be

regenerated. Establishment of new seedlings is not a

goal. Commercial thinning can be designed to satisfy

a number of management goals, each of which can

determine the types, numbers, and patterns of trees that

are removed. Commercial thinning can remove

Figure 44: Two-aged ponderosa

pine stand in the Black Hills.
USDA Forest Service General Technical Report RMRS-GTR-97. 2002 79

Figure 46: An extremely highdensity stand of naturally regenerated ponderosa pine in

the Black Hills Experimental

Forest.

Figure 45: Forest Vegetation Simulator (Crookston 1997) projections of basal area growth over

time for selected Black Hills ponderosa pine management schemes. The even-aged simulations all began with 2000 1-inch trees present in the year 2000. The 1-Thin option precommercially

thinned to 40 BA in 2010. The 2-Thin option added a second commercial thinning to 80 BA in

2040. A seed-cut shelterwood harvest was applied to both options in 2080. Initial conditions for

the uneven-aged individual tree selection (ITS) option assumed 100 BA distributed across 2- to

26-inch d.b.h. classes under a Q = 1.3. Stocking was reduced to 80 BA in each of four entries at

30-year intervals, beginning in 2000. All projections used Site Index = 70. The horizontal line

at 120 BA represents stocking levels at high risk of attack by mountain pine beetles (Schmid

and others 1994).
80 USDA Forest Service General Technical Report RMRS-GTR-97. 2002

smaller, suppressed trees, those with poor form or disease, or remove undesirable species from a mixed-species forest. The number of trees removed can vary

widely, but is usually dictated by a residual stocking

guideline determined by specific management objectives for the site. One such guideline that has been

adopted by the U.S. Forest Service is the Gringrich

thinning curve developed for Black Hills ponderosa

pine (fig. 47). Stocking levels within the management

zone illustrated on this Gingrich chart are considered

suitable for a variety of resource uses within the Black

Hills. Stocking levels below the management zone are

considered less than fully occupied (for example, not

growing at acceptable levels for a managed forest on

the site). Thinning to these levels would create trees

of open-grown crown form and would result in the

establishment of new seedlings in the openings between

trees, thus creating a new age class (not a desirable

result of an intermediate thinning under even-aged

management).

Stocking levels above the management zone on the

Gingrich curve are not considered sustainable for many

resource uses. Forests at these densities grow considerably more slowly and are susceptible to density-dependent mortality, insect and disease attack, or standreplacing wildfires. Understory vegetation is almost

nonexistent, resulting in depauperate habitats for many

wildlife species.

Although not absolutely necessary to maximize fiber yield (fig. 48), at least one commercial thinning

would be advantageous in maximizing product yield

on many even-aged stands in the Black Hills. Most

Figure 48: Total projected merchantable cubic and board foot

yields over the 100-year period

from the Black Hills ponderosa

pine management schemes

shown in figure 45.

Figure 47: Gringrich stocking

curves for ponderosa pine in

the Forest Service’s Rocky

Mountain Region (R2) (Forest

Service Manual, R2 Supplement 2409.17-92-2 1992).

300

250

200

150

100

50

0

0 200 400 600

Trees per acre

Basal area (sq. ft. per acre)

Management

zone

Ponderosa Pine

20

18

16

14

12

10 9 8

7

6

5

4

3

30%

20%

40%

50%

60%

70%

80%

90%

Relative stand density

Quadratic

mean

diameter (inches)

Average

maximum

density

800 1000 1200
USDA Forest Service General Technical Report RMRS-GTR-97. 2002 81

even-aged ponderosa pine forests in the Black Hills

will require at least one thinning entry in a rotation to

remain healthy. The level and timing of thinning is a

factor of the specific stand conditions, management

guidelines for the site, and specific site growth characteristics. SUPPOSE, the PC-based Forest Vegetation

Simulator (FVS) growth and yield model (Crookston

1997), can be used to evaluate thinning alternatives on

a site-by-site basis.

Maximization of merchantable board foot yield

Tree spacing in precommerical thinning and subsequent commercial thinning all affect merchantable

board foot (MBF) yield. Using the FVS growth

simulation model, we compared total rotation MBF

yields under several scenarios for a typical even-aged

Black Hills ponderosa pine stand. The following stocking criteria were used: site index = 62; initial stocking

= 3,000 trees per acre; planted at year 0, reaching d.b.h.

at year 10; 120-year rotation. All scenarios were based

on precommerical thinning at year 30. We attempted

to commercially thin if a minimum 1,000 MBF per

acre could be removed without decreasing the overall

MBF yield. Our goal was to maximize yield without

undue risk to mountain pine beetle loss. We judged

stands to be at risk if basal areas exceeded 120 ft2 per

acre (27.6 m2 per hectare) and quadratic mean diameter (QMD) was greater than 9 inches (22.9 cm).

Merchantable board foot yield was maximized at

the 9 foot by 9 foot (2.7-m by 2.7-m) precommercial

thinning spacing with no subsequent commercial thinning (table 5). However, the extremely high basal areas

under this scenario would make it highly susceptible

to mountain pine beetle (fig. 18). In addition, tree size

was too small at the 9 foot by 9 foot (2.7-m by 2.7-m)

spacing to allow a commercial thinning before the end

of the rotation. We were able to model a commercial

thinning with the 10 foot by 10 foot (3.1-m by 3.1-m)

spacing, but the stand was still susceptible to beetles

and the overall yield dropped slightly (table 5). The

12 foot by 12 foot (3.7-m by 3.7-m) precommercial

thinning spacing with a subsequent commercial thinning to remove all MBF volume at age 80 proved to be

the best compromise between maximizing merchantable board foot yield and minimizing mountain pine

beetle risk. Under this scenario, board foot volumes

were 3,900 MBF less than under the 9 foot by 9 foot

(2.7-m by 2.7-m) spacing (table 5). If a more open stand

is desired, a precommercial thinning to 20 foot by 20

foot (6.1-m by 6.1-m) will produce the largest

diameter trees with little risk of beetle infection, but

total MBF yield will be about one-third less than the

previous scenario (table 5). We tried a number of additional thinning scenarios at various spacings, but none

performed better than the ones listed here.

We should note that these scenarios only apply to

the conditions listed above and are included here for

illustrative purposes only. Readers should not assume

that these results would directly apply to every ponderosa pine stand in the Black Hills. Irregular spacings,

site conditions, ages at thinning, presence of additional

age classes, and so forth, will all affect yields. We

therefore urge managers to utilize FVS to model scenarios for their local conditions.

Prescribed burning

Prescribed fire has not been used to a great extent to

eliminate regeneration in the Black Hills, but it is a

technique that should be explored further. Prescribed

burning would best be done when seedlings are quite

small and fuels ladders are either infrequent or nonexistent to avoid loss of larger trees. Under even-aged

systems, prescribed burns can be done while seedlings

are essentially in the grassy stage or less than 1 foot

tall to eliminate the densest concentrations of seedlings.

In uneven-aged systems, excess regeneration established after one cutting cycle could be removed by

burning prior to the next entry cycle. For example, an

individual-tree uneven-aged stand that was harvested

on the Black Hills Experimental Forest in the mid1980s is currently overstocked in the understory size

classes, even though it is only halfway through its cutting cycle (fig. 43). Careful underburning in this stand

could have eliminated many of these trees before they

got large enough to become a problem.

Table 5: End of rotation per acre, tree density (TPA), basal

area (BA), quadratic mean diameter (QMD), and total

merchantable board foot yields (MBF) for various

precommercial tree spacings (feet) and two subsequent

commercial thinnings.

End of Rotation Values

Treatment TPA BA QMD MBF

No Thin 627 230 8.2 8,652

7x7 554 236 8.8 14,549

9x9 452 227 9.6 16,848

10x10 356 195 10.0 15,891

12x12 247 157 10.8 14,462

15x15 163 122 11.7 12,945

20x20 96 85 12.8 9,251

10x10 Com. Thin 288 154 9.9 15,542

12x12 Com. Thin 174 117 11.1 13,473
82 USDA Forest Service General Technical Report RMRS-GTR-97. 2002

Prescribed burning can also efficiently remove fuel

loadings from logging slash and stimulate understory

forage production. In areas with heavy needle and litter accumulations around the base of ponderosa pine

trees, the fuel loadings should be racked away from

the base because these fuels can smolder at the base of

the trees for long periods of time, and damage pine

roots (Sackett 1980). Proper timing of prescribed burns

to maximize soil moisture can alleviate some of this

damage.

Careful burning under the right conditions can

scorch the lower branches of trees without consuming

the entire crown and killing the tree. Such scorching

can kill lower branches and effectively prune the tree,

improving its form and decreasing the chance of crown

ignition from future fires (fig. 49).

Uniform prescribed burning could reduce structural

diversity of forests, but burning in a manner that does

not blacken the entire forest floor can actually increase

diversity. Therefore, leaving portions of a stand

unburned will likely come closer to mimicking the natural fire regimes that occurred in the Black Hills prior

to European settlement. For the same reason, the loss

of occasional overstory trees, or occasional groups of

trees, during a prescribed burn should not be considered detrimental. Unlike mechanical silviculture treatments, prescribed burning is not exact. It cannot guarantee the removal or survival of individual trees. It

can only attempt to improve the present condition of

the forest. Nor can burning be applied in as timely a

fashion as mechanical treatments. Weather, fuel and

soil moisture conditions, and regional smoke restrictions can severely restrict when burning can occur, leading to delays in treatment of several years or more.

Prescribed fire should therefore not be considered a

panacea in the management of ponderosa pine, but only

one of many tools that can be used to manage pine

ecosystems in the Black Hills.

Artifical Reforestation

Principles

Natural regeneration is the preferred method of regenerating ponderosa pine trees in the Black Hills due

to the relative abundance of precipitation throughout

the growing season, as well as the dependable seed

production of ponderosa pine in this region. However,

natural regeneration is sometimes not an option due to

a large-scale fire, tornado, or other catastrophic disturbance that eliminates seed sources within the area to

be reforested. Both seeding and planting can be used

in the Black Hills. Successful seeding depends on several conditions, including a suitable seedbed, ample

seed supply, and an environment conducive for germination and establishment of seedlings. Planting success depends on healthy local seedling stock, proper

soil moisture, and correct handling and planting techniques.

Tree Improvement Program

The Black Hills National Forest has a tree improvement program in progress to enhance the productivity

of the forest by establishing well-adapted, fast-growing, pest- and disease-resistant trees on productive sites.

The program includes activities for seed collection to

develop an adequate seed inventory of source-identified seeds, establishment of seed production areas to

provide seeds for specific zones within the Black Hills

National Forest, and efforts to locate the superior

ponderosa pine parent trees identified by Van Deusen

and Beagle (1970) for use in progeny studies. Figure 49: Prescribed burns can lessen the risk of crown

fires by killing and pruning lower branches.
USDA Forest Service General Technical Report RMRS-GTR-97. 2002 83

The majority of the Black Hills National Forest falls

within three seed zones: 621, 622, and 623. A seed

production area, Buskala Seed Production Area, has

been established on the Spearfish/Nemo Ranger District near the boundary of seed zones 621 and 622. This

area will have source-identified seeds from better-thanaverage trees to provide a local seed source for artificial regeneration in zones 621 and 622. Seed production areas for other zones within the Black Hills National Forest are currently in the process of being established.

In the late 1960s, Van Deusen and Beagle located

and described cone and seed characteristics of several

superior trees (better than average appearing) among

six regions of the Black Hills (Van Deusen and Beagle

1970). The collection regions included the northern

hogback, northern limestone, metamorphic, granitic,

southern limestone, and southern hogback. Seedlings

produced from the seed sources were planted in a common plantation on the Black Hills Experimental Forest. Ten-year progeny growth results were reported by

Shepperd and McElderry (1986). Six parent seed

sources for the western and northern Black Hills exhibited exceptional survival and growth. The progeny

plantation still exists on the Black Hills Experimental

Forest, so it is possible that seeds could be collected

from well-performing progeny. The Black Hills National Forest staff is now in the process of relocating

the original parent trees to collect cones and map their

locations. If any of the trees are dead, missing, or have

undesirable traits, new ones will be selected to achieve

a target of 30 plus trees per district on the National

Forest. Locating and collecting seed from the identified superior ponderosa pine trees will allow for a

greater genetic diversity for artificial regeneration.

Site Preparation

Proper site preparation can increase the success of

both direct seeding and planting. Site preparation

should be initiated as soon as possible after the disturbance that eliminated the seed source for natural seedlings. Grasses, forbs, and shrubs can inhibit seedling

establishment. Competition from other plants may reduce survival of planted seedlings in burned or logged

areas by 30 percent or more for each year planting is

delayed (Heidmann 1988; Stewart 1978). If a hardwood overstory is present and the goal is to manage

for ponderosa pine, the hardwood overstory should be

reduced or eliminated to reduce competition for resources (Boldt and Van Deusen 1974).

There are four primary methods of site preparation

for ponderosa pine: mechanical, chemical, prescribed

burning, and a combination of the three (Heidmann

1988). Hallman (1993) lists numerous types of specialized equipment for site preparation along with their

function, description, advantages, disadvantages, and

places to obtain them. The purposes of mechanical

site preparation are to remove plant competition and

slash, loosen compacted soil, and scarify the forest floor

(Hallman 1993). Scalping 18 to 24 inches in an area

to be planted to reduce grass competition is a common

practice in the Black Hills. Some important things to

consider while using heavy equipment for mechanical

site preparation include soil compaction, loss of topsoil, and cost effectiveness.

Herbicides are often used to control vegetation that

would otherwise compete with pine seedlings for moisture, nutrients, and sunlight. Herbicides are often used

in concert with other site preparation techniques such

as prescribed burning. The use of herbicides has been

limited, however, due to concerns about the unknown

and often controversial toxicity of the chemicals

(Hallman 1993). Although the potential exists, herbicides have not been used extensively to control competing vegetation when planting or seeding ponderosa

pine in the Black Hills.

Prescribed fire is another way to remove plant competition and slash (Hallman 1993). The fire temperature must be hot enough to kill the vegetation

(Heidmann 1988), but cool enough to lessen the loss

of volatile soil nutrients. Sites should be burned when

the fuel is dry but the soil is moist enough to avoid

oxidation of the nutrients and soil organic matter. An

exposed mineral soil seedbed is conducive to ponderosa pine seed germination. To minimize soil erosion

on slopes after a prescribed burn, sites should be burned

when conditions are beneficial for germination and

establishment of pine seedlings. Typically, burning

in spring prior to the growing season will best meet

these requirements. Other mechanical treatments

can be used to reduce soil erosion following prescribed burns. Monitoring of the area for invasion

of noxious weeds is warranted, especially in areas

that were sodbound. Hallman (1993) lists numerous

types of specialized equipment for treating prescribed burns, along with their function, description,

advantages, disadvantages, and places to obtain

them.

Establishing pine regeneration by seeding areas that

were subjected to intense wildfire that eliminated the

overstory might be difficult due to increased soil temperature. Surface temperatures during the first growing season are often too high for seedling establishment

due to the blackened soil, especially on southern and

western aspects.
84 USDA Forest Service General Technical Report RMRS-GTR-97. 2002

Seeding

Seed collection

Ponderosa pines in the Black Hills usually produce

a good to excellent seed crop every 2 to 5 years (Boldt

and others 1983). Seeds should be collected from trees

that display desirable traits of growth, form and resistance to pests. Favorable tree characteristics identified by Boldt and Van Deusen (1974) include: growth

rate, age, stem, branches, bark, and health. Trees that

equal or exceed the average site index height for their

age and have an average diameter growth of 2 inches

(5 cm) or more per decade indicate a superior growth

rate. Vigorous growth is indicated by dark bark and

wide fissures that show a bright orange color. Trees

that are 75 to 150 years old should be chosen. These

trees should have a straight stem without any forks or

excessive taper for good form. Branches should be

small in diameter, short in length, average four or less

branches per whorl, nonpersistent after death, and be

at a right angle to the bole. Live crown should be 40 to

60 percent of the total tree height. Look for trees without any evidence of successful attack by insects, diseases, or porcupines (Erethizon dorsatum). Needles

should be green, and there should be evidence of good

cone production in past years. To ensure that the seed

collected have the desirable characteristics, seeds

should come directly from cones on the trees, rather

than those from squirrel caches (Boldt and Van Deusen

1974). If the objective of the seed collection is to promote genetic diversity, however, then collection from

squirrel caches is fine.

Van Deusen and Beagle (1970) described the cone

and seed characteristics of several superior ponderosa

pine trees among six regions of the Black Hills. Over

the entire area, the average cone length was 2.65 inches

(6.7 cm) with a range of 0.44 inch (1.1 cm). The number of seeds per pound was variable within a collection area as well as between regions. One could expect to find from 8,000 to 23,000 seeds per pound of

cones collected. There was a trend toward an increase

in average number of seeds per pound from south to

north. Viable seeds per cone averaged around 57.

Seeds are extracted from cones by shaking or tumbling. It is estimated that 6 to 19 seeds may be lost

per cone using this method. Because there are yearto-year variations in cone and seed characteristics,

a seed collector should first sample the current cone

crop before making a mass collection. Cones are

ripe when the color turns from green to purplish

brown (Krugman and Jenkinson 1974). In addition,

the specific gravity of cones containing ripe seeds

in the Black Hills is 1.00 (Oliver and Ryker 1990).

Seeds are typically dispersed from September to

January.

Seed storage

Viable ponderosa pine seeds must be dried to a moisture content of 4 to 8 percent, placed in an airtight container, and stored at 32  ̊F (0  ̊C) or less. Storage at

0  ̊F (–18  ̊C) is preferred (Schubert 1974). Seeds

should be viable for up to 15 years (Krugman and

Jenkinson 1974).

Germination treatment

Stored seeds germinate better if they are subjected

to cold stratification (Krugman and Jenkinson 1974).

To stratify seeds, first place them in water for 1 or

2 days, then in a moist medium and maintain temperature around 33 to 41  ̊F (0.6 to 5  ̊C) for 30 to 60 days.

To test for seed viability, germinate a sample of the

seeds under near-optimum conditions of aeration, moisture, temperature, and light. Published germination

tests for ponderosa pine have used a variety of growth

media, temperature, and light regimes (Krugman and

Jenkinson 1974). Germinating stratified seed in Petrie

dishes on moistened blotter paper under a diurnal regime of 8 hours of light at 86  ̊F (30  ̊C) and 16 hours

of darkness at 68  ̊F (20  ̊C) should give consistent results. Tests should be run for 30 days to ensure complete germination. To avoid mold, seeds should be

washed in a 3 percent chlorine bleach solution and

rinsed in distilled water before being placed into the

Petrie dishes, and removed as soon as they germinate.

Sowing techniques

Several devices and techniques for sowing seed have

been used or considered in the Black Hills, but none

have been evaluated experimentally (Boldt and Van

Deusen 1974). Hallman (1993) discusses several pieces

of equipment to carry out direct seeding and their advantages and disadvantages.

Direct seeding has been used successfully since 1905

for reforestation in the Black Hills (Boldt and Van

Deusen 1974; Harmon 1954; Wagar and Meyers 1958).

This technique can be fast and economical if properly

done. Direct seeding typically costs less than hand

planting, but survival is usually higher for hand-planted

seedlings.

Broadcast seeding is one of the simplest methods

of direct seeding; seeds are scattered uniformly over

the area to be revegetated. Broadcast seeding has

been successful in the Black Hills (Boldt and Van

Deusen 1974), but one problem is the potential for

multiple seeds to be placed in one spot. When optimum climatic factors allow germination and survival
USDA Forest Service General Technical Report RMRS-GTR-97. 2002 85

of too many seeds, the resultant clusters of young pines

will require thinning (Wagar and Meyers 1958).

Factors for successful direct seeding were identified by Wagar and Meyers (1958) for the Black Hills,

with precipitation being one of the most important.

Stocking was highest when seeds were sown during

periods of abundant precipitation. For instance,

seedings that resulted in at least 50-percent stocking

received on average 8 inches (20 cm) of precipitation

from October to April and about 15 inches (38.1 cm)

from May to September during each of the first 3 years

after sowing. In contrast, stocking averaged less than

10 percent when precipitation was 6 inches (15 cm)

from October to April and 11 inches (28 cm) from May

to September. Distribution of precipitation is also important. Seedling mortality can be high if there are hot,

dry periods during late summer and early fall within

the first 3 years of sowing. Greenhouse studies have

shown that ponderosa pine seedling survival and

growth are best when seedlings receive 1 inch (2.54 cm)

or more of water evenly distributed throughout the

month (Noble and others 1979).

Topography and soil influence soil moisture availability and thus seedling success. Wagar and Meyers

(1958) reported survival to be highest on lower, gentle,

north and east slopes where soil moisture was most

favorable. Southern and western aspects typically had

lower survival, especially on slopes greater than 30 degrees, which often have thin soils. Recently burned

areas are likely to have higher erosion rates. Even limestone soils with 12 percent slopes and metamorphic

soils with slopes of 20 percent have shown severe erosion and loss of seeds (Wagar and Meyer 1958).

Competition with grasses and forbs does not seem

to be a problem in years of abundant precipitation

(Wagar and Meyers 1958). In dry years, however, survival was low and the survivors averaged smaller than

seedlings on adjacent bare ground. Seeded pines do

not compete well with hardwoods such as aspen, birch,

or bur oak.

Broadcast seeding, spot seeding, and sowing with a

corn planter give similar survival results. The amount

of seed varies depending on the sowing method. For

spot seeding, 0.2 to 2.5 pounds of seed (12,000 ponderosa pine seeds per pound) per acre is sufficient. With

spot seeding, seeds can be situated in superior

microsites and covered with soil to improve germination and lessen losses to rodents (Schubert 1974).

Broadcast seeding requires more seeds with at least 4

to 6 pounds per acre when conditions are favorable

(Wagar and Meyer 1958). Broadcast seeding can be

performed from the air or the ground. Germination

success can be improved by preparing a loose seedbed

or by disking after sowing (Schubert 1974).

Seed protection

Because ponderosa pine seeds are eaten by many

mammals and birds in the Black Hills, predation on

seeds can influence the outcome of reforestation attempts. Early attempts to control seed predation by

protecting seeds with chemicals and by trapping animals have been shown to be costly and ineffective

(Keyes 2000). Recent efforts are focusing on creating

strategies that utilize our knowledge of feeding habits

and life cycles of seed predators.

Seed predators occur in all phases of forest development, with the greatest population densities in the

early seral stages (West 1992). Small mammals, such

as chipmunks, squirrels, and deer mice (Peromyscus

maniculatus) cause the most seed loss in ponderosa

pine direct seeding programs (Evans 1988). Small

mammals have predictable cyclic population patterns,

with high densities in the fall and low densities in the

spring (West 1992). Birds such as Merriam’s turkey

rely heavily on ponderosa pine seed for winter forage.

Thus, direct seeding should occur in the spring when

small mammal populations are lower and other forage

is available.

Several methods can be used to determine the probability of seed predation. Direct sampling of small

mammal populations with Sherman live traps will provide an estimate of small mammal density (Keyes

2000). A relatively inexpensive way to quantify seed

consumption is to use small, mesh-covered exclosures

that will allow seeds to fall through, but keep animals

from reaching them. Comparing the number of seeds

in the exclosure to an uncovered area next to it can

indicate consumption levels (Gashwiler 1967).

If seed predation is causing a regeneration problem,

there are several management options for mitigation.

Options include reducing per-capita seed consumption,

avoiding large populations of seed predators, and reducing seed predator populations (Keyes 2000). A

manager can reduce the per-capita seed consumption

of ponderosa pine seed by providing alternative food

sources, such as sunflower seeds. This technique has

been shown to increase lodgepole pine seed survival

by 30 to 60 percent (Sullivan and Sullivan 1982). If

this method is used, alternative food sources must

be continued until an acceptable number of seedlings are established (Keyes 2000). Any seed to be

used as an alternate food source should first be rendered nonviable to avoid introduction of invasive

nonnative plants.
86 USDA Forest Service General Technical Report RMRS-GTR-97. 2002

Reducing large population levels of small mammals

can also reduce seed consumption. Poisoning small

mammals is a short-lived approach because recolonization is rapid. Furthermore, the use of poison can

also kill nontarget animals. A better way of reducing

small mammal population levels is to reduce the habitat they rely on. Reducing woody debris and shrub

cover will decrease the habitat quality and may increase

predation by larger predators (West 1992). Per-capita

mammal seed consumption has been shown to increase

during good seed years, but with more of available

seeds, the consumption is compensated (West 1992).

Therefore, the success of seeding operations to regenerate ponderosa pine can be enhanced if they are scheduled during good seed years.

Lastly, seed predation should be seen as another

natural process that occurs in an ecosystem. The influence of seed predators in the ponderosa pine forest is

not all negative. In fact, ponderosa pine seed is an

important food source for many animals and birds.

Accomodating seed predation is often the most realistic approach.

Planting

Raising seedlings at a nursery and subsequently

planting them on the site to be reforested can avoid

many of the problems associated with artificial seeding of ponderosa pine (Hallman 1993). Seedlings

grown in nurseries are selected from seed sources that

exhibit good form, growth, and disease resistance. The

controlled conditions in nurseries eliminate many of

the uncertain growing conditions in the field and associated early seedling mortality. Unhealthy and poorly

formed seedlings are culled before seedlings are

shipped from the nursery. Although planting seedlings

is much more expensive than seeding, the rate of reforestation is quicker because healthy, vigorous seedlings with established root systems are planted.

Successfully planting seedlings is dependent on the

ability of the planter to do the job correctly. There are

many steps in getting a seedling from the nursery into

the ground at the planting site, and careful handling of

the nursery stock is of utmost importance. It is also

imperative that seedlings to be planted in the Black

Hills should come from a seed source within the Black

Hills, ideally from as close to the planting site as possible.

The absence of dwarf mistletoe (Arceuthobium

campylopodum) in the Black Hills is another reason to

be extremely careful about the source of planting stock.

Dwarf mistletoe infects ponderosa pine forests all over

the Western United States, but the Black Hills so far

has not been infected. The potential for dwarf mistletoe to be introduced to the Black Hills is greatly increased when seedlings are grown among other seed

sources in nurseries outside the Black Hills. Any seedlings grown at an outside nursery and transported to

the Black Hills should be carefully inspected for dwarf

mistletoe.

Bare-root seedlings

Bare-root seedlings are grown in exposed seedbeds,

lifted from the soil, and shipped to the planting site

with the roots separated from the soil (Tinus and

McDonald 1979). Sometimes seedlings are transplanted into another seedbed to make the root systems

more compact and to create more fine lateral roots.

Seedlings are classified based on age and treatment

designated by two numbers. The first is the number of

years the plants grew as a seedling within the same

seedbed; the second is the number of years grown as

transplants. Therefore, a bare-root seedling designated

a “2-1” means it has grown for 2 years as a seedling

plus 1 year as a transplant. A bare-root seedling designated a “2-0” is a 2-year-old seedling grown for 2 years

in the same bed without transplanting (Smith and others 1997).

To date, only one study (Boldt 1968) has investigated which class of ponderosa pine planting stock

should be used for Black Hills plantings. Boldt examined the survival and height growth of 1-0, 2-0, 1-1,

and 2-1 planting stock on two burned sites in the Black

Hills. One site represented an area marginal for planting with only 18 inches (45.7 cm) of annual precipitation, while the other site had high potential for timber

production with 24 inches (61 cm) of annual precipitation. After the third growing season, survival was

greater than 70 percent for all planting stock classes

on both sites. The trees showed substantial differences

in average height at the end of the fifth growing season, however. On the marginal site, the average heights

were 10.9, 15.4, 18.8, and 17.1 inches (27.7, 39.1, 47.8,

and 43.4 cm) for the 1-0, 2-0, 1-1, and 2-1 stock classes,

respectively. The favorable site had average heights

of 14.7, 17.7, 20.1, and 23.0 inches (37.3, 45, 51.1,

and 58.4 cm) for the stock classes 1-0, 2-0, 1-1, and 2-

1 respectively. Boldt recommended that, because 2-0

planting stock appears to provide the best combination of economy and performance it should be used as

the standard for Black Hills plantings. However, the

author did suggest further research to determine if 2-0

stock will perform as well during dry years, and if not,

whether 2-1 stock might be better.

Increasing survival and growth of bare-root seedlings—Several studies have investigated techniques to
USDA Forest Service General Technical Report RMRS-GTR-97. 2002 87

increase survival and growth of bare-root ponderosa

pine, but none were conducted with Black Hills seed

sources or sites. Until these issues can be studied for

the Black Hills, planters should utilize the information

provided from other studies.

The use of bare-root seedlings for reforestation involves several steps that can stress the seedling and

result in lower survival rates. These steps include lifting, processing, storing, shipping, field handling, field

storing, and planting (Rietveld 1989a). With proper

procedures and care, the loss of growth potential can

be minimized.

Root volume—One of the most advantageous aspects of nursery-raised seedlings is that they have already passed the critical early stage of development;

the seedling already has a stem, shoots, buds, and a

root system. For a seedling to survive, the root system

must be viable and able to grow fast enough to maintain contact with the soil moisture supply. Seedlings

with larger root systems have better survival, growth,

and drought resistance. One study in Oregon showed

that, after two growing seasons, ponderosa pine seedling survival and growth were significantly greater for

seedlings that were planted with initial root volumes

of greater than 0.43 inch3 (>7 cm3

) compared to root

volumes less than 0.28 inch3 (<4.5 cm3

) (Rose and others 1991).

Shoot-root ratios — Don’t choose a seedling based

solely on its height. Instead, choosing a seedling with

a large root system and a relatively small top appears

to be advantageous (Heidmann 1988). Shoot-root ratio is a good indicator of internal water stress and potential survival of an outplanted seedling because shoot

and root sizes directly affect water loss and uptake.

Lopushinsky and Beebe (1976) reported that low shootroot ratios increased survival and height growth of

outplanted ponderosa pine seedlings on a dry site in

north-central Washington. The authors suggest that the

seedlings with lower shoot-root ratios survived better

because (1) desiccation and moisture stress immediately after planting were minimized, and (2) later internal water stress was low enough to permit some root

growth, which improved the absorptive ability of the

root system. Seedlings with a high shoot-root ratio

will have a greater transpiring surface in relation to

the root’s surface area, which could be detrimental

during a drought (Heidmann 1988).

Root growth potential—The ability of seedlings

to grow new roots is referred to as root growth potential (RGP) (Ritchie and others 1985). RGP is used to

estimate planting stock quality because it incorporates

several morphological and physiological features into

a biologically meaningful estimate of the ability of a

plant to grow new roots (Rietveld 1989a). High RGP

values in ponderosa pine are strongly correlated with

high field survival (Heidmann 1988). Primary techniques for estimating RGP include soil culture, hydroponic culture, aeroponic culture (Rietveld 1989b), and

volume displacement (Harrington and others 1994).

Lifting and storage of bare-root seedlings—Seedlings are often lifted at nurseries and stored over winter in freezers so that they are readily available to customers in the spring. In nature, seedlings undergo vegetative dormancy as temperatures lower and photoperiod shortens (Hocker 1979). To break from this dormancy, seedlings must experience some exposure to

low temperatures. Stone (1970) reported that ponderosa pine seedlings require exposure to night temperatures at or below 43  ̊F (6  ̊C) for at least 60 days to

achieve maximum root growth after dormancy. Fall

lifting and long-term storage have several operational

and management benefits (Hocking and Nyland 1971

cited in Omi and others 1991), but they can be detrimental to plant growth and development.

Seedlings should be lifted at the peak of their dormancy to best survive long-term storage (Sloan 1991).

Long-term storage can reduce seedling quality because

seedlings are no longer exposed to photoperiods (Lavender and Wareing 1972), temperatures may be too cold

to satisfy chilling requirement, seedlings may become

desiccated, and carbohydrate reserves decline

(Faulconer 1988; Ritchie 1982, 1986). Loss of carbohydrate reserves may lead to reduced root initiation,

thus lowering seedling survival and growth when

outplanted. Furthermore, some benefical mycorrhizae

fungi, such as Pisolithus tinctorius, do not survive cold

storage (Alvarez and Linderman 1983).

In general, ponderosa pine seedlings lifted in November have good survival rates (Omi and others 1991,

1994; Stone and Schubert 1959). A preliminary study

at Lucky Peak Nursery in Idaho indicated that although

ponderosa pine seedling survival after two growing

seasons was similar for seedlings lifted in October, November, December, March, and April, growth for the

same period was greatest for seedlings lifted in November, December, and April (Sloan 1991). The seedlings lifted in mid-April had the greatest growth, which

the authors attributed to the short 2-week storage time

before planting. Another study of an Oregon seed

source indicated that lifting ponderosa pine seedlings

in September followed by long-term storage lowered

survival after two growing seasons, while lifting in

November was as good as or better than spring lifting

(Omi and others 1994).

Root dipping—Roots are commonly dipped in a

variety of substances to prevent bare-root seedlings
88 USDA Forest Service General Technical Report RMRS-GTR-97. 2002

from drying out in storage, desiccating at the planting

site, and to improve seedling survival and growth after

planting (Sloan 1994a). Substances used for root dips

include: soil slurries, vermiculite or ground sphagnum

moss, hydrophilic gels, and other materials such as

organic compounds, pesticides, or other chemicals

(Sloan 1994a). These substances are coated on the root

system. Studies investigating the survival and growth

of bare-root ponderosa pine seedlings have been limited to root dips consisting of vermiculite (Ryker 1981;

Sloan 1994b), vermiculite slurry (Sloan 1994b), peat

moss (Ryker 1981), hydrophilic gels (Ryker 1981;

Sloan 1994b; Tuskan and Ellis 1991), and hygroscopic

gels mixed with auxin (Tuskan and Ellis 1991).

Vermiculite is an expanded mica substance that can

hold water tightly and resist drying when coated on a

root system (Sloan 1994a). Hydrophilic gels can absorb between 40 and 500 times their weights in water

depending on the type of solution. Thus far, studies

using vermiculite or the hydrophilic gels, AquagelTM

(Sloan 1994b), ViterraTM (Ryker 1981) and WaterLock

Superabsorbant Polymer B-204 gel (Tuskan and Ellis

1991), have not shown an increase in ponderosa pine

seedling survival or growth. Tuskan and Ellis (1991)

did show an increase in outplanted seedling growth

and survival using a hydrophilic gel fortified with auxins at concentrations of 100 and 300 ppm indole-3-

butyric acid (IBA). Field survival of the outplanted

seedlings with the fortified gel was 15 percent higher

than the seedlings dipped in the gel without auxin, and

28 percent higher than for the nondipped seedlings.

Transporting and handling bare-root planting

stock—Planting stock should be packaged so that roots

remain moist and cool while allowing oxygen to enter

the package and carbon dioxide and other gases to escape (Smith and others 1997). The seedlings should

be refrigerated at temperatures slightly above freezing. Proper precautions should be taken to prevent desiccation of bare roots due to freezing temperatures.

Seedlings should be kept under refrigeration until ready

to plant. Under no circumstances should bare-root

seedlings be transported in open trucks, or allowed in

the sun in their unopened transport bags. Lethal temperatures can occur inside the bags after just a few

minutes exposure to full sunlight. Physical damage

while handling seedlings can hinder seedling growth

and survival after planting. The most common damage is

the loss of fine roots, which are important for water absorption and carbohydrate storage (Rietveld 1989a).

Containerized seedlings

Containerized seedlings are grown in small soilfilled containers, usually inside a controlled-environment

greenhouse, and are delivered to the planting site still

in the containers in which they were grown. Seedlings

are removed from the containers as they are planted.

Containerized seedlings undergo less transplanting

shock because there is minimum root exposure and

disturbance (Kinghorn 1974). Survival and growth are

usually increased due to the constant contact of the roots

with soil, and the nutrients and water-holding capacity

of the container media. Although production of containerized seedlings is more expensive and transport

of seedlings is more cumbersome, increased survival

and growth can make up for the disadvantages. This is

especially relevant on dry, harsh sites that are difficult

to regenerate. The container tree nursery manual published by the USDA Forest Service lists several types

of containers (Landis 1990a) and growth media (Landis

1990b).

Controlling root growth and form—Narrow, deep

containers are most compatible for ponderosa pine

because they produce taproot systems (Tinus and

McDonald 1979). However, there is concern that the

roots in such a constricted space will start growing in a

spiral and become “pot-bound” when they hit the walls

of the container. While root spiraling is not detrimental to seedling growth in the nursery, it can seriously

degrade seedling quality after outplanting (Landis

1990a).

Several features in newer containers minimize root

spiraling. Some containers contain vertical internal ribs

to reduce root spiraling and possible root strangulation (Smith and others 1997; Tinus and McDonald

1979). The ribs help direct the roots to the bottom of

the container, which has a hole in the bottom. The low

humidity of the air beneath the hole stops the roots

from growing any further, but the roots retain the ability to grow when the seedling is planted (Landis 1990a).

Although this technique prevents root spiraling, the

distribution of the root system in the container does

not correspond to that of naturally grown seedlings.

Ponderosa pine seedlings found in nature produce

long lateral roots within the top 12 inches (30.5 cm) of

the soil (Stein 1978), which provide a foundation to

aid in windfirmness. In contrast, seedlings grown in

containers have lateral roots that are forced to grow

downward, producing a dense, fibrous root mass

bunched around the taproot in the upper soil layers.

When the seedling is planted, new lateral roots are produced by growth of new root tips from the cut ends of

the existing laterals initiated higher up the stem (Stein

1978).

McDonald and others (1984a) reported that coating

the inside of containers with a mixture of acrylic latex

paint and CuCO3 (concentration 50 to 100 grams per
USDA Forest Service General Technical Report RMRS-GTR-97. 2002 89

liter of paint) halted lateral root growth at the container

wall. Inhibition of the initial lateral root growth leads

to production of secondary lateral roots, which are once

again halted when they reach the container wall. The

resulting roots systems are more fibrous and evenly

distributed throughout the container (Landis 1990a).

Containers treated with CuCO3 promote better seedling stability after outplanting due to the production of

roots in the middle and upper zones of the container

(Wenny 1988). Normal root growth resumes when the

seedling is removed from the container and a more

natural, branched root system is produced after

outplanting (McDonald and others 1984a). It should

be noted that the acrylic latex paint was phytotoxic to

the seedlings, but the paint’s effects were overridden

by the CuCO3 in the tests reported by McDonald and

others (1984a). In another study, McDonald and others (1984b) reported that a combination of CuCO3

(concentration 50 grams per liter of acrylic latex paint)

coated on the side of the container wall and inoculation with ectomycorrhizal fungi (Suillus granulatus and

Pisolithus tinctorius) increased the formation of

ectomycorrhizae on the roots of ponderosa pine seedlings.

Growth conditions—Growing containerized seedlings in the greenhouse allows greater control of environmental and nutrient conditions. Larson (1967) investigated the effect of air and soil temperature on initial development of ponderosa pine seedlings from the

Black Hills. Root growth responded more to soil temperature, while top growth responded more to air temperature. The optimum air and soil temperatures for

initial root growth of ponderosa pine were near 59  ̊F

(15  ̊C) air and 73.4  ̊F (23  ̊C) soil, but a constant temperature of 73.4  ̊F (23  ̊C) was more favorable for

entire seedling growth than any combination of alternating day and night temperatures. Based on these results, Tinus and McDonald (1979) recommend a constant greenhouse temperature setting of 73.4  ̊F (23  ̊C)

with an allowable range of 68 to 75  ̊F (20 to 24  ̊C).

Optimal greenhouse humidity for germination is 80

percent, but once the radicle has penetrated the soil

surface, optimum humidity is 60 percent (Tinus and

McDonald 1979). Maximum photosynthetic rates are

obtained when light levels are between 775 to 1550

mmol m2

/s-1 (Hadley 1969).

Handling and transporting containerized seedlings—Transporting containerized seedlings depends

on the type of container in which the seedlings are

grown. If the seedlings are grown in tubes or Styrofoam

blocks, the entire container is shipped. Shipping containers require more shipping space and the containers

must be returned to the nursery, which increases the

cost. The roots are highly protected, although the shoots

must still be carefully handled. If the seedlings are

grown as plugs, the seedlings can be transported with

or without the containers. If the plugs are transported

without the containers, less shipping space is required,

but the stock quality can be seriously impaired during

cold storage and handling if seedlings are not completely dormant (Brissette and others 1991).

Seedlings should be transported in either cold storage (33.8 to 37.4  ̊F; 1 to 3  ̊C) or in a covered vehicle

that protects them from direct sunlight and wind. The

number of seedlings transported and stored at a planting site should be limited to the number that can be

planted in one day. Handling of seedlings should be

limited to loading them into planting bags during the

actual planting (Carlson 1991).

Planting techniques

Once the seedlings reach the planting site, they

should be promptly planted. If bad weather or changes

in planting schedules do occur, temporary storage in a

cold storage (33.8 to 37.4  ̊F; 1 to 3  ̊C) facility is recommended. If no cold storage is available, seedlings

should be stored in a cool, shaded spot with a water

supply and good surface drainage (Carlson 1991). Bareroot seedlings should never be stored in the open at

ambient temperatures.

Hallman (1993) describes several types of planting

equipment to be used when planting both bare-root and

containerized seedlings. Of utmost importance is the

reestablishment of the root-soil interface. If hand tools

are used to plant seedlings, care must be taken to excavate and backfill a hole or trench that will not have air

pockets, or glazed surfaces that roots cannot penetrate

(Ronco 1972). If power augers are used to excavate

holes, the auger operator must work closely with the

planter, so that excavated soil does not dry out before

the seedlings are planted. Ronco (1972) also recommends hand scalping an area 18 inches (50 cm) wide

around each planting spot to remove competing vegetation, providing a clean area to pile excavated soil,

and removing debris that might fall into the hole and

prevent the roots from making intimate contact with

the soil.

Heidmann (1988) provides several guidelines for

planting ponderosa pine seedlings. First, select a planting spot carefully and take advantage of favorable soil

conditions. Second, scrape away surface litter and dry

soil before making the hole. Third, the hole should be

deeper than the length of the seedling’s roots. When

planting the seedling in the hole, care should be taken

to maintain a natural vertical position and prevent “J”

or “L” rooting (Hallman 1993). Fourth, once the seedling
90 USDA Forest Service General Technical Report RMRS-GTR-97. 2002

is in the hole, fill it loosely with soil. Fifth, pull the

seedling up toward the soil surface so that the root collar is almost level with the soil surface and pack the

soil around the seedling with the heel of your foot. Containerized seedlings should be planted deep enough to

cover the root plug to avoid desiccation. Replacement

of forest litter around the seedling can help retain moisture (Hallman 1993).

Hand planting seedlings can be labor intensive, but

usually is the only option for steep slopes, shallow soils,

and rough terrain. Because the process of hand planting usually takes longer to get the seedling from the

onsite storage facility into the ground, considerable care

must be taken to maintain root moisture. If bare root

seedlings are being planted, make sure to dip the roots

in water as soon as they are removed from the cold

storage and placed in the planting bag to be carried

around the site. Make sure the planting bag has some

form of wet sawdust, peat moss, or burlap to ensure

that roots stay moist. Planters should only carry as

many seedlings as can be planted in 2 hours to ensure

that roots stay moist. Furthermore, the planters should

not expose the seedlings to wind or sun for more than

5 minutes (preferably less than 1 minute) because the

roots will desiccate. When separating the seedlings,

the planters should be quick but careful and attempt to

reduce breakage of the roots (Long 1991).

Mycorrhizal inoculation of seedlings

Trees form symbiotic associations between their

roots and soil fungi called mycorrhizae. Mycorrhizae

benefit seedlings and mature trees because they increase

the surface area of the roots, thus increasing the absorption of water and nutrients. Castellano and Molina

(1989) identified several types of ectomycorrhizal fungi

that associate with ponderosa pine including: Hebeloma

crustuliniforme, Laccaria laccata, Thelephora spp.,

Rhizopogon fuscorubens, Rhizopogon subgelatinosus,

Rhizopogon ochraceorubens, and Rhizopogon evadens.

Riffle and Tinus (1982) reported associations with

Rhizopogon roseolus and Suillus granulatus in ponderosa pines grown in North Dakota. A common mycorrhizal fungus used in artificial inoculation of ponderosa pines in nursery operations is Pisolithus tinctorius

(Castellano and Molina 1989; France and Cline 1987).

Mycorrhizae can be used to increase the survival

and growth of outplanted seedlings. Seedlings with

ectomycorrhizae on soils of low fertility typically have

a higher mineral nutrient content per unit seedling dry

weight than nonmycorrhizal seedlings (Kropp and

Langlois 1990). Uptake of nitrogen was significantly

higher in spruce inoculated with ectomycorrhizal fungus than in noninoculated plants (Alexander and Fairley

1986). Most importantly, ectomycorrhizal seedlings

are usually more resistant to water stress (Kropp and

Langlois 1990). Ectomycorrhizae also produce plant

growth regulators and other secondary metabolites that

aid in the expansion of the root surface area through

increases in branching and rootlet diameter (Kropp and

Langlois 1990). Ectomycorrhizal fungi are also known

to protect the host tree from root decay by species of

Rhizoctonia, Fusarium, Pythium, and Phytophthora

(Kropp and Langlois 1990).

Several factors influence the formation of ectomycorrhizae in nurseries (Kropp and Langlois 1990;

Marx and others 1989). For instance, Pisolithus

tinctorius grows best at soil pH between 4.5 and 5.5,

but is inhibited at pH greater than 6.0 (Marx and Cordell

1988). Because a large pathogen population can inhibit ectomycorrhizal development, soil fumigation of

bare-root facilities before sowing has been recommended to reduce pathogens (Castellano and Molina

1989; Kropp and Langlois 1990). Pesticides such as

triamephon, hexazione, and trichlopyr can inhibit

ectomycorrhizal development (Kropp and Langlois

1990). In addition, fertilizers with high concentrations

of phosphorus and nitrogen decrease the formation of

ectomycorrhizae (Castellano and Molina 1989; Cornett

1982; Kropp and Langlois 1990).

Increased survival and growth of mycorrhizal

seedlings—Inoculation of seedlings with mycorrhizae

during the production of bare-root or containerized

planting stock can help improve the quality of the seedling root system and therefore the survival and growth

after outplanting (Cornett 1982; Heidmann and Cornett

1986; Kropp and Langlois 1990; Riffle and Tinus

1982). Inoculated seedlings have a net advantage over

noninoculated seedlings in soils with low fertility, but

are often equal in size or smaller than noninoculated

seedlings in soils with high fertility (Kropp and

Langlois 1990). Although seedlings in nurseries with

highly fertile soils can grow rapidly without mycorrhizal inoculations, when these seedlings are outplanted

in soil less fertile than the nursery soil, they will lack

the benefit of the mycorrhizal association. Outplanting

stress can be lessened with mycorrhizal inoculations

because the fungus can aid in establishing root contact

with the soil.

Baer and Otta (1981) reported an 18 percent increase

in survival for bare-root ponderosa pine seedlings inoculated with Pisolithus tinctorius outplanted on prairie soil after two growing seasons. Riffle and Tinus

(1982) investigated the influence of six different

ectomycorrhizal fungi on survival and growth of ponderosa pine seedlings planted on a North Dakota site

with nonmycorrhizal prairie soil. After five growing
USDA Forest Service General Technical Report RMRS-GTR-97. 2002 91

seasons, the authors reported greater survival for the

seedlings inoculated with Rhizopogon roseolus (62 percent), Suillus granulatus (56 percent), Pisolithus

tinctorius (52 percent), Cenococcum geophilum

(53 percent), and pine duff (75 percent). Seedlings inoculated with Thelephora terrestris did not benefit from

the inoculation and had similar survival (30 percent)

and growth as noninoculated seedlings. The pine duff

inoculant was obtained from the A1 horizon of a 38-

year old ponderosa pine plantation in North Dakota

near where the experimental seedlings were planted.

Seedlings inoculated with the pine duff had 1058 percent greater biomass than noninoculated control seedlings. The authors suggest the greater success was probably a result of a mixture of native ectomycorrhizal

fungi, but do not recommend using pine duff for inoculation because of the risk of transmitting soil-borne

plant pathogens.

Artificial mycorrhizal inoculation—Soil, spores,

and vegetative mycelium are the three primary sources

for artificial inoculation used in the nursery industry

(Castellano and Molina 1989). Marx and Cordell

(1988) suggest that over 50 percent ectomycorrhizal

formation on the roots may be needed to guarantee a

positive response to inoculation. The area in which

nursery seedlings will be outplanted will most likely

contain native mycorrhizae if it is or was recently forested. One method of inoculating nursery seedlings is

to take soil from the potential reforested area and incorporate it into the seedbed of a bare-root operation

or into the growth media for container seedlings. In

bare-root seedling operations, the inoculum soil and

seeds can be applied together in the nursery soil

(Cordell and others 1987). Typically, up to 10 percent

by volume of soil inoculum is incorporated into the

top 4 inches (10 cm) of the seedbed before sowing

(Castellano and Molina 1989). The use of soil inoculum can have several disadvantages, including the requirement of large quantities of soil, introduction of

pathogens, weed seeds, and rhizomes into the nursery

soil, and the variation of inoculum quality (Castellano

and Molina 1989). The advantage of inoculating with

the endemic mycorrhizal fungi is appealing, although

some studies have shown that the native mycorrhizae

usually replace the nursery inoculant within a year of

outplanting (Castellano and Molina 1989).

Spore inoculum is a popular method for both bareroot and containerized seedling operations due to its

low cost and ease of dispersion (Kropp and Langlois

1990). Spores can be added to irrigations systems, fertilizer spreaders, or applied as a seed coating before

sowing (Castellano and Molina 1989; Kropp and

Langlois 1990). One disadvantage of this method is

that spore inoculum requires large quantities of spores

and is less effective than solid inoculum. However,

Pisolithus tinctorius and species of Rhizopogon, both

of which have been shown to associate with ponderosa pine seedlings (Alvarez and Linderman 1983;

Castellano and Molina 1989; McDonald and others

1984b; Riffle and Tinus 1982), produce large quantities of spores (Kropp and Langlois 1990).

Vegetative mycelium inoculum is usually grown in

culture on a special medium (Castellano and Molina

1989). The inoculum is placed in a peat-vermiculite

carrier and mixed into container growing media. Vegetative inoculation is expensive and labor intensive.

In addition, this type of inoculum has not shown better

survival or growth in seedlings, so it is not recommended as an option.

Management of Associated

Species

White Spruce

The silvical and ecological characteristics of white

spruce in the Black Hills are similar to those of Engelmann spruce (Picea engelmannii) as far as seed size,

regeneration requirements, shade tolerance, and so

forth. However, there are some important ecological

relations to consider when managing white spruce in

the Black Hills. First, white spruce does not occur in

association with any true firs (Abies spp.) in the Black

Hills. Instead, white spruce grows in association with

ponderosa pine, aspen, and occasionally, paper birch

and lodgepole pine. These ecologic associations have

important management implications for white spruce.

Because a shade-tolerant true fir cohort is missing from

these stands, managers can expect somewhat different

regeneration responses when cutting white spruce in

the Black Hills.

White spruce is the most shade-tolerant species in

the mixed forests of the Black Hills, and therefore is

going to be the species that regenerates best under overstory shade. It is also light seeded and can be expected

to disperse seed farther into openings and through

stands than ponderosa pine. White spruce seedbed and

germination requirements are similar to those of ponderosa pine. Presence of a mineral soil seedbed is critical, especially when attempting to naturally regenerate white spruce in vegetation associations that have

sod-forming grasses in the understory. It is important

to ensure that harvest activities in these cases create

sufficient soil disturbance to provide scarified seedbeds. Otherwise, very little of the seed can be expected
92 USDA Forest Service General Technical Report RMRS-GTR-97. 2002

to germinate. Where overstory canopies are open and

allow more light to reach the forest floor, less shadetolerant species such as ponderosa pine, lodgepole pine,

and aspen can be expected to regenerate more abundantly than white spruce. Aspen especially will sprout

prolifically if overstory shade is removed in mixed

spruce-aspen stands.

White spruce theoretically can be managed under

both even-aged and uneven-aged silvicultural systems.

White spruce is a shallow-rooted species with large

crown volumes, and can be expected to be more susceptible to windthrow than ponderosa pine. Care must

be taken when harvesting spruce stands to avoid

windthrow, especially in forests with single-storied

canopies.

Marking guides presented in Alexander (1987b)

should be followed when marking white spruce for

harvesting. As with ponderosa pine, white spruce

should normally be regenerated naturally. In cases

where artificial reforestation is necessary, however,

white spruce seedlings must be planted so they are protected from too much sunlight. Although elevations in

the Black Hills are considerably less than those of

spruce forests in the Rocky Mountains, similar measures must be taken in handling and planting spruce

stock. Ronco’s (1972) planting guidelines for Engelmann spruce are appropriate when planting white

spruce in the Black Hills.

White spruce seedlings can be expected to establish

and grow somewhat more slowly than ponderosa pine

seedlings in the Black Hills. Nevertheless, intermediate treatments will probably be needed to maintain

desirable levels of growing stock for multiple resource

uses. As with ponderosa pine, precommerical thinning will probably be the most cost effective way of

removing excess growing stock, while minimizing

slash accumulations and adverse impacts to wildlife

habitat and forage resources.

Because spruce grows at higher elevations in the

Black Hills and predominantely on northern slopes, its

precipitation regime is more driven by snow, similar

to conditions in the Central Rocky Mountains. Watershed management implications for the spruce type can

therefore be expected to be quite similar to those reported for Engelmann spruce in the Central Rockies

(Shepperd and others 1992).

Aspen

The aspen/paper birch forest type currently covers

about 50,000 acres in the Black Hills (USDA Forest

Service 1996a). Aspen (Populus tremuloides ) occurs

in small isolated clones in the Black Hills between

elevations of 4,000 and 7,000 feet (1,200 to 2,100 m),

predominantely on north-facing slopes with favorable

moisture conditions (Severson and Thilenius 1976).

Most aspen stands occur in the northern half of the

Black Hills in areas receiving greater than 18 inches

(>46 cm) of precipitation per year (Severson and

Thilenius 1976). Isolated aspen clones are often surrounded by ponderosa pine stands (fig. 50) and provide nesting and forage habitat for several bird, big

game, and livestock animals. In addition, aspen plays

an important role in riparian ecosystems by providing

dam building material for beavers (Castor canadensis)

(Parrish and others 1996).

Factors that could affect the continued existence of

aspen in the Black Hills include: fire exclusion during

most of the 20th century, competition from more shadetolerant conifers, lack of younger age classes in existing clones, browsing and barking by animals, susceptibility to diseases, and global climate change. These

factors, along with the lack of extensive mixed conifer/aspen forests, indicate that growing conditions for

aspen in the Black Hills are marginal, at best. Therefore, special actions may be necessary to expand and

conserve existing aspen clones.

Retaining aspen in Black Hills landscapes will require intensive management. Because aspen regenerates primarily by root suckering, opportunities to initiate new aspen stands (or replace clones that are lost)

are limited. Planting aspen is not recommended. If

attempted, planting would require a moist site and

fencing to protect aspen seedlings from browsing

animals. Even with fencing, normal mortality rates

of natural aspen suckers (Shepperd 1993) suggest

that very few planted seedlings would survive.

Therefore, many more seedlings would have to be

planted than would be desired in an established aspen stand. As with all planting efforts, seed or vegetatively reproduced planting stock should be collected from local sources.

Recommended techniques for regenerating or expanding existing clones include removal of competing

conifers, protection of existing new suckers, and stimulation of new suckers (Shepperd 2001). Removing

conifers growing in and around an aspen clone can reduce competition for moisture and light, which will

favor the aspen. Aspen roots extend a considerable

distance away from existing stems. Clearing surrounding conifer forest back 1 to 1.5 tree heights

away from a declining aspen clone will allow new

suckers to establish and expand the area occupied

by the clone.

Given the high deer and elk populations and extensive livestock grazing throughout the Black Hills,
USDA Forest Service General Technical Report RMRS-GTR-97. 2002 93

protection of new sprouts from browsing will be essential in most situations. Fencing aspen stands to

exclude animals has proven effective in intensively

browsed areas (Rolf 2001), but must be retained until

aspen stems reach at least 1.5 inches (3.8 cm) in diameter at breast height (Shepperd 2001). Retaining logging slash on the ground has been found to be effective in deterring browsing damage in the Black Hills

(Rumble and others 1996), but Shepperd (1996) found

that felling all aspen and leaving them onsite was detrimental to suckering. Some aspen genotypes are more

desirable to browsing animals, so some clones may be

damaged more severely than others (Shepperd and

Fairweather 1994).

If removal of competition and protection do not result in new sprouting, it may be necessary to stimulate

suckering. Three things are necessary to initiate and

optimize sucker growth in aspen: interrupting the flow

of auxin to roots (Shier 1973), providing full sunlight

to the forest floor, and achieving soil temperatures of

54 to 68 ∞F (12 to 20 ∞C) (Hungerford 1988;

Landhausser and Lieffers 1998). Cutting mature aspen stems can interrupt the flow of auxin to roots and

(if sufficient numbers of trees are removed), provide

sunlight and warm the soil. Clearfelling is the best

means of harvesting aspen to meet these requirements

and avoid damage to residual stems. However, other

techniques can be effective to stimulate suckering along

the edges of small isolated aspen clones without killing all of the existing stems. Ripping along the edge of

the clone with a tractor or plow can sever lateral roots

and initiate suckering (Shepperd 2001). Similarly, a

light prescribed fire can initiate a new cohort of suckers in an aspen clone without killing all of the existing

stems. Suckers will typically be densest around the

edges of a clone where tree mortality from the fire is

highest and where soil temperatures are raised because

of blackened soil. To maximize the suckering response,

treatments to stimulate aspen suckering should be done

during the dormant season. This minimizes the time

roots have to exist on stored carbohydrate reserves prior

to the next spring when suckering will begin (Shepperd

2001).

A rule of thumb to assess the need to treat aspen

clones in the Black Hills would be to intervene where:

• Clones are deteriorating as indicated by numerous dead or diseased overstory stems, multiple

aspen logs on the ground, and lack of younger

age classes (as indicated by lack of multiple

canopy layers and stem sizes).

Figure 50: An aspen stand adjacent to a ponderosa pine stand.
94 USDA Forest Service General Technical Report RMRS-GTR-97. 2002

• Clones have numerous conifers in the overstory

canopy and adjoining the edge of the clone.

• Clones are attempting to sucker, but the suckers

are being consumed by animals (suckers have a

“hedged” appearance with multiple leaders, none

of which have grown above the reach of animals).

Multistoried aspen clones, those with intact overstory canopies, and isolated clones with a round

globular shape with green branches near the ground

on the exterior edges of the clone are probably in

good shape and not in need of treatment.

Bur Oak

Bur oak (Quercus macrocarpa) is a widely distributed eastern hardwood that achieves the westernmost

limit of its distribution in the Black Hills (Little 1971).

It occurs in the Black Hills either as an understory species associated with ponderosa pine, as a dominant

shrub in the northern Black Hills, or as emergent individuals in ravines and riparian areas along the edges

of the Black Hills (Sieg 1991). Sieg found that bur

oak in the Black Hills could be associated with soil

iron levels, slope, and sedge (Carex spp.) cover.

The age class distribution of bur oak varies from

site to site in the Black Hills (Sieg 1991), but a bimodal age distribution with peaks in the 1900s and 1940s

is typical. Bur oak is relatively intolerant of shade,

and therefore may be displaced by more shade-tolerant associates (Sieg 1991). Fire exclusion, livestock

grazing, invading exotic competitors, and increasing

deer and elk populations all have probably influenced

the distribution and abundance of bur oak in the Black

Hills. Oak may benefit from prescribed fire, but one

attempt to improve oak regeneration with a prescribed

burn proved inconclusive (Sieg 1991). Herbivory and

mast consumption by animals can also affect the ability of oak to persist in the Black Hills.

Where oak is associated with ponderosa pine, management to favor oak may include removal of competing pines or other vegetation, regulation or exclusion

of grazing, and use of prescribed fire to improve seedbeds and stimulate vegetative sprouting. Where management goals are to favor pine, frequent prescribed

fires and increased fall grazing may be desirable to

reduce oak’s presence on the site so pine seedlings can

ultimately be established.

Watershed Management

Water yield is a concern for communities in and

around the Black Hills (USDA Forest Service 1996a).

The water provided by streams that drain out of the

Black Hills is an important resource utilized for water

supplies, irrigation, and recreation of the surrounding

area (Addison 1991). Forested landscapes intercept

rainfall and lower the quantity of water that reaches

the stream. The decrease depends upon the density or

coverage of the forest. Other factors that influence

water yield and streamflow include: climate, geology,

slope and soil conditions, channel conditions, vegetation, riparian area conditions, and instream structures

(Orr 1975).

Historic accounts by the Custer and Dodge Expeditions of 1874 and 1875 noted that streamflows were

more often perennial, riparian zones were more abundant and more lush, and wet meadows were more plentiful in low-gradient valley bottoms than conditions

today. Subsequent postsettlement timber harvesting,

mining, livestock grazing, and beaver trapping changed

the water yield and streamflow of the Black Hills.

These changes damaged the riparian zones and led to

an increase in peak flows and the intensity of flash

floods, and a decrease in the perennial flow of some

streams (Parrish and others 1996). Since the creation

of the Black Hills National Forest and implementation

of fire suppression in the early 1900s, forests in the

Black Hills have become dense and water yields have

decreased.

Black Hills Hydrology

Precipitation follows several potential pathways as

it travels through the ecosystem. First, precipitation

can be intercepted and can evaporate back into the atmosphere before it reaches the ground. Second, it can

be absorbed into the soil and later taken up by the roots

of a plant and transpired back into the atmosphere.

Third, as the soil becomes saturated with moisture, subsurface flow can transport water very slowly to a

stream. Or, once the soil becomes completely saturated and no more can soak into the ground, water runs

into streams as overland flow.

The type of rock that precipitation falls on influences the pathway it will take. For instance, the central crystalline core of the Black Hills is largely impervious to moisture, and water that falls upon it runs off

as surface flow, or remains in shallow soils near the

surface. In contrast, the sedimentary rock that surrounds

the central core is porous and plays a significant role in

the ground-water hydrology of the area. Water traveling

over porous rock types such as limestone and sandstone can disappear into sinkholes and underground

streams. The water goes underground to recharge the

numerous aquifers in the Black Hills. At times, the
USDA Forest Service General Technical Report RMRS-GTR-97. 2002 95

underground water reappears as springs elsewhere (Orr

1975). This underground movement of water has major implications for management activities intended to

increase water yield. The only way to increase water

yield to areas downstream would be to increase the

flow so much as to exceed the amount that can physically be transported underground. Orr (1975) suggests

that management of relatively small amounts of water

at many locations upstream from the “loss” zone could

increase water yields.

Addison (1991) developed monthly rainfall/runoff relationships for 11 Black Hills drainage basins:

Fall River at Hot Springs, Beaver Creek near Buffalo

Gap, Battle Creek near Keystone, Grace Coolidge

Creek near Game Lodge, Battle Creek at Hermosa,

Spring Creek near Hermosa, Castle Creek above

Deerfield Reservoir, Rapid Creek above Pactola Reservoir, Boxelder Creek near Nemo, Elk Creek near

Rapid City, and Spearfish Creek at Spearfish. In most

basins, the previous month’s discharge was shown to

be the best predictive variable to determine rainfall/

runoff relationships. Current month’s precipitation

was most important during the months of April, May,

and June.

Timber/Water Yield Relationships

The influence of forested landscapes on water yield

has been investigated in the Black Hills in several studies (Orr 1968, 1972, 1975; Orr and VanderHeide 1973;

Smith 1983). In general, water discharge increases after

timber harvest or wildfire due to the decreased interception by the vegetation and a decrease in the evapotranspiration rate. Anderson (1980) reported an average increase of 2.24 inches (5.7 cm) after 25 percent

of the timber volume was cut.

Orr (1968) investigated the soil-moisture patterns

and trends after thinning and patch clearcutting in a

dense 70-year-old, second-growth pine stand on limestone soil. Basal area was 193 ft2 per acre (44.3 m2 per

hectare) for the control plot, 80 ft2 per acre (18.4 m2

per hectare) for the thinned plot, and 0 ft2 per acre (0

m2 per hectare) for the clearcut. Evapotranspiration

was significantly lower on the thinned plot than on the

densely stocked control plot, indicating more moisture

was held in soil storage on the thinned plot. This was

especially important during years of drought. During

drought years, evapotranspiration was greater on the

thinned plots, but there was more soil moisture available as well as higher seepage potential. The clearcut

treatment had the highest water seepage potential since

evapotranspiration from trees was eliminated. However, this increase in moisture availability cannot be

sustained because soil moisture storage is lowered as

the new forest is established.

Orr and VanderHeide (1973) described the water

yield characteristics of three small watersheds in the

northeast Black Hills near Sturgis. Average basal areas were 120 ft2 per acre (27.6 m2 per hectare), 130 ft2

per acre (29.8 m2 per hectare), and 166 ft2 per acre

(38.1 m2 per hectare) for watersheds 1, 2, and 3, respectively. Annual water yields over a period of 6 years

were 25, 27, and 23 percent of annual precipitation for

watersheds 1, 2, and 3, respectively, which marginally

supports the plot study results discussed in Anderson

(1980) and Orr (1968).

Precipitation patterns among the different regions

where ponderosa pine forests can be found differ significantly. For instance, in a study of climatic regimes

of four ponderosa pine regions, both northern Arizona

and the Black Hills were found to have approximately

the same amount of annual precipitation (Pearson

1951). In northern Arizona, however, the majority of

precipitation falls in the winter months as snow, with

some rain during July and August due to monsoon

weather patterns. Baker (1986) reported that, in the

Beaver Creek watershed of Arizona, over 97 percent

of the annual water yield is generated in the winter

months because of snowmelt, and that by early May,

the streambeds are dry. In the Black Hills, the majority of precipitation falls between April and July, with

12.4 percent of the precipitation from November to

February (Driscoll and others 2000). Therefore, results of water yield studies from Beaver Creek should

not be used for Black Hills watershed management.

Studies from the Colorado Front Range ponderosa pine

zone might be more appropriate since the precipitation patterns are somewhat similar to those in the Black

Hills (Gary 1975).

Seasonal water yields are influenced by the amount

and timing of spring and early summer precipitation.

In the Black Hills, general thaw is common from the

middle to the end of March. By the end of March,

flows start to increase in the streams. In April, a sharp

increase in flow is attributed to the combination of precipitation and melting of accumulated snow. Flows

reach their maximum during May or June. Although

precipitation is highest in June, streamflow does not

increase proportionally due to the increased evapotranspiration of the forested stands. Most of the July to

September precipitation is lost to evapotranspiration,

and little contributes to streamflow (Orr and

VanderHeide 1973).

In the Black Hills, snowmelt contributes primarily

to soil recharge and only affects streamflow indirectly

(Orr 1975). Creating openings in the forest canopy
96 USDA Forest Service General Technical Report RMRS-GTR-97. 2002

was thought to increase water yield by providing aerodynamics that favored snow accumulation (Baker

1986). Cutting in patches, strips, or blocks had been

shown to increase snow accumulation and streamflow

in the Colorado Front Range and Rocky Mountain subalpine zone (Gary 1975; Leaf 1975). However, later

work at Fraser Experimental Forest has shown that the

lack of interception losses back to the atmosphere when

trees are cut is the primary contributor to increased

streamflow in snow-dominated systems (Troendle and

King 1987). Removal of trees in any fashion will therefore increase runoff to some degree (Shepperd and others 1992).

If openings are created, evaporation of snow in them

will be twice as high as the rate found in the understory of a forest (Gary 1975). The snow in openings

will also melt sooner in the spring while transpiration

is lower, and more of the runoff will reach the stream.

Gary suggests that the pattern of the cuts determines

whether runoff will be increased. For instance, large

clearcut blocks or selective cuts of individual trees will

increase water yields far less than if the same volume

was harvested in a system of small, dispersed forest

openings.

Furthermore, snow will be scoured from sites exposed to wind, and they will also have greater evaporation losses. Slope aspect also influences water yield

(Cline and others 1977). Clearcut north slopes in Idaho

were reported to show a substantial gain in water yield

versus south slopes. The difference in water yield between slope aspects was a result of quicker establishment of vegetation on the south-facing slopes (Cline

and others 1977).

In conclusion, any silvicultural activity or natural

disturbance that removes ponderosa pine trees from a

forest will potentially increase water yield. Conversely,

the introduction of new trees, or growth of existing

trees, will potentially decrease water yield. The increase or decrease is proportional to the amount of

stocking removed, but usually 25 to 30 percent of the

growing stock in a forested watershed must be removed

before there is a measurable increase in water in the

stream leaving the watershed.

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110 USDA Forest Service General Technical Report RMRS-GTR-97. 2002

Common name Scientific name

Alders Alnus spp.

American elm Ulmus americana

American robin Turdus migratorius

American sweetvetch Hedysarum alpinum

Armillaria root disease Armillaria ostoyae

Arrowleaf balsamroot Balsamorhiza sagittata

Aspen Populus tremoides

Baneberry Actaea rubra

Beaked hazelnut Corylus cornuta

Bearberry Arctostaphylos uva-ursi

Beaver Castor canadensis

Black-backed woodpecker Picoides arcticus

Blackbellied clerid Enoclerus lecontei

Black-capped chickadee Parus atricapillus

Black-headed grosbeak Pheucticus melanocephalus

Blue staining fungus Ceratocystis montia

Bluebell = Harebell Campanula rotundifolia

Bracken fern Pteridium aquilinum

Brown creeper Certhia americana

Brown-headed cowbird Molothrus ater

Bur oak Quercus macrocarpa

Bushy-tailed woodrat Neotoma cineria

Canada violet Viola canadensis = Viola rugulosa

Chipping sparrow Spizella passerina

Chokecherry Prunus virginiana

Common juniper Juniperus communis

Cream peavine = Yellow vetchling Lathyrus ochroleucus

Currants Ribes spp.

Dark-eyed junco Junco hyemalis

Deer mice Peromyscus maniculatus

Diploida tip blight Sphaeropsis sapinea

Downy woodpecker Picoides pubescens

Dryspike sedge Carex foenea = Carex siccata

Dusky flycatcher Empidonax oberholseri

Dwarf mistletoe Arceuthobium campylopodum

Engelmann spruce Picea engelmannii

Evening grosbeak Coccothraustes vespertinus

Fairybell Disporum trachycarpum

Firs Abies spp.

Fringed sagewort Artemisia frigida

Gray jay Perisoreus canadensis

Green ash Fraxinus pennsylvanica

Grouseberry Vaccinium scoparium

Hairy woodpecker Picoides villosus

Ironwood Ostrya virginiana

Kentucky bluegrass Poa pratensis

Leafy phlox Phlox alyssifolia

Least chipmunk Tamias minimus

Lewis’ woodpecker Melanerpes lewis

Lindley’s aster Aster ciliolatus = Aster lindleyanus

Little bluestem Andropogon scoparius = Schizachyrium scoparium

Appendix A: Common and scientific names of species listed
USDA Forest Service General Technical Report RMRS-GTR-97. 2002 111

Littleseed ricegrass Oryzopsis micrantha

Lodgepole pine Pinus contorta

Longspur violet Viola adunca

Low northern sedge Carex concinna

MacGillivray’s warbler Oporornis tolmiei

Manitoban elk Cervus elaphus manitobensis

Maryland sanicle Sanicula marilandica

Merriam’s turkey Meleagris gallopavo merriami

Mountain bluebird Sialia currucoides

Mountain cliff fern Woodsia scopulina

Mountain pine beetle Dendroctonus ponderosae

Mule deer Odocoileus hemionus

Needle cast Elytroderma deformans

Ninebark Physocarpus monogynus

Northern bedstraw Galium boreale

Northern flicker Colaptes auratus

Northern flying squirrel Glaucomys sabrinus bangsi

Northern goshawk Accipiter gentiles atricapillus

Nuttall’s cottontail Sylvilagus nuttallii

Oregon grape Berberis repens

Ovenbird Seiurus aurocapillus

Paper birch Betula papyrifera

Pasqueflower Anemone patens = Anemone nuttalliana = Pulsatilla

patens

Pine engraver Ips pini

Pine siskin Carduelis pinus

Pink shinleaf Pyrola asarifolia

Poison ivy Toxicodendron rydbergii

Ponderosa pine Pinus ponderosa

Porcupine Erethizon dorsatum

Poverty oatgrass Danthonia spicata

Prickly rose Rosa acicularis

Purple meadowrue Thalictrum dasycarpum

Pussytoes Antennaria spp.

Pygmy nuthatch Sitta pygmaea

Red crossbill Loxia curvirostra

Red raspberry Rubus idaeus

Red rot Dichomitus squalens

Red squirrel Tamiasciurus hudsonicus

Red turpentine beetle Dendroctonus valens

Redbellied clerid Enoclerus sphegeus

Red-breasted nuthatch Sitta canadensis

Red-naped sapsucker Sphyrapicus nuchalis

Rocky Mountain elk Cervus elaphus nelsoni

Rocky Mountain juniper Juniperus scopulorum

Rough-leaved ricegrass Oryzopsis asperifolia

Ruby-crowned kinglet Regulus calendula

Ruffed grouse Bonasa umbellus

Russet buffaloberry Sheperdia canadensis

Sedges Carex spp.

Shoestring root rot Armillaria mellea

Sideoats grama Bouteloua curtipendula

Silvery lupine Lupinus argenteus

Slender wheatgrass Agropyron caninum = Elymus trachycaulus

Smooth brome Bromus inermis

Common name Scientific name
112 USDA Forest Service General Technical Report RMRS-GTR-97. 2002

Southern pine tip moth Rhyacionia neomexicana

Spreading dogbane Apocynum androsaemifolium

Spurred gentian Halenia deflexa

Star lily Leucocrinum montanum

Starry false Solomon’s seal Smilacina stellata = Maianthemum stellatum

Sumacs Rhus spp.

Sun sedge Carex heliophila

Swainson’s thrush Catharus ustulatus

Sweetroots Osmorhiza spp.

Sweet-scented bedstraw Galium triflorum

Thirteen-lined ground squirrel Spermophilus tridecemlineatus

Three-toed woodpecker Picoides tridactylus

Timber oatgrass Danthonia intermedia

Timothy Phleum pratense

Townsend’s solitaire Myadestes townsendi

Trogositid beetle Temnochila chlorodia

True mountain mahogany Cercocarpus montanus

Twinflower Linnaea borealis

Virginia’s warbler Vermivora virginiae

Vole Microtus spp.

Warbling vireo Vireo gilvus

Western gall rust Peridermium harknessii

Western pine tip moth Rhyacionia bushnelli

Western serviceberry Amelanchier alnifolia

Western snowberry Symphoricarpos occidentalis

Western tanager Piranga ludoviciana

Western wheatgrass Agropyron smithii

White coralberry Symphoricarpos albus

White spruce Picea glauca

White-breasted nuthatch Sitta carolinensis

White-tailed deer Odocoileus virginianus dakotensis

White-tailed jackrabbit Lepus townsendii

Wild honeysuckles Lonicera spp.

Wild lily-of-the-valley Maianthemum canadense

Wild sarsaparilla Aralia nudicaulis

Wild spirea Spiraea betulifolia

Wild strawberry Fragaria virginiana

Willows Salix spp.

Woodland strawberry Fragaria vesca

Woods rose Rosa woodsii

Yarrow Achillea millefolium

Yellow-rumped warbler Dendroica coronata

Common name Scientific name
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