United States 

Department of 

Agriculture 

Forest Service 

Southern 

Research Station 

General Technical 

Report S0-118 

t 

Uneven-Aged Silviculture for 

the Loblolly and Shortleaf 

Pine Forest Cover Types 

James B. Baker, Michael D. Cain, James M. Guldin, 

Paul A. Murphy, and Michael G. Shelton 

D.B.H. > 
Uneven-Aged Silviculture for 

the Loblolly and Shortleaf 

Pine Forest Cover Types 

James B. Baker, Michael D. Cain, James M. Guldin, 

Paul A. Murphy, and Michael G. Shelton 

James B. Baker is chief silviculturist, Michael D. Cain is principal silviculturist, Paul A. Murphy is 

principal mensurationist, and Michael G. Shelton is principal silviculturist, U.S. Department of 

Agriculture, Forest Service, Southern Research Station, Monticello, AR 71656; James M. Guldin is 

principal ecologist, U.S. Department of Agriculture, Forest Service, Southern Research Station, Hot 

Springs, AR 71902. In cooperation with: School of Forest Resources and the Arkansas Agricultural 

Experiment Station, University of Arkansas, Monticello, AR 71656. 
PREFACE 

In 1937, R.R. Reynolds of the USDA Forest Service established the "Good" and "Poor" Farm Forestry 

Forties on the Crossett Experimental Forest in Ashley County, Arkansas, in the first attempt to implement 

uneven-aged silviculture in shade-intolerant loblolly (Pinus taeda L.) and shortleaf (P. echinata Mill.) pine 

stands. Interim results of these studies have been widely published over the years, and the Crossett Farm 

Forestry Forties have become a showcase for uneven-aged silviculture in the loblolly-shortleaf pine forest 

type in the Southern United States. With Reynolds' techniques as a basis, farm-forestry studies were 

established throughout the South to demonstrate the feasibility of selection silviculture on other sites and in 

other southern pine forest types. 

A half-century of experience and research with uneven-aged silviculture in loblolly-shortleaf pine stands 

in the South are summarized in this publication, and silvicultural guidelines for developing and managing 

uneven-aged stands are provided. These results and guidelines are extremely pertinent today because 

selection silviculture can be used effectively to rehabilitate and manage thousands of acres of poorly stocked 

and previously unmanaged private, nonindustrial timberland in the South. Uneven-aged silviculture is also 

relevant to the Ecosystem Management philosophy adopted by the USDA Forest Service in 1992 for 

managing national forests throughout the United States. This publication should be useful to silviculturists, 

foresters, and other resource professionals in developing and managing uneven-aged pine stands. It can also 

serve as a teaching aid in forestry workshops, short courses, and university curricula. 

The authors of this publication are listed alphabetically. Although all authors collaborated in preparing 

the manuscript, their principal contribution was as follows: Cain-introduction, glossary, and coordination; 

Guldin----<:hapter l; Shelton----<:hapters 2 and 5; Baker----<:hapter 3, summary, and coordination; and 

Murphy----<:hapter 4. 

ii 
CONTENTS 

INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 

Chapter I-ECOLOGICAL BASIS OF UNEVEN-AGED SILVICULTURE ....................... 2 

Succession . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 

Disturbance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 

Applying Ecological Principles to Silvicultural Practice ................................. 4 

Silviculture and Stand Development .......................................... 4 

Silviculture and Disturbance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 

Key Ecological Elements of Uneven-Aged Silviculture .............................. 4 

Gap-phase regeneration dynamics ........................................ 4 

Canopy dynamics and shade management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 

Traits of Loblolly and Shortleaf Pines that Influence Silvicultural Options ...................... 5 

Chapter 2--CONCEPTS AND DEFINITIONS ........................................... 7 

Silviculture Versus Forest Management ........................................... 7 

Even-Aged Versus Uneven-Aged Silviculture ........................................ 7 

Stand Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 

The Uneven-Aged Silvicultural System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 

Stocking ............................................................. 9 

Forest and Stand Regulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 

Volume/Guiding-Diameter-Limit (VGDL) Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 

Basal Area-Maximum Diameter-q (BDq) Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 

Chapter 3-IMPLEMENTING UNEVEN-AGED SILVICULTURE ............................ 14 

Well-Stocked Stands with Uneven-Aged Structure .................................... 14 

Inventorying the Stand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 

Regulating Stand Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 

Establishing the Cutting Cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 

Marking Trees for Harvest . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 

Allowable cut . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 

Kinds of trees to be marked . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 

Establishing and Evaluating Reproduction ...................................... 23 

Controlling Competing Vegetation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 

Well-Stocked Stands with Even-Aged Structure ..................................... 25 

Inventorying the Stand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 

Developing Uneven-Aged Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 

Understocked Stands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 

Historical Application of Uneven-Aged Silviculture in Loblolly-Shortleaf Pine Types . . . . . . . . . . . . . 28 

Coastal Plain Loblolly-Shortleaf Pine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 

Interior Highlands Shortleaf Pine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 

Chapter 4-GROWTH, YIELD, AND STAND DEVELOPMENT ............................ 31 

Case Studies and Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 

Loblolly Pine Growth Study . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 

Growth and Yield Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 

Uneven-Aged Versus Even-Aged Production ....................................... 33 

Economics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 

Uneven-Aged Stand Management Decisions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 

Timber Harvesting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 

Even-Aged Versus Uneven-Aged Economic Comparisons . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 

Computer Software Available . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 

iii 
Chapter 5-0PTIONS FOR RETAINING HARDWOODS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 

Single-Tree Selection Option . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 

Unifonn Spatial Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 

Area-Wise Spatial Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 

Group Selection Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 

SUMMARY ...................................................................................... 40 

LITERATURE CITED .............................................................................. 41 

APPENDIX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 

Glossary ofForestzy Tenns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 

Appendix Forms ............................................................................ 53 

FonnA-1 ............................................................................. 55 

Fonn A-2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 

Fonn A-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59 

Fonn A-4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61 

FormA-5 ............................................................................. 63 

ACKNOWLEDGMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 

iv 
INTRODUCTION 

The natural range of the two most important southern 

yellow pines-loblolly (Pinus taeda L.) and shortleaf (P. 

echinota Mill.)-extends throughout the Southeastern United 

States. Loblolly and shortleaf pines can occur as pure 

stands or as mixtures with other pine and hardwood species. 

Oaks (Quercus spp.), gums (Liquidambar styraciflua L. and 

Nyssa sylvatica Marsh.), and hickories (Carya spp.) are 

common hardwood associates (Baker and Balmer 1983). 

Such wide dispersion of loblolly and shortleaf pines 

suggests that both are well adapted to an array of soil and 

site conditions. Perpetuation of these pines for timber 

production can be achieved by relying on natural pine 

seedfall under four reproduction cutting methods-dearcutting, seed-tree, shelterwood, and selection (Smith 1986). 

The first three methods result in even-aged stands; the 

selection method (single-tree or group selection) is used to 

regenerate uneven-aged stands. Selection methods 

developed for loblolly and shortleaf pine stands during the 

past 50 years are described in this publication. 

Exploitation of the virgin loblolly-shortleaf pine forests 

in southern Arkansas and northern Louisiana began in the 

1890's, and these forests were exhausted by the late 1920's, 

leaving vast acreages of understocked, second-growth 

stands. Although some lumber companies abandoned their 

landholdings and moved west after the virgin southern pines 

were gone, others stayed in the region and began to manage 

their cutover forestland (Reynolds 1980). In the early 

1930's, R.R. Reynolds and his associates pioneered the 

development of the uneven-aged silvicultural system in 

loblolly-shortleaf pine stands in southern Arkansas as a way 

to manage these cutover, understocked stands (Reynolds 

1980). 

The uneven-aged silvicultural system as developed by 

Reynolds consisted of the single-tree selection reproduction 

cutting method, stand structure regulation by volume control in the pine sawlog component, frequent harvests at 1- to 

10-year intervals, and vigorous control of the hardwood 

component. Competition control is especially critical when 

applying uneven-aged silviculture to shade-intolerant species 

such as loblolly and shortleaf pines. 

Ever since the development of uneven-aged silviculture 

for loblolly and shortleaf pines, this technique has been 

controversial. The debate over even-aged versus unevenaged management of southern pines dates from the 1950' s 

(Bond 1953, McCulley 1953), when the Society of 

American Foresters held a regional symposium on the 

subject. However, by the mid-1960's, the even-aged 

system, with clearcutting and artificial regeneration, was 

sweeping the country (Mustian 1978) and was being used on 

forest industry land and on the national forests. Differences 

of opinion about clearcutting reached a national scale with 

arguments and lawsuits over proposed cutting plans on 

national forests. This led to the passage of the Forest and 

Rangeland Renewable Resources Planning Act and the 

National Forest Management Act in the 1970's (USDA, FS 

1989). 

In the late 1980's, the pendulum began to swing away 

from clearcutting and plantation management on the national 

forests. Increasing non-timber use of national forest land 

resulted in pressures from public-interest groups urging the 

adoption of stand management alternatives that did not 

result in clearcuts. This, in tum, led to the socio-political 

concern that the public mandated the use of the uneven-aged 

system on national forests as the method of choice and as an 

aversive response to clearcutting (Hamilton 1991). 

Ownership of forestland in the United States is not 

limited to Federal or State govermnents or to corporations. 

Private, nonindustrial landowners control about 70 percent 

of the commercial forestland in the South. Much of this 

land is producing timber at half its potential. The unevenaged system requires little initial outlay of capital (Reynolds 

and others 1984), so it could be used to provide periodic 

income to private landowners while their understocked 

stands are rehabilitated. However, the choice of one 

silvicultural system over another depends on the landowners' objectives and the condition of their timberland 

(McKee 1985). 

The uneven-aged system is not a panacea because it 

requires some of the highest levels of skill and understanding of any forest management technique in use today 

(Hamilton 1991). Yet, it is a flexible system that can be 

adapted to fit various stand conditions. So it is appropriate 

to document the basic tenets of the uneven-aged silvicultural 

system for loblolly and shortleaf pines in a single 

publication. 

Whether the uneven-aged system can provide noncommodity forest values such as wildlife habitat, recreational opportunities, biodiversity, and scenic beauty has yet 

to be established (Baker 1992). Existing knowledge about 

managing a forest to meet specified objectives of species 

composition, stand structure, stocking, growth, and yield of 

timber is much more voluminous and more scientifically 

based than our knowledge about developing a forest for any 

other purpose (Gibbs 1978). Consequently, our objective in 

this publication is to provide information about uneven-aged 

silviculture mainly for pine timber production. This 

information was synthesized from more than 50 years of 

experience and research with uneven-aged silviculture in 

loblolly-shortleaf pine stands on the Coastal Plain and 

Interior Highlands of Arkansas. Where appropriate, results 

from uneven-aged pine silvicultural research conducted 

throughout the Southeastern United States are included. 

Preliminary recommendations for hardwood retention in 

uneven-aged pine silviculture are also provided for readers 

who have management objectives beyond maximizing pine 

timber production. 
Chapter 1 

ECOLOGICAL BASIS OF UNEVEN-AGED SILVICULTURE 

Silviculture is an ecological art and science subject to 

economic, social, and legal constraints. It is practiced at the 

stand level, which is the basic management unit of the 

forest. Forest management more properly deals with the 

forest as a whole rather than with individual stands. 

Broadly speaking, nature provides two patterns for 

silviculturists to follow. The first is called succession-the 

normal growth and development of an existing forest or 

stand (Kimmins 1987). The second is known as 

disturbance-the partial or complete destruction of an 

existing forest or stand through natural events (Spurr and 

Barnes 1980). Ecologically, succession and disturbance 

combine to determine the development of the forest or 

stand. Silviculture, however, does not precisely mimic 

nature, because nature's ways are far more random and 

sometimes more catastrophic than silviculturists or society 

fmds acceptable. 

A silvicultural prescription is more predictable and 

more regulated than a corresponding set of natural disturbances to better achieve society's expectations or needs. 

Silviculture evolved as a modern, applied science when 

18th-century foresters adapted natural patterns of succession 

and disturbance in managing forests to achieve the landowner's purpose. Today, foresters use silviculture to 

implement both disturbance and stand development in a 

stand in specific ways, which have varying degrees of 

"naturalness" about them. Uneven-aged silviculture offers 

some advantages over even-aged silviculture by emulating 

different stages of succession and different scales of disturbance. 

Succession and disturbance are opposing yet complementary forces. Simply stated, under succession, a 

community progresses from early rapid changes in vegetation to later stages characterized by slow changes. Under 

disturbance, some or all of the vegetation is killed, setting 

succession back to an earlier stage. The actual interplay 

between succession and disturbance, however, is much more 

complex. 

In this chapter, an overview of the ecological basis of 

succession and disturbance is presented, including some 

elements more appropriate to even-aged stands. After this 

overview, the discussion will emphasize the dynamics of 

stand development and disturbance that apply specifically to 

uneven-aged silviculture. 

Succession 

Succession-more specifically, secondary forest 

succession-is what we all think of as the normal growth 

and development of a forest stand. It begins immediately 

2 

following disturbance when new trees start to grow and 

continues through distinct stages that, if unaffected by 

further large-scale disturbance, extend to old-growth. 

Succession can be explained in terms of an idealized 

time continuum. Assume that, at some starting point called 

year zero, a major "catastrophe," such as a forest fire or 

windstorm, eliminates all the vegetation on a site. Secondary forest succession begins with this devegetated condition 

at year zero, just after the disturbance has occurred. From 

this point on, assuming no more catastrophic disturbances, 

the stand passes through four distinct stages of development. 

Two excellent summaries of these stages are presented by 

Bormann and Likens (1979) and Oliver (1981); a more 

indepth discussion of stand development is found in Oliver 

and Larson (1990). These four stages or phases of stand 

development can be summarized as follows. 

The stand initiation stage (reorganization phase) 

begins immediately after the disturbance in year zero. 

Removing the vegetation makes more water, nutrients, and 

sunlight available on the site. New species (herbs, shrubs, 

and trees) become established because of the moist, fertile, 

and open conditions. Many different species with various 

degrees of shade tolerance and different regeneration habits 

become established during this period. The species that 

grow best are generally intolerant of shade (herbaceous 

plants, shrubs, and some trees like pines and sweetgum) and 

those that reproduce by sprouting from existing rootstocks 

(oaks, maples [Acer spp.], and hickories). 

The stem exclusion stage ( aggradation phase) takes 

over when one or more of the resources of the newly 

exposed site become limiting, preventing the further establishment of new plants. Some herbaceous species disappear, 

while others dominate for various periods; eventually the 

main canopy is dominated by trees. The new stand occupies 

the site completely, and competition for nutrients, moisture, 

and light begins in earnest. 

As this stage proceeds, tree growth and competition 

lead to recognizable and predictable patterns of stand 

development. The early successional herbaceous plants can 

no longer persist because the main canopy forms a continuous, dense layer. Intense competition results in a stratified 

canopy of vegetation. Shade-intolerant species must be 

strong competitors to retain rapid height growth and remain 

in the upper canopy. Otherwise, they will lag behind and 

probably succumb to suppressing competition. Shadetolerant species seldom remain in the upper canopy, but can 

persist in the shaded conditions found in the lower canopy. 

Over time, a prontinent layer of shade-tolerant species, such 

as flowering dogwood (Comus florida L.), maples, 

American hornbeam (Carpinus caroliniana Walt.), and 
eastern hophombeam (Ostrya virginiana [Mill.] K. Koch) 

may develop in the lower portions of the main canopy. 

The understory reinitiation stage (transition phase) 

begins when trees in the main canopy begin to succumb, 

either singly or in small groups, to natural mortality caused 

by lightning, wind-throw, or insects and disease. The gap 

in the canopy that results is ecologically significant in that 

resources formerly used by the dead tree are reallocated to 

the surviving vegetation. If there is a closed mid-canopy 

beneath the overstory, shade-tolerant species may respond 

to release and ascend to the overstory. If there is not a 

closed mid-canopy, enough sunlight may penetrate to the 

forest floor to support the establishment of new trees. As 

overstory trees next to the opening also succumb, the 

opening expands, allowing even more light, nutrients, and 

moisture to be used by the new plants. These regeneration 

processes, called "gap-phase regeneration dynamics" (Bray 

1956, Pickett and White 1985, Runkle 1982, Runkle and 

Yetter 1987), are similar to those that occurred during stand 

initiation, only at a smaller scale. This difference in scale, 

however, is of ecological significance because the gaps are 

small enough to be influenced by adjacent overstory 

vegetation. 

The old-growth stage (steady-state phase) is distinguished from the understory reinitiation and stem exclusion 

stages in that the old-growth stage tends toward greater 

stability in biomass and productivity. Regeneration dynamics continue through the gap-phase regeneration process 

described in the transition period. Theoretically, a series of 

gaps created over time will result in a stable balance of trees 

of different species, sizes, and ages. An observer in the 

stand during this stage has difficulty seeing for great 

distances because of the overlapped screening effect of 

foliage from overstory, midstory, and understory trees. 

Again, under ideal circumstances, this period is indeterminate. The coexistence of young and old trees, the 

dynamics of development within gaps and between gaps, 

and the relatively stable biomass and productivity levels 

continue over the long term. Vegetation changes slowly in 

this stage because changes in soil, weather or climate, 

competition, diseases, and insect pests also occur gradually. 

Disturbance 

Natural disturbance is the ecological counterpoint to 

succession. Through succession, plant communities 

develop; through disturbance, that development is altered. 

Some disturbances are severe enough to set a plant community back to the beginning of the stand initiation stage. 

Others are so minor that only one tree is affected, thereby 

advancing development during the stem exclusion, understory reinitiation, and old-growth stages. 

When judged by ecological time scales, the proportion 

of time that disturbances affect a stand is infinitesimal. But 

these periods are extremely important ecologically because 

they allow new generations of vegetation to become 

established and develop. By their very rarity, disturbances 

are of keen interest to ecologists and foresters as physical 

phenomena; by their occurrence, they establish ecological 

conditions within which new plant communities are created. 

Disturbances vary according to three dimensions (White 

1979). Frequency is the rate at which existing disturbances recur or is the mean number of recurrences over 

time. Frequent disturbances occur every few years, 

whereas infrequent disturbances occur once every few 

centuries. Predictability describes the regularity of 

occurrence of the disturbances; i.e., how predictable the 

recurrence of a disturbance is. Magnitude is the duration 

of the disturbance and varies from a few seconds or minutes 

(such as during a wildfire) to several years (such as a 

drought). Reckoned by human time scales, disturbances 

vary from being somewhat to exceedingly rare; however, 

this does not make them any less essential to a holistic view 

of forest ecology. 

Disturbance frequency is generally inversely correlated 

with severity. In nature, a catastrophic disturbance that sets 

succession back to the stand initiation stage is exceedingly 

rare. The concept of disturbance cannot be restricted to 

large, catastrophic events, such as the volcanic eruption of 

Mt. St. Helens in 1980, the wildfires in Yellowstone 

National Park in 1988, or Hurricane Hugo in 1989, spectacular though they may be. 

The severe, partial disturbance in which most of a stand 

is destroyed but part of the overstory and midstory survives 

is more common, but still rare. Stand development after 

such a disturbance is affected by competition not only within 

the newly developing reproduction but also between the 

reproduction and the scattered overstory trees that survived 

the disturbance. The resulting stand is much more variable 

in structure and species composition than a stand that 

follows a complete disturbance. 

Small disturbances that affect one to a few trees are 

the most common, occurring far more frequently than standreplacing disturbances. This solitary mortality is a basic 

element of stand development throughout succession and 

influences the formation of canopy layers, depending on the 

size of the tree that succumbs. During the early stages of 

stand development, the death of an individual tree usually 

improves conditions for its neighbors-in silvicultural 

terms, density-dependent mortality similar to thinning. 

But during the last two stages of stand development, the 

death of a tree in the overstory provides growing space for 

reproduction and development of the understory. At this 

stage, if a tree in the main canopy succumbs, the crowns of 

the neighboring overstory trees may not expand fast enough 

to occupy the resulting canopy opening. Unless there is a 

closed mid-canopy, this disturbance fosters new reproduction or releases advance growth. 

Thus, in late successional stages, the regeneration 

process depends on whether overstory crown expansion 

3 
closes the gap before the understory trees fill the gap from 

below. Understory trees are more likely to make it to the 

overstory if: (1) the gap is large, (2) the trees adjacent to the 

gap do not respond vigorously in lateral crown growth, and 

(3) the gap is enlarged by the death of trees that border it. 

Applying Ecological Principles 

to Silvicultural Practice 

Foresters use silviculture to impose disturbance and 

modify successional development in a stand. Some trees (or 

other plants) are removed so others can develop better. The 

degree to which these prescribed actions "imitate" nature 

depends on how they are implemented. 

The first alternative of the forester is that of no 

treatment. But subsequent alternatives involve removing 

increasing proportions of the vegetation. The choice of 

alternatives must be consistent with the ecology of the 

species that comprise the stand, the existing condition of 

the stand, and the future condition desired by the forest 

owner. 

Silviculture and Stand Development 

The stages of stand development and gradients of disturbance reflect the ecological basis within which silviculturists operate. The early stages of stand development 

set the stage for even-aged silviculture. By imposing disturbances severe enough to promote regeneration across the 

entire stand, the forester can encourage the development of 

intolerant and mid-tolerant species as one or two age classes 

distributed uniformly across the stand. 

The later stages of succession, primarily the understory 

reinitiation stage, provide the ecological basis for unevenaged silviculture. A silvicultural prescription that imitates 

scattered natural mortality in the upper crown classes can 

promote development of reproduction continuously over 

time. The goal of uneven-aged silviculture is to stabilize 

stand structure and biomass (volume) over the long term, 

thus emulating the old-growth stage. But other desirable 

ecological attributes of the old-growth stage (such as 

downed woody debris and low net growth) are less likely to 

be achieved in uneven-aged silviculture. 

Silvicultnre and Disturbance 

Ecologically, silviculture is simply an effort by the 

forester to imitate succession and disturbance. Reproduction cutting imitates disturbance; stand management after 

reproduction cutting imitates stand development. The 

decision to practice even-aged or uneven-aged silviculture 

depends upon many things, of which the most important is 

the landowner's objectives. The next step is to evaluate the 

ecological situation considering those objectives and regarding the silvicultural options. 

Even-aged reproduction cutting methods imitate disturbances that affect an entire stand; uneven-aged repro4 

duction cutting methods imitate disturbances that affect only 

part of a stand. By choosing to pursue uneven-aged silviculture, the forester is opting to work with various smallscale disturbances that disturb only part of the stand and 

promote the later stages of development, especially the 

understory reinitiation stage. 

The most intensive small-scale disturbances do not 

affect an entire stand, but can create large openings within 

a stand. Natural examples include a localized insect 

infestation such as southern pine beetle (Dendroctonus 

frontalis Zimmermann), a locally severe wind, or the 

flareup of a surface fire. Such a disturbance creates a gap 

in the canopy of the stand; reproduction becomes established 

and develops within this opening. Ecological conditions 

within the gap are affected by bordering trees, depending on 

opening size and shape. Group selection is used by 

foresters to approximate these conditions. 

The least-intensive, small-scale disturbance likely to 

occur in a stand is a single tree falling, or dying while 

standing, in the woods. Causes of such individual tree 

mortality include disease, insects, lightning, windthrow, or 

some combination of these. If the dying tree had a large 

crown, reproduction will become established in the gap 

created in the canopy. In the smallest gaps, the opening 

may close before the reproduction can grow into the main 

canopy, and the reproduction may then persist without 

further growth or may even become suppressed and die. 

The occurrence of multiple gaps (where trees next to a 

recently created gap succumb due to some cause linked to 

their proximity to the gap) or the concurrent creation of 

several small gaps within the same area can tip this 

ecological balance in favor of reproduction survival and 

development. Single-tree selection is used by foresters to 

approximate these conditions. 

Key Ecological Elements of Uneven-Aged Silviculture 

Gap-phase regeneration dynamics.--Opening size 

greatly influences understory development. It affects 

species composition and growth of reproduction. Understanding the interplay involved is critical to the forester's 

ability to apply the concepts silviculturally. 

The primary factor to consider is gap size relative to 

the shade tolerance of the desired species or mixture of 

species. Generally, large gaps favor shade-intolerant 

species, and small gaps favor shade-tolerant species. As 

gap size decreases, the adjacent trees increasingly constrain 

the development of reproduction within the gap until, in the 

smallest gaps, the reproduction is suppressed. In addition, 

advance reproduction in place before the gap occurs also 

influences the species composition of reproduction after the 

gap has been created. 

The foregoing applies to circular gaps in flat terrain. 

The situation becomes more complicated where gaps are 

irregular in shape and where terrain is hilly. The less direct 

the exposure to sunlight and the less circular the gap, the 

greater the influence of adjacent vegetation within the gap. 
However, gaps may not be necessary for adequate 

reproduction. Simply reducing the overstory stocking to 

levels that would be considered "understocked" under evenaged management can allow sufficient diffuse sunlight to 

penetrate to the forest floor, if the midstory is also 

understocked. Repeated disturbances to maintain this 

understocked condition can successfully regenerate a stand 

over time. 

Thus, the interplay of ecological condition, gap size, 

competition, and physical resources is the key to understanding regeneration dynamics in the last two stages of 

succession. These patterns can provide an ecological basis 

for practicing either group selection or single-tree selection, 

although the ecological distinctions between these two 

methods of selection are often fuzzy. 

Canopy dynamics and shade management.-The 

silviculturist applies these concepts of small-scale disturbances and gap dynamics by means of shade management. 

The position and shape of a tree's crown determine how 

much solar radiation it can intercept. The decision of 

whether to cut a tree can be linked to the size and vigor of 

a tree's crown, which reflect its demands on soil nutrient 

and moisture resources. As this decision is made for each 

tree in the stand, the degree of shade retained across the 

entire stand is determined. Thus, by managing the shade in 

the stand, the forester directly affects the future development of both overstory and reproduction. 

The result of shade management properly applied in 

uneven-aged silviculture is easily seen by the forester in the 

canopy proftle. The desired species will be present in all 

expected levels of the canopy profile, depending on the 

number and frequency of cutting-cycle harvests. For stands 

that have been under regular cutting-cycle harvests for an 

extended period, the desired species will exist in all levels 

of the canopy. For stands under uneven-aged silviculture 

for only one or two cutting cycles, the desired species will 

be apparent in only the upper and lower layers of the 

canopy. 

One should expect each cntting-cycle harvest to contribute some reproduction to the stand, and this should be 

apparent from both a range of tree sizes and the presence of 

the desired species in the appropriate canopy levels. In 

stands with frequent cutting cycles and prolific reproduction, new reproduction need not be obtained after every 

harvest. Even so, reproduction should follow at least every 

other harvest. As the cutting cycle lengthens or as the 

desired species becomes more difficult to regenerate, reproduction should be obtained after each cutting-cycle harvest. 

In both examples, the presence of different size classes of 

desired species should be clearly seen, not only in the 

diameter distribution but also in the canopy proftle. 

Gap-phase dynamics and shade management can also 

sustain the development of intolerant species in uneven-aged 

stands. The key is to ensure that there is always adequate 

light for desired species to persist and, if possible, to grow 

into the understory and lower layers of the canopy. This is 

done by controlling average stand stocking (basal area) and 

average gap size. An estimate for the desired basal area for 

a given species is the overstory basal area that marginally 

suppresses height growth of the reproduction if overstory 

trees are distributed uniformly across the stand. The goal 

should be to attain this basal area at the end of the cutting 

cycle. Then, the gaps normally created by "cutting the 

worst and leaving the best" are where the establishment and 

development of reproduction will be most vigorous. The 

stand as a whole, both overstory and the sparsely stocked 

understory, will develop throughout the cutting cycle, but 

the more densely stocked portions of the stand will support 

only overstory development. Essentially, this process 

ensures a continuous development of new gaps and expansion of old gaps. 

However, once this balance between stand stocking and 

cutting-eycle length is established, it can be maintained only 

by harvesting at fairly regular intervals. Excessive delays 

in cutting-cycle harvests will alter stand structure because 

the overstory stocking will increase and understory development will slow dramatically under over-stocked conditions. In essence, the stand reverts to a more even-aged 

character, and the process of building good uneven-aged 

stand structure must be restarted. 

Traits of Loblolly and Shortleaf Pines that Influence 

Silvicultural Options 

Loblolly pine in the West Gulf Coastal Plain lends 

itself, perhaps more than any other species in the world, to 

silvicultural flexibility. It is a medium-lived tree with rapid 

juvenile growth and a prolific seed producer in this part of 

its natural range (Balcer and Langdon 1990). It can withstand some overstory shading when young, but the height 

growth of reproduction decreases and mortality increases 

with excessive shade, especially from overtopping hardwoods. However, if loblolly pine seedlings growing with 

hardwood sprouts survive their third year, they will successfully compete with the hardwoods in open conditions 

(Balcer and Langdon 1990). Shade management becomes 

important in such circumstances. Uneven-aged methods that 

enlarge existing regenerated gaps or that further remove 

residual overstory trees within gaps will promote successful 

uneven-aged silviculture with the species. 

Shortleaf pine tolerates wide extremes in temperature 

and moisture and is the most broadly distributed of all the 

southern pines. It produces good to excellent cone crops 

every 3 to 6 years (Lawson 1990). Seedlings grow slowly 

for the first several years as their root systems expand. The 

species has unique seedling characteristics of ecological and, 

perhaps, silvicultural interest-they develop a sharp 

J-shaped crook at the ground line. Associated with this 

crook are axillary and other buds that develop into sprouts 

if the above-ground portion of the seedling is killed. This 

trait persists through roughly the first decade, a likely 

adaptation to fire (Mattoon 1915). 

Shortleaf pine is considered intolerant of shade, and 

does not grow well when suppressed (Lawson 1990). 

5 
However, it can survive suppression for extended periods 

and still respond to release (Mattoon 1915). Shade management becomes important in such circumstances. As with 

loblolly pine, uneven-aged methods that enlarge existing 

regenerated gaps or that further remove residual overstory 

trees within gaps will help uneven-aged silviculture succeed 

with shortleaf pine. Its sprouting ability, rarity of adequate 

seed crops, and ability to persist beneath shade until 

released, all suggest a silvicultural strategy based on 

advance reproduction, perhaps established with prescribed 

fire and linked with the selection method. 

6 

In addition to the silvical traits of loblolly and shortleaf 

pines, silviculturists must also be aware of the characteristics of their competitors. Loblolly and shortleaf pines 

are commonly associated with a variety of southern hardwoods, many of which are more shade tolerant than the 

pines. Therefore, lacking periodic disturbances, a loblollyshortleaf pine stand will eventually be dominated by hardwoods (Cain and Shelton 1994, Cain and Yaussy 1984, 

Switzer and others 1979). Persistent silvicultural effort 

must be expended in uneven-aged pine stands to prevent this 

shift in species composition. 
Chapter 2 

CONCEPTS AND DEFINITIONS 

Precise principles and terminology are essential for any 

profession. Therefore, some basic concepts used in unevenaged silviculture are defined in this chapter. In addition, a 

glossary is provided in the appendix. 

Silviculture Versus Forest Management 

Silviculture is the art, science, and practice of establishing and maintaining the types of stands and forests that 

will meet landowner and society needs on a sustainable 

basis. There is a subtle but clear distinction between silviculture and forest management. Silviculture is principally 

applied in stands. A stand is a contiguous group of trees 

that can be considered a distinguishable unit; the trees are 

similar in species composition, age- or size-class distribution, and condition and are growing on a site of uniform 

quality. By contrast, a forest is a collection of stands. 

Forest management is implemented at the forest level and 

encompasses economics, silviculture, politics, laws, societal 

preferences, protection, roads, and other factors that affect 

the stewardship of a forest. For some landowners, the stand 

and the forest may coincide. 

Even-Aged Versus Uneven-Aged Silviculture 

A silvicultural system is the planned program of 

treatments applied during the entire life of a stand. 

Treatments are formulated to meet the ecological 

requirements of the species under management and the 

objectives of the landowner. When the two do not coincide, 

ecological principles will set the limits of the silvicultural 

system unless the landowner is willing to expend large 

amounts of capital to overwhelm nature. A silvicultural 

system includes reproduction cuttings, site preparation, 

competition control, and tending operations, such as 

thinning. Such activities are intended to promote development of the best trees through maturity by removing cull, 

diseased, and undesirable trees, consistent with the 

landowner's objectives. 

Maturity is the stage when a tree best meets the 

objectives of the landowner. For timber production, it is 

important in deciding when to harvest a tree or group of 

trees and to secure their replacements through regeneration. 

Maturity can be evaluated in several ways. Financial 

maturity occurs when a tree ceases to return an acceptable 

compound interest rate on the investment that it represents. 

Physiological maturity occurs when a tree attains its full 

size, and overmaturity occurs when health and vigor 

decline enough to increase the risk of mortality. 

Reproduction cutting method refers to the way that 

mature trees in a stand are removed and the new stand is 

established. The goal is to create the environmental conditions needed to establish and develop the new stand by 

harvesting and site preparation. The reproduction cutting 

method is perhaps the key element in a silvicultural system 

because it strongly influences the character of the new stand 

and subsequent silvicultural treatments. Thus, regenerated 

stands and silvicultural systems are generally named for 

their reproductive cutting method. Uneven-aged reproduction cutting methods (single-tree selection and group 

selection) generally retain more trees than even-aged 

methods (clearcutting, seed-tree, and shelterwood), and 

the trees are usually more varied in size and spacing. In 

even-aged reproduction methods, trees retained for seed 

production may be completely removed once the stand has 

successfully regenerated, unless they are retained for other 

purposes, such as visual and wildlife habitat enhancement. 

These cutting methods create an array of environmental 

conditions for reproduction, ranging from the open areas 

resulting from clearcutting to the partially shaded understories of single-tree selection. 

Choosing a reproduction cutting method is based on the 

existing stand conditions, silvical characteristics of the 

desired species, landowner objectives, desired future conditions, local timber markets, and economic considerations. 

Although by definition these cutting methods are distinctively different, one method may overlap another, resulting 

in similar stand conditions. For example: (I) small, patch 

clearcuts may appear to be the larger openings created in 

group selection, (2) stands with small, group-selection 

openings may appear to be under single-tree selection, and 

(3) shelterwood stands with trees retained after regeneration 

may produce stands similar to those under single-tree 

selection. 

Even-aged silviculture is based on a rotation, defined 

as the length of time between reproduction cuttings. 

Rotation length, typically 25 to 100+ years in the Southern 

United States, is affected by many factors, including 

landowner goals, timber markets, economics, growth rates, 

and site productivity. Treattnents such as site preparation, 

release, thinning, and the fmal harvest are usually applied 

over the entire stand and are independent of each other. 

The maturity of trees is determined by the collective traits 

of the entire stand. Of course, the final harvest is not the 

only cutting done in even-aged stands; thinning is done 

periodically to control stocking, capture anticipated 

mortality, and improve stand vigor and quality. The 

thinning interval is the length of time between thinnings. 

Conversely, harvesting in uneven-aged stands is based 

on the cutting cycle, defmed as the number of years 

7 
between successive cuttings in the stand. The cutting cycle 

is usually constant, but it can be adjusted to take advantage 

of seed production, market variability, or landowner needs. 

In the Southern United States, cutting cycles generally range 

from 3 to 20 years and are affected by the same factors that 

determine even-aged rotations. Within each cutting cycle, 

all silvicultural treatments common to an even-aged rotation, such as site preparation, release, thinnings, and reproduction cutting, may be applied. However, treatments are 

usually restricted to only those portions of the stand where 

needed. Tree maturity is evaluated on the merits of the 

individual tree or small groups of trees. 

Stand Structure 

Structure refers to the age- or size-class distribution of 

the trees making up a stand. This information hints at the 

stand' s origin and reveals the form of its canopy. A stand' s 

age structure is classified according to the number of distinctive age classes that are present. An even-aged stand is 

composed of a single age class, where the range of tree ages 

does not exceed 20 percent of the rotation length. A twoaged stand contains two distinctive age classes and results 

from even-aged reproduction cutting, such as the seed-tree 

and shelterwood methods, where the residual trees are 

retained well beyond the normal period needed for regeneration. 

Uneven-aged stands are composed of three or more 

age classes that are spatially intermingled. Each class 

makes up a significant portion of the stand' s stocking and 

contains the desired species. Thus, an even-aged pine stand 

with understory and mid-canopy hardwoods cannot be 

classified as an uneven-aged stand if only the pine 

component is being managed. 

Although silviculturists often talk about a stand' s age 

structure, rarely do we know what it is-determining age of 

many trees is simply too time consuming. Thus, the sizeclass distribution within a stand, most commonly expressed 

in d.b.h. (diameter at breast height taken at 4.5 ft above 

ground), is typically used instead of age, especially if it is 

combined with some evaluation of tree vigor and crowu 

features. Moreover, a tree's age is of less concern 

than its ability to respond at an acceptable growth rate when 

released. 

Tree age and size are usually not highly correlated 

within an even-aged stand because all the trees are similar 

in age. Tree sizes, however, can vary due to differences in 

genetics, microsites, spacing, and other factors. Trees that 

do not keep pace become suppressed and die, or they may 

be removed in thinning. Thus, an even-aged stand has a 

bell-shaped d.b.h.-class distribution, is characterized by a 

high degree of uniformity, and has a single canopy (fig. 

2.1). A two-aged stand has a binomial d.b.h.-class distribution and two distinct canopy layers of the species being 

managed (fig. 2.1). 

8 

EVEN-AGED 

UNEVEN-AGED (BALANCED) 

D.B.H.~ 

Figure 2.1. -Diameter distributions and canopy profiles occurring in 

stands with different types of age structure. 

The multiple ages of an uneven-aged stand result in 

a wide range of size classes. Uneven-aged stands typically 

have a reverse J-shaped d.b.h.-class distribution (fig. 2.1). 

There are many small trees, some medium trees, and a few 

large trees of the species being managed. Within an 

uneven-aged stand, tree age is reflected in tree size, with 

small trees tending to be young and large trees tending to 

be old (Shelton and Murphy 1991). However, this 

relationship is also affected by variation in genetics, 

microsites, and competition from larger trees. 

The ideal d.b.h.-class distribution in uneven-aged stands 

is a balanced reverse-J curve (fig. 2.1). It represents a 

compilation of many overlapping bell-shaped curves, each 

curve depicting an age class (Smith 1986). This balanced 

curve can also be called a negative exponential distribution. 

The wide range in size results in an irregular canopy 

structure with multiple layers (Shelton and Murphy 1993). 

Age classes in some uneven-aged stands may not be 

established frequently or at regular intervals because of the 

irregular timing of such events as harvests, fires, competition control, seed crops, weather, and insect and disease 

attacks. The resulting distribution represents an irregular 

uneven-aged stand (fig. 2.1). For most shade-intolerant 

species, the irregular distribution is probably more common 
than the balanced one. The irregular, uneven-aged distribution is similar to the binomial, even-aged distribution. 

This illustrates that a stand can occur anywhere along a 

continuum of possible age structures, ranging from the 

simplest (an even-aged stand) to the most complex (a balanced, uneven-aged stand). In reality, no clear distinction 

may exist between even-aged and uneven-aged structure 

under certain stand conditions. 

In balanced, reverse-J distributions, a constant ratio 

exists between successive d.b.h. classes. This relationship 

defines the curve's shape (steepness or flatness) and is called 

the quotient or q. The calculation is as follows: 

where N; is the number of trees in the ith diameter class and 

N1+ 1 is the number of trees in the next largest class. For 

example, q would be 1.2 if there were 12 trees in the 15-

inch d.b.h. class and 10 trees in the 16-inch d.b.h. class. 

Note that a q of 1.0 results in a flat distribution because the 

number of trees is equal for all classes; a q of 2.0 produces 

a very steep curve because the number of trees in successive 

d. b.h. classes is halved. Class width affects the number of 

trees in the class and therefore the value of q (Murphy and 

Farrar 1988). The q for a distribution with I-inch d.b.h. 

classes is squared to give the same distribution for 2-inch 

classes (for example, a q of 1.2 for I-inch classes would be 

1.44 [1.2 X 1.2] for 2-inch classes). The q is central to 

discussing the fmer points of uneven-aged silviculture 

because it affects sustainable yields. Logically, no constant 

ratio exists between successive d.b.h. classes for irregular, 

uneven-aged stands; this complicates developing marking 

guides and obtaining a sustained yield of timber products. 

The Uneven-Aged Silvicultural System 

The uneven-aged or selection system is the principal 

means for creating and maintaining uneven-aged stands. 

The selection system should not, however, be confused with 

selective cutting, a terrn so corrupted that it is often applied 

to any type of partial cutting, whether it is a reproduction 

cut or an intermediate thinning. In fact, the meaning of 

selective cutting is so vague that it is not accepted in forestry 

terminology (Wenger 1984). The negative connotation of 

selective cutting originated in the unsavory practice of 

"high-grading," where only the best trees in a stand were 

harvested without providing for stand regeneration. Because 

of the similarity of the words ~ion and ~ive, the 

alternative term, uneven-aged system, which emphasizes 

the multiple-age classes necessary to sustain these stands is 

preferred. 

Stands under the uneven-aged system have a continuous, irregular forest cover, recurring regeneration of 

desired species, and the orderly development of trees 

through a wide range of sizes. In the uneven-aged system, 

a balanced or irregular structure is maintained through frequent reproduction cuttings. Single-tree selection and 

group selection are the two recognized reproduction cutting 

methods. In single-tree selection, trees are selected for 

harvest based on their individual merits, such as form, 

quality, growth rate, financial maturity, competition with 

younger more vigorous crop trees, and mortality risk. By 

contrast, group selection focuses on the aggregate condition of small groups of trees. Group selection generally 

produces larger openings than does single-tree selection, 

which sometimes favors the regeneration of shade-intolerant 

species. However, group selection does not allow as much 

flexibility in nurturing individual trees as does single-tree 

selection. 

Diameter-limit cutting, which removes trees above 

a specified diameter, generally has a bad reputation because 

low-quality trees that are above the limit are commonly left. 

Diameter-limit cutting often results in regeneration although 

it is technically not a reproduction cutting method. However, it may simulate the uneven-aged system if: (1) all trees 

above the diameter limit are cut, (2) the diameter limit is set 

to retain some trees of seed-producing size, and (3) competing vegetation is periodically controlled. A disadvantage 

of diameter-limit cutting is that yields widely fluctuate 

because residual stocking is not regulated (Murphy and 

Shelton 1991). The method also does not remove trees of 

low quality and vigor that are below the diameter limit. 

Stocking 

Stocking is a relative term comparing the existing 

stand with the optimum for landowner objectives. In evenaged stands, stocking is maintained by thimting to enable 

crop trees to fully use the site's potential. By contrast, 

stocking in the merchantable portion of an uneven-aged 

stand is maintained at less than full occupancy so that some 

of the site's resources (light, water, and nutrients) are 

available to reproduction. Thus, acceptable stocking in 

uneven-aged stands has both lower and upper limits; this 

allows meeting the combined objectives of obtaining acceptable growth rates for the merchantable trees and acceptable 

density and development of reproduction. The lower limit 

occurs when low stocking causes a growth loss, and the 

upper limit occurs when merchantable trees adversely affect 

the development of reproduction (table 2.1). 

In uneven-aged stands, stocking is commonly measured separately for the merchantable and submerchantable 

stand components. Volume and basal area are usually used 

to evaluate the stocking of the merchantable portion of the 

stand. Stocking in the submerchantable portion is usually 

expressed as the number of seedlings and saplings per acre 

and includes some measure of their spatial distribution, such 

as milacre stocking (the percentage of 0.001-acre plots 

containing at least one seedling or sapling). 

9 
Table 2.1.-Acceptable stocking in uneven-aged loblolly-shortleafpine stands on good sites• 

Measurementt 

Merchantable basal area (Ft2/acre) 

Sawtimber basal area (Percenl of merchantable) 

Merchantable volume (Ff/acre) 

Sawtimber volume (Ff/acre) 

Sawtimber Doyle volume (Fbmlacre) 

Sawtimber International volume (Fbm!acre) 

Sawtimber Scribner volume (Fbm/acre) 

Lower 

45 

60 

1,000 

500 

2,500 

4,000 

3,000 

Limitt 

Upper 

75 

80 

2,000 

1,500 

7,000 

10,000 

8,500 

Site index > 85 ft at 50 years for loblolly pine. Early results from several studies (Murphy and 

Farrar 1985, Murphy and others 1991, Shelton and Baker 1992a) suggest that similar stocking limits are 

applicable to shortleaf pine stands on poor sites (site index of < 65 ft at 50 years). 

t Merchantable trees are 4 inches in d.b.h. and larger; sawtimber trees are 10 inches in d.b.h. and 

larger. Cubic foot volumes are inside bark. 

t Lower limits are for a stand with a basal area of 45 ft2/acre, a maximum d.b.h. of 16 inches, and a 

q of 1.22 for 1-inch d.b.h. classes and using local-volume equations for the Crossett Experimental Forest 

(Farrar and others 1984b). Upper limits are for the target stand existing at the end of a cutting cycle as 

described by Reynolds (1959). 

Forest and Stand Regulation 

Regulation refers to the manner in which harvests are 

scheduled and implemented to provide the sustained, even 

flow of timber or other forest resources. In even-aged or 

two-aged management, regulation is principally achieved 

at the forest level by scheduling the rotation of mature 

stands. Either area regulation (designating the harvested 

area) or volume regulation (designating the harvested 

volume) can be used. The sustained, even flow of timber is 

not a goal at the stand level. By contrast, regulation is 

applied at both the forest and stand levels in uneven-aged 

management, because sustained yields are goals at both 

levels. Either area or volume regulation can be used in 

uneven-aged management. For example, area regulation of 

a 1,000-acre forest composed of uneven-aged stands might 

involve uneven-aged cutting on 100 acres during each year 

of a 10-year cutting cycle. At the stand level, however, 

volume and basal area, coupled with the d.b.h.-class 

distribution, are the accepted regulation techniques in stands 

under single-tree selection. 

Volume/Guiding-Diameter-Limit (VGDL) Method 

The VGDL regulation method of single-tree selection 

has been effectively used in loblolly-shortleaf pine stands in 

southern Arkansas for more than 50 years (Farrar 1984, 

Reynolds 1959, Reynolds and others 1984). A stand is 

regulated by cutting a sawtimber volume equal to the stand' s 

sawtimber growth during the cutting cycle. Harvests are 

conducted when sawtimber volume reaches the upper limit 

acceptable for the development of pine reproduction. The 

expected volume growth for the next cutting cycle (annual 

10 

volume growth times cutting-cycle length) is the allowable 

cut. Length of the cutting cycle can be varied to provide an 

operable timber harvest if the residual stand volume is large 

enough to sustain stand growth. Ideally, stand volume will 

grow to the upper limit by the end of the next cutting cycle. 

Thus, regulation by the VGDL method maintains stand 

volumes within acceptable lower and upper stocking levels. 

The VGDL method can also be adapted to increase stocking 

in understocked stands by cutting less than growth. 

A guiding diameter limit is calculated so that harvesting trees in this diameter class and larger will provide 

the allowable cut. However, this diameter limit is only 

intended as a guide, and high-quality trees with acceptable 

growth may be retained above the limit, while an equal 

volume of lower quality trees may be cut below the limit. 

Thus, the method provides some flexibility in selecting 

individual trees for harvest, although the allowable cut 

calculated for the stand is strictly maintained unless the 

stand is understocked. Using this method requires some 

estimate of the stand's growth rate [see chapter 4] and the 

diameter distribution at the end of the cutting cycle. Implementing this method requires considerable skill because 

cutting in the sawtimber component is subjective. The pulpwood component is not consciously regulated in this method 

because stocking has traditionally been based solely on 

sawtimber volume (Reynolds 1959). 

An example of implementing the VGDL is shown in 

table 2.2. This stand has a sawtimber volume of about 

7,000 board feet (fbm) 1

/acre, which is at the upper stocking 

limit indicated in table 2.1. An annual growth rate of 400 

1 All board-foot values are given in Doyle scale unless otherwise 

stated. 
Table 2.2.-Example of the data and calculations needed to implement the Volume/Guiding-Diameter-Limit (VGDL) regulation method (number 

of trees would be determined by inventory) 

Preharvest volume Cut volume 

• D.b.h. Number By d. b.h. class Cumulative Target Acrual 

Inches Per acre -- - - - - - --- - -- - - --- - - -- - - --- - - - Fbmlacre - -- - - --- - - -- - - - - --- - -- - -- - - -- -

4 18 0 0 0 0 

5 16 0 0 0 0 

6 13 0 0 0 0 

7 12 0 0 0 0 

8 9 0 0 0 0 

9 8 0 0 0 0 

10 7 197 7,013 0 0 

11 7 278 6,816 0 0 

12 6 336 6,538 0 112 

13 5 385 6,202 0 0 

14 4 411 5,817 0 103 

15 4 400 5,406 0 100 

16 3 505 5,006 0 0 

17 3 624 4,501 0 208 

18 2 505 3,877 0 0 

19 2 604 3,372 0 0 

20 2 712 2,768 0 0 

21 414 2,056 414 414 

22 478 1,642 478 0 

23 546 1,164 546 546 

24 618 618 618 618 

Total 125 7,013 2,056 2,101 

• Starting with the largest d.b.h. and accumulating the volume in each smaller d.b.h. class. 

fbm/acre and a 5-year cutting cycle are assumed. The 

volume growth during the cutting cycle would be 2,000 

fbm/acre (5 years X 400 fbm/acre), which is the allowable 

cut. This is sufficient volume for an operable cut and leaves 

a volume that is above the lower limit for stocking (7, 000 -

2,000 = 5,000 fbm/acre). Table 2.2 shows that trees 21 

inches in d.b.h. and larger will provide the allowable cut. 

Thus, 21 inches is the guiding diameter limit. In marking 

the stand, however, some high-quality trees were retained 

above the diameter limit, while an equal volume of lower 

quality trees was cut below the limit. 

The stand in this example is at the upper limit suggested for sawtimber volume, and harvesting is traditionally 

done at or near this limit using the VGDL method. However, harvesting could be done when stocking is below this 

limit depending on stand conditions, timber markets, and 

landowner objectives if there is an operable harvest and 

stocking is not reduced below the lower limit. 

Basal Area-Maximum Diameter-q (BDq) Method 

Regulation by the BDq method of single-tree selection 

avoids some shortcomings of the VGDL method by allowing the objective control of the entire diameter distribution 

(Farrar 1984, Marquis 1978). After each cutting cycle, the 

target structure of the residual stand is def'med by the BDq 

guidelines in the following priority: (1) the target basal area 

is retained, (2) trees larger than the maximum diameter 

(the largest d. b.h. retained in the stand) are cut unless 

needed to meet the target basal area, and (3) the residual 

d.b.h.-class distribution should approach the target q as 

closely as possible. Adjustments for deficit d.b.h. classes 

are made by retaining additional trees in surplus classes. 

The maximum diameter in the BDq method is similar to the 

guiding diameter limit of the VGDL method except that the 

maximum diameter refers to the residual stand, while the 

guiding diameter limit refers to the harvested trees. 

Figure 2.2 shows how basal area, maximum diarneter, 

and q are varied to control stand structure. Varying basal 

area while holding the other factors constant affects the 

number of trees in each d.b.h class and the stand total but 

does not affect the shape of the distribution (fig. 2.2). 

Thus, mean d.b.h. and percentage of the stand in the 

sawtimber component are not affected by changing the basal 

area. By contrast, maximum d.b.h. and q strongly affect 

the shape of the distribution. For example, increasing 

maximum d.b.h. while holding the other factors constant 

11 
BASAL 

50 B ... , .... 40 80 2 R /<C<0 

40 

80 

30 60 . . 80 

. . . 20 40 ' . 

AREA (B) 

No./ 

.... 

100 

158 

211 

D 

q 

Moao Sawtlmber 

d.b.h. basal aru. 

lnchn Peroert 

8.3 •• 8.3 •• 8.3 •• 

= 16 inches 

= 1.2 

... .... --- o L... ............. ~~....._._-===·=---~-~±·cc£.]c: 

5 10 15 

D.B.H. (inches) 

MAXIMUM D.B.H. (D) 

D 50 Ma No./ MNO Sawtlmber 

d.b.h. . ... d.b.h. bual aru. 

12 lnchn lnchn Peroert 

40 12 200 7.3 28 

18 158 8.3 .. 30 16. 20 133 0.1 .. . . 20 ·. . B 60 ft 2 . = / acre 

20 . .. . . . q = 1.2 . 10 "· ....... .. 

··· .. :-- .. :-.:-.;-.:-.:-.:-.:-.-:-.':",,..,, .. 

o~~~~~~~~~~~~~~~~~ 

5 10 15 20 

D.B.H. (inches) 

QUOTIENT (q) 

80 q No./ Moao Sawtlmber 

q .,,. d.b.h. basal area 

lnchn Peroent 

1.0 .. 10.7 82 

1.2 158 8.3 •• 

al' 1.4 ~ 

-!!!. 60. Cl) 

Q) 1.4 238 8.8 37 

B = 60 ft 2

/ acre 

D 16 inches . . 

~ ~ 40 f-

~ 1.2 Ci; 

a:i 20 fCl 1.0 

· . .... .. :·:..-:: ..... _ 

..... .,. .. .... :-.:-.:-.:-.:-.:-.:-;-.:-.· 0 5 10 

D.B.H. (inches) 

15 

Figure 2.2. -Effects of basal area, maximum d.b.h., and q on stand structure. In each illustration, the designated item varies, while the others remain 

constant. Mean d.b.h., is the quadratic mean; sawtimber basal area is for trees JO inches and larger in d.b.h. and is expressed as a 

percentage of total merchantable basal area. 

results in: (1) flattening the d.b.h.-class distribution, (2) 

decreasing the number of trees, and (3) increasing the mean 

d.b.h. and percentage of the stand in sawtimber (fig. 2.2). 

Increasing the value of q while holding the other factors 

constant has the opposite effect as maximum d. b.h. and 

results in: (I) steepening the d.b.h.-class distribution, (2) 

increasing the number of trees, and (3) decreasing the mean 

d.b.h. and percentage of the stand in sawtimber (fig. 2.2). 

Specific BDq targets are selected to meet landowner 

goals, timber markets, species requirements, and site conditions. The BDq method also imposes lower and upper limits 

for acceptable stocking, but limits are gauged by basal area 

rather than volume as with the VGDL method. 

Implementing the BDq method requires knowing the 

diameter distribution at the end of the cutting cycle and the 

expected basal area growth rates [see chapter 4]. The BDq 

12 

method can also be combined with a tree-classification 

procedure to ensure the retention of high-quality, vigorous 

trees as future growing stock. Because the BDq method is 

featured in chapter 3, no example of its application is 

provided here. 

The BDq method can be simplified by ignoring the q 

factor and basing regulation only on basal area and 

maximum diameter. This modification is called the BD 

method, and is similar to the VGDL method except that 

basal area is used for regulation rather than sawtimber 

volume. Data from a preharvest stand inventory are used to 

calculate the diameter limit that will leave the target 

basal area. This sets the maximum diameter to be 

retained in the stand. Using basal area for regulation has 

several advantages: (1) it includes both the pulpwood and 

sawtimber components, (2) no local volume table is needed, 
(3) basal area may be more easily visualized when marking 

the stand than volume, and (4) stocking limits for basal 

area may apply to a wider range of site qualities than those 

for sawtimber volume. Although not widely tested, the BD 

method should produce an uneven-aged stand if a reasonable 

basal area is selected (for example, 45 to 60 ft2

/acre) and 

competing vegetation is periodically controlled. This 

method may be useful in situations such as: (1) the initial 

cutting in stands that have not been under uneven-aged 

silviculture and lack a balanced structure, and (2) where 

marking crews or landowners lack the technical skill or 

experience to apply more complicated methods of 

regulation in cutting only trees larger than the maximum 

diameter. The recommended alternative, however, is to 

consider the maximum diameter as a guide and cut 

individual trees based on their merits as with the VGDL 

method. A disadvantage of this simplified method is that 

yields may fluctuate because stand structure is not 

controlled. 

An example of the BD method is shown in table 2.3. 

The pre harvest basal area is 80 ft2 I acre and the target basal 

area in the residual stand is 60 ft' /acre. Thus, the cut will 

be about 20 ft2/acre. The maximum diameter is determined 

by starting with the largest d.b.h. class and accumulating the 

basal area in each smaller d.b.h. class. This approach shows 

that 20 ft2

/acre is reached about one-third of the way 

through the 16-inch class. Thus, cutting about one-third of 

the 16-inch trees and all of the larger trees would equal the 

allowable cut. In this example, however, some high-quality 

trees were retained above the maximum diameter, while an 

equal basal area of lower quality trees was cut below the 

limit. 

Table 2.3.- Example of the data and calculations needed to implement the Basal Area-Mcuimum Diameter (BD) regulation method (number of 

trees would be determined by inventory) 

Preharvest basal area Cut basal area 

• D.b.h. Number By d.b.h. class Cumulative Target Actual 

Inches Per acre -- ------------------ ----------Ff/acre - - - - - - -- - - - - - - -- - - - - - - -- - - - - - - -

4 14 1.2 80.0 0.0 0.0 

5 18 2.4 78.8 0.0 0.0 

6 19 3.7 76.4 0.0 0.0 

7 17 4.5 72.7 0.0 0.0 

8 14 4.9 68.2 0.0 0.0 

9 11 4.9 63.3 0.0 0.0 

IO 9 4.9 58.4 0.0 0.0 

11 8 5.3 53.5 0.0 0.7 

12 7 5.5 48.2 0.0 0.0 

13 6 5.5 42.7 0.0 1.8 

14 6 6.4 37.2 0.0 0.0 

15 5 6.1 30.8 0.0 0.0 

16 5 7.0 24.7 2.8 1.4 

17 4 6.3 17.7 6.3 4.7 

18 3 5.3 11.4 5.3 5.3 

19 2 3.9 6.1 3.9 3.9 

20 2.2 2.2 2.2 2.2 

Total 149 80.0 20.5 20.0 

• Starting with the largest d.b.h. and accumulating the basal area in each smaller d.b.h. class. 

13 
Chapter 3 

IMPLEMENTING UNEVEN-AGED SILVICULTURE 

Uneven-aged silviculture can be used to develop and 

maintain uneven-aged stands of loblolly and shortleaf pines, 

and it can be implemented in pine stands of various stockings and structures. Options for implementing or sustaining 

uneven-aged silviculture are determined by the existing basal 

areas within the stand (fig. 3.1). Uneven-aged silviculture 

is commonly used in: (1) well-stocked stands with unevenaged structure, (2) well-stocked stands with even-aged 

structure, and (3) understocked stands that have at least two 

size or product classes (Baker 1986, 1991; Reynolds and 

others 1984). How to implement uneven-aged silviculture 

for each of these three stand conditions will be discussed. 

First though, it must be decided whether to use the singletree or group-selection reproduction cutting method because 

some silvicultural techniques depend on which cutting 

method is used. 

eStand is very overstocked by uneven-aged 

standards; an immediate harvest is warranted. 

-!!! " 

~ 90 

~ ct: 

<I: 

..... 75 ;,; 

Consider reducing basal area to acceptable 

levels in two harvests. 

Stand is overstocked by uneven-aged standards; an immediate harvest is warranted for 

basal area reduction. Reproduction is being 

adversely affected. 

Optimum stocking for maximum growth of 

~ 

~ 45 UJ 

..... 

both merchantable trees and reproduction. 

Harvesting is optional depending on the operability of harvest, markets, and landowner 

objectives. 

Understocked but sufficient to rehabilitate; let 

Ill 

~ :c: 

~ 10 

() 

the stand grow and increase stocking. Consider releasing potential crop trees from 

competition as needed. 

Too understocked to manage. If milacre 

ffi 

::e 

stocking of pine reproduction is < 20 % , prepare site and plant or consider natural 

regeneration if there is a pine seed source. 

SILVICULTURAL OPTION 

Figure 3.1.-Silvicultural options to create or sustain uneven-aged 

stands based on basal area of the merchantable component. 

Each of the uneven-aged reproduction cutting methods 

has its strengths and weaknesses, as described in chapter 2. 

Single-tree selection is probably the preferred method for 

most stand and site conditions. It has been developed and 

used more extensively, both through research and industrial 

application in the loblolly-shortleaf pine types, than has the 

14 

other method. However, group selection may be particularly useful for such stand and site conditions as: (1) 

uniform, well-stocked, even-aged stands that are being 

converted to uneven-aged structure, (2) pine-hardwood 

stands where a hardwood overstory is to be retained in 

portions of the stand [see chapter 5], and (3) highly 

productive, moist sites where competing hardwoods and 

herbaceous vegetation are vigorous. Under these conditions, group-selection cutting and appropriate site preparation would help ensure the establishment and development 

of pine reproduction. 

Well-Stocked Stands with Uneven-Aged Structure 

If a stand is well stocked (45 to 75 ft'/acre of basal area 

in merchantable-size trees of good quality [see table 2.1] 

and has uneven-aged structure (at least three distinct size or 

product classes), uneven-aged silviculture using the singletree selection method can perpetuate the stand while 

producing merchantable products from periodic harvests. 

The treatments recommended include: (1) inventorying the 

stand, (2) regulating stand structure, (3) establishing a 

cutting cycle, (4) marking trees for harvest, (5) establishing 

and evaluating reproduction, and ( 6) controlling competing 

vegetation (Baker 1991, Farrar 1981, Reynolds and others 

1984). 

Inventorying the Stand 

An objective of uneven-aged silvicnlture is to modify 

the distribution of trees in a stand to conform to a specified 

structure. Good stand structure is maintained by harvesting 

the excess trees in diameter or product classes that do not 

have good growth or form. Thus, before the stand is harvested, it is important to know the density, size, volume, 

quality, and distribution of the trees. 

The first step is to generate a stand-and-stock table for 

the merchantable component of the stand. Standard inventory methods, if properly implemented, will generally yield 

this information. A 10-percent cruise, using either fixedradius (e.g., 1/5-acre) plots or strips, should provide a good 

estimate of the number of merchantable-size trees by d.b.h. 

class. Trees may be tallied by 1- or 2-inch d.b.h. classes or 

even by product classes: seedlings, saplings (1 through 3 

inches in d.b.h.), pulpwood (4 through 9 inches in d.b.h.), 

small sawtimber (10 through 15 inches in d.b.h.), medium 

sawtimber (16 through 21 inches in d.b.h.), and large sawtimber (22 inches in d.b.h. and larger). The use of2-inch 

d.b.h. classes or product classes often increases the pro-
ductivity of the inventory and marking crews. A prism 

cruise could also be used, althougb a prism under-samples 

small trees. Sample stand inventory and summary forms 

(A-1 and A-2) are provided in the appendix. 

Simulated inventory data from a hypothetical, 40-acre, 

well-stocked and well-structured stand (Compartment A, 

Stand 1) are presented in figures 3. 2 and 3. 3. Once the 

inventory is completed and summarized, a stand-and-stock 

table is prepared (table 3 .1) using the total number of trees 

per acre for each d.b.h. class provided in the inventory 

summary (fig. 3.3). The stock table can be developed by 

assigning volumes to trees in the respective d.b.h. classes. 

A local volume table or a volume equation is sufficiently 

accurate to obtain the tree volumes. Volumes are needed at 

this time to ensure that an operable cut exists. More precise 

volumes for timber-sale purposes will be obtained when the 

stand is marked. 

Table 3.1.----Stand-and-stock table for hypothetical stand (Compartment 

A, Stand I) derived from inventory data in figure 3.2 (tree 

volumes determined from a local volume table) 

Trees per Volume 

D.b.h. acre Basa1 area 

Inches Number Ft2!acre Ft3!acre Fbmlacre 

4 30 2.6 15 0 

5 20 2.7 35 0 

6 18 3.5 61 0 

7 16 4.3 87 0 

8 14 4.9 110 0 

9 12 5.3 129 0 ------------------------------------------------ IO IO 5.4 141 281 

II 8 5.3 143 318 

12 7 5.5 154 392 

13 6 5.5 160 463 

14 5 5.4 159 514 

15 4 4.9 149 533 ------------------------------------------------ 16 

17 

18 

19 

4 

3 

3 

2 

5.6 

4.7 

5.3 

3.9 

173 

148 

168 

126 

673 

624 

758 

604 

20 2.2 71 356 

21 0 0.0 0 0 ------------------------------------------------ 22 

23 

24 

Total 

0 

0 

164 

0.0 

0.0 

3.1 

80.1 

0 

0 

!02 

2131 

0 

0 

618 

6134 

Note that the columns for recording the number of 

trees by d. b.h. classes on both the inventory and inventory 

summary forms (figs. 3.2 and 3.3) are divided into three 

tree retention/harvest classes-growers, thinners, and 

cutters. Figure 3 .4 illustrates some tree quality, form, and 

vigor characteristics associated with each class. 

Growers are trees of good quality, form, and vigor 

that are growing at an acceptable rate and that do not exceed 

the prescribed maximum tree diameter. Growers should be 

left in a stand as crop trees for future harvest. Cutters are 

trees (1) of poor quality, form, or vigor or that are growing 

at an unacceptable rate; or (2) not expected to survive 

through the next cutting cycle; or (3) competing with a 

higber quality tree; or (4) exceeding the maximum diameter 

prescribed in the management objectives and are not needed 

to maintain the prescribed basal area. As many cutters as 

possible should be harvested during the next cyclic cut 

without reducing the prescribed residual basal area. 

Thinners are trees that do not meet the grower or cutter 

criteria. These trees could either be cut in the next cycle or 

left in the stand for future harvest. Most of the trees 

marked are in this class. 

The tree classifications described above are flexible 

because of various degrees of quality, form, vigor, and 

competitiveness. For example, a poor-quality tree 

(damaged top) that is competing with a good-quality tree 

may be classified as a cutter; the same tree growing in the 

open and not competing with a grower may be classified as 

a thinner. Likewise, a tree with severe crook or sweep 

may be classified as a cutter whether it is competing with 

a better tree or not, whereas a tree with a slight crook or 

sweep would only be classified as a cutter if it were 

competing with a better tree. 

It is also important to understand that growers and 

thinners can change in classification over time. Growers 

can become thinners or cutters, and thinners can become 

growers or cutters. Classifying the trees during the 

inventory process yields important information about the 

quality of the stand and provides a basis for marking (and 

harvesting) the stand to ensure improved growth and quality 

in the future. 

Ideally, stands should be inventoried toward the end of 

each cutting cycle. However, for well-stocked and wellstructured stands inventoried before the previous harvest, 

growth-and-yield models may be used to project stand 

development at the end of a future cutting cycle [see chapter 

4] (Farrar and others 1984b; Murphy and Farrar 1982, 

1988). This approach should be used, however, for only 

one or two cutting cycles, after which the stand should be 

reinventoried and trees marked for harvest according to 

current data. 

Part of the inventory process is to map the forest types 

and stocking levels of the stand (fig. 3.5). Alternatively, if 

the stand is exantined before the inventory, observations 

about the distribution of forest types and stocking can be 

recorded then. The stand map will be useful when marking 

trees for harvest because size classes and stocking levels will 

probably not be distributed uniformly across the tract. 

Stand maps enable timber markers to distribute more of the 

15 
STAND INVEl\'TORY WITH TREE CLASSIFICATION 

Location Compartment A Stand 1 Acres _1Q__ Date~ 

Prism Factor/Plot Area 1/5-acre Crew JBB MGS MDC 

POINT/PWT NUMBER _l_ OF ...1lL 

PINE 

D.b.h. (inches) 

GROWERS THINl\'ERS CUTIBRS HARDWOODS 

4 .. 3 : 2 l 0 

5 : 2 l l 0 

6 : 2 : 2 0 : 2 

7 : 2 l l 0 

8 : 2 0 I l 

9 .. 3 1 0 0 

·------------------·------------------· -------------------· ~------------------· ------------------- 10 0 l : 2 0 

11 : 2 : 2 1 .. 3 

12 l .. 3 0 0 

13 : 2 0 l l 

14 l : 2 l 0 

15 .. 3 l 0 0 

-------------------·------------------· ·------------------· ·------------------ ------------------- 16 l 0 : 2 0 

17 0 .. 3 : 2 lJ 

18 : 2 l 0 0 

19 l 0 0 0 

20 0 1 0 0 

21 0 0 0 0 

·------------------ ~------------------· ~------------------· ·------------------ ------------------· 

22 0 0 0 0 

23 0 0 0 0 

24 0 0 l 0 

Figure 3.2. -Completed stand inventory form for a plot taken in a hypothetical stand. 

16 
D.b.h. (inches) 

Seedlings 

1 ft-0.5 in 

Saplings 

1 - 3 in 

STAND INVENTORY WITH TREE CLASSIFICATION 

Stand Inventory (Summary of pine stems per acre) 

Stand location Compartment A Stand 1 Date 5/ 11194 

GROWERS THINNERS CUTTERS TOTAL %CUTIBRS 

53 

42 

1----------------- ------------- --------------- --------------- ,._______________ ---------------

4 !5 13 2 30 

5 10 8 2 20 

6 9 9 0 18 9 

7 8 6 2 16 

8 7 5 2 14 

9 8 3 12 

1----------------- -------------- --------------- --------------- r---------------- ---------------

10 7 2 10 

11 5 3 0 8 

12 2 2 3 7 22 

13 3 2 6 

14 2 2 5 

15 2 0 2 4 

---------------- >--------------- --------------- ---------------- r---------------- ---------------

16 3 0 4 

17 3 

18 2 0 3 15 

19 0 2 

20 0 0 

21 0 0 0 0 

---------------- 1--------------- --------------- ---------------- 1---------------- ----------------

22 0 0 0 0 . 

23 0 () 0 0 100 

24 0 0 

Figure 3.3.-Completed stand inventory summary form/or a hypothetical stand (twemy 115-acre plots taken in a 40-acre stand). 

17 
4 

3 

9 10 

.. . . . 

6 • 

• {j Cutters ~Thinners .Growers 

1 Cutter: poor quality (damaged top), suppressing growers. 

2 = Thinner: poor form (stem crook), not suppressing growers. 

3 = Cutter: poor form (stem crook), suppressing growers. 

4 Cutter: exceeds maximum diameter and not needed to maintain prescribed basal area. 

5 Cutter: poor form (main stem forked), competing with growers. 

6 Cutter: poor form (severe lean). 

7 = Thinner: minor stem crook, not competing with growers. 

8 = Cutter: insect infestation, not expected to survive through next cutting cycle. 

9 = Thinner: damaged top, not severely competing with growers. 

10 Thinner: density control, competing with growers. 

Figure 3.4.- Characteristic pine tree classes based on retention or harvest criteria. 

allowable cut in areas heavily stocked with various size or 

product classes. For example, the hypothetical stand (fig. 

3.5) has more basal area in its eastern half (type I) than in 

the western half (types II and III). Thus, using the map, the 

markers would know to mark heavily in the type I area and 

lightly in the type II and III areas of the stand. 

Regulating Stand Structure 

Once the stand has been inventoried and the data 

summarized in a stand-and-stock table (table 3.1), decisions 

must be made about regulating stand structure. Two techniques are discussed in chapter 2: (1) the VGDL method 

(described in detail by Farrar 1984, Reynolds 1959, and 

Reynolds and others 1984) and (2) the BDq method (Farrar 

1981, 1984). Because the BDq method uses an objective 

approach and can employ a computer program for devel18 

oping a target stand structure and marking guidelines, it is 

the recommended technique and will be used to develop the 

hypothetical examples throughout this chapter. 

With the BDq method, stand structure is determined by 

the target residual (after-cut) basal area (B), the maximum 

d.b.h. to be retained (D), and the q-ratio. Recommended 

ranges of these three variables are: B (45 to 60 ft'/acre), D 

(12 to 30+ inches), and q (1.1 to 1.4 for 1-inch d.b.h. 

classes; 1.2 to 2.0 for 2-inch d.b.h. classes). The range for 

residual basal area (B) encompasses the stocking levels that 

provide good sawtimber growth while allowing reproduction 

to develop in the understory. The range of maximum d.b.h. 

(D) is set to allow for good seed production (minimum D of 

12 inches) and to provide flexibility in developing large or 

old trees as needed. The range of q is set to allow 

flexibility in stand structure. 
STAND MAP 

Compartment A Stand 1 5/11 /94 

1

1

1

II 

1 

r -;;:J=;:t;;=;!;;;;;;il=;:t;;;;;F;;•~nc:;::•~llnEe~I;;;;;;;;;;!:=~\~._ I.\ 

~ '~ N 

\\ . ..l 1 ~ J I :,' Type II ! 1 

g: Type I \ 

°i ,',' P 95 BA \ 

~\\ ".,., H 10 BA \ j Ou •.. ~,iii 

;= " 

II •• •• •• I "E 

~ ~ •• 1' J!! ~~ Type HI •••••• '1 "§ II • : ~ 

~~ PSOBA !- :: H 0 BA • ~ 

:: ~ 

:: .·· \ 

:: ...... · : ' 

:'.:'. = = = = = = _<i!ivi[ ClllllL _ - - - - - - \: 

Figure 3.5.-Map of hypothetical stand (Compartment A, Stand 1) illustrating basal area (BA) stocking/or pine (P) and hardwood 

(H) insquarefeetperacre. 

A computer software program' calculates a "target" stand 

structure for specified combinations of B's, D's, and q's. 

The program also calculates and displays numbers of trees 

and their basal areas in each d.b.h. class before harvest 

(based on the inventory data). It also displays the number 

of trees and basal area to be harvested from each d.b.h. 

class that will best approximate the target structure. An 

example of the computer output generated by running the 

program (using inventory data from table 3.1) is presented 

in table 3.2. Table 3.3 is this information expanded to 

produce a stand-and-stock table. 

The computer output can be further summarized by 

delineating product classes; i.e.; pulpwood (4 through 9 

inches in d.b.h.), small sawlogs (10 through 15 inches in 

d.b.h.), medium sawlogs (16 through 21 inches in d.b.h.), 

and large sawlogs (22 inches in d.b.h. and larger). By 

summing the numbers of trees to be cut for each product 

class, marking guides can be prepared to mark and cut the 

stand to a prescribed structure (table 3.4). This procedure 

should be followed after each cutting cycle to determine a 

marking prescription for the next cutting cycle. 

2 King, Bettina; Murphy, Paul A. 1993. TARGET: A program for 

calculating target stand structure and marking guides for uneven-aged 

loblolly-shortleaf pine stands on medium and good sites. Available by 

writing USDA Forest Service, P.O. Box 3516, Monticello, AR 71656, or 

calling (501) 367-3464. 

Establishing the Cutting Cycle 

For uneven-aged stands of loblolly and shortleaf pines 

on good sites (site index [S.I.] = > 85 ft at 50 

years), cutting cycles can range from 3 to 10 years. On 

poor sites (S .I. = < 65 ft at 50 years), cutting cycles can 

range from 8 to 20 years. 

Cutting-cycle length depends primarily on residual 

growing stock (immediately following a cyclic cut), site 

productivity or growth rate of the residual trees, and the 

minimum operable cut. The length of the cutting cycle is 

established (1) to maintain stocking within the prescribed 

limits (45 to 75 ft2

/acre of basal area) and (2) to provide an 

operable cut (approximately 1,200 furn/acre at the end of 

the cutting cycle). For example, a well-stocked and wellstructured uneven-aged stand on a good site will grow about 

3 ft2

/acre/yr in basal area or about 400 furn/acre/yr in 

sawlog volume. If the target residual basal area is 60 ft', 

then the cutting cycle should not exceed 5 years to keep the 

preharvest basal area from exceeding 75 ft2 (i.e., 3 ft2 x 5 

years = 15 ft2 + 60 ft2 residual basal area = 75 ft'). If a 

residual basal area of 45 ft2 were left, then the cutting cycle 

could be extended to 10 years (i.e., 3 ft2 x 10 years = 30 ft2 

+ 45 ft2 residual basal area = 75 ft2). However, the cutting 

cycle could also be set as low as 3 years because at a growth 

rate of 400 furn/acre/yr, 1,200 furn (an operable cut) could 

be harvested in 3 years. 

On poor sites, a well-managed, uneven-aged stand will 

grow about 1.5 ft2 of basal area or about 150 furn/acre/yr. 

Thus, cutting cycles could range from 8 to 20 years-8 

years yielding a minimal operable cut of 1,200 furn and 20 

years providing a maximum basal area stocking of 75 ft2• 

Adopting the shortest cutting cycle that will ensure an 

operable cut offers the most opportunities for seedling establishment following logging disturbance. In areas where pine 

seeds are produced infrequently, this may be a valuable 

advantage. Cutting cycles can be flexible if they stay within 

the constraints of operable cuts and acceptable stocking. 

Marking Trees for Harvest 

Three steps are involved in marking uneven-aged stands 

for harvest under single-tree selection: (1) determine the 

allowable cut using either the VGDL method or the BDq 

method, (2) determine the kinds of trees to be marked to 

cut, and (3) mark the trees for harvest. 

Allowable cut.-in uneven-aged stands, the allowable 

cut is the forester's estimate of the trees that can be 

removed to allow optimal development of the stand 

(Reynolds and others 1984). Under the BDq method, 

subtracting the target structure volume from the existing 

stand volume gives an allowable cut by diameter classes, 

product classes, or for the total stand. 

For example, table 3.3 shows that the current volume 

of the stand is 6, 134 furn/acre and that a BDq target 

structure for a 5-year cutting cycle has a volume of 4,409 

19 
Table 3 .2.~ Sample output (on a per-acre basis) for hypothetical, wieven-aged stand (Compartment A, Stand I) generated by the TARGET computer program 

using stand inventory data from table 3.1 and the following stand structure parameters: Residual Basal Area (BA) = 60jt2!acre; Maximum 

Diameter (D) = 21 inches; q value= 1.2 

D.b.h. 

Inches 

4 

5 

6 

7 

8 

Target 

Number 

22.2 

18.5 

15.4 

12.9 

10.7 

BA 

Ft' 

1.9 

2.5 

3.0 

3.4 

3.7 

Before-cut 

Number 

30.0 

20.0 

18.0 

16.0 

14.0 

BA 

Ft' 

2.6 

2.7 

3.5 

4.3 

4.9 

c t 

Number 

6.7 

1.3 

2.2 

2.7 

2.8 

BA 

Ft' 

0.6 

0.2 

0.4 

0.7 

1.0 

After-cut 

Number 

23.3 

18.7 

15.8 

13.3 

11.2 

BA 

Ft' 

2.0 

2.5 

3.1 

3.6 

3.9 

9 8.9 4.0 12.0 5.3 2.6 1.2 9.4 4.1 ----------~------------------------------------~---------~---------------------------------~---------

10 

11 

12 

13 

14 

7.4 

6.2 

5.2 

4.3 

3.6 

4.1 

4.1 

4.1 

4.0 

3.8 

10.0 

8.0 

7.0 

6.0 

5.0 

5.4 

5.3 

5.5 

5.5 

5.4 

2.2 

1.5 

1.6 

1.4 

1.2 

1.2 

1.0 

1.2 

1.3 

1.3 

7.8 

6.5 

5.4 

4.6 

3.8 

4.2 

4.3 

4.3 

4.2 

4.1 

15 3.0 3.7 4.0 4.9 0.9 1.1 3.1 3.8 ----------~------------------------------------~---------~---------------------------------~---------

16 

17 

18 

2.5 

2.1 

1.7 

3.5 

3.3 

3.1 

4.0 

3.0 

3.0 

5.6 

4.7 

5.3 

1.3 

0.8 

1.1 

1.8 

1.2 

1.9 

2.7 

2.2 

1.9 

3.8 

3.5 

3.4 

19 1.4 2.8 2.0 3.9 0.5 0.9 1.5 3.0 

20 1.2 2.6 1.0 2.2 0.0 0.0 1.0 2.2 

21 1.0 2.4 0.0 0.0 0.0 0.0 0.0 0.0 ----------~------------------------------------~---------~---------------------------------~--------· 

22 

23 

24 

Total 

0.0 

0.0 

0.0 

128.2 

0.0 

0.0 

0.0 

60.0 

0.0 

0.0 

1.0 

164.0 

furn/acre. Thus, cutting the stand to the target structure 

would yield 1,981 furn/acre. All trees larger than 20 inches 

in d.b.h. would be harvested, as well as those representing 

the differences between the target and the current stand in 

each size or product class (table 3.3 and fig. 3.6). If a 

particular size or product class in the current stand had 

fewer trees than the target stand, no trees would be marked 

in that class. After experience is gained, determining the 

allowable cut may become more of a silvicultural decision 

guided by tree classification with stand structure being a 

secondary consideration. 

The marking prescription for the sample stand is 

shown in table 3.4. To achieve the prescribed stand structure, one-sixth of the pulpwood-size trees, one-fourth of the 

small sawlog-size trees, one-third of the medium sawlogsize trees, and all of the large sawlog-size trees should be 

harvested. Care should be taken to minimize damage to 

residual trees during logging. In some cases, such as on 

steep slopes or where large logging equipment is used, a 

few additional trees (2 to 3 ft2/acre of basal area) in the 

pulpwood and small sawlog classes could be left to offset 

mortality from logging damage. 

Kinds of trees to be marked.-Two main silvicultural 

goals guide the choice of trees to be marked. The first goal 

is to create openings for pine reproduction by harvesting the 

20 

0.0 

0.0 

3.1 

0.0 

0.0 

1.0 

0.0 

0.0 

3.1 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

80.l 31.8 20.l 132.2 60.0 

trees larger than the prescribed maximum d.b.h. The 

second goal is to improve the overall quality of the residual 

stand by applying intermediate treatments (thinnings, 

improvement cuttings, release cuttings, etc.) to the trees 

smaller than the prescribed maximum d.b.h. (Reynolds and 

others 1984). 

The quality of individual trees and their potential for 

future growth should be carefully evaluated when marking 

the stand. The basic principle is to retain the best trees in 

the stand until they exceed the prescribed maximum d.b.h. 

Trees of good form and vigor ("growers") and those that 

show evidence of past cone production should be retained; 

trees of poor form-those having sweep, crook, excessive 

branchiness, and other undesirable physical characteristicsand trees having poor vigor or those that are diseased or 

infested with insects ("cutters") should be harvested. If 

other factors are equal, trees retained should be uniformly 

spaced within similar diameter or product classes. 

Figure 3. 7 is an example of a completed tally form 

recording trees marked for a cyclic cut with instructions for 

marking the four product classes taken from table 3 .4. A 

sample tally form (A-3) is provided in the appendix. The 

sample tally form can be modified to accommodate I-inch 

d.b.h. 
N 

..... 

Table 3.3.-Stand-and-stock table (on a per-acre basis) for hypothetical stand (Compartment A, Stand 1) derived from inventory data and TARGET computer program (tree volumes determined from a 

local volutne table) 

Tanet stand Before-cut stand Cut After-cut stand 

D.b,h. No. trees BA Volume No. trees BA Volume No. trees BA Volume No. trees BA Volume 

Inches Fr Ft3 Fbm Ft2 Fr' Fbm Fr Ff Fbm Fr2 Ft3 Fbm 

4 22.2 1.9 11 0 30.0 2.6 15 0 6.7 0.6 3 0 23.3 2.0 12 0 

5 18.5 2.5 33 0 20.0 2.7 35 0 1.3 0.2 2 0 18.7 2.5 33 0 

6 15.4 3.0 53 0 18.0 3.5 61 0 2.2 0.4 8 0 15.8 3.1 53 0 

7 12.9 3.4 70 0 16.0 4.3 87 0 2.7 0.7 15 0 13.3 3.6 72 0 

8 10.7 3.7 85 0 14.0 4.9 110 0 2.8 1.0 22 0 11.2 3.9 88 0 

9 8.9 4.0 % 0 12.0 5.3 129 0 2.6 1.2 28 0 9.4 4.1 101 0 ~- ......... __________________ ..,_.,. ________ ......... _______________________ .... ________ .,. ________________________________________ .., ____________ ...... __ _ 

10 7.4 4.1 105 209 10.0 5.4 141 281 2.2 1.2 31 62 7.8 4.2 110 219 

11 6.2 4.1 110 246 8.0 5.3 143 318 1.5 1.0 27 61 6.5 4.3 116 257 

12 5.2 4.1 114 290 7.0 5.5 154 392 1.6 1.2 35 88 5.4 4.3 119 304 

13 4.3 4.0 115 332 6.0 5.5 160 463 1.4 1.3 39 112 4.6 4.2 121 351 

14 3.6 3.8 114 369 5.0 5.4 159 514 1.2 l.3 38 124 3.8 4.1 121 390 

____ 15 3.0 3.7 111 398 4.0 4.9 149 533 0.9 1.1 32 115 3.1 3.8 117 418 .,. ____________________ .. _ ... _______________________ ,.. __ .., _______ .. __ ... _______________________________ ... ______ .,.,..,.. .. _____ .. __ ... _____________ .., 

16 2.5 3.5 107 419 4.0 5.6 173 673 1.3 1.8 56 217 2.7 3.8 117 456 

17 2.1 3.3 103 433 3.0 4.7 148 624 0.8 1.2 39 164 2.2 3.5 109 460 

18 1.7 3.1 97 437 3.0 5.3 168 758 1.1 1.9 61 275 1.9 3.4 107 483 

19 1.4 2.8 91 435 2.0 3.9 126 604 0.5 0.9 30 145 1.5 3.0 96 459 

20 1.2 2.6 85 427 1.0 2.2 71 356 0.0 0.0 0 0 1.0 2.2 71 356 

______________________________ 21 1.0 2.4 78 414 0.0 0.0 0 0 0.0 0.0 0 0 0.0 0.0 0 0 ........... _________________________________ .......... _________ .., _____________________________________ ... ____ .,,...., .. .,. ... __ 

22 0.0 0.0 0 0 0.0 0.0 0 0 0.0 0.0 0 0 0.0 0.0 0 0 

23 0.0 0.0 0 0 0.0 o.o 0 0 0.0 0.0 0 0 0.0 0.0 0 0 

24 0.0 0.0 0 0 1.0 3.1 102 618 1.0 3.1 102 618 o.o 0.0 0 0 

Total 128.2 60.0 1,578 4,409 164.0 80.l 2, 131 6,134 31.8 20.1 568 1,981 132.2 60.0 1,563 4,153 
Table 3.4. -Prescribed marking tally (on a per-acre basis) for hypothetical stand (Compartmenl A, Stand 1) with the following stand structure parameters: Residual Basal Area (BA)= 60ft2/acre; Maximum Diameter (D) = 21 inches; q value= 1.2 

'.[argf.1 D~fQr~-s;;n! After:£Jit 

D.b.h. No. trees BA No. trees BA No. trees BA No. trees BA 

Inches Fi' Fi' Fi' Fi' 

4 22.2 1.9 30.0 2.6 6.7 0.6 23.3 2.0 

5 18.5 2.5 20.0 2.7 1.3 Pulpwood 0.2 18.7 2.5 

Tow 

6 15.4 3.0 18.0 3.5 2.2 Cut 18of110 0.4 15.8 3.1 

110 trees/acre, or 

7 12.9 3.4 16.0 4.3 2.7 1treein6 0.7 13.3 3.6 

8 10.7 3.7 14.0 4.9 2.8 1.0 11.2 3.9 

9 8.9 4.0 12.0 5.3 2.6 1.2 9.4 4.1 

--------------------------------------------------------------------------------------------------- 10 7.4 4.1 10.0 5.4 2.2 1.2 7.8 4.2 

11 6.2 4.1 8.0 5.3 1.5 Sm1 ~awtimber 1.0 6.5 4.3 

Total 

12 5.2 4.1 7.0 5.5 1.6 Cut 9 of 40 1.2 5.4 4.3 

40 trees/acre, or 

13 4.3 4.0 6.0 5.5 1.4 1treein4 1.3 4.6 4.2 

14 3.6 3.8 5.0 5.4 1.2 1.3 3.8 4.1 

15 3.0 3.7 4.0 4.9 0.9 1.1 3.1 3.8 

--------------------------------------------------------------------------------------------------- 16 2.5 3.5 4.0 5.6 1.3 1.8 2.7 3.8 

17 2.1 3.3 3.0 4.7 0.8 Med. Sawtimber 1.2 2.2 3.5 

18 1.7 3.1 3.0 Total 5.3 1.1 Cut 4of13 

trees/acre, or 1.9 1.9 3.4 

13 

19 1.4 2.8 2.0 3.9 0.5 1treein3 0.9 1.5 3.0 

20 1.2 2.6 1.0 2.2 0.0 0.0 1.0 2.2 

21 1.0 2.4 0.0 0.0 0.0 0.0 0.0 0.0 

--------------------------------------------------------------------------------------------------- 22 0.0 0.0 0.0 } 0.0 0.0 } 0.0 0.0 0.0 

Total Le;. Sawtimber 

23 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 

l Cut all trees 

24 0.0 0.0 1.0 3.1 1.0 3.1 0.0 0.0 

Total 128.2 60.0 164.0 80.l 31.8 20.l 132.2 60.0 

22 
30 Target stand 

Before-cut 

After-cut 

25 Cyclic cut 

Oi" 

t; 

-!!!. 20 fil 

~ """ 

~ 15 (i5 

as 

Cl 

10 

5 

4 6 8 10 12 14 16 18 20 22 24 

D.B.H. (inches) 

Figure 3.6.~Target, before-cut, and after-cut stand and cyclic cut. 

classes or the use of a local volume table that disregards 

merchantable height or log height. 

Until experience is gained, the following procedure will 

guide the marking of trees for harvest in uneven-aged 

stands. First, subdivide the allowable cut and the stand into 

four more-or-less equal units. Then, in the first quarter, 

mark one-quarter of the total allowable cut, keeping a tally 

of the trees marked. After the first quarter has been 

marked, check the tally against the prescribed marking 

intensity. If the marking has been too light, increase 

marking intensity in the appropriate size classes in the next 

quarter; if the marking has been too heavy, decrease the 

marking intensity in the heavily marked classes in the next 

quarter. The stand map showing areas of heavy stocking 

can be used to help decide where to mark lightly or heavily 

in particular size classes. 

Establishing and Evaluating Reproduction 

If uneven-aged loblolly-shortleaf pine stands with adequate seed crops are maintained within acceptable stocking 

levels (table 2.1), and if cyclic cuts are made and competition is controlled periodically, then pine seedlings should 

become established and develop. The reproduction may 

appear uniformly over the stand, particularly following an 

above-average or bumper seed crop or, more typically, in 

patches or small groups within the stand. Depending on 

seedbed conditions, pine seed crops, and severity of understory competition, pine reproduction can "trickle in" over 

several years after a harvest. Patience is required in 

obtaining and developing reproduction. Pine seedlings and 

saplings, growing in partial shade of a pine overstory, will 

not develop as rapidly as those growing in full sunlight. 

Thus, the development of the reproduction will be slow until 

it is released by removing some overtopping pines in the 

overstory. 

The need for evaluating the establishment and development of reproduction depends on stand and site conditions 

and the experience of the forester. In locations where 

reproduction is easily obtained and develops rapidly, the 

need for frequent evaluations is not great. But, where 

reproduction is difficult to obtain and development is slow 

(because of infrequent seed crops or severe competition), 

more attention is needed. 

The density and vigor of reproduction should be evaluated each time the stand is inventoried. If the pine 

reproduction is inadequate ( < 200 well-distributed stems per 

acre), or if the reproduction is not growing at least 6 inches 

in height per year (Chapman 1945, Wahlenberg 1960), 

additional site disturbance and/or vegetation treatments may 

be needed. 

Research on Upper Coastal Plain sites has shown that 

natural loblolly and shortleaf pine reproduction tends to be 

greatest in uneven-aged stands when: (1) overstory/midstory 

hardwoods and/or understory vegetation are controlled 

(Cain 199lb, 1992, 1993b), (2) the seedbed is disturbed by 

logging during the cyclic cuts (Cain 1987, 1988, 1994), and 

(3) there are better-than-average pine seed crops ( > 100,000 

potentially viable seeds per acre) (Cain 199lc, 1993b). 

Pine reproduction in the understory can be evaluated by 

tallying well-established pine seedlings and/or saplings on a 

minimum of 100 uniformly spaced, milacre plots in the 

stand. If group selection is being used, the plots should be 

located in the group openings rather than uniformly 

throughout the stand. The pine reproduction should also be 

evaluated in terms of its "free-to-grow" status and the 

coverage of competing (nonpine) vegetation. A sample 

evaluation form (A-4) is provided in the appendix. For 

evaluation purposes, reproduction can be classified as either 

adequate ( > 200 well-distributed stems per acre or > 20 

percent milacre stocking) or inadequate ( < 200 stems per 

acre or < 20 percent milacre stocking). 

Controlling Competing Vegetation 

Vegetation management or competition control in 

uneven-aged stands serves two purposes: (1) as a sitepreparation tool it promotes the early establishment and 

growth of pine reproduction (Cain 1988, 1992) and (2) as a 

pine-release tool it aids in the survival and intermediate 

development of pine seedlings and saplings (Cain 1991a, 

!99lb, 1993a). 

With single-tree selection, periodic control of competing vegetation (usually in conjunction with a harvest cut) 

across the entire stand is recommended and serves both 

these purposes. With group selection however, competition 

control may be needed only in the group openings or regeneration areas. Two distinct treatments are often used with 

23 
UNEVEN-AGED PINE MARKING TALLY 

Stand location Compartment A Stand I Acres ...'!Q_ Crew JBB MGS MDC Date 5118194 

PULPWOOD (MERCHANTABLE HEIGHT IN FEET) 

D.b.h. 10 15 20 25 30 35 40 45 50 55 60 PULPWOOD: 

Target No. 720 

4 111111111:: 111111111:. 1111111111!1: 11111111111. 111111111111: llllillllilu lllllllllu .. Marking Ratio 

72Q;4400 Qr 1·6 

5 "· "' "· LJ : : (cut:total) .. 

6 a:. ""· "' ": e:. Instruction: D :I : O"fc 14JOI of the 4400 trees 

are cutters thus about !Ii 

7 a:. Biii: Biii: "' ... "' llll:t of trees marked should be 

cutters. 

8 .. liilB: • liil:I llllllH!I, "" " " 

9 ... "' "· .. o " "" ... -------- -------- ________ ... _______ ----------------!-------------.. _____ ._ ____ ._ _____ " 

---- --------------------- SAWTIMBER (16-FOOT LOG HEIGHT) 

SMALL SA WLOGS: 

D.b.h. 1 l'h 2 2 1

h 3 31

h 4 Target No. l(iQ 

10 l!lllllil:t 111111111: 111111: Marking Ratio 

:l60:1600 or 1;4 

(cut: total) 

11 111:. lllllil:I liilllll: 

Instruction: 

12 :t 1111111111:1 1!1111:. : 22'.!li (ii.2! oUhe 1600 

£rg_g£ {ll'- CJJ.tJ.t:.TS,. thus all 

trees marked should be 

13 : 111111:1 1111111:. LJ cutters. 

14 llllill: B:t 111:. 

15 "' llu D 

------- ----------- ---------- ---------- -----------f----------- --------- ~-------- --------------------· 16 "' 111111:1 111:: MEDIUM SA WLOGS: 

Target No. 12Q 

17 11: 111111:: 111:: Marking Ratio 

160:520 or 1:3 

18 

(cut:total) 11: 1111. II. 

Instruction: 

19 11: D 1 "" 1781 of the 520 tree' 

are !,;;;utters thus about 1h 

20 of tre~:.i marked ::ihoul!;I 11~ .. : "'""r' 

21 .. .. ------- ---------- ---------- ---------- ---------- ---------- --------- -------- -------------------- 22 .. :I .. .. LARGE SAWLOGS: 

Target No . ..1Q_ 

23 : .. : Marking Ratio 

40:40 Qr 1:1 

24 : .. .. (cut:total) 

Instructions: 

Cut all trees. 

Figure 3. 7. -Completed tally form for marking the hypothetical stand. 

24 
group selection-site preparation in the group openings 

shortly after the harvest and pine release 3 to 5 years later. 

Because loblolly and shortleaf pines are shade intolerant, adequate light (approximately 50 percent of full 

sunlight) must reach pine reproduction for survival and 

growth (Baker and Guldin 1991, Baker and Langdon 1990). 

Excessive shading can be caused by a dense canopy of 

overstory, midstory, and/or understory vegetation. If seed 

production is adequate and if pine overstory basal area is 

maintained within acceptable levels (table 2.1, fig. 3.1) and 

if there is no shading from understory vegetation, then 

sufficient pine reproduction will survive and develop to 

perpetuate the stand. 

To ensure that adequate sunlight reaches developing 

pine reproduction, periodic control of competing hardwoods 

and/or herbaceous vegetation is often required, especially on 

moist, productive sites. If the pine reproduction is receiving 

adequate light, most of the seedlings and saplings should 

exhibit good apical dominance, be vigorous in appearance, 

and be growing at least 6 inches in height per year. If pine 

reproduction is absent or does not have these characteristics, 

competition control is probably needed. Specific guides for 

competition control are based on estimates of competing 

ground cover and stocking of pine reprodnction (fig. 3.8). 

Free-to-grow Competing vegetation 

pine (percent ground cover)t 

reproduction * 

(Milacre stocking) Light Medium Heavy 

(<40%) (40%-70%) (>70%) 

Light NO IMMEDIATE 

(<20%) CONTROL CONTROL CONTROL 

Medium NO POSTPONE 

(20%-50%) CONTROL CONTROL CONTROL 

Heavy NO NO NO 

(>50%) CONTROL CONTROL CONTROL 

• Milacre stocking = Number of milacres with at least one pine seedling 

(1fttallto0.5 inch in d.b.h.) or sapling (0.6 inch to 3.5 inches in d.b.h.) 

divided by the total number of milacres. 

t Percent ground cover is determined by ocular estimation. 

Figure 3.8.~Guide to competition control for pine reproduction in 

uneven-aged stands. 

Competing vegetation can be controlled by chemical or 

mechanical means. Prescribed winter fire may also be used 

in certain situations. For example, in shortleaf pine stands, 

reproduction will often sprout after being top-killed by fire; 

and in stands on poor sites where cuning cycles are long ( 10 

to 15 years), reproduction may survive prescribed winter 

fire used toward the end of the cutting cycle. For most 

stand and site conditions however, dormant-season burning 

cannot be applied frequently enough or intensely enough to 

control competing vegetation. 

Experience has shown that chemical control (using 

approved, selective herbicides every 10 to 20 years, depending on site productivity and the vigor and aggressiveness of 

the competing vegetation) is the most effective means of 

vegetation management in uneven-aged stands. Good sites 

(>85 site index [S.I.]) will require control more frequently 

than poor sites ( < 65 S .I.). Because of the open-canopy 

pattern of uneven-aged pine stands at recommended basal 

area levels (45 to 75 ft2

/acre), a ground cover of lush 

herbaceous vegetation ( > 70 percent) on good sites may 

prevent the establishment and growth of natural pine reproduction, even when pine seeds are abundant and hardwood 

competition is absent (Cain 1985, 1991b, 1992). 

Table 3.5 lists some competing vegetation conditions 

typically encountered in uneven-aged stands and some 

management alternatives. For southern pines, specific 

recommendations for controlling competing vegetation are 

available in published references (Cantrell 1985, Miller and 

Mitchell 1988, Nelson and Cantrell 1991, Walstad and Kuch 

1987). 

Table 3.5.- Typical competing vegetation conditions encountered in 

wieven-aged management and some control alternatives 

Competing vegetation Management alternatives 

Excessive (> 10 ft2/acre of basal Cut and sell if operable, or cut and 

area) overstory and/or midstory leave, or inject with herbicide. 

(>4 inches ind.b.h.) hardwoods. 

Dense hardwood understory ( <4 Release individual pines by 

inches in d.b.h.) with <200 free- mechanical or chemical removal of 

to-grow pine seedlings and/or pine overtopping hardwoods, or apply a 

saplings per acre. broadcast herbicide treatment. 

Herbaceous vegetation and/or vines Apply a broadcast treatment with 

that prevent pine seedling or sapling approved, selective herbicide. 

development. 

Excessive hardwood basal area Conduct at least three annual or 

( > 10 ft2/acre) or vines in even- biennial, prescribed, winter burns 

aged pine stands that are to be before the first basal-area reduction 

converted to uneven-aged structure. harvest, and cut residual hardwoods 

or inject with herbicide . 

Well-Stocked Stands with 

Even-Aged Structure 

On occasion, landowners or resource managers would 

like to convert even-aged stands to uneven-aged structure. 

This can be done by imposing either the single-tree selection 

or the group selection cutting method. With group 

selection, some openings would be created by harvesting all 

trees in part of the stand (generally 5 to 20 percent, 

depending on the cutting cycle). These openings would 

become the regeneration areas in which new age classes 

would be established over several cutting cycles [see chapter 

5]. 

The difficulty and duration of the conversion process 

using single-tree selection depend on the initial stand condition and age. Uniform, well-stocked (basal area > 90 

ft' I acre), old ( > 70 years of age) even-aged stands are 

25 
generally more difficult and take longer to convert than 

irtegular, younger (30- to 50-year-old) stands that have 

< 80 ft2/acre of basal area. To convert to uneven-aged 

structure using single-tree selection, the same six techniques 

explained in this chapter under "Well-Stocked Stands with 

Uneven-Aged Structure" should be followed with a few 

exceptions. Because the establishment of new age classes 

within the stand is essential to developing uneven-aged 

structure, the most critical element of the conversion 

process is the timely establishment and development of pine 

reproduction. To obtain new age classes, overstory pine 

basal area must be reduced and hardwood competition must 

be controlled. 

Thus, establishing an appropriate residual basal area of 

high-quality, seed-producing pines is imperative, even at the 

expense of a desired maximum d.b.h. and q. Once several 

new age classes have become established over two or three 

cutting cycles, then greater attention can be paid to the stand 

structure. 

Inventorying the Stand 

The initial inventory of the even-aged stand is done 

primarily to determine the current stocking on which the 

initial basal-area reduction cut is based. Thus, the intensity 

or accuracy of the inventory is not as critical as with 

uneven-aged stands, as described earlier. As a minimum, 

about 20 prism points per 40 acres (using a JO-factor, basalarea prism) should be taken to determine average basal area 

of the stand. When this estimate is used, the stand can be 

marked to reduce the current basal area to 45 to 60 ft2/acre, 

depending on cutting cycle length and basal-area growth rate 

of the stand. If the current basal area exceeds 95 ft2/acre, 

two cuts may be required to prevent excessive mortality 

caused by a single, severe thinning. The first cut would 

reduce the basal area from 95 + to 75 ft2

/acre; 3 to 5 years 

later a second cut would reduce basal area to 45 to 60 

ft2/acre. 

When marking the stand, remove all cutters, then 

thinners, and enough growers to achieve the prescribed 

basal area. The marking should favor an irregular spacing 

of trees. Most of the trees should be marked in the mid- to 

upper-d.b.h. sizes. It is not important to abide by a rigid 

maximum d.b.h. or q in the initial basal-area reduction cut; 

the important thing is to reduce overstory stocking and 

increase the amount of light reaching the forest floor sufficiently to promote the establishment and growth of pine 

seedlings. After two cyclic cuts, and after at least two new 

age classes have been established, a complete stand inventory should be conducted and BDq regulation imposed. 

Developing Uneven-Aged Structnre 

The following hypothetical example describes the 

conversion of a typical even-aged pine stand to uneven-aged 

structure. The 50-year-old stand, growing on a medium site 

26 

(S.l. = 70 ft at 50 years), is uniform and has an average 

basal area of 90 ft2 /acre (table 3.6 and fig. 3.9a). A stand 

having a residual basal area (B) of 55 ft2

/acre, a maximum 

tree diameter (D) of 21 inches, and a q factor of 1.2 is 

prescribed (tables 3.7 and 3.8). The cutting cycle is 10 

years. 

The first cut results in a residual basal area of 55 

ft2/acre after 35 ft2 and 2, 114 furn/acre are removed (table 

3.8 and fig. 3.9a). At an annual growth rate of 2 ft2

/acre in 

basal area and 200 furn/acre in sawlog volume, in 10 years 

the stand has 75 ft2

/acre of basal area and 4, 100 furn/acre of 

sawlog volume (fig. 3.9b). In addition, a new age class of 

10-year-old pine reproduction has been established. 

Table 3 .6. - Stand-and-stock table (on a per-acre basis) for a typical, 50-

year-old, even-aged stand (Compartment B, Stand 2) {tree 

volumes determined from a local volume table] 

Number of Volume 

D.b.h. trees Basal area 

Inches Ft' Ft' Fbm 

4 6 0.5 3 0 

5 8 I.I 14 0 

6 11 2.2 38 0 

7 14 3.7 76 0 

8 18 6.3 142 0 

9 19 8.4 204 0 ------------------------------------------------- 10 22 12.0 309 618 

11 26 17.2 463 1033 

12 18 14.1 396 1009 

13 11 10.1 293 848 

14 9 9.6 286 925 

15 4 4.9 149 533 ------------------------------------------------- 16 0 0.0 0 0 

17 0 0.0 0 0 

18 0 0.0 0 0 

19 0 0.0 0 0 

20 0 0.0 0 0 

21 0 0.0 0 0 

Total 166 90.1 2.966 4,966 

The stand is harvested again after 10 years to the 

prescribed BDq, reducing basal area to 55 ft'/acre. In 10 

more years (20 years after the initial harvest cut), the stand 

has grown back to 75 ft2/acre of basal area, and a third age 

class has been established (fig. 3.9c). By this time, three 

age classes exist in the stand-70 (residual overstory), 20, 

and 10. 

The stand is cut again following the original BDq 

prescription; then after another 10 years (30 years after the 

initial harvest cut) four age classes are present and the bellshaped, normal diameter distribution curve of the initial 

even-aged stand is giving way to a reversed-} diameter 

distribution curve representative of an uneven-aged stand 
50 

~ 40 B = 

0 D = ~ q = 

CD 30 ~ <t:. 

~ 20 

1i5 

as 

Q 10 

0 

s 

50 

~ 40 " 

0 

i 30 ~ <t:. 

~ 20 

1i5 

as 

Q 10 

0 

s 

Initial -- Year 0 (a) 

55 112 /acre 

21 inches 

1.2 

4 8 12 16 20 

Initial + 20 years (c) 

4 

75 B 

8 12 16 20 

D.B.H. (inches) 

Reproduction (<10 years old) 

Before cut 

After cut 

[:J Cyclic cut 

50 

40 

30 

20 

10 

0 

50 

40 

30 

20 

10 

0 

Initial + 10 years 

75 B 

;,;.;.:.·.~:-:4:::::::: . 

55 B .:<""""" .. ~:-.~-. 

s 4 8 12 16 

Initial + 30 years 

\} 

\i 

Y·: 

_;s:.· .. 55 B 75 B 

s 4 8 12 16 

D.B.H. (inches) 

S = Seedlings (<0.6 inch in d.b.h.) 

B = Basal area 

D = Maximum diameter 

(b) 

20 

(d) 

20 

Figure 3. 9. -Hypothetical conversion of an even-aged stand to uneven-aged structure during 30 years of management. 

(fig. 3.9d). At this point, the guidelines described for a 

well-stocked stand having uneven-aged structure can be followed to move toward a balanced, uneven-aged structure. 

Understocked Stands 

Uneven-aged silviculture is well suited for rehabilitating an understocked stand, particularly if the stand has 

sufficient stocking in at least two size or product classes 

(i.e., pulpwood and sawlogs, or saplings and pulpwood) 

(Baker 1989b, Dennington and Baker 1989, Reynolds and 

others 1984). 

To determine if a stand has sufficient stocking to be 

rehabilitated by uneven-aged silviculture, a 10-percent 

inventory of the merchantable-size ( > 3.6 inches in d.b.h.) 

trees is required. The sample stand inventory form (A-1) 

provided in the appendix can be used. In addition, pine 

27 
Table 3.1.-Sample output (on a per-acre basis) for hypothetical, even-aged stand (Compartment B, Stand 2) generated by TARGET 

computer program using stand inventory data from table 3.6 and the following stand structure parameters: Residual 

Basal Area = 55 ft2 /acre; Maxinmm Diameter = 21 inches; q value = 1. 2 

T~rget Jkfore:£Yt Cut Aft!:;r-cut 

D.b.h. Number BA Number BA Number BA Number BA 

Inches Ft' Fi1 Fi1 Ft' 

4 20.4 l.8 6.0 0.5 0.0 0.0 6.0 0.5 

5 17.0 2.3 8.0 1.1 0.0 0.0 8.0 1.1 

6 14.2 2.8 11.0 2.2 0.0 0.0 11.0 2.2 

7 11.8 3.2 14.0 3.7 1.4 0.4 12.6 3.3 

8 9.8 3.4 18.0 6.3 5.3 l.8 12.7 4.5 

9 8.2 3.6 19.0 8.4 7.0 3.1 12.0 5.3 ------------------------------~------------------------------------------------------------

10 6.8 3.7 22.0 12.0 9.8 5.4 12.2 6.6 

11 5.7 3.8 26.0 17.2 13.1 8.6 12.9 8.6 

12 4.7 3.7 18.0 14.I 8.6 6.7 9.4 7.4 

13 4.0 3.6 ll.O 10. I 4.6 4.2 6.4 5.9 

14 3.3 3.5 9.0 9.6 3.7 3.9 5.3 5.7 

15 2.7 3.4 4.0 4.9 0.8 l.O 3.2 3.9 ------------------------------------------------------------------------------------------- 16 2.3 3.2 0.0 0.0 

17 l.9 3.0 0.0 0.0 

18 1.6 2.8 0.0 0.0 

19 1.3 2.6 0.0 0.0 

20 LI 2.4 0.0 0.0 

21 0.9 2.2 0.0 0.0 

Total 117.7 55.0 166.0 90.1 

reproduction should be evaluated by counting the wellestablished pine seedlings and/or saplings on a minimum of 

100, uniformly spaced, milacre plots in the stand. A sample 

evaluation form (A-4) is provided in the appendix. Pine 

reproduction should also be evaluated in terms of its 

freedom-to-grow and the coverage of competing vegetation. 

Notes on the free-to-grow status of the pines will help in 

detecting the need for release. 

From this information, one can determine if there is 

adequate stocking to rehabilitate the stand, and the time 

required to reach full stocking can be estimated (Baker 

1989b). Stocking can be quantified by using the sample 

worksheet form (A-5) provided in the appendix, which was 

derived from solving the following equation for each d.b.h. 

class: 

Stocking (percent) = 0.16667(N) + 0.00404(E.D) + 0.00434(l::IY) 

\\'here: N = number of trees ~ 1 ft in height per acre. 

ED= sum of d.b.h. of trees ~l inch in d.b.h., and 

IJD2 = sum of squared d.b.h. of trees :eel inch in d.b.h. 

This stocking equation was derived by fitting USDAForest Service's, Forest Inventory and Analysis (FIA) 

stocking guides to Chisman and Schumacher's (1940) treearea ratio equation. Thus, the stocking equation is a 

measure of stocking based on the number of stems per acre 

and basal area of stems >4.5 ft tall. 

28 

0.0 0.0 0.0 0.0 

0.0 0.0 0.0 0.0 

0.0 0.0 0.0 0.0 

0.0 0.0 0.0 0.0 

0.0 0.0 0.0 0.0 

0.0 0.0 0.0 0.0 

54.3 35.1 11!.7 55.0 

Uneven-aged stands having at least 15 to 25 percent 

stocking or 5 to 10 ft'/acre of merchantable basal area 

(distributed equally among the size or product classes) can 

grow to an acceptable stocking of 60 percent or 45 ft2/acre 

of basal area in 15 years or less if hardwoods are controlled 

(Bal< er 1989b). Because the rehabilitation rate depends on 

the development of the residual trees and reproduction in the 

stand, control of competing vegetation is crucial. Hardwoods that overtop pines, or that could within the next 10 

years, should be cut or controlled with a herbicide. 

The free-to-grow pines (saplings through pole-size) that 

have at least a 20-percent live crown and display apical 

dominance will develop quickly, and stocking should rapidly 

reach an acceptable level. Once stocking exceeds 60 

ft2/acre of basal area, BDq reguiation of structure and 

periodic harvesting can begin, as described in this chapter 

under "Well-Stocked Stands with Uneven-Aged Structure." 

Historical Application of Uneven-Aged Sihiculture in 

Loblolly-Shortleaf Pine Types 

Uneven-aged silviculture has been the focus of research 

and practice in both the West Gulf Coastal Plain of southern 

Arkansas and the Interior Highlands of northwest Arkansas. 

In the Coastal Plain, the method has been applied, both in 

research and in practice, in the mixed-species forest type 
!:($ 

Table 3.8.-Stand-and-slock table (on a per-acre basis) for hypothetical, even-aged stand (Compartment B, Stand 2) derived from inventory data and the TARGET compuJer program (tree volumes determined 

from a local volume table) 

D.b.h. 

Inches 

4 

5 

6 

7 

8 

9 

10 

11 

12 

13 

14 

15 

16 

17 

18 

19 

20 

21 

Total 

TamJ_Slalld 

No. trees BA 

20.4 

17.0 

14.2 

11.8 

9.8 

8.2 

6.8 

5.7 

4.7 

4.0 

3.3 

2.7 

2.3 

1.9 

1.6 

1.3 

1.1 

0.9 

117.7 

Fr 

1.8 

2.3 

2.8 

3.2 

3.4 

3.6 

3.7 

3.8 

3.7 

3.6 

3.5 

3.4 

Fl' 

10 

30 

48 

64 

78 

88 

% 

101 

104 

105 

104 

102 

3.2 " 

3~ N 

2.8 n 

2.6 ~ 

2.4 n 

~2 n 

55.0 1,445 

Volume 

Fbm 

0 

0 

0 

0 

0 

0 

192 

226 

2(16 

304 

338 

365 

386 

396 

402 

398 

391 

318 

3,982 

lleforeccul Staod 

No. trees BA 

6.0 

8.0 

11.0 

14.0 

18.0 

19.0 

22.0 

26.0 

18.0 

11.0 

9.0 

4.0 

Fi' 

0.5 

1.1 

2.2 

3.7 

6.3 

8.4 

12.0 

17.2 

14.l 

10.l 

9.6 

4.9 

0.0 0.0 

0.0 0.0 

0.0 0.0 

0.0 0.0 

0.0 0.0 

0.0 0.0 

166.0 90.l 

Ft' 

3 

14 

38 

76 

142 

204 

309 

463 

396 

293 

286 

149 

0 

0 

0 

0 

0 

0 

2,373 

Volume 

Fbm 

0 

0 

0 

0 

0 

0 

618 

1033 

1009 

848 

925 

533 

0 

0 

0 

0 

0 

0 

4,966 

No. trees BA 

0.0 

0.0 

0.0 

1.4 

5.3 

7.0 

9.8 

13.1 

8.6 

4.6 

3.7 

0.8 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

54.3 

Fr 

0.0 

0.0 

0.0 

0.4 

1.8 

3.1 

5.4 

8.6 

6.7 

4.2 

3.9 

1.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

35.1 

Cut 

Volume 

Ft3 

0 

0 

0 

8 

42 

75 

138 

234 

188 

121 

117 

30 

0 

0 

0 

0 

0 

0 

953 

Fbm 

0 

0 

0 

0 

0 

0 

275 

521 

480 

351 

379 

108 

0 

0 

0 

0 

0 

0 

2114 

After-cut Stand 

No. trees BA 

6.0 

8.0 

11.0 

12.6 

12.7 

12.0 

12.2 

12.9 

9.4 

6.4 

5.3 

3.2 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

111.7 

w 

0.5 

1.1 

2.2 

3.3 

4.5 

5.3 

6.6 

8.6 

7.4 

5.9 

5.7 

3.9 

0.0 

0.0 

0.0 

o.o 

0.0 

o.o 

55 

Ft1 

3 

14 

38 

68 

100 

129 

171 

229 

208 

172 

169 

119 

0 

0 

0 

0 

0 

0 

1,420 

Volome 

Fbm 

0 

0 

0 

0 

0 

0 

343 

512 

529 

497 

546 

425 

0 

0 

0 

0 

0 

0 

2852 
dominated by loblolly pine but containing minor and varying 

proportions of shortleaf pine. In the Interior Highlands, the 

method has been applied primarily in practice, bnt with 

increasing research support, in shortleaf pine forests. 

For both forest types, the method has been used 

primarily to grow pine; hardwoods have been viewed simply 

as competitors of pine and thus aggressively controlled. We 

know then, that uneven-aged silviculture can successfully 

produce pine. The question is whether mixed pinehardwood stands can be managed with uneven-aged silviculture. The challenge is to include hardwood species that 

are shade intolerant when developing uneven-aged stand 

structures and canopies that are ecologically sustainable [see 

chapter 5]. 

Coastal Plain Loblolly-Shortleaf Pine 

The longest record of research and experience with 

uneven-aged silviculture in Arkansas is in the Coastal Plain 

loblolly-shortleaf pine type from the work begun by R.R. 

Reynolds at the Crossett Experimental Forest (Reynolds 

1980). Because loblolly pines are shade intolerant, 

Reynolds and bis colleagues quickly realized that the key to 

sustained, uneven-aged silviculture was reproduction. 

Reynolds and his successors prescribed a combination of 

single-tree selection and group selection. Reynolds' work 

established that, with uneven-aged silviculture, this forest 

type is best regenerated and developed using short (5- to 10-

year) cutting cycles. 

Because loblolly pine is such a prolific seed producer in 

natural stands, establishing reproduction under selection 

cutting has usually been less of a concern than its development. Reynolds was unconcerned with opening size if all 

the trees to be removed were poorer in quality than others 

in the same size class. In the West Gulf Coastal Plain, 

loblolly pine produces an adequate seed crop 7 to 8 years 

out of 10; under this hail of pine seeds, most openings are 

quickly stocked with pine reproduction as a result of the 

normal ground scarification caused by logging. 

Because cutting cycles were short, Reynolds and his 

associates did not worry when a given cutting cycle failed to 

yield reproduction because it would be only a short time 

before another cutting was scheduled. If the typical results 

at Crossett are to be adapted to species less prolific than 

loblolly pine, such questions for securing reproduction as 

cutting during favorable seed years and additional site 

preparation, must be addressed. 

Besides producing large seed crops, both the reproduction and the residual stand develop rapidly in the West 

Gulf region. A level of residual basal area that inhibits pine 

reproduction can quickly develop after a harvest. To ensure 

continued development of all size classes, Reynolds used 

short cutting cycles and carefully monitored residual 

stocking after the harvest. By allowing the stand basal area 

to vary between 60 and 75 ft2/acre, of which 65 to 75 

30 

percent was in sawtimber, Reynolds could maintain 

ingrowth of pine seedlings and saplings into the 

merchantable size-classes. 

Aggressive hardwood control, primarily with the use of 

herbicides, was the key to the success of the selection 

method on the Crossett Experimental Forest. The challenge 

facing researchers in the Coastal Plain today is to refine the 

method for use in mixed pine-hardwood stands. 

The major industry practitioner of uneven-aged 

management in the Coastal Plain is Deltic Farm and Timber 

Company, Inc., which manages about 200,000 acres of 

loblolly-shortleaf pine. Deltic uses a 7-year cutting cycle 

and regulates stand structure by volume control (VGDL) in 

the sawlog component of the stand. Their foresters are not 

too concerned about uniform size distributions in all 

diameter classes; however, their goal is to maintain at least 

three product sizes (pulpwood, small sawlogs, and large 

sawlogs) plus reproduction in their stands. Deltic 

aggressively controls competing hardwoods periodically, 

thus their stands are primarily pine in the upper and midcanopies. 

Interior Highlands Shortleaf Pine 

Deltic, also practices uneven-aged silviculture in the 

Interior Highlands of Arkansas, supplying a sawmill in the 

town of Ola with pines from about 200,000 acres of 

shortleaf pine in the northern Ouachita Mountains. The 

management strategy that Deltic uses there is similar to 

that used in its Coastal Plain loblolly pine stands, with one 

notable exception. Because of the slower growth rate of 

shortleaf pine in the Interior Highlands, harvesting is done 

about every 10 years rather than about every 7 years as in 

Coastal Plain loblolly pine. Hardwoods of all sizes that 

compete with the pines are aggressively controlled. As in 

the Coastal Plain, well-structured and fully stocked pine 

stands managed under uneven-aged silviculture for 40 years 

can be seen on Del tic land in the Interior Highlands. These 

stands demonstrate classic, uneven-aged appearance with 

crowns of pines contributing to a multi-layered canopy. 

In the early 1990's, the Ouachita and Ozark National 

Forests began using uneven-aged silviculture in shortleaf 

pine stands on the Interior Highlands, with plans to convert 

15,000 acres annually from even-aged to uneven-aged 

structure. This strategy is part of the ecosystem management philosophy adopted by the USDA Forest Service in 

1992. 

Researchers are only beginning to understand unevenaged silviculture for shortleaf pine. The oldest experimental 

plots have been managed for little more than a decade 

(Murphy and others 1991). More recent research involves 

a wide array of studies, both with small plots (Shelton and 

Baker 1992b) and at the stand level (Baker 1992, 1994; 

Guldin and others 1993). 
Chapter 4 

GROWTH, YIELD, AND STAND DEVELOPMENT 

Knowledge has been accumulating about the growth of 

uneven-aged, loblolly-shortleaf pine stands. This information comes from case studies, designed experiments, and 

growth and yield models, which are usually derived from 

comprehensive experimental studies (table 4.1). Although 

growth and yield models are the most helpful in 

decision-making, each source can provide valuable information for managing uneven-aged stands. 

Case Studies and Experiments 

The oldest information on uneven-aged silviculture for 

loblolly-shortleaf pine stands comes from the Crossett 

Experimental Forest in the Coastal Plain of southern 

Arkansas. A 29-year history is available for a cutting-cycle 

study (Reynolds 1969), and a 41-year history is available 

for the Crossett Farm Forestry Forties (Reynolds and others 

1984). Site index for lob lolly pine on the Crossett 

Experimental Forest is 90 ft at age 50. A 33-year history is 

also available for a tract in southwest Arkansas with a lower 

loblolly pine site index (80 ft at age 50) (Farrar and others 

1984a). A case study in east-central Mississippi (Farrar and 

others 1989) occurred on a site index intermediate to the 

Arkansas studies (85 ft at age 50). 

Despite differences among these studies in stocking, 

merchantability, etc., some useful inferences can be made. 

Records indicate that long-term, annual growth per acre in 

southern Arkansas can be expected to average around 3 ft2 

of basal area, 84 to 116 ft3 of merchantable volume, and 

about 400 furn of sawtimber (table 4.1). The Mississippi 

study showed lower production. 

Information from the Piedmont in central Georgia 

(Brender 1973) is from stands of a lower site index (73 to 77 

ft at age 50). The growth is correspondingly lower than for 

the Coastal Plain sites (table 4.1). 

Not much information is available for stands where 

shortleaf pine is the dominant or sole species. A 10-year 

history is available for a 67-acre tract in southeastern Texas 

(Gibbs 1958) (table 4.1). However, the tract had been 

cutover and was understocked; consequently, the first 10 

years did not indicate expected growth under long-term 

management. Another case study for shortleaf pine comes 

from three experimental watersheds in the Ouachita 

Mountains of Arkansas (Murphy and others 1991). The 

watersheds were managed by the basal area-maximum 

diameter-quotient (BDq) method with a residual basal area 

of 60 ft'/acre, a maximum d.b.h. of 20 inches, and a q of 

1.2 (I-inch d.b.h. classes). Despite only 6 years of 

management, basal area and merchantable volume growth 

(table 4.1) conform to that predicted by a growth and yield 

model (Murphy and others 1991), although sawtimber 

growth was lower than predicted. 

Table 4.1.-Growth comparisons from uneven-aged stands of loblolly and shortleaf pines in the South 

Cutting Annual growth 12er acre 

Study area Study cycle Site index Basal Merch. Sawtimber 

Location Physiography Species size duration length (base age 50) • Product area volume volume Source 

Acres Years Years Ft Sawtimber Ft' Ft' Fbm 

Arkansas Coastal Plain Lob-shlf 960 29 3,6,9 90 Large NAt 84 432 Int. 1A" (I) 

Arkansas Coastal Plain Lob-shlf 34! 41 1,5 90 Medium 3.2 116 397 Doyle (2) 

Arkansas Coastal Plain Lob-shlf 401 41 1,5 90 Large 2.9 95 412 Doyle (2) 

Arkansas Coastal Plain Lob-shlf 26 15 6 80 Large 2.9 88 423 Doyle (3) 

Mississippi Coastal Plain Lob-shlf 40 27 85 Large 2.2 62 299 Doyle (4) 

Mississippi Coastal Plain Lob-shlf 40 27 5 85 Large 2.5 62 229 Doyle (4) 

Texas Coastal Plain Shortleaf 67 10 10 NA NA NA NA 169 Int. !4" (5) 

Georgia Piedmont Lob-shlf 288 21 8 77 Large NA 77 319 Int. t,4" (6) 

Georgia Piedmont Lob-shlf 260 19 8 73 Small NA 75 290 Int. IA" (6) 

Arkansas Interior Highlands Shortleaf 35 6 6 53 Medium 2.0 57 157 Doyle (7) 

• Source: (1) Reynolds 1969; (2) Reynolds and others 1984; (3) Farrar and others 1984a; (4) Farrar and others 1989; (5) Gibbs 1958; (6) Brender 

1973; (7) Murphy and others 1991. 

t NA = Not available. 

: Poor Farm Forestry Forty, Crossett Experimental Forest. 

§ Good Farm Forestry Forty, Crossett Experimental Forest. 

31 
Loblolly Pine Growth Study 

Case studies generally indicate the potential for volume 

production and are benchmarks with which to compare other 

stands. However, they do not answer such questions as: 

"what is the effect of site quality on growth?" Replicated 

experiments provide more data. 

In a study begun in 1983 (Murphy and Shelton 1994), 

eighty-one 0.5-acre plots were installed in southern 

Arkansas and northern Louisiana in stands of three site 

index classes-< 80 ft, 81 to 90 ft, and > 90 ft. The plots 

were cut to combinations of 40, 60, and 80 ft2

/acre of merchantable basal area; maximum diameters of 12, 16, and 20 

inches; and a q of 1.2 for I-inch d.b.h. classes. Competing 

hardwoods were injected with herbicide, and all shortleaf 

pines were cut, leaving only loblolly pines in the merchantable stand. After 5 years the plots were remeasured. 

The 20-inch maximum residual d.b.h. probably represents an upper limit in today's economy, while the 12-inch 

maximum residual d.b.h. is the minimum size for reliable 

seed production. The residual basal areas of 40 and 80 

ft2 /acre are beyond the normal operating densities for 

uneven-aged Ioblolly pine stands. They were chosen to test 

whether management at these density extremes is sustainable. A basal area of 40 ft'/acre may not be adequate 

stocking, and 80 ft2/acre may be too dense to allow pine 

reproduction to become established and develop. Evidence 

suggests that uneven-aged Ioblolly pine stands should not 

exceed 75 ft2

/acre of basal area at the end of a cutting cycle. 

So, only growth for currently recommended basal areas for 

a 5-year cutting cycle will be considered. 

Because the results are preliminary, trends are more 

significant than absolute growth. Figure 4.1 shows the 

trends in net basal-area growth for the normal range of 

density that would be used in a 5-year cutting cycle. The 

average basal-area growth was 3 ft2

/acre/yr. Annual basalarea growth tended to increase with an increase in residual 

basal area and decrease with an increase in maximum 

diameter or site index. The reason for less basal-area 

growth on good sites might be that there is less ingrowth 

into merchantable d.b.h. classes because vigorous competition impedes the establishment and development of loblolly 

pine reproduction. Moreover, the stands on poor sites might 

have had more submerchantable trees than those on the 

better sites before the study was installed (Murphy and 

Shelton 1994). The reason for less basal-area growth in 

stands having trees of larger maximum diameter might be 

that those trees are older and less vigorous than stands of 

smaller trees. 

Overall, the average merchantable volume growth was 

111 ft3

/acre/yr. Figure 4.2 depicts the growth trends for 

merchantable cubic-foot volume. As with basal-area 

growth, volume growth tended to increase with increasing 

residual basal area and decrease with an increase in maximum diameter. However, no effect of site index was 

detected in the analysis. 

Annual sawtimber growth averaged 420 furn/acre over 

all treatments. The effects of residual basal area, maximum 

diameter, and site index on sawtimber growth were all positive (fig. 4.3). An increase of 10 ft in site index resulted in 

about a 9-percent increase in board-foot growth . 

• Maximum d.b.h. 12 inches tQl Maximum d.b.h. 16 inches L:.:J Maximum d.b.h. 20 inches 

32 

0 

50 55 60 50 55 60 50 55 60 

INITIAL BASAL AREA (ft 2/acre) 

Figure 4.1.-Annual net basal area growth per acre for loblolly pine stands in the West Gulf Coastal Plain after the first 5 years of single-tree selection 

silviculture. 
• Maximum d.b.h. 12 inchM 

~ Maximum d.b.h, 1e lnchM 

~ Maximum d.b.h. 20 lnchee 

50 55 50 

INITIAL BASAL AREA (ft ~acre) 

Figure 4.2.-Annual merchantable cubic-foot volume growth per acre 

for loblolly pine stands in the West Gulf Coastal Plain after 

the first 5 years of single-tree selection silviculture. 

Growth and Yield Models 

Stand-level growth and yield models are available for 

uneven-aged loblolly-shortleaf pioe and for uneven-aged 

shortleaf pioe. The model for loblolly-shortleaf pioe 

(Farrar and others 1984b; Murphy and Farrar 1982, 1983) 

was developed from long-term studies conducted on the 

Crossett Experimental Forest. The user specifies initial 

merchantable and sawtimber basal areas and cuttiog cycle. 

The model calculates projected sawtimber and merchantable 

basal areas; current and projected merchantable and sawtimber cubic-foot volumes; and current and projected Doyle, 

Scribner, and International \4-ioch board-foot volumes. 

Because the data came from a small area with a uniform 

site, the model is restricted to the site iodexes of 85 to 95 ft 

for loblolly pioe. 

The second model (Murphy and Farrar 1985) was 

developed for uneven-aged shortleaf pioe stands in the 

Interior Highlands of Arkansas and eastern Oklahoma. The 

user must specify ioitial merchantable and sawtimber basal 

areas, cutting cycle, and site iodex to use this model. The 

model provides projected sawtimber and merchantable basal 

areas; current and projected merchantable and sawtimber 

cubic-foot volumes; and current and projected Doyle, 

Scribner, and International \4-ioch board-foot volumes. 

Rather than describing how to use these models, you 

should obtain the pertioent publications and spreadsheet 

templates that will do the calculations [see "Computer 

Software Available" at the end of this chapter]. 

Uneven-Aged Versus Even-Aged Production 

Controversy has raged ioterrninably about the timber 

production of uneven-aged versus even-aged stands. The 

issue is further clouded by disagreement over the length of 

the growth period that should be used for comparison. The 

intensity of the debate is ameliorated if it is realized that 

selection of one system over another depends upon owner 

objectives, and volume production may be just one of these. 

Nonetheless, there have been several comparative studies 

for the loblolly-shortleaf pioe type. 

Baker and Murphy (1982) compared the 36-year 

production of four reproduction cuttiog methodsclearcuttiog, heavy seed-tree, siogle-tree selection, and 

diameter-limit cutting-io loblolly shortleaf pine stands io 

southern Arkansas. Strictly speakiog, the diameter-limit is 

not a reproduction cuttiog method but was included to 

represent the usual cutting practice io 1942 when the study 

was iostalled. After 36 years, the single-tree selection, the 

heavy seed-tree, and the diameter-limit stands had produced 

significantly more annual board-foot volume per acre (selection, 377 furn; heavy seed-tree, 362 furn; diameter-limit, 

330 furn) than the clearcut (260 furn). It is important to 

note, however, that no thioning was done io the clearcut 

stands during the 36-year period. The seed-tree stands were 

also not thioned except that the seed trees were removed 15 

years after the initial harvest. Their volume growth is 

iocluded io the totals for the seed-tree method. The siogletree selection and clearcut stands produced significantly 

lower annual merchantable cubic-foot volume per acre (84 

and 93 ft'. respectively) than the seed-tree (117 ft', seed 

trees iocluded) and the diameter-limit (107 ft3) stands. 

Usiog a combination of case studies and growth and 

yield model simulations, Baker (1987) compared two evenaged (plantation and natural stand) and two uneven-aged 

systems (siogle-tree selection with high and low stocking). 

The even-aged systems produced more cubic-foot volume, 

while the iotensively managed, even-aged plantation and the 

high-stockiog, uneven-aged system produced the most sawlog volume. 

Baker and others ( 1991) and Guldin and Baker 

(1988) compared the empirical yields from conventional 

silviculture versus iotensive silviculture as applied to plantations, natural even-aged stands, and uneven-aged stands of 

loblolly-shortleaf pioe. They concluded that merchantable 

cubic-foot yields are highest for iotensively managed plantations; sawtimber cubic-foot yields are highest for intensively 

managed uneven-aged and even-aged natural stands, and 

board-foot yields are higher for uneven-aged stands. The 

differences in yields are probably attributable to stocking; 

i.e., growth iocreases with stocking. Plantations, which 

have the highest merchantable cubic-foot growth, generally 

have the optimum stocking of merchantable trees. Unevenaged stands, which have the highest sawtimber growth, 

generally have the highest proportion of stocking in 

sawtimber trees. The underscale of the Doyle rule in small 

trees favors uneven-aged stands because their sawtimbersized trees are generally larger. 

Interest is also great io compariog log quality of trees 

in even-aged versus uneven-aged stands. Guldin and 

Fitzpatrick (1991) analyzed the log grades, knots, and 

33 
• Maximum d.b.h. 12 inches ~ Maximum d.b.h. 16 inches t;'3 Maximum d.b.h. 20 inches 

SITE INDEX 75 SITE INDEX 85 SITE INDEX 95 

50 55 60 50 55 60 50 55 60 

INITIAL BASAL AREA (ft2/acre) 

Figure 4.3.-Annual board-foot (Doyle rule) growth per acre for loblolly pine stands in the West Gulf Coastal Plain after the first 5 years of single-tree 

selection silviculture. 

volumes of the first two logs of loblolly pine trees in 

plantations and natural even-aged and uneven-aged stands. 

Trees in uneven-aged stands had higher grade butt logs than 

trees in plantations. Log quality was similar in trees from 

uneven-aged and even-aged natural stands, but the evenaged stands had butt logs of higher quality although with 

more taper. They concluded that more intensive management will be needed to produce plantation-grown loblolly 

trees that are comparable in quality to those produced in 

natural stands. 

Economics 

The decision to practice uneven-aged versus even-aged 

management can be based par1ly on economics. The 

economics of uneven-aged stand silviculture will be 

examined and then compared with even-aged silviculture. 

Uneven-Aged Stand Management Decisions 

Two major variables that the forest manager can control 

in uneven-aged stands are cutting cycle and stocking. The 

minimum cutting cycle depends upon the residual stocking, 

34 

the growth rate of the stand, and the minimum operable cut. 

The maximum cutting cycle is contingent upon how dense 

the stand can become without impeding the development of 

desirable reproduction. Stocking and cutting cycle are 

interdependent. If the cutting cycle is increased, residual 

stocking must be decreased so that the stocking will not 

become too great for reproduction to become established and 

develop. Within these confmes, however, stocking and 

cutting cycle can be determined by financial criteria. 

Extending the results of Duerr and Bond (1952), Chang 

(1981) formulated the simultaneous determination of the best 

growing-stock level and cutting cycle using maximum net 

present value as the criterion. Applying marginal analysis, 

Chang found (1) that the extra revenue gained by extending 

a cutting cycle for a year should equal the cost of holding 

both the land and timber for the additional year, and (2) that 

the marginal revenue gained by having an additional unit of 

growing stock should equal the cost of holding that 

additional unit for the length of the cutting cycle. An 

increase in the interest rate decreases both cutting cycle 

length and growing-stock level. However, stumpage price 

did not affect either cutting cycle or growing-stock level. 

Chang's analysis dealt with growing stock in terms of stand 

volume. The analysis could be done with stand-table 
projection or individual-tree growth models. 

Hotvedt and others (1989) examined optimum management regimes for uneven-aged loblolly-shortleaf pine 

stands in terms of net present value and sawtimber production. Residual basal area, cutting cycle, and the ratio of 

sawtimber basal area to merchantable basal area were the 

variables investigated. These variables were constrained 

within reasonable biological limits. They found that 

optimum management regimes based upon maximum net 

present value had short cutting cycles (4 to 5 years) and low 

ratios of sawtimber basal area to merchantable basal area 

(0.55). Management regimes based upon maximum 

sawtimber production tended to have high residual basal 

areas (60 to 65 ft2/acre), high ratios of sawtimber basal area 

to merchantable basal area (0. 70 to 0. 80), and short cutting 

cycles ( 4 to 6 years). Opting for high sawtimber production 

results in management regimes with lower net present values 

than regimes selected on maximum net present value. 

Hotvedt and Ward (1990) investigated the problem of 

optimal management; i.e., maximizing net present value 

over an infinite period, of uneven-aged loblolly-shortleaf 

pine stands with different initial stand structures. They 

concluded that: (1) there is no single best stand structure for all uneven-aged stands, (2) the initial stand 

condition will determine the best strategy for converting the 

stand to an optimal structure, and (3) understocked stands 

would be easier to convert to a stable stand structure than 

overstocked stands. 

The concept of fmancial maturity can also be applied to 

individual trees and their growth rates in uneven-aged 

stands, as described by Duerr and others (1956). It is 

based upon the premise that a tree can be kept if its 

marginal value growth rate is greater than the alternative 

rate of return. The concept can be extended to include the 

effect of removing neighboring trees (Duerr and others 

1956) and trees that will replace the cut tree (Murphy and 

Guldin 1987). It can be applied to both the performance of 

individual trees and selection of a maximum diameter in 

BDq regulation. Figure 4.4 shows the board-foot growth 

rate of loblolly pine trees growing at different annual 

diameter-growth rates in an uneven-aged stand managed 

under a 5-year cutting cycle. Within the constraints of the 

residual volume or stand structure imposed by regulation, 

financial maturity can help in selecting trees to cut. For 

example, if the alternative rate is 6 percent, then all trees 

growing slower than this could be candidates for harvest. 

Another use of financial maturity would be in selecting the 

maximum diameter with BDq regulation. If the alternative 

rate is 8 percent and an annual diameter growth rate of 0 .4 

inch can be expected on large trees, then a maximum 

diameter of 16 to 17 inches might be selected. Financial 

maturity is one of many concepts that can be used to manage 

uneven-aged loblolly pine stands. 

~ 0.14 

~ 

I 0.12 

0.10 

~ 000 

~ 000 

0.04 

~ ~ 0.02 

- 0.2-inch d.b.h. growth 

- - - 0.3-inch d.b.h. growth 

• • • • • 0.4-inch d.b.h. grO'Nl:h 

o'--~-'-~~-'-~~"-~---'~~-'-~~-'-~--' 

10 12 14 16 16 20 24 

INITIAL D.B.H. (Inches) 

Figure 4.4.-Annual board-foot (Doyle rule) growth rate of loblolly pines 

in uneven-aged stands on good sites (S.l. =90), with a 5-year cutting cycle. 

Timber Harvesting 

Little information is available on timber harvesting in 

uneven-aged loblolly and shortleaf pine stands. Kluender 

and others (1992) analyzed harvesting production on the 

Farm Forestry Forties, located on the Crossett Experimental Forest in southern Arkansas. Two stands had been 

under uneven-aged management for 53 years. Felling was 

done by chainsaw; felled trees were limbed and topped 

before being skidded by grapple skidders. Harvesting 

productivity (measured as cubic feet per hour) for both 

felling and skidding was influenced most by the diameter of 

the stems cut. In addition, a slight change in the size 

distribution of removed stems greatly affected productivity. 

In another study, Kluender and others ( 1994) analyzed 

different harvesting intensities--dearcut, shelterwood, and 

single-tree selection-in shortleaf pine stands in the 

Ouachita Mountains. The harvest operation consisted of 

chainsaw felling and skidding by cable and grapple skidders. 

Because the single-tree selection cut was the first one in 

essentially even-aged stands, the results do not necessarily 

indicate harvest productivity in stands managed by 

single-tree selection for a long period. Nonetheless, some 

valuable guidelines can be obtained from the study. The 

authors found that felling time was affected by the d.b.h. of 

harvested stems, the average distance between harvested 

trees, and harvest intensity (the proportion of the stand that 

was cut). Skidding time was affected by pull distance, 

skidder type, number of stems per pull, harvest intensity, 

and average volume per skidder cycle. 

35 
These studies indicate that harvest productivity will be 

higher in uneven-aged stands if large trees can be cut, the 

distance between marked trees can be decreased, and 

skidding distance can be shortened. All these factors can be 

controlled. 

Even-Aged Versus Uneven-Aged Economic Comparisons 

Although some economic comparisons have been made 

between even-aged and uneven-aged stands, the results are 

mixed. Moreover, no economic comparisons have been 

made between an even-aged forest with stands of various 

ages and an uneven-aged forest of the same acreage. The 

following review is mostly confined to loblolly-shortleaf 

pine stands. Some general conclusions follow the review. 

In a limited economic comparison, Chang (1981) 

concluded that uneven-aged management might be favored 

at high interest rates (using net present value) because of the 

more frequent but smaller revenues from an uneven-aged 

stand versus the larger but less frequent revenues from an 

even-aged stand. Baker (1987) compared two even-aged 

(plantation and natural) and two uneven-aged (low and 

high stocking) management systems for loblolly pine using 

three criteria-net present value, benefit/cost, and cost 

efficiency (total production/total discounted costs). The 

natural, even-aged system ranked highest in net present 

value, benefit/cost, and cost efficiency for merchantable 

volume production. The uneven-aged, high-stocking 

alternative ranked highest in cost efficiency for sawtimber 

production and second highest for benefit/cost. No 

sensitivity analysis was done to see what effect variations in 

interest rates, costs, etc., had on the rankings. 

Baker and others (1991) and Guldin and Guldin (1990) 

evaluated several studies with a 36-year history of 

management in loblolly-shortleaf pine stands on the West 

Gulf Coastal Plain in terms of net present value, 

benefit/cost, and cost efficiency. The studies included 

plantations, natural even-aged stands, and natural unevenaged stands. When the initial growing stock was not 

considered a cost, the uneven-aged stands ranked highest in 

terms of net present value. However, if initial growing 

stock was considered as a cost, the uneven-aged stands 

ranked lower than most even-aged alternatives. The evenaged natural stands ranked higher than both plantations and 

uneven-aged stands in terms of benefit/cost and cost 

efficiency. With a decrease in the differential paid for 

sawtimber versus small roundwood, net present value of 

uneven-aged stands decreased while that for even-aged 

systems increased. When growing stock was a cost and the 

interest rate was 4 percent, uneven-aged stands with high 

initial growing stock had higher net present value than those 

stands with lower initial volumes. But at higher interest 

rates (7 and JO percent), uneven-aged stands with low initial 

growing stock had higher net present values than those with 

higher initial volumes. 

36 

Redmond and Greenhalgh (1990) compared the investment alternatives of rehabilitating understocked loblollyshortleaf pine stands using uneven-aged management versus 

liquidating the stands and establishing a loblolly pine plantation. Initial stocking levels were JO, 30, and 50 percent of 

full stocking. The investment alternatives were evaluated 

using net present values and interest rates of 4, 7 .125, and 

JO percent. They found that uneven-aged management was 

best for 30- and 50-percent stocked stands when the interest 

rate was 7 .125 percent or higher. At these stocking levels, 

plantation management was best at 4 percent interest 

(liquidation of the existing stand provided additional returns 

that made plantation management more attractive). For 

stands with JO-percent stocking, plantation management was 

best at all interest rates; the recovery period was too long 

for uneven-aged management to be competitive. 

Straka and Baker ( 1991) examined three different alternatives for managing storm-damaged loblolly shortleaf pine 

stands: (1) uneven-aged silviculture, with 25 to 30 percent 

initial stocking, (2) even-aged silviculture in natural stands 

with chemical release of suppressed pine seedlings, and (3) 

pine plantation silviculture. Net present values were 

calculated at 4-, 7-, and JO-percent interest rates and with 

and without land costs. At 4-percent interest, the plantation 

had the highest net present value whether or not land cost 

was included. Conversely, at 7- and JO-percent interest, 

uneven-aged silviculture and natural, even-aged silviculture 

had higher net present values than the plantation. However, 

when land cost was included at 7- and 10-percent interest 

rates, all three options had negative net present values. 

These studies are not conclusive. However, if the landowner has decided upon uneven-aged silviculture and 

economic return is a primary objective, the following 

guidelines should be helpful: 

( 1) Other factors being equal, the rate of financial 

return from uneven-aged stands is markedly 

decreased if the value of the initial growing stock 

is considered a cost. 

(2) Short cutting cycles and low sawtimber growingstock levels might increase net present value 

under some conditions (such as high interest 

rates). 

(3) A range of 15 to 17 inches is probably a 

good choice for maximum diameter in BDq 

regulation. 

(4) Moderately understocked stands probably represent the best financial opportunity for unevenaged silviculture. 

(5) Recommended growing stock for a residual stand 

on a 5-year cutting cycle might be a basal area of 

60 ft'/acre, a maximum d.b.h. of 16 inches, and 

a q-value of 1.2 (I-inch d.b.h. classes) for BDq 

regulation on an 85- to 90-ft site index. 
Computer Software Available 

The stand-level growth and yield model for 

uneven-aged loblolly-shortleaf pine (Farrar and others 

1984b; Murphy and Farrar 1982, 1983) and the one for 

nneven-aged shortleaf pine (Murphy and Farrar 1985) are 

available (with instructions) as spreadsheet templates for 

Borland® Quattro® Pro 4.0. To receive a copy, send either 

a 3.5- or 5.25-inch diskette and a stamped, self-addressed 

diskette mailer to the following address: USDA Forest 

Service, P.O. Box 3516, Monticello, AR 71656-3516. 

37 
Chapter 5 

OPTIONS FOR RETAINING HARDWOODS 

Pines and hardwoods are common associates 

throughout the Southern United States. However, the 

establishment and management of pine-hardwood stands has 

only recently been proposed (Phillips and Abercrombie 

1987, Sims and others 1981, Zahner 1982). Much of the 

interest in these stands results from current environmental 

issues and changes in wood utilization processes and 

markets (Lentz and others 1989). Some reasons for creating 

or maintaining pine-hardwood stands are: (1) new markets 

exist for hardwoods, (2) multiple-resource goals desired by 

many land-owners are satisfied, (3) diversity of tree species 

is increased, ( 4) habitat for some wildlife species is 

improved, (5) stands are more esthetically pleasing to some 

landowners, and (6) poorly stocked pine stands may be 

managed as mixed pine-hardwoods. 

Although some landowners may desire pine-hardwood 

stands, attempting to manage this composition has its 

problems: (1) shade-intolerant pine reproduction may be 

difficult to establish and develop, (2) hardwoods reduce pine 

growth rates, (3) revenue is less because hardwood products 

on upland sites are of low value, (4) fewer options exist 

for applying broadcast treatments, such as herbicides or fire, 

and (5) the different growth rates of pines and hardwoods 

complicate management. Experience indicates that a pinehardwood composition will be especially difficult to 

maintain in uneven-aged stands because of problems in 

obtaining the recurring pine reproduction needed to sustain 

uneven-aged structure. Some strategies are discussed here 

that may achieve a compatible balance between pines and 

hardwoods in uneven-aged stands. Timber production is 

again assumed to be a major silvicultural objective. 

Single-Tree Selection Option 

Uniform Spatial Distribution 

Chapters 1, 2, and 3 emphasize that a principal goal of 

uneven-aged silviculture is to create an environment where 

recurring pine regeneration can survive and develop at 

acceptable rates to sustain future harvests. However, 

overtopping hardwoods suppress the reproduction of the 

shade-intolerant pines more than an equivalent basal area of 

overtopping pines (Becton 1936, Shelton and Murphy 1993, 

Wahlenberg 1960). Hardwoods generally produce about 

twice the shade or canopy coverage of an equivalent pine 

basal area (Reynolds 1950; Shelton and Baker 1992a, 

1992b; Shelton and Murphy 1993; Tappe and others 1993) 

because hardwoods have broader leaves, more robust 

crowns, and are shorter than pines. Of course, characteristics of hardwood species vary greatly, and shadeintolerant species may produce much less shading and 

coverage than shade-tolerant ones. 

38 

Some adjustment in pine stocking levels must be made 

if a hardwood component is to be retained (Shelton and 

Baker 1992b). As a rule of thumb, pine basal area should 

be reduced by 2 ft2

/acre for each 1 ft2/acre of retained 

hardwoods. This is illustrated in table 5 .1 for a stand in 

which 60 :ft'/acre of pure pine would be reasonable stocking. 

Clearly, there is a limit to the amount of uniformly 

distributed hardwoods that can be retained in uneven-aged 

stands without severely affecting pine timber production and 

the regeneration process. Perhaps 5 to 10 ft2/acre of 

hardwood basal area could be retained with pine stocking of 

45 to 55 :ft'/acre. If pine basal area drops below 45 ft2/acre, 

timber production will likely be reduced. 

Table 5.1.-Combinati.ons of merchantable pine and hardwood basal areas 

that will produce the same overstory competition as that of 60 

ft2 /acre of pine basal area 

• Pine Hardwood Total 

- - - - - - - - - - - - - - - - - - - Ft2!acre - - - - - - - - - - - - - - - - -

60 0 60 

m 5 ~ 

40 

30 

10 

15 

50 

45 

'eased on the general rule-of-thumb that hardwoods produce twice 

the shade or canopy coverage as an equivalent pine basal area. 

Structural goals for the hardwood component can be 

set in a manner similar to that described for the pine 

component, although no suitable guidelines exist other than 

for basal area. It seems reasonable that retaining 5 ft2/acre 

of merchantable-sized hardwoods might include four 

pulpwood-sized trees (1.5 ft2

/acre); two, small, sawtirnbersized trees (2 :ft'/acre); and one, large, sawtirnber-sized tree 

(1.5 ft2

/acre). Guldin (1991) discusses a rationale for 

combining targets in western, mixed-conifer stands that 

could be adapted for pine-hardwood stands in the 

Southern United States. Ideally, desired structure for 

hardwoods would be achieved and maintained by harvesting, 

but the volumes may be too low to support an operable 

harvest in many local markets. Some nonindustrial private 

landowners might achieve structural targets for hardwoods 

by cutting firewood. 

Area-Wise Spatial Distribution 

An alternative to retaining a hardwood component on 

each acre of an uneven-aged pine stand is to leave hardwoods in certain parts of the stand while maintaining pure 

or nearly pure pine in the rest of the stand. This area-wise 

distribution could concentrate hardwoods on some terrain 

feature, such as drainages or north-facing slopes. These 
areas have the highest hardwood site quality and are where 

uneven-aged pine silviculture is most costly and difficult 

because of competing vegetation. Another option would be 

to leave hardwoods in clumps or clusters as they occur 

within the existing stand. 

Regulation in these stands requires a preharvest 

inventory as described in chapter 3 and a decision about the 

acreage to be allocated to pines and hardwoods. Management of the pine areas would follow traditional pine 

guidelines or those for retaining a minor hardwood component as previously discussed. Some landowner objectives 

will be best met by not cutting within the hardwood areas. 

Other landowners might want to cut firewood or conduct 

commercial timber harvests based on appropriate silvicultural guidelines for hardwoods. 

Concentrating hardwoods in certain areas is the 

simplest and most biologically sound way to retain a 

hardwood component within uneven-aged pine stands 

under single-tree selection. This approach also benefits 

wildlife by providing cover and migration corridors and 

concentrating mast-producing trees. The area allocated to 

pines and hardwoods can be varied to produce the balance 

ofresources desired by individual landowners. Operational 

concerns probably limit the acceptable combinations of pines 

and hardwoods more than biological limitations. The 

advantages of an area-wise distribution of pines and hardwoods in uneven-aged stands are: (1) the possibility of 

retaining a significant hardwood component, (2) optimization of species-site relationships, (3) protection of 

ecologically sensitive areas, (4) protection of hardwoods 

during vegetation management in the pine component, (5) 

simplification of stand regulation and marking, and (6) 

provision for diverse wildlife habitats (Shelton and Murphy 

1993). 

Group Selection Options 

Group selection creates or maintains an uneven-aged 

stand by establishing a new age class of regeneration in 

scattered small openings after each cutting cycle. When 

applied over several cutting cycles, it will produce a 

fragmented stand of small, even-aged groups. The 

regeneration effort is focused within the openings. Group 

selection results in much larger openings than usually occur 

under single-tree selection. These large openings may be 

needed for the development of pine reproduction when a 

significant hardwood component is retained or herbicide use 

is restricted. In addition, group selection appears to be a 

suitable method for regenerating the intermediate-tolerant 

oaks (Murphy and others 1993). Concentrating regeneration 

within openings may also result in less logging damage to 

residual trees. 

Openings are located where stand regeneration is 

needed, such as in groups of mature trees or in areas with 

low stocking and/or poor-quality trees. The environmental 

requirements of the desired reproduction are critical to 

setting suitable opening sizes and shapes. Opening size is 

also affected by the character of the surrounding trees 

(height, density, and species) and the terrain (slope and 

aspect). Although specific guidelines have yet to be 

developed for pine-hardwood stands, opening diameters that 

are two to three times the potential height of the bordering 

trees at maturity seem to be reasonable for regenerating 

pines and oaks (Murphy and others 1993). If a significant 

oak component is desired, preharvest treatments may be 

needed to obtain sufficient advance reproduction on some 

sites. Openings should typically range from 0.33 to 1.5 

acres in loblolly-shortleafpine-hardwood stands. The shape 

of the openings should be varied to meet the specific 

characteristics of the area, with the general restriction that 

the width should be no less than half the length. 

Regulation techniques suitable for group selection are 

still hotly debated, probably because they have not been 

adequately field tested over long periods. Techniques for 

single-tree selection (VGDL and BDq), as discussed in 

chapter 2 can be used, but the cut must be allocated between 

the openings and the rest of the stand (Law and Lorimer 

1989). Area regulation can also be used to determine the 

number of openings to create during each cutting cycle; this 

technique seems to have merit early in the conversion of 

even-aged stands to uneven-aged structure (Murphy and 

others 1993). Until further information is available, 

reasonable guidelines for group selection in pine-hardwood 

stands are: (I) create openings with diameters two to three 

times the potential height of the bordering trees at maturity, 

(2) create openings in 5 to 20 percent of the stand depending 

on the cutting-cycle length, and (3) use cutting cycles of 5 

to 10 years on good sites ( > 85 ft at 50 years), 10 to 20 

years on poor sites ( < 65 ft at 50 years), and something in 

between on medium sites. The residual stand between the 

openings should be thinned during each cutting cycle as 

necessary. For reasonable timber production, basal areas 

should be 70 to 80 ft2

/acre for pines and 10 to 30 ft2/acre for 

hardwoods. 

39 
SUMMARY 

The uneven-aged silvicultural system is based on the 

ecological concepts of natural disturbance and succession. 

The small-scale disturbances associated with the selection 

method represent natural disturbances that occur when a 

single tree or a small group of trees in a stand dies. 

Successional development represents the stand-reinitiation 

stage; i.e., the establishment of reproduction in small 

openings. 

Loblolly and shortleaf pines can be regenerated and 

managed successfully by using the uneven-aged silvicultural 

system. For selection silviculture to be successful with 

these shade-intolerant species, the forest manager must 

know how to: (1) regulate stand structure, (2) maintain 

appropriate stocking, and (3) control competing vegetation. 

The goal of these processes is shade management, which is 

critical for the establishment and development of shadeintolerant species beneath overstory trees. 

The steps for implementing uneven-aged silviculture in 

loblolly-shortleaf pine stands include: (1) selecting a 

reproduction cutting method, (2) inventorying the stand, (3) 

regulating stand structure, (4) establishing a cutting cycle, 

(5) marking trees for harvest, (6) establishing and 

evaluating reproduction, and (7) controlling competing 

vegetation. If these steps are followed, uneven-aged stands 

of loblolly and shortleaf pine can be developed and 

maintained over extended periods. 

Long-term case studies and rigorous field experiments 

have established the growth and yield potential for unevenaged stands of loblolly and shortleaf pines growing on poor 

to good sites throughout the Southern United States. On 

good sites, well-regulated and well-structured stands should 

average about 3 ft2 of basal area growth and about 400 fbm 

(Doyle) of sawlog growth per acre annually; growth rates 

for poor sites are about half those for good sites. Total 

merchantable cubic-foot volume production is generally 

higher in even-aged stands, while sawtimber production is 

generally higher in uneven-aged stands. Selection silviculture is often more financially feasible with high interest 

rates, when stocking is maintained at relatively low levels 

(45 to 60 ft2 of basal area per acre), and when short cutting 

cycles (3 to 5 years on good sites) are used. 

Even though uneven-aged silviculture has been mainly 

researched and applied in pure pine stands, some options 

may be available for retaining hardwoods in pine stands. 

Some midstory and overstory hardwoods may be retained in 

40 

uneven-aged pine stands if shade is managed rigorously or 

if hardwoods are spaced strategically. Group selection 

probably lends itself better to the retention of hardwoods in 

uneven-aged pine stands than does single-tree selection. 

There are advantages and disadvantages to the practice 

of uneven-aged silviculture (Bal<er 1989a, Barnett and Bal<er 

1991, Williston 1978). Some of the advantages include: 

(1) Periodic and flexible harvests tal<e place without 

interruption for stand regeneration. 

(2) Stands are upgraded if fast-growing, high-quality 

trees are left to regenerate the stand. 

(3) Volume production is concentrated on valuable 

sawtimber trees. 

(4) Cut-over or understocked stands can be quickly 

restored to full stocking. 

(5) Stands may be more esthetically pleasing to some 

people and provide more varied habitat for 

wildlife. 

(6) Stands are not as vulnerable to complete 

destruction by wildfire, ice storms, disease, and 

insects as are even-aged stands. 

Some of the disadvantages of uneven-aged silviculture 

include: 

(1) Some area-efficient management practices, such 

as prescribed burning and chemical treatments, 

are difficult to apply. 

(2) Harvesting may be more difficult and expensive. 

(3) More management skill and supervision are 

required than for other methods. 

( 4) Competition for light and space occurs in the 

understory, midstory, and overstory, thereby 

slowing the early development of the young crop 

trees. 

The uneven-aged silvicultural system is one of several 

suited for regenerating and managing loblolly and shortleaf 

pine stands in the South. Some are more suitable to specific 

site and stand conditions and may meet landowner objectives 

better than others. This publication can help resource 

managers determine if the selection method is a viable 

alternative for meeting their land-management objectives 

and provide the technical information necessary for 

implementing and practicing uneven-aged silviculture. It 

should also be useful to educators as a teaching aid for 

uneven-aged silviculture. 
LITERATURE CITED 

Baker, J.B. 1992. New perspectives research: multidiscipline research for multi-resource management. In: 

Proceedings, 45th annual meeting Southern Weed 

Science Society; 1992 January 20-22; Little Rock, AR. 

Champaign, IL: Southern Weed Science Society: 171-

176. 

Baker, James B. 1986. The Crossett Farm Forestry Forties 

after 41 years of selection management. Southern Journal 

of Applied Forestry. 10(4): 233-237. 

Baker, Jam es B. 1987. Production and financial 

comparisons of uneven-aged and even-aged management 

of loblolly pine. Jn: Phillips, Douglas R., comp. 

Proceedings of the 4th biennial southern silvicultural 

research conference; 1986 November 4-6; Atlanta, GA. 

Gen. Tech. Rep. SE-42. Asheville, NC: U.S. 

Department of Agriculture, Forest Service, Southeastern 

Forest Experiment Station: 267-273. 

Baker, James B. 1989a. Alternative silvicultural 

systems-South. In: Proceedings, National Silviculture 

Workshop-Silvicultural challenges and opportunities 

in the 1990's; 1989 July 10-13; Petersburg, AK. 

Washington, DC: U.S. Department of Agriculture, 

Forest Service: 51-60. 

Baker, James B. 1989b. Recovery and development of 

understocked loblolly-shortleaf pine stands. Southern 

Journal of Applied Forestry. 13(3): 132-139. 

Baker, James B. 1991. Uneven-aged management of 

loblolly-shortleafpine. In: Chung, Hsu-Ho; Chen, YenChang; Huang, Y. Star, comps. Forestry administration 

and forestry technology; 1990 November 7-8; Taipei, 

Taiwan, R.0.C. Taipei, Taiwan, R.O.C.: Taiwan 

Forestry Research Institute and Council of Agriculture: 

93-98. 

Baker, James B. 1994. An overview of stand-level 

ecosystem management research in the Ouachita/Ozark 

National Forest. In: Baker, James B., comp. Symposium 

on ecosystem management research in the Ouachita 

Mountains: pretreatment conditions and preliminary findings; 1993 October 26-27; Hot Springs AR. 

Gen. Tech. Rep. S0-112. New Orleans, LA: U.S. 

Department of Agriculture, Forest Service, Southern 

Forest Experiment Station: 18-28. 

Baker, James B.; Balmer, William E. 1983. l.oblolly pine. 

In: Silvicultural systems for the major forest types of the 

United States. Agric. Handb. 445. Washington, DC: 

U.S. Department of Agriculture: 148-152. 

Baker, James B.; Guldin, James M. 1991. Uneven-aged 

management of Arkansas forests. Technical Briefing 

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45 
APPENDIX 

47 
Glossary Of Forestry Terms' 

All-aged silviculture -- See uneven-aged silviculture (cf. 

selection method and all-aged stand). 

All-aged stand -- See uneven-aged stand (cf. even-aged 

stand). 

Allowable cut -- The volume of wood that can be cut from 

a stand during a given period without exceeding the 

stand's net growth during that period. 

Artificial regeneration -- Establishing a new forest by 

planting or direct seeding. 

Basal area -- A measurement designation: (a) of a tree-the 

cross-sectional area (in square feet) of the trunk at breast 

height (4.5 ft above the ground); basal area = 0.005454 

times d.b.h. squared or (b) of an acre-the sum of basal 

areas of the individual trees on the area. 

Benefit-cost ratio -- The ratio of the sum of discounted 

revenues over time divided by the sum of discounted 

costs over time. 

Broadcast treatment -- A treatment (i.e., herbicide, 

prescribed burn) applied over an entire area. 

Climax forest -- The final stage of plant succession in 

which species composition remains relatively stable. 

Pine stands are an intermediate stage preceding the 

climax forest. 

Commercial harvest -- A cut of a sufficient number or 

volume of merchantable-sized trees to make the 

harvestiog operation economically feasible (cf. merchantable timber). 

Competing vegetation -- Plant species that utilize limited 

site resources (i.e., sunlight, nutrients, water, and 

growing space) to the detriment of more desirable crop 

trees. 

Competition control -- Silvicultural treatments to favor one 

or more plant species over others. 

Cost efficiency -- The results of comparing alternatives in 

situations where dollar values of costs are known, but the 

outputs are in nondollar or physical units. For example: 

The volume production per acre over a time period 

divided by the sum of the discounted costs for the same 

time period. 

Crop tree -- A tree to be grown to maturity and for final 

harvest. It is usually selected on the basis of its quality, 

species, and vigor and its proximity to other trees (cf. 

tree classes: growers). 

Cutting cycle -- The planned time interval between major 

harvesting operations in an uneven-aged stand. For 

example, a cutting cycle of 10 years in a stand means a 

harvest every 10 years. 

Density -- Number of trees per unit area. 

Diameter-limit cutting -- A method of harvesting wherein 

all merchantable trees above a specified d.b.h. are 

harvested. In some cases, minimum diameter may be 

the stump diameter. Unless all trees above the 

designated minimum d.b.h. are cut, this cutting method 

could be a form of high-grading. 

Even-aged silviculture -- A silvicultural system that 

involves periodic harvesting of all trees on part of the 

forest at one time or in several cuttings over a short time 

to produce stands of trees all the same or nearly the same 

age. 

Even-aged stand -- A stand of trees that are about the same 

age (usually within 20 percent of rotation age). An 

even-aged stand may be natural or artificially regenerated 

(cf. reproduction cutting method). 

Fbm -- Abbreviation for board-foot measure. 

Financial maturity -- The point in time at which the growth 

or increase in value of a financial asset (such as a tree) 

falls below the alternative rate of interest. 

Forest cover type -- A descriptive term used to group 

stands of similar character, composition, and development. 

Forest management -- Informally, a long-term program of 

proper care to ensure that the forest stays healthy and 

vigorous and provides the products and values the 

landowner desires. Technical definition: applying 

forestry principles, technology, and business practices 

(such as accounting, benefit-cost analysis, etc.) to the 

forest. 

Free-to-grow -- Not overtopped by competing vegetation. 

The term generally applies to seedlings and saplings. 

3 Adapted from Ford-Robertson (1971), Monaghan and Parker (1980), SAF (1993), and Wenger (1984). 

48 
Ground cover -- That proportion of a sample area occupied 

or overtopped by various vegetative components. A 

measure of ground cover is often obtained by ocular 

estimate. 

Group selection -- A method of regenerating uneven-aged 

stands in which trees are removed and new age classes 

are established in small groups. Tue maximum width of 

openings can vary depending on shade tolerance of the 

species but is approximately twice the height of 1nature 

trees in the stand. 

Growing stock -- All live trees in a forest or stand, 

including sawtimber, pulpwood, saplings, and seedlings, 

that have the potential of becoming merchantable. 

Herbaceous vegetation -- Nonwoody species of plants (i.e., 

forbs, grasses, semiwoody plants, and vines) that 

normally die back to the ground in winter. 

High grading -- The practice of harvesting only the biggest 

and best trees from a stand and leaving only the poorest 

to dominate the site. 

hnprovement cut -- A type of intermediate harvest with the 

primary objective of improving the remaining stand by 

harvesting trees of poor quality or form. 

Ingrowth -- Trees that grow out of one diameter or height 

class into another during a specified period of time. 

Ingrowth is usually measured as basal area or volume per 

unit area. 

Log rule -- A table of values that gives estimated board foot 

contents for logs of various diameters and lengths. Tue 

three log rules most used in the United States are the 

International \4-inch, Scribner, and Doyle Rules. Doyle 

is the most common log rule in the South and is the legal 

rule in many Southern States. 

Mature tree -- A tree that has reached the desired size or 

age for its intended use. Maturity can be based on 

financial, biological, or pathological factors (cf. financial 

maturity). 

Merchantable size -- Trees that are >3.6 inches in d.b.h. or 

logs that are > 4 inches in diameter at the small end. 

Merchantable timber -- Standing trees that are of sufficient 

size and volume per acre to provide a commercial 

harvest. 

Milacre -- An area of 0.001 acre (3.725 ft in radius), which 

is convenient for sampling the density and stocking of 

seedling and sapling size classes. 

Milacre stocking -- Proportion of milacres occupied by a 

plant species of interest, expressed as a percentage of the 

total number of milacres sampled. 

Multiple use -- Land management for more than one 

purpose, such as wood production and/or water, wildlife, 

recreation, forage, aesthetics, or clean air. 

Natural stand -- A stand resulting from natural seedfall or 

sprouting. 

Net present value -- A comparison of cost and revenues 

that have been discounted back to the present time, thus 

rendering revenue directly comparable in time to costs. 

All discounted costs are sununed and subtracted from 

discounted revenues. 

Overtopped -- Trees with crowns entirely below the general 

level of the crown cover or below competing vegetation 

and that receive no direct sunlight either from above or 

from the sides. 

Precommercial thinning -- The elimination of trees in a 

submerchantable-size stand (trees too small to be sold for 

forest products) to increase the growth rate of residual 

trees (cf. thinning). 

Prescribed burn -- The controlled use of fire to 

achieve forest management objectives. Prescribed fire 

can be used to prepare seedbeds for natural pine 

regeneration, reduce hazardous fuel levels, control 

unwanted vegetation, improve visibility, and improve 

wildlife habitat. 

Prescription stand -- See stand prescription. 

Product classes -- A loose term generally signifying the 

size limits of trees from which manufactured materials 

can be derived (cf. pulpwood, sawlog). 

Pulpwood -- Wood to be converted into pulp for the 

manufacture of paper, fiberboard, or other wood-fiber 

products. Pulpwood-size trees are usually 4 to 9 inches 

in d.b.h. 

q (quotient) factor -- The ratio of the number of trees in 

any given diameter class to the number in the next 

smaller diameter class. For example, the q would be 

1.2 if there were 12 trees in the 15-inch d.b.h. class and 

10 trees in the 16-inch d.b.h. class. 

Regeneration cut -- A cutting to remove the old trees and 

leave enviromnental conditions favorable for establishment of reproduction. 

Regulation -- Scheduling the harvest within a stand to 

ensure a sustained, even-flow of forest products. When 

using area regulation, the harvest is based on a defined 

area. When using volume regulation, the harvest is 

based on timber volume. 

49 
Release -- (a) A treatment designed to free young trees 

from undesirable, usually overtopping, competing 

vegetation or (b) cuttings made to regulate the species 

composition and improve the quality of very young 

stands. 

Reproduction -- (a) Young trees that will grow to become 

the future forest; or (b) the process of forest replacement 

or renewal, which may be artificial (by direct seeding or 

planting) or natural (from sprouting or natural seeding). 

Reproduction cutting method -- Techniques used to 

harvest crop trees either in a single cut (clearcut) or in a 

series of partial cuts (i.e., group selection, seed-tree, 

shelterwood, single-tree selection) while facilitating the 

regeneration of forest stands. 

Reversed J-shaped distribution -- A d.b.h.-class 

distribution wherein the number of trees declines as 

d.b.h. increases (cf. q factor). 

Sapling -- A small tree, usually 0.6 to 3.5 inches in d.b.h. 

Sawlog -- A log large enough to be sawed into lumber. 

Sawtimber -- Trees in size classes that are usually specified 

by a range in d.b.h.: small sawtimber is usually 10 to 15 

inches, medium sawtimber is usually 16 to 21 inches, 

and large sawtimber is usually >22 inches in d.b.h. 

Seedcrop -- Quantity of seeds produced and dispersed by a 

plant. Loblolly and shortleaf pine seeds are dispersed 

from October through February, with peak seedfall in 

November, throughout the Southeastern United States. 

Seedling -- A tree, usually less than 0.6 inch in d.b.h., that 

has grown from a seed. 

Selection method -- Harvesting individual trees or small 

groups of trees at periodic intervals (usually 5 to 15 

years) based on their physical condition, size, age, or 

degree of maturity. The goal is to produce an 

uneven-aged stand (cf. group selection, single-tree 

selection, uneven-aged forest management, uneven-aged 

silvicultural system). 

Shade tolerance -- A tree's capacity to develop and grow in 

the shade of, and in competition with, other trees. 

Single-tree selection -- An uneven-aged reproduction 

cutting method in which trees are selected from all d. b.h. 

classes for harvest or retention based on individual tree 

merits. 

Site index (S.I.) -- A measure of forest site quality based on 

the average height (in feet) of the tallest (never 

50 

suppressed) trees of a species at a specified age (usually 

50 years for natural stands). Site index is usually an 

approximation in uneven-aged stands because the tallest 

trees were probably overtopped during the regeneration 

phase. In this publication, the subjective site quality 

classes for loblolly-shortleaf pines at 50 years are as 

follows: good sites ( > 85 S .I.), medium sites ( 65 to 85 

S.I.), and poor sites ( <65 S.I.). 

Site preparation -- Preparing an area of land for planting, 

direct seeding, or natural reproduction by clearing, 

chemical vegetation control, manual vegetation control, 

burning, disking, bedding, windrowing, raking, or 

combinations of these treatments. 

Stand prescription -- Usually a document written by a 

forester prescribing present and future treatments for a 

forest stand aimed at accomplishing certain forest 

management objectives. 

Stand structnre -- The distribution of age or size classes of 

trees within a forest stand. 

Stand types -- Forest stands categorized by species 

compos1t10n. Examples: 

Pine type = > 75 percent merchantable pine basal 

area; 

Pine-Hardwood type = 50 to 74 percent merchantable 

pine basal area; 

Hardwood-Pine type = 25 to 49 percent merchantable 

pine basal area; 

Hardwood type = < 25 percent merchantable pine 

basal area. 

Stocking -- An estimate of growing-space occupancy. 

Stocking levels are defined in terms of desirable density, 

basal area, or tree-area ratio for best growth and 

management. Examples: fully stocked-a stand with all 

the growing space effectively occupied but having 

ample room for the developing crop trees; overstockedovercrowding in a stand leading to retarded growth of 

crop trees; understocked-a stand with the growing space 

not effectively occupied by crop trees. 

Stumpage -- The value or volume of a standing tree, or 

group of trees, uncut "on-the-stump." 

Submerchantable size -- Trees too small to be harvested 

for products (cf. merchantable size, reproduction, 

sapling, seedling). 

Succession -- The replacement of one plant community by 

another until ecological stability (climax forest) is 

achieved. For example, an abandoned farm, if left to 

nature, would gradually go through different stages of 

vegetative cover and fmally reach the climax forest stage 

after 100 or more years (cf. climax forest). 
Sustained yield -- Management of forest land to produce a 

relatively constant amount of timber and/or revenue. It 

implies maintaining the best possible forest health and 

site productivity. 

Thinning -- Generally, a partial harvest in an immature 

stand to reduce the number of trees per acre and 

encourage the remaining trees to grow faster and produce higher quality wood (cf. precommercial thinning). 

Timber marking -- The process of designating trees to be 

cut or trees not to be cut, usually by spraying a spot of 

brightly colored paint at the base of the tree and another 

at eye level. It implies selecting the trees to be removed 

on the basis of sound forest management principles to 

meet a specific objective. 

Tree-area ratio -- The ratio of the ground area allocated to 

trees on a sample plot to the total sample plot area. It 

can be used as an expression of stocking. 

Tree classes -- Retention/harvest criteria for classifying 

trees in uneven-aged stands. 

Examples: 

Cutters-Trees of poor quality, form, and vigor that 

are growing at an unacceptable rate, are not 

expected to survive through the next cutting cycle, 

or exceed the maximum tree diameter prescribed 

in the management objectives. 

Growers-Trees of good quality, form, and vigor that 

are growing at an acceptable rate and do not 

exceed the maximum tree diameter prescribed in 

management objectives. 

Thinners-Trees that could either be harvested 

immediately or left in the stand for future harvest. 

Uneven-aged forest management -- A forest management 

system that involves frequent partial cuttings to produce 

uneven-aged stands. 

Uneven-aged silvicultural system -- The manipulation of a 

stand for a continuous forest cover, recurring regeneration of desirable species, and the orderly growth and 

development of trees through a range of age or diameter 

classes to provide a sustained yield of forest resources 

and values. 

Uneven-aged stand -- A stand composed of three or more 

age classes. A balanced uneven-aged stand consists of 

three or more age classes that are spaced at uniform 

intervals from reproduction to mature trees. Irregular 

uneven-aged stands do not contain all the age classes 

necessary to ensure that trees will reach maturity at short 

intervals indefinitely. 

Value growth rate -- The rate at which a fmancial asset is 

growing or increasing in value, usually measured in 

percent. 

Volume table -- A table used to estimate the volume of 

wood in (a) standing trees, based on dimensions such as 

d.b.h. and merchantable height or (b) logs, based on 

diameter and length. 

51 
Appendix Forms 

53 
STAND INVE"ITORY WITH TREE CLASSIFICATION 

Location ____________ _ Acres ________ _ Date ________ _ 

Prism Factor/Plot Area Crew _________ _ 

POINT/PLOT NUMBER OF 

PINE 

D.b.h. (inches) 

GROWERS THINNERS CUTTERS fL4'RDWOODS 

4 

6 

8 

1-------------------1-------------------· ·------------------ 1-------------------· ------------------· IO 

12 

14 

·------------------1-------------------· ·------------------· 1-------------------· ------------------- 16 

18 

20 

'"'------------------·------------------· 1--------------------1-------------------· ·------------------ 22 

Form A-1.-Sample stand inventory form. 

55 
STAND INVENTORY WITH TREE CLASSIFICATION 

Stand Inventory (SUmmary of pine stems per acre) 

Stand location ______________ _ Date ______ _ 

D.b.h. (inches) GROWERS THINNERS CUTI'ERS TOTAL % CUTI'ERS 

Seedlings 

Saplings 

------------------ -------------- ---------------- ~--------------- >---------------- ---------------- 4 

6 

8 

------------------- --------------- >---------------- ---------------- ;..--------------- ---------------- 10 

12 

14 

:...------------------ -------------- --------------- --------------- --------------- --------------- 16 

18 

20 

------------------ -------------- --------------- ... --------------- --------------- r----------------

22 

funn A-2.-Sample stand inventory summary form. 

57 
UNEVEN-AGED PINE MARKING TALLY 

Stand location ___________ ~- Acres _______ Crew ______ Date-------

PULPWOOD (MERCHANTABLE HEIGHT IN FEET) 

PULPWOOD: 

D.b.h. 10 15 20 25 30 35 40 45 50 55 60 Target No._ 

Marking Ratio 

4 

(cut:total) 

Instruction: 

6 

8 

1-------· -------- -----------------'-------- ----- ------ .._ ______ ----- ---------- -----1--------------------

SAWTIMBER (16-FOOT LOG HEIGHT) 

SMALL SAWLOGS: 

D.b.h. 1 l'h 2 2'h 3 3'h 4 Target No._ 

Marking Ratio 

lO 

(cut: total) 

Instruction: 

12 

14 

------ ---------- ---------- ---------- ---------- ---------- ---------- -------- ------------------- 16 MED. SAWLOGS: 

Target No._ 

Marking Ratio 

(cut:total) 

18 

Instruction: 

20 

------1----------- !"'---------- 1----------- ----------- ----------- 1----------- 1---------1--------------------

22 LARGE SAWLOGS: 

Target No._ 

Marking Ratio 

24 (cut: total) 

Instruction: 

Form A-3.-Sample tally form for marking uneven-aged pine stands. 

59 
PINE REPRODUCTION AND UNDERSTORY EVALUATION IN UNEVEN-AGED STANDS 

Stand location _______________________ _ Acres-------------

Date __________ _ Crew _________ _ Remarks 

(For each milacre, place a./ in appropriate boxes across the form.) Page __ of __ 

DOMINANT SUBMERCH. PINE UNDERSTORY VEGETATION MERCH. TREE COVER 

Milacre FfG FfG OT OT DOMINANT GROUP PERCENT 

No. 

SAP SDL SAP SDL NONE HERB VINE WOODY COVER NONE PINE HWD PIH 

ABBREVIATIONS AND TERMINOLOGY: 

FI'G = Free-to-grow from understozy vegetation; OT = Overtopped by understory vegetation; SAP = Pine sapling (0.6 to 3.5 inches in d.b.h.); SDL = 

Pine seedling (1 ft tall to 0.5 inch in d.b.h.); HERB = Herbaceous (forbs, grasses, and semiwoody plants); WOODY = Nonpine woody vegetation; HWD 

=Hardwood; PIH =Pine/hardwood; SUBMERCH. PINE =Pine :!:3.5 inches in d.b.h.; 1\1ERCH. TREE = tree ~3.6 inches in d.b.h. If SAP or SDL 

is OT, then the dominant group is that overtopping vegetation; otheiwise, the dominant group is the type of vegetation with the greatest coverage. Ocularly 

estimate "Percent Cover" to nearest 10% (used with fig. 3.1). A milacre is 3.72 ft in radius. 

Form A-4.-Sample tally form for evaluating pine reproduction and understory competition. 

61 
DETERMINATION OF STOCKING LEVELS 

Cl C2 C3 C4 

D.b.h. class Number Stocking % stocking 

Inches Per acre Constant Per acre 

Seedlings 0.167 

1 0.175 

2 0.192 

3 0.218 

4 0.252 

5 0.295 

6 0.347 

7 0.408 

8 0.477 

9 0.555 

lO 0.641 

11 0.736 

12 Q.840 

13 0.953 

14 1.074 

15 1.204 

16 J.342 

17 1.490 

18 1.646 

19 1.810 

20 1.983 

TOTAL STOCKING 

NOTES: 

Column 2 is the cruise summary from the stand. 

Column 3 was derived from: Stocking(%) ~ 0.16667(/V) + 0.00404L(D) +0.00434E(D'). 

Column 4 is the product of C2 and C3, which is summed to give the stand total. 

Column 5 was derived from 0.005454(D)2. 

Colwnn 6 is the product of C2 and C5, which is summed to give the stand total. 

C5 

Basal area 

Constant 

0.000 

0.000 

0.000 

0.000 

0.087 

0.136 

0.196 

0.267 

0.349 

0.442 

0.545 

0.660 

0.785 

0.922 

1.069 

1.227 

1.396 

1.576 

1.767 

1.969 

2.182 

BASAL AREA 

Form A-5. -Sample worksheet fonn fer determining stocking percent and basal area per acre from cruise data. 

C6 

Basal area 

Per acre 

63 
ACKNOWLEDGMENTS 

The authors offer a special word of thanks to the following individuals for their time and effort in reviewing 

preliminary drafts of this publication and providing helpful comments and suggestions: 

Rod Busby, USDA Forest Service, Southern Research Station (formerly Southern Forest Experiment 

Station), New Orleans, LA. 

Wayne Clatterbuck, Tennessee Department of Agriculture, Division of Forestry, Nashville, TN. 

Carl Fiedler, School of Forestry, University of Montana, Missoula, MT. 

Tom Foti, Arkansas Natural Heritage Commission, Little Rock, AR. 

Dave Graney, USDA Forest Service, Southern Research Station (formerly Southern Forest Experiment Station), 

Fayetteville, AR. 

John Gray, Consulting Forester, Little Rock, AR. 

Ron Haugen, USDA Forest Service, National Forests in Texas, Lufkin, TX. 

Jackie Haymond, Clemson University Cooperative Extension Service, Clemson, SC. 

John Hodges, Department of Forestry, Mississippi State University, Mississippi State, MS. 

Brian Lockhart, School of Forest Resources, University of Arkansas, Monticello, AR. 

Tom Lynch, Department of Forestry, Oklahoma State University, Stillwater, OK. 

Tim Mersmann, USDA Forest Service, Ouachita National Forest, Mena, AR. 

Ray Newbold, School of Forestry, Louisiana Tech University, Ruston, LA. 

Bill Pell, USDA Forest Service, Ouachita National Forest, Hot Springs, AR. 

Louis Rainey, Deltic Farm & Timber Co., Inc., El Dorado, AR. 

Tom Waldrop, USDA Forest Service, Southern Research Station (formerly Southeastern Forest Experiment 

Station), Clemson, SC. 

Jimmy Walker, USDA Forest Service (retired), Atlanta, GA. 

Larry Willett, University of Arkansas Cooperative Extension Service, Monticello, AR (now with Louisiana State 

University Cooperative Extension Service, Baton Rouge, LA). 

Bob Wittwer, Department of Forestry, Oklahoma State University, Stillwater, OK. 

Frank Wright, Deltic Farm & Timber Co., Inc., El Dorado, AR. 

Ray Yelverton, USDA Forest Service, Ouachita National Forest, Glenwood, AR. 

65 
DISCLAIMER 

The use of trade, firm, or corporation names in this publication is for the information and convenience of the reader. Such 

use does not constitute an official endorsement or approval by the U.S. Department of Agriculture of any product or service 

to the exclusion of others that may be suitable. This publication reports research involving pesticides. It does not contain 

recommendations for their use, nor does it imply that the uses discussed here have been registered. All uses of pesticides must 

be registered by appropriate State andfor Federal agencies before they can be recommended. 

CAUTION: Pesticides can be injurious to humans, domestic animals, desirable plants, and fish or other wildlife if they are 

not handled or applied properly. Use all pesticides selectively and carefully. Follow recommended practices for the disposal 

of surplus pesticides and their containers. 

The United States Department of Agriculture (USDA) prohibits discrimination in its programs on the basis of race, color, 

national origin, sex, religion, age, disability, political beliefs, and marital or familial status. (Not all prohibited bases apply 

to all programs.) Persons with disabilities who require alternative means for communication of program information (braille, 

large print, audiotape, etc.) should contact the USDA office of Communications at (202) 720-5881 (voice) or (202) 720-7808 

(TDD). 

To file a complaint, write the Secretary of Agriculture, U.S. Department of Agriculture, Washington, DC 20250, or call (202) 

720-7327 (voice) or (202) 720-1127 (TDD). USDA is an equal employment opportunity employer. 
Baker, James B. and others. 1996. Uneven-aged silviculture for the loblolly and 

shortleafpine forest cover types. Gen. Tech. Rep. S0-118. Asheville, NC: U.S. 

Department of Agriculture, Forest Service, Southern Research Station. 65 p. 

The results of a half-century of experience and research with uneven-aged 

silviculture within the loblolly-shortleaf pine type of the Southern United States 

are sunuuarized, and silvicultural guidelines for developing and managing unevenaged stands are provided in this publication. 

Keywords: Basal-area-maximum diameter-q (BDq) regulation, group 

selection, growth and yield, natural stand management, Pinus echinata Mill., 

Pinus taeda L., single-tree selection, volume/guiding-diameter-limit regulation.