| ||Front Cover|
| ||Title Page|
| ||Table of Contents|
| ||Course description|
| ||General introductory readings|
| ||Informal laboratory write-ups|
| ||List of general definitions|
| ||Lecture notes supplement|
| ||Laboratory exercises|
| Material Information
||Laboratory handbook for Forestry 3162 Silviculture
||Silviculture Laboratory handbook for Forestry 3162
||249 p. : ill., maps ; 28 cm.
||Jokela, Eric Jon, 1953-
University of Florida -- Dept. of Forestry
||University of Florida Cooperative Extension Service, Institute of Food and Agriculture Sciences, EDIS
||Place of Publication:
||Forestry schools and education -- Study and teaching ( lcsh )
Trees -- Identification ( lcsh )
Forest plants -- Identification ( lcsh )
||government publication (state, provincial, terriorial, dependent) ( marcgt )
abstract or summary ( marcgt )
bibliography ( marcgt )
non-fiction ( marcgt )
||This handbook volume 1 includes course description and outline, general introductory readings, guidelines for laboratory write-ups, list of general definitions, lecture notes supplement and laboratory exercises for Forestry 3162 course, Spring 1998.
||Statement of Responsibility:
||edited and compiled by Eric J. Jokela.
||Electronic resources created as part of a prototype UF Institutional Repository and Faculty Papers project by the University of Florida.
| Record Information
||University of Florida
||University of Florida
||All rights reserved, Board of Trustees of the University of Florida
||oclc - 69847736
|Table of Contents
Front Cover 1
Front Cover 2
Table of Contents
General introductory readings
Informal laboratory write-ups
List of general definitions
Lecture notes supplement
Introduction to silvics
Stand structure and composition
Forest site: The concept and its measurement
Site evaluation: Standard method and species comparison
Silviculture thinning laboratory
A thinning operation in slash pine
The shelterwood system
Plantation sampling procedures
Silviculture field trip
Appendix A: Mapping/cover types
Appendix B: Field tatum guide
Appendix C: USDA silvicultural practices handbook
Appendix D: Supplemental silvicultural guidelines developed specifically for national forests in Florida
LABORATORY HANDBOOK FOR FORESTRY 3162
edited and compiled by
Eric J. Jokela
Department of Forestry / School of Forest Resources and Conservation
Institute of Food and Agricultural Sciences/ University of Florida
The publications in this collection do
not reflect current scientific knowledge
or recommendations. These texts
represent the historic publishing
record of the Institute for Food and
Agricultural Sciences and should be
used only to trace the historic work of
the Institute and its staff. Current IFAS
research may be found on the
Electronic Data Information Source
site maintained by the Florida
Cooperative Extension Service.
Copyright 2005, Board of Trustees, University
edited and compiled
Eric J. Jokela
Department of Forestry
School of Forest Resources and Conservation
University of Florida
330 ^7/ 84^'
TABLE OF CONTENTS
I. COURSE DESCRIPTION AND OUTLINE........................... 6
II. GENERAL INTRODUCTORY READINGS.............................. 10
III. GENERAL GUIDELINES FOR LABORATORY WRITE-UPS................ 12
IV. LISTS OF GENERAL DEFINITIONS.............................. 15
V. LECTURE NOTES SUPPLEMENT.................................. 38
VI. LABORATORY EXERCISES...................................... 68
A. Introduction of Silvics............................... 69
B. Stand Structure and Composition....................... 84
C. Forest Site: The Concept and Its Measurement........... 96
D. Site Evaluation: Standard Methods, Species
Comparisons, and Soil-Site equations (with
Appendices) .... ............. ... ................ ...... 102
E. The Effects of Thinning on Rotation.................. 136
F. A Thinning Operation in Slash Pine.................... 141
G. The Shelterwood Method of Reproduction................ 149
H. Regeneration--Plantation Sampling...................... 154
I. Silviculture Field Trip............................... 162
J. Silviculture Examination and Prescription Handbook... 163
1. Appendix A -- Mapping/Cover Types................ 198
2. Appendix B -- Field Tatum Guide................... 206
3. Appendix C -- USDA Silvicultural Practices
Handbook................ ........... 211
4. Appendix D -- Supplemental Silvicultural
Guidelines for Florida............... 237
Volume 2. (sold in bookstore)
VI. REQUIRED SUPPLEMENTAL READINGS........................... i
A. General Information.................................. 6
1. Straka, T.J. and W.F. Watson, Costs and cost trends
for forestry practices in the South.............. 7
2. Morris, L.A., and R.G. Campbell, Soil and site
potential .......... ......... ............ ....... 14
3. Hanlon, E.A., and K.R. Munson, Forest soils of
Florida: Useful groupings for forestry purposes. 38
B. Species Site Selection................................ 44
1. Haines, L.W., and J. Gooding, Site selection: slash
pine vs. other species........................... 45
2. Pait, et al., Species variation, allocation, and
tree improvement ............................... 64
3. Schmidtling, R.C., Relative performance of longleaf
compared to loblolly and slash pine under
different levels of intensive culture........... 89
4. Brendemuehl, R.H., Options for management of
sandhill forest land............................ 95
5. Shoulders, E., Comparison of growth and yield of
four southern pines on uniform sites in the
Gulf Coastal Plain.............................. 102
6. Hook, D., Waterlogging tolerance of lowland tree
species in the South ........................... 116
C. Regeneration Artificial and Natural................. 132
1. Barnett, J.P., and J.B. Baker, Regeneration methods 133
2. Van Lear, D.H., and T.A. Waldrop, Prescribed burning
for regeneration................................ 149
3. Baker, J.B., J.M. Guldin, and R.W. Guldin, Natural
regeneration methods for loblolly and shortleaf
pines........................ .................. 165
4. Guldin, J.M., and J.B. Baker, Yield comparisons
from even-aged and uneven-aged loblolly-
shortleaf pine stands........................... 170
5. Dennington, R.W., and R.M. Farrar, Longleaf pine
management .......................................... 178
6. Kennedy, H.E., and R.L. Johnson, Silvicultural
alternatives in bottomland hardwoods and their
impact on stand quality......................... 197
7. Kays, et al., Factors affecting natural regeneration
of Piedmont hardwoods........................... 211
8. Ewel, et al., Recovery of Florida cypress swamps
from clearcutting.............................. 216
D. Pine Thinning...... ........................ ...... 220
1. Bennett, F.A., and E.P. Jones, Slash pine thinning
and its effect on growth....................... 221
2. Nebeker, et al., Thinning practices in southern
pines with pest management recommendations.... 231
3. Hughes, J.H., and R.C. Kellison, Stocking control -
silvicultural thinning during the rapid growth
4. Mann, W.F., Jr., and H.G. Enghardt, Growth of
planted slash pine under several thinning
regimes........................... .......... 277
E. Effects of Silvicultural Practices on Stand
and Site Properties (Site Preparation, Release)....... 289
1. Stone, E.L., Site quality and site treatment....... 290
2. Lowery, R.F., and D.H. Gjerstad, Chemical and
mechanical site preparation..................... 297
3. Miller, et al., A regional study of the influence of
woody and herbaceous competition on early
loblolly pine growth............................. 308
4. Minogue, et al., Vegetation management after
plantation establishment....................... 319
5. Neary, et al., Site preparation and nutrient
management in southern pine forests.............. 343
6. Dyck, W., and M. Skinner, Potential for productivity
decline in New Zealand radiata pine forests..... 356
7. Swindel, et al., Multi-resource effects of harvest,
site preparation, and planting in pine
flatwoods .................. .................... 371
8. Riekerk, H., Water quality effects of pine
flatwoods silviculture.......................... 381
9. Riekerk, H., Best management practices for upland
and wetland forests............................. 385
F. Nutrition of Southern Pines........................... 389
1. Jokela, et al. Fertilization of southern pines at
establishment ............ ........... ............ 390
2. Bengtson, G.W., Nutrient Conservation in forestry:
A perspective ................. ................. 405
3. Ballard, R., Optimum nitrogen rates for
fertilization of loblolly pine plantations....... 414
4. Neary, et al., Understanding competition for soil
nutrients the key to site productivity on
southeastern Coastal Plain spodosols............ 419
G. Multiple Use Silviculture Wildlife Interactions..... 438
1. Melchiors, M.A., Wildlife management in southern
pine regeneration systems........................ 439
2. Mathisen, J.E., Integrating wildlife habitat
objectives with silvicultural prescriptions..... 469
3. Burk, et al., Wild turkey use of streamside
management zones in loblolly pine plantations... 475
4. Landers, J.L., Prescribed burning for managing
wildlife in southeastern pine forests............ 482
5. McComb, W.C., and G.A. Hurst, Herbicides and
wildlife in southern forests.................... 492
6. Hooper, et al., The red-cockaded woodpecker: notes
on life history and management ...'.............. 502
7. Conner, et al., Red-cockaded woodpecker use of
seed-tree/shelterwood cuts in eastern Texas..... 510
8. Dickson, J.G., Birds and mammals of pre-colonial
southern old-growth forests..................... 517
9. Marion, W.R., and L.D. Harris, Relationships
between forest productivity and fauna in the
flatwoods of the southeastern Coastal Plain..... 525
10. Repenning, R.W., and R.F. Labisky, Effects of
even-age timber management on bird communities
of the longleaf pine forest in northern Florida. 533
11. Yahner, R.H., Changes in wildlife communities near
edges ............................................ 544
Course Title: Forestry 3162 Silviculture (4 credits)
Prerequisites: FOR 3153C or PCB 3043, FNR 3131C or Consent of
Course is designed for: Juniors
Instructor: Dr. Eric J. Jokela
353 Newins-Ziegler Hall
Text: The Practice of Silviculture (8th Ed.) D.M. Smith, 1986
SILVICULTURE Vol. 1 Laboratory Handbook for Forestry 3162
(E.J. Jokela), Vol. 2 Supplemental Readings for Silviculture
(bound document sold in bookstore; Required).
Principles of Silviculture (Second Ed.) T.W.
Daniel, J.A. Helms, and F.S. Baker, 1979 (Strongly recommended)
Silvics of North America. Volume 1. Conifers, Volume 2.
Hardwoods. 1990 (R.M. Burns and B. H. Honkala, Tech. Coord.)
U.S.D.A. Forest Service, Agric. Hdbk. 654 (Strongly
recommended for professional library).
Silvical Summaries of Selected Southeast Forest Trees (E.J.
Jokela, S.R. Colbert, and J.E. Smith).
Purpose and Objectives:
1) To promote an understanding of the principles governing
establishment, treatment and control of forest stands;
natural and artificial regeneration systems; intermediate
cuttings; intensive cultural practices; and silvicultural
2) To provide field examples and practical experience in the
design, prescription, and implementation of applied
silvicultural techniques for managing forest stands for
commodity and non-commodity objectives.
Methods of Instruction:
1) Lectures (3 hours per week) major source of theory and
Discussion: To emphasize important topics
Provide information from recent research
2) Laboratory (4 hours per week, plus one Saturday, TBA).
Major source of practical and applied
Periods will be spent primarily in the field
3) Textbook assigned pages in required texts and
supplemental readings in laboratory handbooks
4) Field trip (Required; overnight stay) to observe
silvicultural practices and meet with natural
resource management professionals
1) Examinations covering lecture laboratory 55%
topics and assigned reading (Final = 25%; Mid-Term I
15%; Mid-Term II 15%).
2) Oral field examination and written report on thinning -10%
3) Oral presentation/defense of silvicultural prescription 10%
4) Satisfactory completion of laboratory assignments -25%
5) Instructors evaluation of professional and technical
6) Tardy assignments will be penalized one letter grade/day
Topic and Reading Assignment
Introduction: Silviculture as a part of forestry
I. Tending and Intermediate Cuttings
Thinning Concepts/Thinning Effects/
Text (Smith): 1-32
Daniel, Helms, and
Baker (DHB): 3-14
Improvement Cuttings/Salvage Cuttings/
Tree Nutrition/Forest Fertilization
Seed Biology/Seed Ecology/Tree Improvement
Site Preparation/Nursery Practices
Natural Regeneration/Vegetative Reproduction/
III. Reproduction Methods/Silvicultural Systems
IV. Special Topics
Multiple Use Silvicultural Systems/
and Wildlife Interactions
See Table of Contents and Silviculture Handbook Vol 2.
REQUIRED ADDITIONAL READINGS
RECOMMENDED READINGS FOR THE LABORATORY
Tree Growth and Development
Site Quality Evaluation
Thinning Effects on Forest Trees
The New Forester:
by Carl H. Reidel
"The society which scorns excellence in plumbing as a humble activity, and
tolerates shoddiness in philosophy because it is an exalted activity, will have
neither good plumbing nor good philosophy. Neither its pipes nor its theories
will hold water"
a poster. I don't know the au-
thor, but what he said describes
my vision for forestry and foresters.
Forestry in the future must, as the
quotation suggests, pay more atten-
tion to its "plumbing" skills and to its
philosophical foundations. We must
become a profession of philoso-
pher-plumbers who have a mastery
of our applied skills and a firm grasp
of the theories and philosophies
that shape our policies and plans.
As good "plumbers" we must
strengthen considerably our skills as
land managers. We must truly be-
come applied ecologists-biologists
who have intimate knowledge of the
natural systems we are managing:
We must know as much about the
herbaceous plants and songbirds
and small mammals that shape
the patterns of life on the specific
lands we manage as:we do about
commerically valued trees and game
animals. We must revive our profes-
sion's' earlier concern with
woodsmanship and field skills, with
natural history and silviculture. We
must be practitioners in every sense
of that word, able to apply the latest
research findings to specific prob-
lems skillfully and sensitively. This is
not to downgrade, in any way, com-
mitment to scholarship and theory;
but rather to insist that every fores-
ter be able to implement that knowl-
edge on the land.
My concern for "plumbing" is
based on the belief that if foresters
are to retain their role as land mana-
gers, they will have to demonstrate
their clinical skills as well as their
grasp of theory. How can foresters
be trusted to manage a natural pre-
serve when they can't identify the
birds or wildflowers on the area,
much less understand their special
environmental requirements? How
can foresters even be trusted to mark
timber for intermediate cutting if
they are insensitive to the practical
problems of felling a tree or locating
a skid trail on a rocky sidehill?
For those of us several decades out
of college, this return to good
plumbing will mean some intensive
retraining. And for more recent
graduates, it means continuing edu-
cation and on-the-job training. For
future forestry education, it will
mean a return to field training
camps and supervised internships.
That will require some major
changes in curricula, perhaps replac-
ing some advanced analytical studies
with applied training for those fores-
ters who intend field careers upon
graduation. We simply cannot train
every forester in advanced computer
sciences and biochemistry if we are
also to produce foresters with credi-
bility as land managers.
I know I am on controversial
ground, so let me be as clear as possi-
ble. I do not agree with those who
insist that all graduate foresters
spend their first five years setting
chokers, marking trees, and scaling
logs to prove they are lumberjacks.
I'm asking for something quite dif-
ferent. I'm asking for foresters with
a wide breadth of professional skills
who can be equally at home in the
forest with a local birdwatcher, a
logging contractor, or an ecologist
from Berkeley-foresters who truly
appreciate the forest as a total sys-
tem. That's a big order, but I don't
think we can settle for less and sur-
vive as a profession!
This new forester will .need some
new. "people skills" as well. If we are
to be effective in a complex'future
society, we must do much better in
making public involvement a reality.
Most of us are uncomfortable as pub-
lic speakers and write poorly. We
generally lack group leadership
skills and are reluctant to get in-
volved in local politics. And these
handicaps are beginning to show as
planners and lawyers are increas-
ingly the professionals calling the
tune in state legislatures, and at
executive levels of government and
I must admit great frustration in
trying to think of any remedies for
our lack of social and administrative
skills. For one thing, we should re-
consider the practice of frequently
transferring personnel. It is impos-
sible to gain an intimate knowledge
of either a forest or a human com-
munity if you are relocated every few
years. Perhaps we should return to
an earlier policy on transfers ex-
pressed in the 1928 U.S. Forest Ser-
"As a rule the district ranger's
prestige, and therefore his
usefulness, increases with the
stay in, and consequent
firmer establishment of him-
self as a part of the commu-
nity. For this reason, frequent
transfers are not desirable."
Some people skills can be taught,
but most come from the experience
of living in a community long
enough to have a real stake in the
results of your decisions. It takes the
best of plumbers time to discover
where all the underground pipes
and valves are located.
Finally, our profession needs a
searching view of its philosophical
foundations. Without a clear under-
standing of the values, beliefs, and
(Turn to page 60)
The New Forester
(From page 6)
theories that shape our practice, all
I've said about "plumbing" is for
naught. An ax, in the hand of a
skilled technician who is unclear of
his/her philosophy of forestry, is a
dangerous weapon, not a tool. When
the time comes to apply a manage-
ment prescription on the ground,
philosophy becomes the most practi-
cal of disciplines.
If the future I've attempted to
sketch is at all realistic,, we can no
longer justify our role as forest man-
agers in terms of vague doctrines
from the past. Proverbs like multiple
use and sustained yield will no
longerdo. They deny the reality of a
future ofuncertainty and limits, and
fail to speak to the priorities and
problems of a nation in transition.
For too many foresters, multiple-
use management remains rooted in
the belief that timber is the primary
product of an ideal forest, and that
all else is a byproduct. Until our con-
cept of multiple use is enlarged to
accept truly multiple goals as the
ends of management, and not
merely as necessary compromises-
with our traditional va.'tes, we will
not gain the confidence of the
people we serve. We will never be
able to practice what we preach until
we believe what we preach.
A searching review of our under-
standing of multiple use will be dif-
ficult, but not nearly as traumatic as
will a serious examination of the doc-
trine of sustained yield. While mul-
tiple use is little more than a slogan
for many foresters, sustained yield is
the "first commandment". It's the
doctrine of faith our profession
cherishes most in times of change.
Bill Duerr described sustained
yield as otr security blanket in time
of uncertainty. These are his words:
S"You can cling to the secu-
rity of the faith you learned
at your mother's knee-that
is, at the knee of the Found-
ers. You can do what virtually -
every public forester iti the
western world has done for
the past few centuries: take
shelter in a policy of sustained
yield. Under this policy, you
will manage the forest to the
same goal of producing the
same, hopefully large, physi-
cal quantity of wood period
by period into the indefinite
future. Under this policy,
you will find peace with your-
Peace with yourself, maybe, but
not with the future. If we insist on
traditional interpretations of sus-
tained yield as the basis for forest
management, we must be willing to
also accept a greatly reduced role for
foresters in the management of
forest lands in the future. We will
become a profession of timber spe-
cialists managing only those acres so-
ciety is willing to dedicate to long-
term, single-use management for
specific wood products. Others will
manage the bulk of forest lands-
where flexible concepts of sustained
yield are required. We will be the
plumbers, but not the architects or
builders of the nation's land-
That is a role for forestry I am not
willing to accept. I would rather risk
the dangers of seeking new tenets of
faith to guide our profession-I'd
rather experiment with enlarged
philosophies of forest management
that accept short-term change and
uncertainty as opportunities for in-
novation. In place of goals limited to
sustaining the physical output of
boards and campground visits, we
need goals that relate our practice of
forestry to the quality of life in this
nation-to social equity, environ-
mental protection, and national se-
I want to see foresters participa-
ting in the important decisions about
land-use planning, resource policy,
and environmental management on
a national scale. That will happen
only when we can offer the nation a
new and enlarged philosophy of
forestry that helps create the future,
not one that simply projects the past.
Perhaps this only means enlarging
those traditional doctrines of multi-
ple use and sustained yield to include
a broader understanding of the
- forest as a total ecosystem inextrica-
bly linked to human communities-a
philosophy that seeks to sustain all
the forest's values, and that is big
enough to encompass the changing
goals and aspirations of our people.
But whatever titles we give our
theories, they must be big enough to
offer a wide range of management
alternatives-alternatives based on a
sound understanding of ecology,
economics, and culture. Forest man-
agement must be ingenious, not doc-
trinaire. Forestry must become a
profession with the courage to be
comprehensive, in theory and prac-
Whether our pipes or ideas hold
water in the future depends on our
willingness to be honest in examin-
ing ourselves and our profession.
There is no more powerful way to
create the future than to begin imag-
ining a future for our profession that
we can enthusiastically pursue. Let
us begin, now.
This article is an excerpt from a keynote;
address at a recent meeting of the ,Northern.
California Section of the Socety ofAmencan
Foresters. Carl Reidel is President of The!
American Forestry Association. I
INFORMAL LABORATORY WRITE-UPS
(Main Points Which Should Be Included)
I. Title of Exercise
Crew members names, date, etc.
II. Methods and Objectives of Exercise
III. Study Area Location and Description
Pertinent Stand Information (i.e., legal location, stand map, stand
area, basal area, age, dbh, species composition, age, site index, LCR,
IV. Management Objective
V. Results and Discussion discussion of pre-cut conditions, your recom-
mendations for treatment, method of thinning or cutting used, post-cut
conditions, justification. Use questions in exercise to supplement your
discussion. Be sure to include stand tables, pre and post-cut histo-
grams as part of your report (label appropriately). Cite reference
(management guides) where needed.
VI. Conclusions should include general recommendations for future treat-
ment and forecast 10 year basal area growth.
** View this as a write up for your supervisor who is interested in what
you did, why you did it and for whom you did it. From this report, your
supervisor should be able to locate this stand and see the implementa-
tion of your silvicultural activities. View your recommendation as a 10
year management plan.
Suggestions for writing Silviculture Laboratory Reports
1. Follow lab instructions and address all points mentioned.
2. Organize report into distinct sections: Introduction,
Materials and Methods, Results, Discussion, Conclusions,
References, and include neat graphs/tables. You may combine
Results and Discussion if appropriate.
3. Make sure that your thoughts, results, interpretations appear
in the right sections.
4. Describe Materials and Methods with enough detail to allow
anyone to repeat what you did. You can attach a copy of the
pertinent section of the lab exercise in an Appendix and
reference it for more detail.
5. Be consistent in the style for your citations. Give name(s)
and year published for one or two authors. If more than two
authors, give name of first author followed by et al. and the
year. In References list all authors.
6. Use linespacing 1.5 or 2 to allow for comments. Numerate
pages, figures and tables!
7. Check the logic of your sentences: make sure about cause-
effect relationships; avoid unnecessary speculation; use your
data and the literature to support your interpretations.
8. Check spelling Use dictionaries if necessary!
9. Avoid repetitions of statements. This represents lazy writing
style and detracts from the professional quality of the
10. Avoid words like "strongly", "appreciable", "considerably",
"almost", that often, do not convey essential information.
Effective technical writing is succinct; mean what you say and
say what you mean. Write informatively!
11. Put title above tables and under graphs, starting "Table..."
and "Figure...", respectively. Remember, tables and graphs
must stand alone; therefore, provide informative titles,
12. 2-D graphs are often less impressive than 3-D, but they are
easier to read.
13. "Data" should not be represented as singular i.e., the data
were analyzed using.... and not data is.
14. Use technical terminology in your writing. Avoid meaningless
colloquial terms, avoid using contractions; proof read; and be
consistent with your tense (i.e., third person, past tense).
(10) crew members
purposes and procedures
tables with titles
(10) tables in order
text in order
grammar and clarity of expression
IV. Technical Content (Accuracy of Data and Discussion)
(60) Stand Analysis and Site Condition
maps of stand and plot
stand history using histograms as support stand structure pre-
cut and post cut BA x DBH
live crown ratio
Recommendations and Implementation for next 10 years
method of thin
V. Professional (General)
Forestry 4162 -- Silviculture
LIST OF GENERAL DEFINITIONS 1/
1. Adaptation (1) The processes) whereby individuals (or parts of indi-
viduals), populations or species change in structure, form or function
in such a way as better to survive under given environmental conditions.
.(2) Also the resultant structure, form or function.
*2. Aspect The compass direction toward which a slope faces (Also called
3. Association A plant community of some particular kind usually regarded
as (1) the "fundamental unit" of plant ecology (the equivalent of spe-
cies in taxonomy) and defined mainly by floristic composition, not by
habitat; or (2) a major subdivision of a formation, restricted to (the
presumed) climax communities.
4. Autecology The ecology of an individual organism or taxonomic group in
contrast to synecology which is the ecology of a community (See also,
5. Autotrophic Of organisms that manufacture their own food exclusively
from inorganic substances occurring in soil, air, or water (e.g., trees)
(See also, heterotrophic).
6. Biomass The total quantity, at a given time, of living organisms of
one or more species per unit area (species biomass) or of all species in
a community (community biomass).
7. Biosphere That part of the Earth's envelope comprising the lower atmos-
phere, the seas and the land surface, in which living organisms exist in
their natural state.
8. Brush Shrubby vegetation and stands of-tree species that do not pro-
duce commercial timber. Note: Brushwood growing in a forest is called
*9. Bud, axillary A bud borne in the axil of a leaf (Also called lateral
*10. Bud, interfascicular A bud borne between the needles of a pine tree.
*11. Cambium, bark A layer of meristematic cells that produces bark cells
(Also called cork cambium). Not to be confused with vascular cambium
which produces xylem and phloem.
1/ Most of the definitions are taken from "Terminology of Forest Science,
Technology, Practice and Products (by F.C. Ford-Robertson, 1971), with
some editing to fit the needs of the course.
* An asterisk designates definitions from other sources.
12. Canopy The more or less continuous cover of branches and foliage
fored collectively by the crowns of adjacent trees and other woody
13. Class, age (1) One of the intervals, commonly ten years, into which
the age range of tree crops (and sometimes other vegetation) is divided
for classification or use. (2) Also the trees or vegetation is falling
into such an interval.
14. Class, crown Any class into which trees forming a crop or stand may be
divided on the basis of both their crown development and crown position
relative to the crowns of adjacent trees and the general canopy.
15. Class, tree Any class into which the trees forming a crop or stand may
be divided for a variety of purposes, such as for determining a type of
16. Climax The culminating stage in plant succession for a given environ-
ment, the vegetation being conceived as having reached a highly stable
17. Clone Any group of plants derived from a single individual an
ortet by vegetative reproduction. Note: All members ramets of a
clone have the same genotype and consequently tend to be uniform.
18. Community Any assembly of organisms living together, no particular
ecological status being implied. Note: With plants, a closed community
is one whose components are so completely utilizing the site as to ex-
clude further entrance.
*19. Competition Takes place when two or more organisms strive for light,
moisture, nutrients or space that is in limited supply. A tree seedling
comes into competition in turn with other tree reproduction and herbs,
small shrubs, tall shrubs and finally larger ones.
20. Composition, stand The representation of tree species in a forest
stand. Note: Expressed quantitatively as percent by volume or basal
area of each species; percent by number only at the seeding stage.
21. Conifers The most important order of the Gymnospermae comprising a
wide range of trees, mostly evergreens, bearing cones (hence coniferous)
and needle-shaped or scale-like leaves, producing timber commercially
.known as softwood.
22. Continuum An area over which the vegetation and/or the animal popu-
lation is considered as varying continuously in composition, so that
homogeneous communities cannot be distinguished in it.
*23. Coppice A crop of shoots arising from adventitious or dormant buds
near the base of woody plants that have been cut back.
24. Crop (1) The vegetation growing on a forest area, more particularly,
the major woody growth forming the forest crop (See stand). (2) Any-
25. Crown The upper.part of a tree or other woody plant, carrying the main
branch system and foliage, and surmounting at the crown base a more or
less clean stem.
*26. Decomposers Organisms, usually bacteria or fungi, that break down the
bodies or parts of dead plants and animals into simpler compounds.
*27. Density, population The number of individuals in a population per unit-
28. Density, stand In silviculture, a quantitative measure of tree stock-
ing, expressed either relatively as a coefficient, taking normal num-
bers, basal area or volume, (from yield table data) as unity, or abso-
lutely, in terms of number of trees, total basal area, or volume per
unit area. (2) More precisely, a measure of the degree of crowding of
trees within stocked areas, commonly expressed by various growing-space
ratios-of crown length to tree height; crown diameter to d.b.h.; crown
diameter to tree height; or of stem (triangular) spacing to tree height
a. Absolute stand density The absolute or measured quantity per unit
area (That is, trees per acre or square feet per acre).
b. Management zone The area defined by the upper and lower boundaries
in acceptable.relative densities in stands managed for a particular
c. Reference level The absolute stand density that we would normally
expect in a stand of given characteristics under some standard con-
ditions (usually average maximum competition, but may be no competi-
d. Relative stand density derived from average maximum competition -
The ratio (proportion or percent) of absolute stand density to the
reference level based on average maximum competition.
e. Relative stand density derived from no competition The ratio
(proportion or percent) of absolute stand density to the reference
level based on no competition.
f. Stocking level a residual stand density, expressed as relative
stand .density, that achieves some management objective.
*29. Distribution, species The geographic range (continuous or discontinu-
ous) of species at any one time.
30. Dystrophic Of habitats, particularly soils and water, that are low in
basic nutrients and toxic (See also Eutrophic, and Oligotrophic).
*31. Ecology The study of organisms in relation to their environment and
the mutual relations between groups of organisms.
*32. Ecosystem Any self-sustaining community of organisms including its
organic and inorganic environment.
*33. Ecotype An ecological race of sub-species resulting from natural selec-
tion by the special conditions of a particular habitat. Ecotypes may be
distinguished as edaphic, climatic, or biotic.
34. Edaphic Pertaining to the soil in its ecological relationships.
35. Emergent (1) a tree whose crown at maturity projects well above the
level of the highest forest canopy. (2) Aquatic vegetation that bears
*36. Energy, radiant All the waves coming from the sun; it includes the
37. Eutrophic Of habitats, particularly soils and water, that are rich or
adequate in nutrients (See also Dystrophic and Oligotrophic).
*38. Flora (1) Plants collectively; especially the plants of a particular
region or time. (2) A systematic compilation describing such plants.
39. Forest (1) Generally, an ecosystem characterized by a more or less
dense and extensive tree cover. (2) More particularly, a plant commu-
nity predominantly of tree and other woody vegetation growing more or
less closely together. (3) An area managed for the production of timber
and other forest products, or maintained under woody vegetation for such
indirect benefits as protection or catchment areas or recreation.
40. Forestry (1) Generally, a profession embracing the science, business
and art of creating, conserving and managing forests and forest land for
the continuing use of their resources, material or other. (2) The sci-
ence, the art and the practice of managing and using for human benefit
the natural resources that occur on and in association with forest lands.
41. Formation A vegetational unit that is homogeneous ecologically, flor-
istically and developmentally (such as the deciduous climax forest).
42. Genotype (1) The entire genetic constitution (expressed or latent) of
one individual. (2) The genetic constitution of an individual as ex-
pressed in terms of selected heritable characters. (3) The hereditary
materials (germ plasm) considered as a unit.
43. Habitat The abode, natural or otherwise, of a plant or animal, con-
sidered particularly in relation to all the environmental influences
44. Hardwood A conventional term for the timber of broad-leaved trees, and
the trees themselves, belonging to the botanical group Anglospermae.
Hardwoods are almost invariably distinguished from softwoods by the
presence of vessels in their timber, irrespective of physical hardness
or softness in either case.
45. Heartwood The inner layers of wood which, in the growing tree, have
ceased to contain living cells and in which the reserve materials,
(e.g., starch) have been removed or converted into more durable substan-
ces. Note: Generally darker in color than sapwood.
46. Herb Any seed-producing plant that does not develop persistent woody
tissue above ground, i.e., includes both forbs and grasses.
47. Heterotrophic Of organisms that cannot live without an external source
of organic food (e.g., forest tent caterpillar). (See autotrophic)
48. Humidity, relative The ratio, generally expressed in percent, of the
vapor pressure present in the atmosphere to that required for saturation
at the same.temperature.
49. Hydric (Hygric) Of sites or habitats characterized by decidedly moist
or wet conditions (See mesic or xeric).
50. Index, site A particular measure of site class, based on the height of
the dominant trees in a stand at an arbitrarily chosen age.
51. Mesic Of sites or habitats characterized by intermediate moisture con-
ditions, i.e., neither decidedly wet hydricc) nor decidedly dry xericc).
*52. Microhabitat A small habitat such as a tree stump or a space between
clumps of grass.
53. Mychorrhizae (1) the phenomenon of the probably symbiotic, or at least
non-parasitic, association between the root or rhizome of a green plant
and a fungus. (2) Also the structure produced by the combination of
the modified rootlet with fungal tissue.
54. Niche (1) The ultimate unit of the habitat, i.e., the specific spot
occupied by an individual organism. (2) By extension, the more or less
specialized relationships existing between an organism, individual or
synusia, and its environment.
55. Oligotrophic Of habitats, particularly soils and water, that are low
in basic nutrients.
56. Overstory That portion of the trees, in a'forest of more than one
story, forming the upper or uppermost canopy layer.
57. Phenology The science that deals with the time of appearance of char-
acteristic periodic phenomena in the life cycle of organisms in nature
e.g., migration of birds, flowering and leaf-fall in plants, particu-
larly as these phenomena are influenced by locality factors.
58. Phenotype An organism is observed, i.e., as judged by its visually
perceptible characters resulting from the interaction of its genotype
with the environment. Note: Identical phenotypes do not necessarily
59. Plant, indicator Any plant that, by its presence, its frequency, or
its vigor indicates any particular property of the site especially,
but by no means exclusively, of the soil.
60. Pole (1) A still young tree, from the time its lower branches begin to
i-e, up to the time when the rate of height growth begins to slow down
and crown expansion becomes marked. (2) In the U.S. defined as a young
tree of more than 4 inches and generally less than 8 to 12 inches in
61. Population A community of individuals sharing a common gene pool.
62. Prairie An extensive tract of level or rolling land that was origin-
ally treeless and.grass covered. Usually it is occupied by tall grasses
and has a deep fertile soil.
*63. Reaction The effects which one or more organisms produce upon their
64. Regeneration (1) The renewal of a tree crop, whether by natural or
artificial means. (2) Also the young crop itself. Note: Renewal by
self-sown seed or vegetative means, e.g., coppicing, root suckers, ligno-
tubers, as also the resultant crop, is termed natural regeneration and
the crop self-grown; renewal by sowing or planting, as also the result-
ant crop, is artificial regeneration (also called reproduction).
65. Release Freeing a tree or a group of trees from more immediate compe-
tition by cutting (liberation cutting) or otherwise eliminating, growth
that is overtopping or closely surrounding them (See thinning).
66. Reproduction, advance Young trees that have become established natu-
rally before regeneration cuttings are begun or a clearcutting is made
(also called advanced growth).
67. Reproduction, vegetative Propagation not involving the union of
gametes (as in budding, cuttings, layers, and grafts) in contrast to
(sexual) reproduction by seed (See clone).
68. Rhizome A stem, generally modified (particularly for storing food
materials) that grows along but below the ground surface and produces
adventitious roots, scale leaves, and suckers irregularly along its
length, not just at the nodes (See runner, stolon).
*69. Runner An above-ground, more or less horizontal stem that forms roots
and shoots at some of the nodes under favorable conditions (See rhizome,
70. Sapling A loose term for a young tree no longer a seedling but not yet
a pole, i.e., more than a few feet high and an inch or so in d.b.h.
typically growing vigorously and without dead bark or more than an occa-
sional dead branch. In the U.S. it usually refers to trees between 2
and 4 inches in d.b.h.
71. Seedling (1) Generally, a young tree, shrub, etc. grown from seed,
from its germination up to the sapling stage; (2) in nursery practice a
very young tree that has not been transplanted, i.e., is growing where
it germinated in the seed bed.
72. Shrub A woody, perennial plant differing from a perennial herb in its
persistent and woody stem(s), and less definitely from a tree in its
lower stature and the general absence of a well-defined main stem (See
73. Silvics The study of the life history and general characteristics of
forest trees and stands, with particular reference to locality factors,
as a basis for the practice of silviculture.
74. Silviculture (1) Generally, the science and art of cultivating (i.e.,
growing and tending) forest crops, based on a knowledge of silvics.
(2) More particularly the theory and practice of.controlling the estab-
lishment, composition, and constitution and growth of forests.
75. Site An area considered in terms of its environment, particularly as
this determines the type and quality of the vegetation the area can
carry. Note: Sites are classed either qualitatively by their climate,
soil and vegetation into site types or quantitatively, by their poten-
tial wood production into site c~asses.
*76. Slope The inclination of the surface of the land from the horizontal,
usually expressed in percent or degrees.
77. Softwood A conventional term for both the timber and trees belonging
to the botanical group Gymnospermae.
78. Soil, heavy A soil consisting of mineral particles that are primarily
0.05 millimeters or less in diameter, i.e., silt or clay soil.
79. Soil, light Soils consisting of mineral particles primarily more than
0.05 millimeters in diameter, i.e., sands.
80. Spectrum, biological (1) A statement showing, for the flora of a com-
munity or region, the percent of its species belonging to each life
form. (2) The progression: Protoplasm, cells, tissues, organs, organ
systems, organisms, populations, communities, ecosystems, the biosphere.
81. Stand A community particularly of trees possessing sufficient uniform-
ity as regards composition, constitution, age, spatial arrangement, or
condition, to be distinguishable from adjacent communities, so forming
the silvicultural or management entity.
82. Stand, all-aged A stand that contains trees of all or almost all age
classes, including those of exploitable age.
83. Stand, even-aged A stand composed of trees having no, or relatively
small differences in age. Note: By convention the maximum difference
admissible is generally 10 to-0 years, though with rotations of more
than 100 years, differences up to 30% of the rotation may be admissible.
*84. Stolon A horizontal stem on the surface of the ground where it propa-
gates vegetatively by forming new shoots and roots at the nodes (See
*85. Structure, species The number and kinds of species present and also
the.diversity of species that is the relationship between species and
numbers of individuals or biomass and the dispersion (spatial arrange-
ment) of individuals of each species that are present in the community.
86. Structure, stand The distribution and representation of age and/or
size (particularly diameter) classes (constitution), and of crown or
other tree classes.
87. Succession The gradual supplanting of one community of plants by
another. Succession is primary (by pioneers) on sites that have not
previously borne vegetation, secondary after the whole or part of the
original vegetation has been supplanted.
88. Sucker A shoot arising from below ground level, either from the rhi-
zome or from a root (designated a root sucker).
*89. Synecology The study of the structure, development, and interdepen-
dence of communities of organisms, and of their environmental relation-
90. Synusia Any component of a community of one or more species, belong-
ing to the same life-form, having similar environmental requirements
and occurring in a similar habitat, e.g., lines in forest, and includ-
ing stratified communities, e.g., a layer of moss plants.
91. Thinning A felling made in an immature crop or stand, in order pri-
marily to accelerate diameter increment, but also by suitable selec-
tion, to improve the average form of the trees that remain, without --
at least according to classical concepts -- permanently breaking the
92. Tolerance The ability of an organism or biological process to subsist
under a given set of environmental conditions. Note: The range of
these under which it can subsist, representing its limits of tolerance,
is termed ecological amplitude. For trees, the tolerance of most prac-
tical importance is their ability to grow satisfactorily in the shade
of, and in competition with other trees; if intolerant of shade, they
are termed light demanders, if tolerant, shade bearers.
93. Tree A woody perennial plant typically large and with a single well
defined stem carrying a more or less definite crown.
94. Tree, crop Any tree forming or selected to form a component of the
final crop. Note: Generally a tree selected in a young stand or plan-
tation for carryFng through to maturity.
95. Type, forest (1) Generally a category of forest or forest land,
actual or potential (also called forest site type). (2) More particu-
larly, a category of forest defined by its vegetation (particularly its
composition) and/or locality factors (also called forest cover type).
96. Understory (1) Generally, trees and woody species growing under an
overstory. (2) In range management any plants growing under the canopy
formed by others more particularly, herbaceous and shrub vegetation
under a brush wood or tree canopy.
97. Variation, genetic The occurrence of differences among individuals
due to differences in their genetic composition.
98. Vegetation The plants of an area or region; the plant life collec-
99. Xeric Of sites or habitats characterized by decidedly dry conditions.
*100. Zone, tension An area where two ecosystems are in competition, such
as the prairie-forest tension zone.
Forestry 4162 -- Silviculture
DIFFERENTIATION AND DEVELOPMENT OF STANDS
1. Stand An aggregation of trees or other growth occupying a specific
area and sufficiently uniform in composition (species), age
arrangement, and condition as to be distinguishable from the
forest or other growth on adjoining areas.
Even-aged Applied to a stand in which relatively small age differen-
ces exist between individual trees. The maximum difference in
age permitted in an even-aged stand is usually 10 to 20 years,
though where the stand will not be harvested until it is 10 to
200 years old, larger differences up to 25 percent of the rota-
tion (period of years required to establish and grow timber
crops to a specified condition of maturity) age may be allowed.
Uneven-aged Applied to a stand in which there are considerable dif-
ferences in age of trees and in which three or more age classes
All-aged Applied to a stand in which theoretically trees of all
ages up to and including those of the felling age are found.
Two-storied Applied to a stand in which two height classes of con-
siderable differences occur, the overstory and understory. The
term is not applicable to a forest in process of reproduction,
in which the appearance of two stories is the temporary result
of an incomplete process.
Irregular Stand Everything else.
Pure A stand in which at least 80 percent of the trees in the main
crown canopy are of a single species.
Mixed A stand in which less than 80 percent of the trees in the
main crown canopy are of a single species.
Fully stocked A forest stand in which all growing space is effec-
tively occupied, but having ample room for development of the
Overstocked A condition of overcrowding in a stand leading to
Understocked A stand in which the growing space is not effectively
occupied by crop trees.
2. Stand density Density of stocking expressed in number of trees, basal
area, volume, or other criteria, on a per acre basis.
3. Basal area The area, usually expressed in square feet, of the cross
section at breast height of a single tree or of all trees in a
4. Crown closure The closing together of the crowns of trees in a forest
as in the youth of a stand, or after thinning.
5. Shade density The complement of the percentage of light passing through
the crowns, assuming unbroken light to have, at the time of
measurement, a value of 100 percent.
6. Crown density The compactness of the crown cover of the forest, depen-
dent upon (1) the distance apart and (2) the compactness of the
individual crowns. A loose term combining the meanings of crown
closure and shade density.
7. Crown class A designation of trees in a forest with crowns of similar
development and occupying similar positions in the crown cover.
Differentiation into crown classes is intended for application
in even-aged stands and within the small even-aged groups in
which the trees in an uneven-aged stand are often arranged. The
following crown classes are commonly recognized.
Dominant Trees with crowns extending above the general level of the
crown cover and receiving full light from above and partly from
the side; larger than the average trees in the stand, and with
crowns well developed but possibly somewhat crowded on the sides.
Codominant Trees with crowns forming the general level of the crown
cover and receiving full light from above, but comparatively
little from the sides; usually with medium-sized crowns more or
less crowded on the sides.
Intermediate Trees shorter than those in the two proceeding
classes, but with crowns either below or extending into the
crown cover formed by codominant and dominant trees, receiving a
little direct light from above, but none from the sides; usually
with small crowns considerably crowded on the sides.
Overtopped Trees with crowns entirely below the general level of
the crown cover receiving no direct light either from above or
from the sides.
8. Tree class'- A designation of all trees in a forest that are alike in
certain specified characteristics such as vigor, insect suscep-
tibility, or value according to such attributes as crown class;
age class size, form, and density of crown; diameter; log
grades; and clear length. More often applied in uneven-aged
9. Crown cover The canopy of green leaves and branches formed by the
crowns of all trees in a forest.
10. Overstory That portion of the trees in a forest stand forming -the upper
11. Understory That portion of the trees in a forest stand below the over-
12. Ground cover All herbaceous plants and low-growing shrubs in a forest.
13. Forest floor (Duff) All dead vegetative matter on the mineral soil sur-
face in the forest, including litter and unincorporated humus.
14. Litter The uppermost layer of the organic debris, composed of freshly
fallen or slightly decomposed organic materials. Commonly desig-
nated by the letter L.
15. Humus The plant and animal residues of the soil, litter excluded, which
are undergoing decomposition.
16. Humus layer The top portion of the soil which owes its characteristic
features to its content of humus. The humus may be incorporated
or unincorporated in the mineral soil. Humus layer includes the
F and H layers.
F-layer A layer of humus consisting of partly decomposed organic
matter, below the litter and above the H-layer.
H-layer The.lower part of the humus layer consisting principally of
amorphous organic matter.
17. Mor A type of forest humus layer of unincorporated organic material,
usually matter or compacted or both, distinctly delimited from
the mineral soil unless the latter has been blackened by washing
in organic matter.
18. Mull A type of forest humus layer consisting of organic and mineral
matter so mixed that the transition to the underlying layer is
From: Committee on Forestry Terminology. 1958. Forestry Terminology. Third
Edition. Society of American Foresters. Washington, D.C.
Forestry 4162 Silviculture
GROWTH AND YIELD OF STANDS
1. Increment The increase in diameter, basal area, height, volume,
quality, or value of individual trees or stands during a given
Gross Increment refers to values uncorrected for losses by mor-
tality or deterioration.
Net Increment refers to values corrected for losses by mortality or
2. Current Annual Increment The growth for a specific year.
3. Mean Annual Increment The total growth divided by the total age.
4. Periodic Increment The growth for any specified period commonly 10 to
5. Periodic Annual Increment The growth for any specified period divided
by the number of years in the period.
6. Mortality Death or destruction of forest trees as a result of competi-
tion, disease, insect damage, drought, wind, fire, and other
7. Ingrowth (Recruits) The volume or number of trees that have grown past
an adopted lower limit of measurement during a specified period.
8. Growing Stock The sum (by number or volume) of all the trees in a for-
est or a specified part of it.
9. Stand Table A summary table showing number of trees by species and
diameter class for any given area.
10. Stock Table A summary table showing the volume of trees by species and
diameter class for any given area.
11. Volume Table A table showing for a given species the average contents
of trees of given sizes in a specified unit of volume.
12. Yield Table A table showing for one or more given species on given
sites the progressive development of a stand at periodic inter-
vals covering the greater part of its useful life. It usually
includes average diameter and height, basal area, number of
trees, and final yields, and may include volumes of thinnings
and other data. An empirical yield table is prepared for actual
average stand conditions; a normal yield table is prepared for
fully stocked stand conditions.
From: Committee on Forestry Terminology. 1958. Forest Terminology. Third
Edition. Society of American Foresters. Washington, D.C.
All-aged management-of a forest crop or stand that contains trees of all or
almost all age classes including those of exploitable age.
Annual (growth) layer-a growth layer produced in one year. In the temperate
zones, layer and year generally coincide. In cross-section, it appears as an
annual (growth) ring.
Band dendrometer-an instrument for continuously measuring and recording, or
for obtaining periodic readings of, changes in the overbark girth of a tree,
by means of a band encircling the stem.
Bark gauge-an instrument for measuring the thickness of bark.
Basal area-the area of the cross-section of a tree stem near its base, generally
at breast height (4.5') and inclusive of bark. Normally expressed in units
Bias-the difference between the expectation of the sample estimator and the
true population value, depriving a statistical result of representativeness
by systematically distorting it.
Biltmore stick-a graduated stick used to estimate tree diameters by holding
it at right angles to the axis of the stem and comparing the graduations cut
by lines of sight tangential to either edge of the stem. Note: The graduations
assume observation at a specified distance of the stick from the eye.
Board foot-the amount of timber equivalent to a piece of 1 x 1 ft. and 1 in.
Breast height-on standing trees; a standard height from ground level for
recording diameter, girth, or basal area. In the U.S. measurements are
normally taken at 4.5 feet while in Europe breast height is equivalent to
1.30 m or 4 ft. 3 in.
Caliper-an instrument for determining tree and log diameters by measurement
of their rectangular projection on a straight graduated rule via two arms at
right angles to the rule itself.
Canopy-the more or less continuous cover of branches and foliage formed
collectively by the crowns of adjacent trees and other woody growth.
Co-dominant-one of the four main crown classes recognized on a basis of
relative status and condition in the crop, more particularly for establishing
thinning recommendations; the trees have their crowns in the upper canopy but
are less free than the dominants.
Composition-of a forest crop or stand the representation of tree species in it.
Expressed quantitatively as % by volume or BA of each species.
Cord-a unit of gross volume measurement based on external dimensions. A
standard cord contains 128 cubic feet and generally implies a stack 4 x 4 feet
vertical cross-section by 8 feet long.
Crown-the upper part of a tree or other woody plant, carrying the main branch
system and foliage.
Coppice shoot-any shoot arising from an adventitious or dormant bud near the
base of a woody plant that has been cut back.
Coppice system-silvicultural systems in which crops originate from shoots,
suckers or seed and the rotation is generally short.
Crown class-any class into which the trees forming a crop or stand may be
divided on the basis of both their crown development and crown position
relative to the crowns of adjacent trees and the general canopy.
Dendrometer-generally, any instrument for measuring or estimating the
dimensions of trees or logs.
Diameter tape-a tape measure specially graduated so that the. diameter may
be read directly when the tape is placed around a tree stem or log.
Dominant-typically a species which exerts the greatest influence on its
character because of its life-form and/or great abundance. Generally, an
individual or species of the upper layers of the canopy.
Epicormic branching-a shoot arising spontaneously from an adventitious or
dormant bud usually in response to light.
Even-aged-of a forest, crop or stand composed of trees having no, or
relatively small differences in age. By convention the maximum difference
admissable is 10-20 years.
Extensive forestry-the practice of forestry on a basis of low operating &
investment costs per acre.
Forb-any herbaceous plant that is neither a grass nor at all like one.
Forest-generally, an ecosystem characterized by a more or less dense &
extensive tree cover. More specifically, a plant community predominantly
of trees and other woody vegetation, growing more or less closely together.
An area managed for the production of timber and other forest produce, or
maintained under woody vegetation for such indirect benefits of catchment
areas or recreation.
Forest type-a category of forest defined by its vegetation, size and density.
Ground cover-herbaceous plants and low shrubs occupying an area.
Growing stock-all the trees growing in a forest or in a specified part of it,
generally expressed in terms of number or volume.
Hardening off-the natural process of adaptation by plants to cold, drought,
etc.; or preparing seedling or rooted cuttings in a nursery for transplanting
or planting out by gradually reducing watering and/or shade and/or shelter
and thus inducing changes in the leading shoot that render it more resistant
to desiccation, cold, etc.
Hardwoods-a term for the timber of broadleaved trees and the trees themselves,
belonging to botanical group Angiospermae. Hardwoods are almost invariably
distinguished from softwoods by presence of vessels in their timber.
Herb-any seed-producing plant that does not develop persistent woody tissue
above ground, i.e., includes both forbs and grasses.
Histogram-a graphical representation of a frequency distribution in which
rectangles proportional in area to the class frequencies are erected on
sections of the horizontal axis, the width of each section representing the
corresponding class interval of the random variable.
Hypsometer-any instrument for measuring the heights of standing trees or their
stems from observations taken at some distance from them.
Hydric-of sites or habitats characterized by decidedly moist or wet conditions.
Increment-the increase in girth, diameter, basal area, height, volume, quality
or value of individual trees or crops.
Increment borer-an auger-like instrument with a hollow bit and an extractor,
used to remove thin radial cylinders of wood from trees having annual growth
rings, so as to.determine increment and age.
Intensive forestry-the practice of forestry so as to obtain a high level of
volume and quality through the application of the best techniques of silvi-
culture and management.
Intermediate tree-trees with crowns either below or extending into the crown
cover formed by co-dominant or dominant trees, receiving little direct light
from above, and none from the sides.
Juvenile phase-the period during life of a tree 1) before flowering occurs,
2) before a mature type of foliage appears.
Leader-the terminal, topmost shoot characteristic of the growth of plants or
trees. Forked growth is the development of two or more leaders often the
result of injury.
Litter-the uppermost layer of organic debris on a forest floor. Essentially
the freshly fallen or only slightly decomposed vegetable material, i.e.,
foliate, bark, twigs, flowers, fruits, etc.
Log scale boardfoot-a unit of measure of the content of a log or run of logs
in boardfeet determined by tables showing the estimated or calculated
amount of lumber that can be sawed from logs of a given length and top diameter
Mean annual increment (MAI)-the total increment up to a given age divided
by that age.
Merchantable height-the height above ground or above stump height, to which
a tree stem is saleable.
Mesic-of sites or habitats characterized by intermediate moisture conditions,.
i.e., neither decidedly wet nor decidedly dry.
Milacre-an area of 1/1000 acre. A common unit of area in vegetation and
regeneration studies, using quadrats.
Mixed-an adjective used to described .a forest crop or stand, composed of
two or more species; by convention, generally to the extent of: 20% of
species other than principal one based on numbers, BA or volumes.
Monoculture-raising crops of a single species, generally even-aged.
Mor-a layer of organic material lying on the surface of and unmixed with
the mineral soil.
Mortality-the volume of trees that were in a stand initially and have died.
Mull-a soil whose upper mineral layer has become intimately mixed with
amorphous organic material.
Multiple-use-any practice of forestry fulfilling two or more objectives
of management, i.e., timber production and watershed.
Natural selection-part of the evolutionary process resulting in the survival
and reproduction of the best adapted individuals.
Overstory-that portion of the trees in a forest of more than one story,
forming the upper or uppermost canopy layer.
Periodic increment-the increment during any specified period commonly 10-20
years. Calculated as the size of the tree at the ending of a period minus
the size at the beginning divided by that .# of years.
Plantation-a forest crop or stand raised artificially, either by sowing
Podzol-a soil characterized by a superficial layer of raw humus above a grey
A horizon of mineral soil depleted of iron and aluminum through leaching.
The leachates accumulate in the B horizon.
Pole-a young tree of not less than 4 in. dbh and usually 8-12 inches dbh.
Post-a length of timber generally round or square cut used as a pillar or
other support in building.
Productivity-the ratio of amount of output to the total time and money
spent on production.
Reaction wood-wood with distinctive anatomical characters, formed by leaning
or crooked stems in branches.
Reconnaissance-a preliminary inspection or survey of a forest to gain general
information useful for future management. The sample generally is less than
10% by area to determine timber volumes within the forest.
Residual-a quantity remaining after some other quantity has been extracted.
Rotation-the planned number of years between the formation or regeneration of
a crop or stand and its final cutting at a specified stage of maturity.
Sapling-a young tree no longer a seedling but not yet a pole. Usually a few
feet high and an inch or so in dbh, typically growing vigorously and without
Second growth forest- Forest growth that has come up naturally after some
drastic interference with the previous forest crop, i.e., fire, insects or
Seeding-a young tree or shrub grown from seed from its germination up to
the sapling stage.
Silvics-the study of the life history and general characteristics of forest
trees and stands with particular reference to environmental and local factors,
as a basis for silviculture.
Silviculture-the art and science of growing and tending forest crops. The
theory and practice of controlling the establishment, development, growth
and regeneration of forests.
Site-an area considered in terms of its environment, particularly as this
determines the type and quality of the vegetation present.
Site index-a measure of the capacity of a site to produce forest trees,
expressed in terms of the height attained by dominant trees at a given age.
Slash-the residue left on the ground after felling and tending and/or
accumulating there as a result of storm, fire, girdling, and poison.
Snag-a standing dead tree from which the leaves and most of the branches
Softwood-a conventional term for both timber and trees belonging to the
botanical group Gymnospermae.
Specific gravity-the ratio of the ovendry weight of a sample to the weight
of a volume of water equal to the volume of the sample at some specific
Sprout-a shoot arising from the base of a woody plant, whether from the stool
or as a sucker.
Stand-a community of trees possessing sufficient uniformity as regards
composition, constitution, age, spatial arrangement or condition, to be
distinguishable from adjacent communities, so forming a silvicultural or
Stand density-a quantitative measure of tree stocking, expressed either as
a coefficient, basal area or volume in relative terms. In absolute terms,
it is expressed in number of trees, basal area r volume/area.
Stock-a group of plants of common lineage, which although not taxonomically
distinct from others of the species or variety, are distinguishable on the
basis of productivity, vigor, resistance to disease or other ecological
or physiological characters.
Structure-of a forest crop or stand, the distribution and representation of
age and/or size particularly diameter- classes and of crown or other tree
Stumpage-standing timber as viewed by an exploiter. The value of timber
as it stands uncut, in terms of an amount per cubic unit.
Suppressed-one of the four main crown classes recognized on a basis of
relative status and condition in the crop trees that have their crowns in
the lower layers of the canopy.
Sustained yield-the yield that a forest can produce continuously at a
given intensity of management.
Taper-the decrease in thickness, generally in terms of diameter, of a tree
stem or log from the base upwards.
Tensionwood-reaction wood formed on the upper sides of branches and stems
of dicotyledonous trees, and characterized anatomically by lack of cell wall
lignification and often by the presence of an internal gelatinous layer in
Thinning-a felling made in an immature crop or stand in order primarily to
accelerate diameter increment but also, by suitable selection, to improve
the average form of the trees that remain.
Tolerance-the ability of an organism or biological process to subsist under
a given set of environmental conditions.
Transpiration-the process by which water vapor passes from the foliage and
other parts of a living plant to the atmosphere.
Tree-a woody perennial plant, typically large and with a single well-defined
stem carrying a definite crown.
Understory-trees and wood species growing under the canopy formed by others.
Herbaceous and shrub vegetation under a tree canopy.
Unevenaged-of a forest, crop or stand, composed of intermingling that differ
markedly in age. A minimum of 10-20 years is generally accepted.
Windthrow-uprooted by wind.
Witches' broom-an abnormally bushy, local growth of parts of the branch system
on woody plants characterized by shortening of the internodes and excessive
Wolf tree-a vigorous tree, generally of bad growth form, that occupies more
growing space than its value warrants, so harming or threatening to harm,
potentially better neighbors.
Xeric-of sites or habitats characterized by decidedly dry conditions.
Yield-the harvest, actual or estimated, of trees and stands, expressed by
board feet, or a proportion of the standing crop.
terminology of forest science, technology practice and products. F.C. Ford-
Robertson (ed.). Society of American Foresters. 1971.
ae Acid equivalent The weight in pounds of the active ingredient or
Annual plant Plants that complete their life cycle in one year.
Band treatment Applied to a continuous restricted area such as on or along
a crop row rather than over the entire field area.
Basal treatment Applied to encircle the stem of a plant above and at the.
ground so that foliage contact is minimal.
Biennial plant Plants with a two year life cycle.
Broadcast treatment Applied over an entire area.
Brush control Control of woody plants such as sprout clumps, shrubs, trees,
Cambium Tissue lying just under the bark which produces new wood and bark
cells in the tree.
Contact herbicide A herbicide that injures plant tissues upon contact.
Concentration The amount of active ingredient or herbicide equivalent in a
quantity of carrier (such as water, oil, or dust) expressed as percent,
Ib/gal, ml/L, etc.
dbh Diameter breast height -Diameter of trees at a point 4 feet above
Directed application Precise application to a specific area or plant organ
such as to a row or bed or to the lower leaves and stems of plants.
Dormant season That period of the year when plants are not actively growing,
generally from-late autumn through the winter months..
Emulsion The suspension of one liquid as small drops in another liquid
(for example, oil dispersed in water).
Ester A formulation of a herbicide made from an acid plus an alcohol. Ester
formulations are in the oil phase.
Foliar application Application of a herbicide to the leaves or foliage of
Formulation A herbicidal preparation of active and inert ingredients supplied
by a manufacturer.
Frill Series of overlapping axe cuts completely around the circumference of
trees. Axe cuts can be filled with herbicide from any suitable container
if tree injection equipment is not available.
Granule or Granular A dry formulation of herbicide and other components
as small particles, generally less than 10 cubic millimeters.
Growing season That period of the year when plants are actively growing,
generally from early spring to autumn.
Hardened off Term denoting stage of plant development when terminal buds
have formed and stem and root tissues have ceased growth. Dormant
stage of pine seedlings is often denoted by purplish or bronze colored
Herbicide A chemical used for killing plants or severely interrupting their
normal growth processes.
Label All information printed on or attached to the herbicide container.
It contains the brand name, amount of active ingredients, contents,
manufacturer's address, registration numbers, hazard warnings, direc-
tions for use, and emergency first aid measures.
Metering injector Tool designed to pierce tree bark and release a small
measured amount of undiluted herbicide.
Mistblower A power sprayer that is capable of producing a spray of very
small droplet size.
ml milliliter 1/1000 of a liter. 14.8 ml = 1 tablespoon = 0.5 fl. oz.
Non-metering injector Tool designed-to pierce tree bark and release an
unmeasured amount of diluted herbicide.
Nonselective herbicide A chemical that is generally toxic to plants with-
out regard to species (may be due to dosage rate, method of application,
Pellet -.A dry formulation of herbicide and other components as particles
usually larger than 10 cubic millimeters.
Perennial plant Plants that live for more than two years and may live in-
Persistent herbicide A herbicide which breaks down slowly and interferes
with regrowth of native vegetation.
Preemergence Prior to emergence of the specified weed or planted crop.
Preplanting application Applied on the soil surface before seeding or
Rate The amount of herbicide equivalent or acid equivalent applied per
unit area of other treatment unit.
Root collar Portion of tree stem at ground level or the junction of the
above- and below-ground portions of the tree.
Selective herbicide A chemical that is more toxic to some plant species
than to others (may be due to dosage rate or method of application).
Single-hack girdle A single line of overlapping axe cuts made through
the bark and into the wood. Same as a frill.
Spot treatment Application of herbicides to a small area.
Spray drift Movement of airborne spray away from the intended area of
Surfactant A material which favors or improves the emulsifying, dispers-
ing, spreading, wetting, or other surface modifying properties of
Translocated herbicide A herbicide that is moved within the plant.
Tree injection Method of placement of herbicides under bark into the
actively growing portion of the tree.
Vapor drift The movement of chemical vapors away from the area of appli-
Volatile herbicide A herbicide that vaporizes readily when applied at
normal rates and normal temperatures so that its vapors may cause
serious injury to desirable plants away from the site of application.
Weed A plant growing where it is not desired. Plants are considered
weeds when they interfere with activities of man or his welfare.
Weed control The process of limiting weed infestations or killing weeds
for aesthetic, economic, public health, or other reasons.
w_ Wettable powder A finely divided dry herbicide formulation that can
be suspended readily in water.
FOR 4162 Silviculture
Lecture Notes Supplement
This is the first in a series of handouts that will cover important
definitions and concepts that the student will find essential in understanding
the material presented in the accompanying lecture.
As the title suggests, this is to be used to supplement your notes, not
to serve as an outline to be filled in. These handouts were created with the
idea that the material, covered in them will save time (and writer's cramp)
during the lecture, and make the material available to you when supplementing
your notes at your leisure and, if you prefer, in your own words.
Lecture Topic: Silviculture Introduction
Silvics: The study of the life history and the general characteristics
of the forest trees and stands, with particular reference to
environmental factors as a basis for the practice of silvicul-
ture, i.e., tends to deal with the individual tree species and
their growth response in a variable environment.
Silviculture: The art and science of producing and tending a forest
through the application of knowledge of silvics; more speci-
fically, it is the theory and practice of controlling forest
establishment, composition and growth, i.e., the science of grow-
ing and reproducing permanent stands of timber as opposed to a
science of individual trees and species.
Multiple-use silviculture: The management of forest stands where timber
production is not the primary objective of stand treatments,
e.g., maintainTnigor improving forest amenities like watershed
protection, shelterbelts, wildlife habitat management, recrea-
tional vegetation management, disturbed land revegetation, and
forest commodities such as Christmas trees and maple syrup produc-
Intensive silviculture: The application of several unusual practices to
the establishment and management of plantations with the objec-
tive of increasing the quantity and quality of the wood produced.
Regional silviculture: The study of the significant biological, physical
and economic qualities of forest regions and their effect on
Primary objectives of silvicultural practices include:
control of species composition
control of stand density
control of forest growth
Secondary objectives of silvicultural practices:
protection and'enhancement of site
salvage and protection of forest crops
Normal silvicultural actions follow accepted principles, theories, and prac-
tices for enhancing the regeneration, growth, development and
utilization of forests for multiple benefits.
Silvicultural Processes. During the course of this semester we will cover a
number of standard silvicultural processes including the following:
seed tree cut
Hopefully, at the end of this semester, you should know the following about
what they involve.
when they are used
why they are used
examples of each, showing the variability in their uses.
Forestry 4162 Silviculture
Lecture Notes Supplement
The subject matter of silviculture is logically divided into three parts:
1. Reproduction cuts the purpose of these cuts is to remove the forest
crop and create an environment suitable for regeneration.
2. Intermediate cuts refers to the treatment of the stand during that
portion of the rotation not included in the regeneration period.
3. Protection of the stand against injuries.
In light of the above organizational breakdown, the first discussion topic
in lecture will center on intermediate cuts.
Lecture Topic: Release Cuts
Release:, a cut made in an attempt to free young stands of desirable trees
(saplings or younger) from competition by undesirable species.
Cleaning: cuttings made in sapling stands in order to free best trees
from undesirables which are likely to overtop them; a release cut in which the
desirable species to be released are of approximately the same age as those
undesirable species that are competing with the desirable species; i.e., the
whole stand being treated is of sapling age or younger.
Liberation: a release cut made in an attempt to free a young, desirable
stand from the competition of older, overtopping individuals, i.e.,
older trees are cut-to release young stand (sapling or younger) that
NOTE: After the trees pass from the sapling class into the pole class,
stand treatments fall into other categories and are no longer classi-
fied as a release treatment.
Release cuttings are conducted to regulate composition and to improve the
quality of very young stands. Typically an attempt is made to free young
stands of desirable trees from competition by undesirables. The method
of release (cutting, foliar herbicide, basal herbicide, stump herbicide,
soil herbicide, girdling) will vary with the management species, size/ex-
tent and species of competition, stand area, season of the year, environ-
mental setting and economics.
LECTURE NOTES SUPPLEMENT
ORGANIZATION OF INTERMEDIATE CUTS
NOTE: REFER.TO THIS WHENEVER IT IS UNCLEAR ABOUT THE ORGANIZATION
OF THE CUTS AND HOW THEY RELATE TO EACH OTHER:
- RELEASE CUTS
- IMPROVEMENT CUTS
-HIGH (CROWN) THINNING
- REPRODUCTION CUTS (COVERED LATER IN THE COURSE)
Lecture topic: Thinnings
Intermediate cuttings: the treatment of stands during that period not
included in the period of regeneration. They include release, improve-
ment, thinning, salvage, and pruning operations.
Crop trees: trees that are carried through the rotation. They are of
preferred or acceptable species, have a dominant position in the stand,
with excellent form and vigor. Very sound trees.
Storage trees: trees that are a little lower in priority. They may be
carried through part of the rotation, but will eventually by thinned
out to favor the crop trees. They are usually dominants or codominants
with good form and vigor, but are generally slower growers.
Surplus trees: trees that are of undesirable species and/or of poor form
and vigor. They are usually smaller than the others, are poor risks
and may be cull. If they are left in the stand, they will reduce or
add no value to it.
Understory trees: trees of preferred or acceptable species that are inter-
mediates or suppressed. These trees may comprise the future stand.
Thinning: Cutting made in immature stands in order to stimulate the growth
of the trees that remain and to increase the total yield of useful ma-
terial from the stand.
Low thinning: a cut that removes the lower crown classes to favor the best
dominant and codominant trees. Depending upon the severity of the cut,
only the poorest overtopped trees may be removed. Or, in a very heavy
cut, all but the best codominant and dominant are removed.
High (crown) thinning: trees are removed from the upper crown classes in
order to open up the canopy and favor the development of the most prom-
ising trees of these same classes.
Selection thinning: the dominant trees are removed in order to stimulate
the growth of the trees of the lower crown classes.
Mechanical thinning: trees to be cut or retained are chosen on the basis
of a predetermined spacing or pattern with little or no regard for
their position in the crown canopy.
Free thinning: cuttings designed to release crop trees without regard for
their position in the crown canopy. A method unrestricted by adherence
to any one of the other methods of thinning.
NOTE: There is often confusion when the terms "selection thinning," "selection
system," and "selective cuttings" are battered back and forth. This
may be of help in your comprehension of these often-misused terms.
"Selection thinnings" are intermediate cuttings designed for use in even-
aged stands to stimulate growth on the residual substratum (i.e.,
smaller trees, poles) and not to open the, canopy so as to permit re-
production on the forest floor. (Typically, the vegetative structure
produced by selection thinning is that of dense, intermediate poles
which in turn produce a dense, low shade and inhibits, rather than
promotes, the reproductive processes.) The objectives are to redistrib-
ute the growing space and secure the best returns in working with the
existing stand, not to replace it with a new stand. Selection thinning
does not alter the even-aged form of the stand or lead to the creation
of an all-aged stand.
"Selection system" is a silviculture system in which mature timber is
removed either as single trees or small groups (from here and there)
and repeated indefinitely at short intervals to stimulate reproduction
and create or maintain an uneven-aged stand.
"Selective cutting" is a type of exploitative cutting that removes only
certain species and size classes of high value; silvicultural require-
ments and sustained yield is largely ignored.
"Selection cutting" is annual or periodic removal of trees from an uneven-
aged forest in order to realize yield and establish a new uneven-aged
crop. (i.e., selection cutting is a method of applying the selection
system to the forest.)
--Five factors should be considered in a thinning program:
-Method of thinning
-Timing of cutting
-Residual stocking levels
-Method of control
-Removal of primary products
These factors tend to be interdependent and a function of economics and
natural limitations at each cutting.
--Each method of thinning is peculiar relative to:
-Trees favored vs. tree removed
-Advantages and disadvantages
-The conditions where it is best used
--In theory, the first thinning should be conducted as soon as competition
among trees begins. In practice, many silvicultural and economic cri-
teria are used to determine the timing of the initial thinning.
--Subsequent thinnings are determined by the growth rate of the residual
stand and economic considerations.
--Residual stocking levels will be determined by:
-site specific factors
(In general, maintain the greatest dbh growth possible without sacrifi-
cing ft volumes.)
--Thinnings are directed and controlled through the use of contract specifi-
cations and tree marking.
--The method of logging used in a thinning operation will vary with the
method of thinning, the desired products, and site-specific factors.
Lecture Notes Supplement
-Accelerate Growth of Residual Trees
-Concentrate Growth on Better Quality Trees
-Aid Litter Decomposition
-Harvest Potential Mortality
-Maintain Full Production per-Acre on Selected Trees
In Thinning we exercise selectivity, and that costs $.............. so the
value gained must pay back the costs at interest!
We temper Successional trends by:
-altering species composition
-insuring representation of species we might lose through natural
We temper Developmental trends by:
-eliminating small trees or making room for ones that might otherwise die
-reducing competition by reducing numbers /acre
-stimulating diameter growth to speed size development
DOMINANT -- crown extends above main canopy level
E -- full sunlight from above and at sides
-- well developed, large crown
largest diameters..., and good vigor
^ CODOMINANT -- crowns form main canopy layer
S- sunlight from above but restricted at sides
-- crown medium size...but not small
INTERMEDIATE -- crown reaches only into lower part of main canopy
-- full sunlight only PARTLY from above at best
S-- crown small and crowded (constricted)
OVERTOPDED -- entirely below main crown canopy
-- no direct sunlight
L- -- usually the smallest trees with poorly developed crowns
-- low vigor
Some GOALS of Thinning:
-Provide more "space" for selected trees (Space = Resources)
-Concentrate the growth potential on these selected trees
-BUT maintain sufficient stocking to capture FULL productive potential
-Harvest potential mortality trees
vet' / n-1rnc
Individual tree response shows up as.....
Increased DIAMETER growth.....,
......Thinning does NOT stimulate added
quality "controls" height growth
stand-wide height growth.....site
For Thinned Stands a Production Function Looks Like:
_ __ __
To test the concept that to maximize fiber production over the long run, we
harvest at the culmination of mean annual increment:
Unthinned stands (from Gingrich -- for SI-65)
MAI peaks at 55 years when an upland oak stand has 3100 cu ft per acre
so, two 55-year rotations for fiber gives 6200 cu ft but one 110-year
rotation yields only 5150 cu ft.
To check that thinning does not increase yields of fiber crops:
Age Cu Ft Cut
Age Cu Ft Cut
2115 from thinnings
Based upon data in Gingrich 1971. U.S. For. Serv. Res. Pap. NE 195.
Intensity of thinning.......how much you remove or leave
Method of thinning.......the approach taken and types of trees removed or
METHODS OF THINNING
-- Grade A.....remove overtopped
-- Grade B....remove overtopped + intermediates
-- Grade C....remove overtopped, intermediates and some
-- Grade D....remove overtopped, intermedidates and most
Crown Thinning -- Removes trees from middle and upper crown positions to
favor development of the most promising trees, with due regard to
L,4 Selection Thinning -- Remove all trees larger than some prescribed
l--ert ^ selective cutting diameter limit, leaving the smaller ones to grow
Mechanical Thinning -- Where spacing dictates the choice of residuals
Spacing Thinning -- Leave residuals at fixed, regular spacing intervals
and remove ones from around them
Row Thinning -- Leave trees.in designated rows and cut away intervening
.' Tree Thinning -- Find Crop trees that fit your standards and release them
,f< ,A #' as needed by taking out competing trees....leaving any that do not
Affect the crop trees
AND STAND DIAMETER DISTRIBUTION CHANGES THIS WAY:
-- --- r
KEL C 7/ OV
Early thinning allows most flexibility, because tree crowns and vigor seem
less irreversibly fixed.
A thinning PROGRAM for a stand sets up the times for and methods of thinning
to insure continuous optimum tree growth and stand production, plus regulate
the flow of intermediate products from the stand....
.....so it stimulates growth of trees that remain
recovers useful materials from the intermediate-aged stand
WITHOUT permanently breaking open the canopy layer.
A thinning regime for a stand provides for:
--continuous stimulation of the growing stock
--timely harvest of potential mortality trees
And this leads to:
--uniform diameter growth of the selected trees you favor
--faster diameter growth of the residual trees
--realization of the full potential yields from the site
S\ N MEr
Schedule a first thinning so you maximize the economic gain (profitability)
for the stand over the long run.
Optimum thinning intensity attains maximum individual tree growth suitable for
the intended product but commensurate with the maintenance of full net
production per acre.
Thin BEFORE competition builds again to result in appreciable mortality and
before crop tree growth declines appreciably
We have NO standardized thinning regimes for all places
We have NO standardized residual densities for all places
We have NO single method of thinning that satisfies all needs
You should prescribe a program for each stand to fit thanners
Lecture Notes Supplement
Lecture Topic: Improvement and Salvage Cuts, Pruning
Improvement Cuts: Cuts made in stands past the sapling stage for the pur-
pose of improving composition and quality by removing trees of undesir-
able species, form, or condition from the main canopy.
Salvage Cuts: Cuts that remove trees from the upper crown classes that
have been or are in imminent danger of being killed or damaged by in-
jurious agents other than competition between trees.
Pruning: The shedding of branches from the bole of a tree, either by
natural or artificial means, for the purpose of creating clear, knot-
free wood in subsequent years' growth.
-Improvement cuttings are correcting mismanagement (or no management) in the
past. If liberation or cleaning operations had been applied earlier, timber
stand improvement (TSI) could largely be avoided and the stand produced would
have been in better condition.
-In salvage cuts, if dead or dying trees are removed from the lower crown
classes, we would call it thinning by definition because competition was the
initial cause of death.
-In a salvage cut, if the trees are being removed for the purpose of protec-
ting the stand from insects or disease, then the salvage cut can be further
qualified as a sanitation cut.
--Improvement cuttings should be conducted as needed to improve the quality
and composition of the stand; however, the exact timing will likely depend
upon the merchantability of the material or the amount of money available
--Salvage cuttings are largely conducted to minimize financial losses, there-
fore they are generally only conducted when an operation is economical;
i.e., will pay for itself.
--Good judgment must be used in applying a salvage cutting. There is no rea-
son to develop an understocked stand as a result of such cuttings unless it
is for reproduction purposes (i.e., consider the alternative results of a
salvage vs. a regeneration cutting).
--A successful salvage cutting requires that the operation be completed before
the wood deteriorates. The rate of deterioration varies by species as does
value. The order of species salvaged should optimize economic income.
--The primary objectives of pruning are to produce knot-free lumber or veneer
and to promote tight (rather than loose) Knots in lumber.
--A properly conducted live pruning removes those branches which use more
photosynthate than they produce (i.e., growth should not be reduced).
--Application of pruning requires consideration of the value, form, and growth
of individual trees. Further, the timing of the operation relative to sea-
son of year and rotation age must also be considered.
Lecture Notes Supplement
Selection System attempts with EACH cutting to:
1. Create a new age class
2. Tend the stand to maintain a proper distribution of age classes
3. Harvest the mature age class
And in a balanced uneven-aged stand each age class occupies an equal
proportion of space
Selection Reproduction Methods include:
-Individual tree selection method
-Group selection method
Balance among age classes in uneven-aged stands achieved by influencing the
distribution of diameter classes through tending operations
During each cut remove:
-The mature age class & REPLACE it with regeneration of a NEW age cass
-The EXCESS numbers per diameter class so you more effectively allocate
growing space among residuals of that class...(or this amounts to taking
out the numbers needed to balance ground space among the age classes).
What trees to keep among the immature ones:
-Those of BEST quality, soundness, & vigor
-Those offering the BEST risk for future survival & growth
-The BEST species
What trees to cut by priority (among immature classes):
1st The defective & diseased trees
2nd High risk trees that might not survive another cutting cycle
3rd Low value trees of any species
4th Least desirable species
5th Excess numbers of good trees of the desired species
And do this within limits of your plan to balance the diameter distribution so
you actually allocate equal ground space to each age class
SELECTION SYSTEM -- CONTINUED
Wise use...now...in moderation...to have some for the future
The best TIME to use resources relative to the future...deciding to use
NOW or LATER...putting this into perspective
For renewable resources like timber, conservation means applying a silvicultur-
al system so we can use the resources NOW with assurance we will produce more,
on time, for the future
MINIMUM ecological standards...so we do not cause an irreversible ecological
harm over the long run...
-Continuous vegetative cover (trees after trees)
-Safeguard major landforms (especially drainages)
(Given these, we should expect NO irreversible ecological change)
INDIVIDUAL TREE SELECTION:
-Make opening to regenerate new trees in the space previously occupied by
individual mature trees
-Remove sufficient numbers of mature trees to cover the area allocated to
that age class
-Thin out individual immature trees to balance their distribution...redis-
tribute their proportional area among fewer trees so they grow bigger,
(This gives you a SELECTION SYSTEM!!)
This gets criticized due to:
-Inability to regenerate shade-intolerant species
-Unwillingness to invest in tending of small trees
-Unwillingness to invest in investor to determine the diameter distribu-
tion & needs for tending
-Sometime occurrence of clustering among mature trees
Group selection system:
-Identify family groups of mature & immature trees
-Harvest the mature groups from the intended cutting area...and no more...
to open the way for regeneration
-Thin the family groups of immature trees to maintain a balance among them
(And if done properly this gives you a selection SYSTEM!!)
SELECTION SYSTEM -- Continued
This gets praise because you can increase chances for regenerating shade-
intolerant species IF the group openings have a proper size & shape
This fails because:
-Trees don't always occur in family groups
-Inventory does not tell the amount of area in family groups...nor their
-Groups differ in shape, size, & distribution
-Unwillingness to tend immature groups
(And failure to achieve the latter makes it a mere diameter-limit type of
PATCH SELECTION SYSTEM:
-Apply individual tree selection & ALL that implies
-Insert a few patch cuttings to regenerate shade-intolerant species over
part of the regeneration area
-Figure patch cuts in as a part of the proportional area allocated to the
NEW age class
(And this compromise should give you a SELECTION SYSTEM, also!!)
OTHER PARTIAL CUTTINGS
Non-harmfull Cuttings do NOT:
-Upset soils or expose them for long times
-Plug up natural drainages or change landforms
Cuttings outside the silvicultural system:
-Give irregular yields of unpredictable amounts
-Take a chance on species composition of regeneration
-Accept non-uniform distribution of growing stock
-Make ownership an opportunistic endeavor
(...That is, you relax control & take what you get)
This is SELECTIVE cutting:
-Creaming, culling, or high-grading
-Exploitation that removes certain trees of high value
-Known silvical requirements AND sustained yield being wholly or largely
(See S.A.F. definition...)
Diameter limit cutting
Maturity selection removals
Vista & scenery cuttings
(Or any other cutting where you relax requirements of the silvicultural system)
(But hopefully some of these satisfy some other system...like wildlife manage-
ment system...watershed management system, etc...)
Features of Even-aged Systems:
-Trees compete with others of same age
-Fast early growth due to FULL sunlight
-Even competition across the stand
-Special ecological conditions that change as the stand matures
-Branching influenced by crowding
-Special thinning programs needed
-Complete removal at end of rotation
-New regeneration contains many shade-intolerant trees
-Repeated selectivity in thinning upgrades the growing stock
Other Partial Cuttings -- Continued
Features of Uneven-aged Systems:
-Trees compete with OLDER ones or have dominating positions depending on
-Early slow growth due to partial shading
-Heterogeneous competition across the stand, and that changes as the tree
-Stand ecological conditions never change...or change little
-Branching influenced by crowding & tree age (crowding changes over time
for a tree)
-Special felling & skidding needed to protect immature growing stock
-No complete removal...ever!
-Regeneration mostly tolerants
-Continued selectivity should upgrade growing stock
Features of Selective Cutting:
-No deliberate tending...trees may suffer from crowding
-Environmental changes irregular & unpredictable (Due to wide variance in
stocking across the stand)
-Harvest removes choice trees leaving poor & unmerchantable ones for the
future...plus some good ones, too
-Species composition & distribution of regeneration varies across the
stand...and in proportion to the degree of cutting at different places
-Lack of tending gives NO selectivity to upgrade the growing stock
-Stand ecological conditions difficult to predict
... PROPER PLANTING METHODS
Regardless of the method of planting, it is most
important to keep the tree roots damp at all times.
Carry the trees in a bucket with the roots under wet
moss or burlap. Take out only one tree at a time when
Bucket Damp moss covering roots
Plant the trees about one-half inch deeper than
they grew in the nursery. The old soil line can be
recognized by the paler colored bark on the stem
and also a slight bump or swelling at this point.
The hole or slit should be deep enough to
prevent curling or bunching up of the roots.
It is most important that the soil be firmly
packed around the roots after planting. Special
care should be taken to close the bottom of the
hole as well as the top.
Considerable time can be saved and root injury
prevented if a little time is spent separating and
sorting the trees before planting. Sorting should be
done in a shady place protected from the wind.
A. PLANTING BY MACHINE
Planting machines are usually limited to areas
that can be worked with farm equipment. Some of
the heavier machines pulled with a crawler tractor
can plant in heavy brush or rough terrain.
These machines plant at the rate of 800-1,000
trees per hour, so it is practical to use them only
on large plantings.
Since there are several types of planting ma-
chines, it is impractical to give machine planting
procedures here. Be sure the machine used opens
an adequate planting slit and that it packs the trees
in firmly. Before starting, get instructions on the
use of the machine from the local forester or the
owner of the machine. If planting is to be done on a
custom basis be sure the operators are trained,
B. PLANTING BY HAND
1-Planting with a Spud -
Insert spud straight
down and push for-
ward to an angle of
about 30 degrees
Lift spud slightly
in the some plane
Insert spud two
inches from last
Push forward and
Push spud down at
same angle in order
to obtain a new
Pull spud toward you
until it is straight up;
this will give you a
hole that is wide
at the bottom
Fill in last hole by
stamping with heel
Note: For best results hold tree to side of hole and
allow dirt to flow by it when hole is beingclosed.
Avoid wiggling spud back and forth as this will
result in an hour-glass shaped hole which is diffi-
cult to close. Pushing spud too far forward or
pulling it too far back will loosen soil around hole
and make setting of tree difficult.
2-Planting with a Mattock or Grub Hoe -
Set tree at correct
depth and remove
Insert spud about
two inches from
Drive grub into
ground; keep handle
parallel to surface
Lift handle 8"
slightly towards you
Pull handle back
slightly to close
bottom of hole
Push handle forward
to close top of hole
Slide hand to
grub head; pull
Place tree against aide
(not end) of opening;
shake down roots
4-Planting in a Furrow -
Stamp hole closed
-eave no air
3-Planting with a Shovel -
Place shovel with
concave side fac-
ing you; push
With shovel in nor-
mal position and
at 30* to ground,
push shovel in to
intersect first cut
grub; tamp soil
into hole with grub
.- -.*. :..' .- -: ..
Plow a furrow just deep enough to roll back
the sod; generally 3 inches to 4 inches is deep
enough. Use a shovel, spud or mattock and plant
in bottom of furrow next to the furrow slice. If
the land is sloping, plow on the contour.
VI -- PLANTATION MAINTENANCE
Once a plantation has been successfully estab-
lished it should be protected from grazing, fire,
insects, and disease.
Grazing is very detrimental to the planting. It
is one of the simplest problems to solve. All that
is necessary is a fence that will keep out the
Check periodically from mid-spring until fall
for signs of insects or diseases attacking the
plantation. If any signs are apparent, samples of
the damage or the fact that such a condition exists
should be brought to the attention of the forester.
On sites where the trees are in danger of be-
coming smothered with competing grass or brush,
plans should be made at the time of planting to
control them. On the heavier soils, you may wish to
cultivate the entire area. If heavy brush comes in
after planting you may have to keep it cut back
until the plantation is well established.
Selective herbicides have been developed and
may be used to control unwanted vegetation in the
plantation. For more information regarding these
herbicides, contact your forester or county agent.
After the trees have been planted for a year or
two, a survival count should be made. If the sur-
vival falls below 65 to 70 percent, the blank spaces
should be replanted.
2. Remove bar and
place seedling at
4. Pull handle of bar
toward yourself to firm
soil at bottom of roots.
7. Push forward
then pull backward
to fill hole.
Fig. 7-4. Steps in the use of the bar-slit method of planting
soil (Sketch by U. S. Forest Service.)
1. Drive grub hoe into 2. Place seedling against 3.
ground, lift handle, straight side at
and pull hoe back. correct depth.
4. Finish filling in
soil and pack
it with heeL
seedlings in sandy
Fill bottom of hole
and pack soil
5. Firm around
Fig. 75. The side-hole method of planting. (Sketch adapted from one by U. S.
9. Firm soil
with the foot.
lIable Seed characteristics of some selected tree species in the United States.
GOOD SEED CROPS
AVG. NUMBER SEEDS
lEMP. (oF.) DURATION
White Pine (E.)
No. Red Oak
Intonation was taken front Seeds of Woody Plants in the United States. U.S.D.A. Handbook No. 450.
Repr c_ ucI'S~t~
I. Cc...c,- .
A. A l\--a* -. S4-.~;'p
C-e.ar. ivterval be+%-4eK
stes.c ss ive adj scey+ *fe)litr.
Cwseu.;l i~ -.ed a r,*- )
MtfI: VoI ca(l Caf
uhetJ t a.q e i
Ca cv6l'4-ro'ss ,
..= ws8- 0- 1 --
F"" % a.\I k eJ!cv%'o
Ftr. o6. Forst worked under the election Iytem.
Mb. d i CceI c0 l,
(. l e
3z. Gv-Oe reCle.-ow
3, SiY p se-lechov
81 l' 17
1. pv-ro v je iee S 4-sep
. . ,
TIn. Sk\e.el.vLrw ood
A. U M'-vwCSvm SWe t u
A- old Crop wi-k
B. Secadlv 4f9-ll
Sf~AC `Ce* 4 bpOCILC^'dA)
C ,v .I' ,
Reg. a~h, a a.)(
S. S4*o rKe Ier-sked
Fie. is. Uniform system,'showing successive stage of generation in beech fomst. a,
old crop with closed canopy, prior to seedin fellio b, ~eedi stage c, secondary staue
', fnal stage p ; young rgenerated crop.
t mfttNtt-ft trt
ttttttt tt ....t.
e ttt t .. ...i
tHif sTI I .......ummnM mutetriltg laa s I
Ft.* 37. Shelter-wood strip system, showing process of felling through a cutting section.
s,. severance cuttings; felling direction w,, wind direction.
C. (SvouP e
A. Twd-hl aI <^
WI+k Ivow. o
5. C. D.- SiCcez$ ie.
S4-..leJ o- em ixyv.-
0 L4- *%4...
ttItt W Ett
Fzc. Group system, showing sucauive tages of eenerurado. a, initial pps, with groups
of advance growth b d, sucesivesta iu of enlargment of groups I regemoeted young
crop, showing wavy outline
\ I.d+'Jid.'a.l r9. ~re ,eosl
=-Cfu, +, le.M..u Ip ,.)
jIT. ^r \ kmaMI I GCA
+0o C& +~Sl^e
---~-- --Y~8~gtrammrr-r_~ ~I,
. rce J Sprc.C G s;+o.
-V.w. seeA, 3 4elfa
?., te e .n ey.+ .
W. R 4ewuta6 o+
($bkvr+) o.lJ Spv~c-
P P~o aers.
Re. eP k*L pet 8ce
~~~,~~~~ ~eh~ 5LOCL
;'rC~L~. (9.&aYlk C
t -t t t f T
Fla. 3s. Swim Fetmehrc s.howingt success stage of egeneration in mired forest of
spruce, silver fr, and beech a, mixed crop 4o-o years old averagee 6o years), ready for
generation to begin; b, beech regeneration appearing a the rmilt of a seeding llihng I e,
reeneration of beech and silve r establishing itself, and spruce appearing in gps ; d, young
crop with selected tra of the old wood retained for incrment purposes young crop up to
So year of age, after the nal felling, showing irregular appearance.
4.W etrS lenje.vra wm ch 4 6902.)
rp4e a s+'ip S1s5tEOti co'r-*'? o*.t
" V\&a"Ow She f1+uao J+Ir.sI ey+e% 'K<
A 1k. e- "arCtf1ob ad ad uaCIq 9
"6M 1-W The objec b4 se +e
is 4-to C.V^d1 S'%. p4tio as -
'the s -o -t see dJi v.I "Ik ip
0 4%eide v5 4a $ dMaib+&
ivbc.ftvISt. b;aC b"4 VA l
$9.iw\- b.' ,?&l(rqxS aei;an
A+ C6V. %teveK a^ op 'tt
0-- aKljs bk ar.
+ "r Y'tr S, .
S+nrip Sleczt em Ss+<
Os 0= \14 a
Fo. 48. Wacr's BladersmawAklag. Step felling advancing from N. to S.
giving pomection against both sun and wind. f, felling direction i q, wind
direction s old wood I r, regenerated a.
.Sp~e~ Sl'lrrrr k~
V tL 4 *G d DP 4cj
BKleAdecsalw scl f / -:S cj
Fla. p. Profile o portion of an organid Badrwmarmwa foret, showing three felling
units. ling dircion from N. to S. (Vertic scale about to times horizontal scale.)
'F. Wle.d. Skle.-1v.Aj
(T4 P b + -r 4srt
IBt T ia fe.Mc?)
TE. s. F< Ree*WW
C La u) A
Po. S. Wedge lin on leel ground, showing orgil strips (a nd
mequet =dadlen qa in.d du Tmaor. epo cat rar hon
by dotted line. Dotted arrows indicua direction of tbber emraction.
o A;peavrkce4 -4
) QV C a-h' 0K
I1. <&veLf SQteJ 'tbt
2. Tceeyv m.e 1^
3. 5 d -dz-.eP
v_. C fpae.
A- C ,p j.e
Ca'cLe Wt +,k
FIG. 72. Coppic with standards. a, immediately before ctting b, immediately after
cutting. Roation of coppice a yar I rotation of standards oo years. Numbers d.e
note aes of standards.
A. immedately b
13 T .Autef iaT M
e- J+-cnlvd d.
Oc-f+x- c.-"ilwS /4- eJ
a.re dcen-sa w +i-K
Introduction to Silvics
Purpose- Each tree species has characteristic growth and regeneration habits
and requires certain environmental conditions for satisfactory development.
These are called silvical characteristics. The silviculturist must know
how the environment will affect the growth and development of the trees he
wishes to manage.
1. To familiarize the student with the concepts of individual silvical
characteristics and how to relate them in the field.
2. To help the student understand the importance of silvical character-
istics as a base for the practice of silviculture.
Silvics- The study of the life history and general characteristics of
forest trees and stands, with particular reference to environmental
factors, as a basis for the practice of silviculture.
Life History- The growth and reproductive habits of a species, from the
germinating seed through old age, including susceptibility to
General Characteristics The typical morphologic characteristics and the
habitat conditions in which a species may be found, including
climate, soils, topography, and associated plants.
Forest tree A woody perennial plant typically large and with a single,
well-defined stem carrying a more or less definite crown in close
association with other trees to form a forest stand.
Forest stand A community particularly of trees possessing sufficient
uniformity as regards composition, constitution, age, spatial ar-
rangement or condition to be distinguishable from adjacent commun-
ities, so forming a silvicultural or management entity.
Environmental factors The biotic and abiotic factors of the total
environment that affect forest trees and stands. For example,
radiation, temperature, atmosphere, biotic, and edaphic factors.
Organization of Silvical Summaries A silvical summary is a condensation
of the major characteristics of species into a concise, orderly for-
mat for quick reference and comparison. It is by no means complete,
but contains the material most used in the application of silvics.
Each summary follows the general format of the outline below. An
accompanying slide presentation and lecture should provide an ex-
plantation and insight into each of the topics.
I. Natural Range
II. Habitat Conditions
C. Association species
III. Life History
A. Sexual reproduction
2. Seed production characteristics
3. Seed beds
B. Asexual reproduction
C. Growth and development
Silvical Summary (slash, longleaf, loblolly)
Application of Silvics
APPLYING SILVICS TO STAND MANAGEMENT -
SOME GUIDING CONCEPTS-/
William R. Harms-
Abstract.--Three concepts are proposed: (1) Any silvicul-
tural decision affects all future silvicultural decisions. Failure
to appreciate that silvicultural action influences environmental
variation and thereby tree and stand growth in complex and long
lasting ways can result in costly errors that may be difficult
or impossible to correct. (2) Bringing any growth factor closer
to its optimum level will increase production. Applying a know-
ledge of silvics to the concept of limiting factors can enable
the silviculturist to diagnose and often correct site and stand
conditions that prevent attainment of potential growth. (3)
Even-aged stands develop in a regular, predictable pattern. Six
distinct stages of development can be recognized: 1--regenera-
tion, 2-establishment, 3-precompetition, 4--competition/pre-
mortality, 5-competition/self-thinning, and 6--post competition.
At each stage there are needs and opportunities for silvicultural
intervention to maintain or improve growth.
Taken together, these concepts provide a rational basis
for developing biologically and economically sound silvicultural
Silvics is the study of the biology of forest stands and forest trees,
how they grow, reproduce, and respond to changes in their environment.
Silviculturists apply knowledge of silvics to control establishment, growth,
species composition, and quality of forest vegetation. Forming a useful
picture of the silvics of a species in specific situations is difficult,
however, because of the complexity of the many processes and.conditions
involved in plant-environment interactions.
In the broad expanse of the loblolly pine (Pinus taeda L.) ecosystem this
complexity looms especially large. The species occurs in the Atlantic and Gulf
Coastal Plains and the Piedmont Plateau, from Delaware and central Maryland
south to central Florida and west to eastern Texas. This range encompasses
substantial differences: (a) in the floristic composition of the forests,
(b) in the amount and distribution of rainfall, (c) in temperature and length
of growing season, and (d) in soils, fertility.levels, and drainage. The
infinite number of possible combinations of temperature, light, soil properties,
nutrients, and moisture greatly complicates our understanding of tree growth.
But to this must be added the further complications imposed by the variety of
purposes that silviculture must serve, such as wood and fiber production,
recreation, watershed, and wildlife values.
l/Paper presented at the Symposium on the Loblolly Pine Ecosystem (East Region),
Raleigh, NC, December 8-10, 1982.
S/Research Forester, USDA Forest Service, Southeastern Forest Experiment
Station, Forestry Sciences Laboratory, Charleston, South Carolina 29407.
In practice, complexity is reduced because a silviculturist deals with
only one area at a time, and on each area species combinations and manage-
ment objectives are restricted. But even where loblolly pine is grown in
even-aged stands on specific sites, the situation is complex enough'that
successful management requires a firm grasp of the interplay among stand
growth and development, the enviornment, and silvicultural manipulations.
In focusing on a particular forest property, site, or stand, silvicul-
turally important factors can be grouped into four categories: (1) factors
universally present such as solar radiation, carbon dioxide, soil, and water
which respond little if any to manipulation; (2) factors which are site
specific and can be modified by silvicultural techniques such as species
composition, stand density, local soil moisture and nutrient levels; (3)
factors from the first two groups that are at critical levels or limiting
for growth; and (4) factors inherent in the species that relate to the
primary silvical attributes that govern growth responses, such as tolerance
to shade, tolerance to competition, and tolerance to site extremes in mois-
ture and nutrients. All four groups of factors must be considered in devel-
oping a silvicultural prescription.
There are two major sources of published information about these factors
as they relate to loblolly pine. Wahlenberg's (1960) monograph is most
comprehensive; it treats all aspects of biology, ecology, and silviculture in
considerable detail, and is in no way out of date. A short, but also very
useful, summary of facts is given in the "Silvics of Forest Trees of the
United States" (USDA Forest Service 1965). The monograph by Brender (1973)
is another useful, but geographically restricted, source of information.
In this paper, I present some concepts about use of silvical knowledge
in the management of loblolly pine stands for wood and fiber. There is little
that is new in these ideas, and all are subject to interpretation, but together
they provide a basis for guiding the silviculturist in applying knowledge of
the silvics of loblolly pine to optimize stand growth and yield.
1. In General, any Silvicultural Decision Affects all Future Silvicultural
Foresters are aware that most cultural practices have short- and long-
term implications for management. For example, the density at which a stand
is established will affect final yield and determine the need for thinning.
The complex interacting effects may not always be appreciated when silvicul-
tural prescriptions are written, however.
The usual silvicultural measures for achieving the aims of management
can be grouped as (a) regeneration and establishment of the stand, (b)
tending the stand during the rotation, mostly through competition and density
control, and (c) site amelioration, that is, maintaining or creating an
optimum environment for growth. The effectiveness of these measures is
evaluated in terms of survival and tree growth. The problem is one of pre-
scribing the silvicultural actions and treatments that will produce the
combination of tree numbers and size that will maximize yield.
All the silvicultural measures can affect all tree responses. The
situation is further complicated by the fact that each of these measures
includes a variety of treatments whose effects will vary depending on past
and future treatments. The extent and complexity of the interactions are
diagrammed in Figure 1.
Figure l.--The silvicultural complex. A diagrammatic representation of the
interrelationships among silvicultural measures and tree responses. Relation
between measures and responses are shown by solid lines, and among measures
by dashed lines.
The common factors controlling this web of interactions are the ecosystem
processes and the nature of their response to silvicultural manipulation. In
the loblolly pine ecosystem we are dealing with an extremely variable environ-
ment, and with a species whose growth potential is very much a function of
The principle value to be obtained from this concept is an awareness
that silvicultural actions influence environmental variation and in turn
tree and stand growth in complex, long-lasting ways. Failure to appreciate
these influences can result in costly errors that may be difficult or
impossible to correct.
2. Bringing any Growth Factor Closer to its Optimum Level will Increase
Silvicultural prescriptions are, by definition, prepared for a particular
stand. The silviculturist first examines and describes the stand in terms of
such things as stand structure, species composition, soils, site quality,
microclimate and such site factors as will influence the kind of silvicultural
treatments that can be applied. He then must examine the information for
the presence of existing or potential problems that may affect management
objectives. In particular he must identify limiting factors, physical and
biological, that will affect growth. For loblolly pine such factors as
excessively wet or dry sites, eroded soils, soils low in nutrients, a heavy
understory or overstory of hardwood competitors, or an abundance of honey-
suckle and other vines, would signal problems.
The significance of limiting factors is expressed by the various laws
of the minimum such as those of Liebig and Mitscherlich (Kramer and Kozlowski
1979). In essence, these laws state that increasing any factor that is below
its optimum will improve the rate of growth, but increasing the factor farther-
est from the optimum will give the greatest increase. An example of the
application of this concept to loblolly pine is the suggestion made by Langdon
and McKee (1981) that in certain situations fertilization of wet sites
deficient in phosphorus, calcium, nitrogen, or other nutrients can reduce
the need for drainage to improve growth. They have proposed a relationship
between site productivity, soil moisture and nutrients, based on the idea of
limiting factors, to explain the responses to drainage, bedding, and fertili-
zation that have been reported in the literature (fig. 2).
We know from basic knowledge of the factors involved that site productivity
is dependent on soil moisture and nutrient availability and their interactions.
On very dry sites, nutrients are less critical than moisture because lack of
water adversely affects all physiological processes and conditions--chemical
as well as physical. As moisture becomes more plentiful, nutrition plays an
increasingly greater role in determining productivity. Where a site is too
wet, however, chemical reactions caused by lack of oxygen in the soil change
the availability of nutrients, in some cases causing deficiencies and/or
toxic reactions. The usual correction for this condition is to remove excess
water by drainage or bedding. However, Langdon and McKee point out that
nutrients may be more limiting than water on some sites, in which case
response to fertilizer may, up to a point, obviate the need for costly
drainage (fig. 2).
Some limiting factors cannot be reasonably eliminated: irrigation of
drought sites to relieve moisture deficits, for example, is not normally
cost effective although in some situations eliminating competing vegetation
may give short term relief (Zahner 1968). On the other hand, loblolly is
( Y Y 4
.__ _______ I
CVEH PC0.7 rAet
CVEn wC.L CRAVnI
Figure 2.-An hypothesized relationship between site productivity, soil
moisture, and nutrient availability. A site of low nutrient availability
at point A, when drained would increase in productivity to B, while ferti-
lizing to medium or high levels would raise productivity to C or D without
drainage. Within the region E, drainage as well as fertilizer is necessary
(Langdon and McKee 1981).
intolerant of shade and release from competing and overtopping hardwoods
has been shown to pay large dividends (Langdon and Trousdell 1974).
A working knowledge of a species' silvics and its environmental
requirements, and the application of the concept of limiting factors can
enable the silviculturist to diagnose, and often correct by cultural measures,
stand and site conditions that prevent attainment of potential growth.
3. Even-aged Stands Develop in a Regular, Predictable Pattern.
The growth processes responsible for stand development are controlled
by genetic and environmental factors acting on the physiological processes
of the tree. Silvicultural manipulations create and maintain, insofar as
possible, optimum conditions for growth by controlling environmental factors.
Since silvicultural manipulations are prescribed, and influence growth
over the lifetime of a stand, it is important that the silviculturist appre-
ciate and understand the dynamics of stand development. In the following
discussion, pure, even-aged loblolly pine stands are assumed. The trees are
uniformly distributed on a uniform site, undisturbed by silvicultural activi-
ties, excessive interspecific competition, or damage from such factors as
fire, insects, and disease. The development of such ideal stands serves as
a useful benchmark fromwhich to judge the effects on growth of disturbance
by management and other external influences.
Stand dynamics can be described in terms of a sequence of six distinct
developmental stages: (1) regeneration, (2) establishment, (3) precompeti-
tion, (4) competition/premortality, (5) competition/self-thinning, and
(6) postcompetition. Once established, the natural path or trajectory a
stand follows through time as it develops is the result of progressive
changes in diameter, height, and crown dimensions that take place as a
result of growth differences among the individual trees making up the stand.
As the stages indicate, competition is the major driving force in the develop-
Stand development is most easily understood by examining the changes
over time in number of surviving trees and quadratic mean diameter. Other
appropriate measures are basal area, volume, and biomass. The development
of hypothetical stands through the six stages is characterized below and
illustrated in Figure 3 for three density levels. Silviculturally important
conditions are also noted.
Stages 1 and 2. Regeneration and establishment.--The stand is created
during these stages either naturally from seed or by planting. Silvicultural
treatments are primarily preparatory. Potential seed crop is evaluated,
seed trees are released, preharvest site preparation such as burning is
conducted, or postharvest mechanical site preparation competition control,
and planting are done. Development of the new stand is characterized by
seedling root growth and growth of the photosynthetic system. The end of
the establishment stage is arbitrarily defined to be when mean stand height
reaches 4-1/2 feet, i.e., when the stand has measurable d.b.h.
Stage 3. Precompetition.-This stage covers the period from establish-
ment up to the time when competition between trees begins. Precompetition
is characterized by unrestricted growth. Mean stand diameter is increasing
equally for all density levels, and any recognizable size differences among
individual trees are the result of genetic variation, microsite differences,
and small differences in time of germination, or size of seedling at planting.
This is a period of rapid root and shoot growth; the developing crowns require
large amounts of nutrients, little of which are as yet returned to the soil
through litterfall (Jorgensen and Wells 1980). The site is not being fully
utilized by the pines, and much of the soil volume-is being taken up by
woody and herbaceous vegetation. During this stage, concentration of avail-
able nutrients can be a limiting factor controlling tree growth. A signi-
ficant amount of nutrients is tied up in the forest floor, and fertilizers
may be needed.
The stand trajectory during this stage follows a path of increasing
mean diameter and a constant number of trees.
Stage 4. Competition/premortality.--The more trees per unit of area
the sooner the precompetition stage will give way to the competition/
premortality stage. Theoretically, this stage can begin at stand establish-
ment if the seedlings are so close together that competition begins at once.
Stage 4 covers the period from the beginning of competition between trees
to the competition of crown closure when competition-induced mortality begins.
During this period the crowns continue to enlarge, differentiation into
crown classes begins, and the root systems, presumably, extend to fully occupy
the soil. As the crowns and root systems enlarge, competition for space,
moisture, and nutrients begins to reduce the growth rate of individual trees.
The silvicultural considerations during this stage are to reduce competi-
tion: by precommercial thinning if the stand is young, by a commercial cut
if the stand is old enough and trees are large enough to provide one.
The stand trajectory continues to follow a path of increasing diameter
and constant number of trees. Because of intensifying competition, however,
there is a reduction in mean diameter growth compared to stands of the same
age that are less dense and therefore still in the precompetitive stage.
Stage 5. Competition/self-thinning.-The self-thinning stage begins
when the stand completely occupies its growing space, i.e., when crown closure
is complete and branches at the base of the canopy are dying from lack of light.
The photosynthetic surface approaches a maximum at this stage. Competition
for light, moisture, and nutrients has reached the point where the smallest,
weakest, trees are no longer able to obtain sufficient amounts for growth,
and they begin to die. The root and crown space they release is soon occupied
by the remaining trees. Growth, competition, and mortality become continuing
and controlling factors in development of the stand. The development trajec-
tory continues to follow a path of increasing mean diameter, but because of
the thinning process, number of trees is no longer constant; rather, it is
After a stand has been self-thinning for a time, a pattern emerges in
which the relationship of mean stand diameter to surviving number of trees
becomes linear on a log-log scale (fig. 3). Many species of plants grown in
pure even-aged stands have been found to follow this pattern (Yoda et al.
1963). It has also been found, with all species so far studied, -that the
slope of the log-linear portion of the self-thinning curve varies but little
from the value of 3/2, where mean plant dry weight rather than d.b.h. is
used. The only difference between species appears to be in the height of
the line above the horizontal axis; and for any given species the height
appears to be independent of site quality (White and Harper 1970). This
implies that a stand on a low quality site will take longer to reach the
self-thinning line than a stand of the same species and density on a better
site, but .that both stands will reach it with the same mean d.b.h. and number
of stems. This relationship, known as the 3/2's power law of self-thinning,
was first described by Japanese researchers (Yoda et al. 1963). When plotted
as numbers of trees over diameter, the relationship is equivalent to Reineke's
(1933) stand density measure.
Taking into consideration the self-thinning law, even-age forest stand
development can be generalized to cover all stand densities at which competi-
tion will sooner or later be a factor. Stands of a particular species will
tend to follow trajectories that eventually bring them to the same limiting
line defined for that species by the self-thinning law. Once on the line,
all stands will follow it for the duration of the self-thinning stage.
Fi e 3.-The dynamics of even-aged stand development. Development trajec-
tories as expressed by change over time in mean stand dbh and number of trees
per unit area are shown by (-). The relationship of mean stand dbh to density
in same aged stands is shown by (--). See text for explanation.
The self-thinning process maintains full biological occupancy of the
site and the 3/2 pover law defines the limiting density. Thus, for a given
number of surviving trees, there is a maximum mean stand diameter that cannot
be exceeded except by a reduction in number of stems to allow for continued
growth. It follows that stands at their limiting density will tend to be
producing maximum biomass for a particular combination of mean diameter and
number of trees.
The implications of the self-thinning stage are obvious. Such stands
are overstocked, potential yield is being lost to mortality, trees established
at some cost will not be harvested, and competition is having its maximum
impact on the growth of individual trees. The silvicultural strategy is to
avoid this stage either by periodically reducing density to a premortality
state by planned thinning, or by prescribing and establishment density so
as to attain rotation age short of self-thinning.
To properly plan establishment density and intermediate cuts, a knowledge
of stand dynamics and of growth rate in relation to site quality must be
applied. As pointed out above, the height of the self-thinning line appears
to be a species constant; the critical idea for the'silviculturist is thus
the rate at which a stand approaches the line. In general, the better the
growth the faster the approach. Inherent site productivity and treatments
such as drainage, fertilization, and thinning are all factors that will
influence rate of development and hence should influence decisions regarding
establishment density and the need for thinning.
Stage 6. Post mortality.--The self-thinning stage ends at some ill-
defined time when stand growth slows because of aging. The need for an
increasing growing space decreases, overall mortality declines, and mortality
attributable to disease and declining vigor becomes more important than
mortality due to competition. During this stage, yield reaches the maximum
or ceiling value for the species and site.
Data are plotted in Figure 4 from two loblolly pine spacing studies.
The curves show trajectories of stands of differing initial densities and
ages, in the competition/premortality, and the competition/self-thinning
stages of development. The limiting desnity line shown was calculated from
data obtained from self-thinning stands in the study reported by Harms and
Langdon (1976). All spacings have followed similar trajectories, the only
difference among them being the rate at which they are moving along their
trajectories as they approach the limiting density line.
The job of the silviculturist is to apply knowledge of how trees grow
to the business of growing trees and forests that provide sustained and
efficient production of wood, water, wildlife, and recreation. The three
concepts introduced here provide a rational framework that will aid the
silviculturist. By considering the long-term and interacting effects of
cultural treatments and limiting environmental factors, and taking into
account the fact that each stage of stand development is unique and has its
own needs and opportunities for silvicultural intervention, the silviculturist
can produce sound management prescriptions that are compatible with the
physiological requirements, environmental constraints, and economic
necessities of the loblolly pine ecosystem.
to10. ASE as
9-. .. SY
S.. ~ -.---."'^" s1
N ~ EER TREE PER ACRE
Figure 4.--Stand development trajectories of loblolly pine plantations of
different spacings from the Piedmont (*) and coastal plain (0) of South
Carolina. Trajectories are indicated by solid vertical lines; dashed lines
connect stands of the same age and site. Dominant heights of the 6x6
spacing at age 15 are 54 feet for the Piedmont, and 50 feet for the coastal
Brender, E. V. 1973. Silviculture of loblolly pine in the Georgia Peidmont.
Ga. For. Res. Counc. Rpt. No. 33. 74 p.
Harms, W. R. and 0. G. Langdon. 1976. Development of loblolly pine in
dense stands. For. Sci. 22: 331-337.
Jorgensen, J. R. and C. G. Wells. 1980. Nutrient changes in decomposing
loblolly pine forest floor. Soil Sci. Soc. Amer. J. 44: 1307-1314.
Kramer, P. J. and T. T. Kozlowski. 1979. Physiology of woody plants.
811 p. N.Y.: Academic Press.
Langdon, 0. G. and W. H. McKee, Jr. i981-. Can-fertilization of loblolly
pine on wet sites reduce the need for drainage? p. 212-218. In Proc.
First Biennial South. Silvicultural Res. .Conf. USDA For. Serv., Gen.
Tech. Rpt. SO-34. South. For. Exp. Stn., New Orleans, LA.'
Langdon, 0. G. and K. B. Trousdell. 1974. Increasing growth and yield
of natural loblolly pine by young stand management. p. 288-296. In
Proc. Symp. on Management of Young Pines. USDA For. Serv. and Southeast.
Area S&PF, Atlanta, GA.
Reineke, L. H. 1933. Perfecting a stand-density index for even-aged
forests. J. Agric. Res. 46: 627-638.
U.S. Dept. of Agriculture, Forest Service. 1965. Silvics of forest trees
of the United States, H. A. Fowells, compiler. USDA Agric. Hdbk. No. 271.
Wahlenberg, W. G. 1960. Loblolly pine: Its use, ecology, regeneration,
protection, growth, and management. 603 p. Duke Univ., School of
Forestry, Durham, NC.
White, J. and J. L. Harper. 1970. Correlated changes in plant size and
number in plant populations. J. Ecol. 58: 467-485.
Yoda, K., T. Kira, H. Ogawa, and K. Hozumi. 1963. Intraspecific competition
among higher plants. XI. Self-thinning in over-crowded pure stands under
cultivated and natural conditions. J. Biol. Osaka City Univ. 14: 107-129.
Zahner, R. 1968. Water deficits and the growth of trees.. In Water
deficits and plant growth, Vol. II. Plant water consumption and response.
p. 191-254. N.Y.: Academic Press.
Forestry 4162 Silviculture
Stand Structure & Composition
Organization -- Work in crews assigned by instructor.
Purpose -- To promote an understanding of the concept of stand structure and
Equipment needed -- Diameter tape, tabulation forms, increment borer, clino-
meter, 100' tape.
Procedure -- (1) Introductory lecture on stand structure & composition; (2)
familiarize yourself with exercise; (3) determine the stand structure and com-
position of the two assigned stands as directed by the instructor and speci-
fic procedures; (4) prepare informal report; (5) answer questions indepen-
A forest consists of an ecosystem dominated by more or less dense and
extensive tree cover. This collection of trees is sufficiently dense and
covers a large enough area that the forest has a set of local climatic and
ecological conditions that are distinct from those outside.
The forest can be divided into a collection of stands. These are manage-
ment units which make up the forest. A stand consists of a reasonably homo-
geneous unit that can be differentiated from surrounding stands by its age,
composition, structure, site quality or geography.
The development of a forest management program is an intricate process.
Ownership objectives should specify the desired species and products) to be
featured in future management. The forest manager must then determine the
composition and structure of each.stand that will provide sustained yield over
the entire forest and be consistent with the ownership objectives. Without a
definite objective regarding stand structure and composition irregular yields
will be produced intermittently. Mismanagement of this type promotes insta-
bility of markets and employment in the forest economy. Subsequently this
economic instability limits the intensity or level of forest management attain-
able in the region. Control of stand structure and composition provides for a
regular supply of primary products to forest industry. This promotes the
stable economy and market necessary to finance multiple-use (recreation, wild-.
life, water, range) forest management.
What Is Stand Structure And Composition?
Stand structure is related to the (spatial and temporal) arrangement of
individual trees in the forest stand. Specifically.stand structure refers to
the distribution and representation of age and/or diameter classes, and of
crown classes. The most direct criterion of stand structure is age distribu-
tion. For example, a forest stand is considered to be of an even-aged struc-
ture if all of the trees present are of approximately the same age or at least
of. the same age class 1/. In contrast, an uneven-aged stand contains at least
three age classes intermingled on the same area.
Additional criteria may be used to describe/determine stand structure.
Generally stand structure is indicated by the profile of tree crowns in the
stand. This is because on a given site, trees of the same age tend to have a
smooth canopy top while uneven-aged stands tend to produce an uneven canopy
top. In practice, stands of all gradations of structure can be found (Figure
Stand graphs of diameter distributions in forest stands provides the most
definitive method of representing stand structure. Diameter classes are en-
tered on the abscissa and the number of trees per unit area on the ordinate.
2 4 6 8 10 12 14 16 18 20
An implicit assumption of this method of describing stand structure is
that tree diameter is well correlated with tree age. When this assumption is
valid, each type of stand structure has a characteristic diameter distribution
Stand composition refers to the representation of various tree species in
the forest stand. Forests can be classified as pure or mixed species composi-
tion. Truly pure stands are rare occurrences in nature. Therefore an arbi-
trary 90 percent of one species has been selected as separating pure and mixed
stands; i.e., if 90 percent or more of the dominant or codominant trees are of
the same species, the stand is designated as pure.
It is worthwhile to note that stand composition forms the basis of forest
type classification. The term forest type refers to a forest community de-
fined by the composition of the overstory. For example, the slash pine forest
type can be defined as consisting of more than 50% pine with slash pine out-
weighing longleaf and loblolly pine.
I1 The difference in age between the oldest and the youngest tree in the stand
must be less than 20 percent of the length of the rotation.
Figure 1. Various types of stand structure encountered in forestry
practice. (Taken from: Baker, F.S. 1950. Principles of Silviculture.
MacGraw Hill Book Co., New York 414 p.)
Figure 2. Stand graphs of
from: Baker, F.S. 1950.
Book Co., New Yor, 414 p.
various types of stand structures. (Taken
Principles of Silviculture. McGraw Hill
What Factors Control Stand Structure & Composition?
The general nature of a given forest stand is determined by the complex
1. Site (climate, soil, topography)
2. Available organisms (immigration-vs.-emigration)
3. Time/Historical factors (succession, disturbance, management)
At a specific locale (consisting of a certain climate, soil and topo-
graphic position) the structure and composition of a forest stand will be
determined through competition of local flora and fauna for available habitat
over time. If this process continues uninterrupted, a gradually and more or
less orderly replacement of species will take place naturally. This replace-
ment occurs in response to a natural change of the ecological conditions with-
in the forest stand. If the stand should be disturbed (e.g., by insects) a
new set of ecological conditions will be created and competition among avail-
able organisms will again determine the nature of the new forest stand.
The competitive ability of a tree species is determined by it's peculiar
biological and ecological characteristics (i.e., silvical characteristics).
For example, a species tolerance of understory environment, seedbed require-
ments and method of reproduction largely control its ability to form an un-
even-aged stand. The individual susceptibility of various species to damaging
agents affects stand structure and composition. Faunal interactions (e.g.,
girdling, browsing, seed predation, caching) also affect a tree species' com-
petitive status in-the forest stand. Where these interactions differ by plant
species, forest wildlife becomes a decisive factor in controlling stand com-
In contemporary Southeast forestry, the most apparent determinant of
stand structure and .composition is man. Through forest management and mis-
management, man has altered both the environment presented to the organisms
and the organisms available to occupy that environment. Selective logging has
altered the species composition of mixed stands and largely produced an irreg-
ular or storied-stand structure. Intensive planting/seeding programs have
promoted the development of pure even-aged stands; while extensive use of
clearcutting has created a predominance of even-aged forests.
Any type of forest cutting affects the forest outwardly by determining
the arrangement of the trees which are left and that of the new trees which
appear. Therefore all forest cutting affects stand structure and composition.
This is not necessarily undesirable. When scientifically employed, cutting
operations are the principal means available to build up a forest into a tech-
nically sound and continuously productive enterprise. Silviculture indeed
finds its highest expression through the gradual development of a forest skill-
fully arranged as to ages and species, designed to take full advantage of the
soil, and at the same time protected from injurious influences.
What Are the Advantages & Disadvantages of Various Alternatives?
There are certain well defined advantages and disadvantages attributed to
stands of alternative structure and composition. A few of these are summar-
Biologic, economic, administrative advantages of mixed stands:
Better utilization of soil resource by roots.
More efficient cycling of essential minerals.
Crown space is better utilized and closure is better.
More moderate climate within stand.
Healthier and less susceptible to various damaging agents.
Flexibility in meeting changing market demands.
Aesthetic and recreational values are improved.
Diversity of food and shelter for wildlife populations.
Yields may be superior under certain conditions.
Biologic, economic, administrative advantages of pure stands:
Entire forest can be devoted to the most valuable species compatible
with various site conditions.
Management of stands is relatively simple and easy.
Harvesting and marketing costs are reduced.
Simpler to reproduce the desired species.
Biologic, economic, administrative advantages of uneven-aged stands;
Wind throw hazard is very low.
Site is protected from wind and rain at all times.
Less susceptible to various damaging agents.
Light slash accumulations minimize hazard of fire and insect problems.
Permanent and continuous seed source is maintained.
Short investment period.
Small holdings can be managed for steady income.
Less need for noncommercial improvements.
Greater flexibility as cutting can be modified to fit changes in the
Greater ease and certainty of natural reproduction.
Biologic, economic, administrative disadvantages of uneven-aged stands:
Higher logging costs.
Higher administrative costs (individual tree marking, supervision).
More frequent damage to residual.
Higher road maintenance cost because of frequency of management
More management skill required.
Regulation of growth and yield presents difficulties.
Promotes reproduction of tolerant species.
Biologic, economic, administrative advantages of even-aged stands;
Simpler to inventory, manage and harvest.
High volume per area harvests promote use of expensive but efficient
logging which lowers harvesting costs.
Higher quality boles are produced.
More uniform growth rate during rotation and greater uniformity of the
size of trees produced.
Less damage to residual.
Biologic, economic, administrative disadvantages of even-aged stands:
General high probability of noncommercial improvement cuts.
Extended investment period.
Greater risk of loss to damaging agents.
Forest protection program can be expensive.
Low aesthetic and recreational values.
Desired reproduction may be difficult to secure.
How Is Knowledge of Stand Structure & Composition Applied?
There is no ground for believing that one form of stand structure or
composition is always inherently better than another. The choice depends on
careful consideration of the circumstances, not the least important of which
is the existing structure and composition. Desirable changes in these proper-
ties are sufficiently difficult and costly that they should not be undertaken
unless careful analysis of all factors, economic and biological, shows that
alterations are necessary to meet specified management goals (e.g., sustained
yield, increased productivity, etc.). Each alternative combination of struc-
ture and composition will be found appropriate under certain circumstances.
The trained forester must interpret those circumstances and act accordingly.
Part 1 Stand Structure & Composition
Procedure -- In each stand do the following:
1. Sketch the stand profile showing the arrangement of tree crowns.
2. Determine the stand structure which corresponds to this profile.
3. Determine the number of stories (of trees) the stand has.
4. Identify all distinct layers (trees, shrubs, herbs, mosses, lichens)
in the stand.
5. Estimate the year of origin of the stand.
6. Note any evidence of damage (wildlife, wind, disease, etc.).
7. Tally by species and diameter class (2-inch) all trees in the estab-
lished sample plot.
In the office do the following:
1. Develop stand graphs for each respective stand. (Be sure to label
axis and title graphs appropriately)
2. Develop a stand table listing species frequency by crown class for
each respective stand (use Kraft crown class designations, below).
3. Prepare an informal report, as directed by the instructor. As a
minimum be certain to provide the following information:
stand graphs number of stories
stand tables stratification
year of stand origin stand profile sketch
type of stand structure stand origin (planting, fire, etc.)
type of stand composition biologic and economic advantages
for each stand.
Kraft Crown Classes
Used in Site Evaluation
Trees with crowns extending above the general level of the crown
cover and receiving full light from above and partly from the
side; larger than average trees in the stand, and with crowns
well developed but possibly somewhat crowded on the sides.
Trees with crowns forming the general level of the crown cover
and receiving full light from above but comparatively little
from the sides; usually with medium sized crowns more or less
crowded on the sides.
Trees shorter than those in the two preceding classes but with
the crowns extending into the crown cover formed by codominant
and dominant trees; receiving a little direct light from above
but none from the sides, usually with small crowns considerably
crowded on the sides.
Trees with crowns entirely below
cover, receiving no direct light
sides. Synonym: "suppressed".
the general level of the crown
either from above or from the
Upon completion of this exercise you should be prepared to answer the
1. What determines the size of a forest stand?
2. Describe alternative circumstances which might lead to the development of
the various stand structures shown in Figure 1.
3. Why do the canopies of the various stand structures take the form they do?
4. Discuss the natural and orderly species replacement
forest.stand. What is the process called?
that takes place in a
5. List several examples where wildlife/vegetation interactions affect stand
structure and/or composition. Be specific and identify species of flora
and fauna involved.
6. What single factor (if any) do you consider to be most important in deter-
mining stand structure and composition?
7. List five forest trees species likely to be found as major components of
an even-aged stand in the Southeast.
8. For each species listed below, identify three forest tree species likely
to be an associate in a mixed stand.
9. List five forest tree species likely to be found as pure stands in the
10. Discuss-the development (history) of stand structure and composition in
the respective sample stands.
11. Discuss the merits of the existing stand structure and composition of the
sample stands relative to the wildlife resources, water resources, soil
resources and recreation resources in the vicinity of Gainesville.
- Part 2 -
A. Prepare stand graphs for the two hypothetical stands (A + B)(refer to
attached data) -by organizing the diameter data by species in 2-inch diameter
classes (i.e., 1.0-2.9, 3.0-4.9, 5.0-6.9 inches would fall into-2, 4, and
6-inch diameter classes, respectively). Identify which age structure corre-
sponds to the diameter distributions for both stands A + B.
Tree diameter measurements at breast height in two stands in the Lake States*
DBH DBH DBH
Species in. Species in. Species in.
Aspen 5.3 Aspen 8.5 Aspen 11.0 STAND NO. A
Aspen 7.4 aspen 10.2 Aspen 9.6
Aspen 11.7 Aspen 10.4 Aspen 10.6
Aspen 9.8 Aspen 11.7 Aspen 12.0
Paper birch 8.0 Paper birch 10.6 Aspen 10.5
Paper birch 8.1 Paper birch 7.4 Aspen 9.7
Paper birch 5.4 Paper birch 8.3 Aspen 8.1
Paper birch 9.5 Aspen 9.7 Aspen 7.7
Aspen 6.5 Aspen 4.7 Paper birch 6.2
Aspen 6.7 Aspen 9.2 Aspen 10.7
Aspen 8.2 Aspen 10.7 Paper birch 6.7
Aspen 9.7 Bur oak 6.3 Bur oak 4.5
Aspen 13.2 Bur oak 6.2 Aspen 11.3
Aspen 10.4 Aspen 7.3 Aspen 11.5
Aspen 15.6 Paper birch 4.1 Sugar maple 3.8 STAND NO. B
Aspen 16.3 White pine 30.2 White pine 30.4
Basswood 2.1 Sugar male 2.2 Ironwood 2.1
Basswood 1.9 Red maple 5.8 Sugar maple 3.3
Basswood 9.6 Red maple 6.3 Sugar maple 4.1'
Ironwood 1.2 Reds maple 3.1 Sugar maple 4.7
Ironwood 1.3 Paper birch 10.1 Paper birch 6.1
Red maple 1.8 Paper birch 4.1 Paper birch 3.7
Red maple 4.8 Paper birch 3.2 Sugar maple 5.6
Red maple 6.2 Paper birch 6.3 sugar maple 5.4
Sugar maple 1.8 Basswood 10.5 Basswood 3.3
Sugar maple 2.4 Basswood 8.6 Basswood 3.5
Aspen 18.2 Basswood 8.4 White pine 26.2
White pine 24.5 Elm 1.7 Aspen 15.8
Sugar maple 3.3 Red maple 7.0 Sugar maple 5.1
Sugar maple 1.7 Red maple 7.1 Sugar maple 5.6
Elm 1.6 Red maple 1.7 Sugar maple 5.4
Paper birch 2.6 Ironwood 1.3 Sugar maple 6.0
Paper birch 9.2 Aspen 12.3 Sugar maple 7.1
*Basis: one 1/10 acre plot in each stand.
PROBLEM STAND -- DOT TALLY FORM
* Diameter Class
For Ex: 2" = (1.1 3.0 in.)
For Ex: 4" = (3.1 5.0 in.)
Tree No. DBH Species Tree No. DBH Species
Tree No. DBH Species Tree No. DBH Species
Forest Site: The Concept and Its Measurement
Eric J. Jokela
Department of Forestry
University of Florida
Forest Site: The Concept and Its Measurement
Classical Silvicultural Problems
To evaluate the suitability of tree species (or other genetic entities)
for a given locality.
To rate competitive ability of alternative species that are suitable for a
To estimate the growth potential of forest communities that occupy a
In trying to address these problems it was recognized long ago that forest
productivity is the resultant expression of a particular genetic make-up
interacting with a variable environment. That is, forest growth is in part
controlled by the genetic potentials and a limiting environment. The concept
of forest site refers to the sum total of all factors affecting the capacity
to produce forests.
"All factors" can be generally classified as belonging to one of three
"To produce forests" generally refers to gross volume of bole wood/acre/
year, that is, gross mean annual increment (with no deductions for natural
losses). Note that since each factor is dynamic and subject to change, so
then is forest site.
Quantification of Site
The most direct approach for evaluating species suitability, competitive
relations, and ultimate growth at a particular locale is to measure mean
annual increment (MAI) at that locale. Unfortunately, the task is'formidable
and very time consuming -as it requires a total inventory of the forest tract
over the entire rotation. As a result, indirect methods of estimating forest
productivity were derived. Several approaches have been attempted. The
common goal of all methods is to
be well correlated with the locale's productivity and be easy,
simple, and inexpensive to use.
To estimate forest site quality, one must integrate all the interdependent
site factors into some measure of the locale's potential for forest growth. At
least two fundamental approaches may be taken:
Measure some component of the forest ecosystem which is itself in
part an integrated product of the environment, i.e., trees,
subordinate vegetation, soils (as a genetic entity).
Evaluate each environmental factor and conceptually integrate them
into a single estimate.
Regardless of the approach, one must assume the following:
We are working with a particular genetic potential, under conditions of
full site occupancy (i.e., within broad limits, gross production is indepen-
dent of stand density), with a given stand history, with a given rotation age.
Tree height can be utilized as a measure of site on the basis that the
height of free-grown trees of a given species, at a given age, is more closely
related to the capacity of a given site to produce wood of that species than
any other single factor. The height of free-grown trees is less influenced by
stand density than by other measures of tree dimension. Therefore, height may
be used as an index of site quality of evenaged stands, of varying density,
and (within limits) of varying stand history.
The concept of site index was developed as a result of the above consider-
ations. Site index is the height of dominant and codominant trees of a forest
stand at a selected index age. In the Southeast, index age is 25 or 50 years.
For example, if site index is stated as 65, then the dominants and codominants
are 65 feet at age 25. (It is assumed that these trees have been free-
growing and uninjured throughout their life.) Site index estimates are then
related to yield tables arranged according to site index and stand age. These
tables provide the ultimate estimate of land productivity.
However, there are limitations to height, i.e., site index, as a measure
of productivity. Genetically, a tree may be limited in height regardless of
site quality. Tree crown class is a subjective judgment and is therefore
subject to error. Site index is influenced by tree sampling or measurement
errors. Stand history, such as early competition or thinning, may alter crown
position. Although height is generally density-independent, cases occur where
stand density will influence height, e.g., severe competition. These limita-
tions are generally minor, and with the exception of genetic interaction, can
usually be avoided by using proper and careful procedures.
The earliest and most common method of developing site index data centered
on the development of height-versus-age curves. This involved height and age
measurement across a variety of sites and the development of a master curve
describing height growth.; Harmonized curves were then drawn, and site classes
assigned to the appropriate curve.
This methodology assumes that the shape of the height growth curve is the
same for all site classes, localities, and soils; that sites different at 50
years were different at early ages also; that good and bad sites were well
represented in the original data.
More recently, polymorphic site index curves have been developed by uti-
lizing stem analysis procedures to measure actual growth of trees on specific