Primary Definitions
Forestry
The profession embracing the science, art, and practice of
creating, managing, using, and conserving forests and
associated resources for human benefit and in a sustainable
manner to meet desired goals, needs, and values. Note: the
broad field of forestry consists of those biological,
quantitative, managerial, and social sciences that are
applied to forest management and conservation; it includes
specialized fields such as agroforestry, non-industrial
forestry, and wilderness and recreation forestry. (Society
of American Foresters)
Silviculture
1. The art and science of controlling the establishment,
growth, composition, health, and quality of forests and
woodlands, to meet the diverse needs and values of
landowners and society on a sustainable basis. (Society of
American Foresters 1998)
2. The cultivation of forests; the result is a forest of a
distinct form. Silvicultural systems are classified
according to harvest and regeneration methods and the type
of forest that results.
4. Silvics is the study of the life history, requirements
and general characteristics of forest trees and stands in
relation to the environment and the practice of
silviculture.
Arboriculture
1. The culture and management of trees as groups and
individuals primarily for amenity and other non-forestry
purposes.
2. The art of planting, pruning and tending trees, most
often referring to fruit-growing and amenity trees, or
urban forestry.
3. The art, science, technology and business of tree care.
Arboriculture is practiced by arborists. Arborists are
trained to promote tree health, discern tree problems and
take measures to correct them.
Arborist
(see
arboriculture, above)
1. An individual who is trained in the art and science of
planting, caring for and maintaining individual trees.
(ISA)
2. A person possessing the technical competence through
experience and related training to provide management of
trees or other woody plants in a landscape setting.
Generally involved with the development or management of
trees for visual amenity.
Forest Ecology Glossary
Abiotic – Nonliving
components of the environment such as air, rocks, soil
particles, and plant litter.
Adaptive
management – A
process for ecosystem management that allows for continual
change as more information becomes available on resource
conditions and the effects of management actions on
resources.
Age
class – All
trees in a stand within a given age interval, usually 10 or
20 years.
Age
structure – The
number and ratio of age classes within a stand.
Annual
ring – Bands,
which show tree growth for one year, as viewed on the cross
section of a stem, branch, or root, or on a trunk core
sample. Can be counted to determine a tree’s age.
Variation in width of rings records how the tree responded
to growing conditions in different years.
Aquatic
ecosystem – A
water-based system of living organisms interacting with
their environment.
Aquifer
– A
stratum of earth or permeable rock that stores significant
quantities of water. A confined aquifer is sealed above and
underlain below by impermeable material.
Aspect
– The
compass direction that a slope faces.
Autecology
– Ecology
dealing with biological relations between a species or
individual organism and its environment.
Basal
area – A
key descriptive measure of trees and stands. For a tree, it
is the cross-sectional area of the trunk at breast height
(4.5 feet above ground). The basal area of a tree 14 inches
in diameter at breast height (DBH) is approximately 1
square foot. Basal area per acre is the sum of basal areas
of the individual trees on an acre. A stand of 100 14-inch
DBH trees would contain about 100 square feet of basal area
per acre.
BMP
(Best Management Practices) –
a series of guidelines or minimum standards for proper
application of forestry operations, designed primarily to
prevent soil erosion and water pollution, and to protect
certain wildlife habitat values in riparian and wetland
areas.
Biological
control – Controlling
plants, diseases, and animal pests by the use of natural
enemies; or inhibiting the reproduction of pests by methods
that result in the laying of infertile eggs.
Biological
diversity – Richness
and abundance of species and variety of natural communities
in a forest environment. Both the number of species and the
number of individuals of each species are important in
considering the extent of biological diversity in an area.
Also referred to as biodiversity.
Biological
properties – In
soils, this refers to the living organisms in the soils
that assist with decomposition and nutrient cycling
(bacteria, insects, and fungi).
Biomass
– The
total quantity (weight) of biological matter in a unit
area, including all living organisms above and below
ground; or the total quantity of one or more species in a
unit area. Tree biomass components include wood, bark,
foliage, and roots, of a single tree or of all the trees in
a specified area.
Biota
– The
plants and animals of a given region or period, considered
collectively.
Biotic
– Having
to do with the living components of an ecosystem.
Bole
–
The stem or trunk of a tree, excluding its roots and
top,
or branched crown. The part of the tree from which logs may
be cut.
Breast
height – Four
and one-half (4.5) feet above the ground on the uphill
side. Diameter is usually measured and basal area
calculated at this point on the tree.
Brush
– Commonly
refers to undesirable shrubs and small trees.
Buffer
strip –
a belt of relatively undisturbed planted or natural
vegetation maintained along streams to reduce erosion and
siltation, or along roads and field edges to reduce
poaching and wind erosion, and to improve scenery. Buffer
strips also provide wildlife travel corridors and habitat.
Cambium
– The
growing layer of cells beneath the bark of a tree.
Canopy
– The
uppermost layer in a forest, formed collectively by tree
crowns.
Canopy
layers – Forests
with varying age classes may have several height classes.
For example, an overstory canopy layer of trees may overtop
a lower canopy of other trees or shrubs.
Climax
community – A
relatively stable plant community that has evolved through
stages and has a dominant plant population suited to the
environment.
Codominant
trees – Trees
whose crowns form the general level of the stand, receiving
full light from above but comparatively little from the
sides.
See also Crown
class.
Community
– 1.
A natural assemblage of different organisms living and
functioning together in a particular area. Usually named
for the dominant plants, animals, or major physical
components of the area. 2. An assemblage of species,
dependent on each other, and constituting an organized
system through which energy, nutrients, and water are
cycled.
Community
type –
a unique combination of plants and animals that occur in a
particular location and are adapted to similar
environmental conditions.
Conifer
– A
cone-bearing tree with needles, such as pine, spruce, fir,
and larch.
Conk
–
the hard or stiff fruiting body of certain wood decay
fungi, for example, the "shelf fungus" associated with
heart rot.
Connectivity
– Condition
of ecosystem integrity allowing natural processes to work
across a landscape without discontinuity.
See also Corridors;
Fragmentation.
Conservation
– The
protection, improvement, and wise use of the natural
environment (such as the forests, soils, and water systems)
to prevent destruction and exploitation while still
producing goods and services for the human population.
Conservation
biology – The
science of diversity, scarcity, and survival of species.
Deals with active management to protect and maintain
genetic variety within species. Deals also with the concept
of sustainability and relationships between biotic and
abiotic resources.
See also Sustainability.
Corridors
– Generally,
linear strips of habitat linking isolated patches of
natural habitat in the landscape. Establishment and
maintenance may be actively promoted at the state and
regional levels.
See also Connectivity;
Fragmentation.
Cover
–
the protective element within an animal's habitat, which
provides concealment from, or for, predators and shelter
from the weather. Takes many forms, for example, patches of
dense brush, tall grasses, slash or brush piles, the forest
canopy, or other landscape features.
Critical
habitat – Specific
areas within the geographic range occupied by a species
listed by the federal government as endangered or
threatened. The physical and biological features considered
necessary for the survival and recovery of the species.
Crook
–
a tree defect characterized by a sharp bend in the main
stem.
Crop
tree –
Desirable tree left to grow in size and value throughout
the life of a stand.
Crown
–
the portion of an individual tree above the main stem,
consisting of live branches and foliage.
Crown
class – A
relative designation of tree crowns.
Dominant trees are
those whose crowns grow above the general level of the
canopy.
Codominant trees are
those having crowns forming the general level of the
canopy.
Intermediate trees have
crowns growing below the general level of the
canopy.
Suppressed trees are
much shorter than trees in the general level of the canopy.
Crown
closure – The
point when, in a young stand, the crowns of the trees begin
to touch each other.
Crown
differentiation – The
process whereby some trees grow faster and develop large,
full crowns, while others fall behind in height and have
smaller, sparser crowns.
Crown
ratio – A
measure of the length of a tree’s crown relative to
total tree height.
DBH
– The
tree diameter at breast height (4.5 feet above the ground
on the uphill side).
Deciduous
tree – A
tree that loses its leaves or needles during the fall and
winter.
Decomposition
– The
breaking down of dead matter by decay organisms.
Defoliators
– Insects
that feed on foliage.
Den
tree –
A tree having one or more cavities suitable as nesting
sites for wildlife.
Dendrology
– The
study of tree identification.
Dieback
– Any
condition where portions of a tree’s crown die due to
conditions other than shading.
Disturbance
– A
natural or human-caused event, such as a forest fire,
disruptive wind storm, or insect infestation that alters
the structure and composition of an ecosystem.
Disturbance
management – Managing
disturbance events and effects, such as insects and fire,
to approximate natural conditions.
Dominant
trees –
See Crown
class.
Dormancy
– A
biological process in which a plant ceases most growth
activities and simply maintains existing tissue.
Drainage
– An
area of land above a given point on a waterway that
contributes runoff water.
Duff
– Various
stages of decaying organic matter found on the soil
surface.
Dysgenic
selection – Removing
the best trees in the stand while permitting the worst
trees to occupy the site and reseed the new stand. Over
time, the stand becomes filled with individuals of
undesirable species or poor form.
Early-successional
– The
first species to occupy an area after a major disturbance,
often known as “pioneers.” Typically, an
association of plants and animals capable of surviving and
reproducing under harsh environmental conditions.
Ecological
approach – A
type of natural resource management that in developing
management strategies considers the relationships among all
organisms, including humans, and their environment.
Ecological
succession –
the natural process, following a disturbance, in which one
community of plants and animals gradually replaces another,
in response to changing environmental conditions.
Ecology
– The
science that studies the interaction of plants and animals
with their environment.
Ecosystem
– Ecological
system. An interacting system of living organisms and their
environment. The dynamic relationships of living (biotic)
and nonliving (abiotic) components of a region, as well as
the forces, such as weather and wildfire, that affect them.
Ecosystem
health – A
measure of the overall capacity of an ecosystem to maintain
biological diversity, normal productivity, sustainability,
and resilience to disturbance.
Ecosystem
management – A
long-term approach to managing a forest, using ecological
principles and considering biological, physical, economic,
and societal needs, while sustaining or restoring ecosystem
integrity.
See also Adaptive
management.
Ecosystem
structure – The
horizontal and vertical distribution of living and dead
vegetation.
Ecosystem
sustainability –
See Sustainability.
Ecotone
– A
transitional area between two forest or rangeland
communities containing the characteristic species of each
as well as characteristics of its own. A point of abrupt
change, such as a prairie-forest junction or a land-water
interface.
Edaphic
– Of
the soil or influenced by the soil rather than by climatic
factors, especially pertaining to living organisms.
Edge
–
the zone or ecotone where two habitat types come together,
for example, open land and woodland, or forest stands of
different ages or species. Both habitat types contribute
plants and animals to the transition zone, making edge more
valuable to wildlife than either habitat type alone.
Creating substantial edge during a timber harvest can also
reduce the visual impact of the harvest.
Edge
effect – The
tendency toward greater species variety and greater density
of animal and plant life in the margin where two ecological
communities meet.
See also Ecotone.
Elements
– Those
basic substances such as carbon, calcium, nitrogen,
hydrogen, and phosphorus required for tree growth. Some
come from the weathering of bedrock, while others such as
nitrogen come from the air. An element is the same as a
nutrient.
Endangered
species – A
plant or animal vulnerable to extinction in all or a
significant portion of its range. Identified by the
Secretary of the Interior in accordance with the Endangered
Species Act (1973).
Endemic
population level – A
normal (insect) population level.
Entomology
– The
study of insects and their environments.
See also Forest
entomology.
Environment
– The
external conditions, both physical and biological in which
an organism lives. Includes climate, soil, topography, food
supply, and all other influences affecting development.
Ephemeral
stream – A
stream that flows only sporadically, such as after storms.
Epidemic
– Widespread
insect or disease incidence beyond normal proportions.
Exotic
species – A
nonnative plant or animal species introduced by humans,
either deliberately or accidentally.
Extinct
– Said
of a species or other taxonomic group having no living
members.
Feeder
roots – Fine
roots of trees and other vegetation used to absorb water
and nutrients from the soil.
Forb
–
a non-grasslike herbaceous plant; a broad-leaved herb.
Forest
–
a biological community of plants and animals which is
dominated by trees and other woody plants.
Forest
entomology – The
science that deals with insects in forest trees or
products.
Forest
ecology – The
study of life in areas where the dominant vegetation is
trees. This includes both the biology of organisms and how
they interact with each other and their environment.
Forest
fragmentation –
the splitting of forest lands into smaller, detached areas
as a result of road building, farming, suburban
development, and other activities. This can isolate
wildlife populations, and may result in forested areas too
small to meet the habitat requirements of some species.
Wildlife corridors help remedy this problem.
Forester
– A
professional who has been educated in forestry at a college
or university.
Forest
management – The
application of scientific, economic, and social principles
to managing a forest property for specific objectives.
Forest
pathology – The
science that deals with diseases of forest trees.
Forest
Plan – A
document that guides all natural resource management
activity and establishes management standards and
guidelines for a National Forest, embodying the provisions
of the National Forest Management Act (1976).
Forest
Practices Act – Washington
State legislation designed to protect public resources such
as water and wildlife from effects of indiscriminate
management practices. All forest operations on private
lands must com-ply with regulations administered by state
forestry personnel.
Forest
stewardship –
environmentally and socially responsible use, management
and development of forest resources in order to maintain
and enhance the value of the forest for present and future
generations.
Forest
Stewardship Program –
a program funded by the USDA Forest Service to encourage
private forest landowners to practice sustainable,
multiple-use land management. Cost-share assistance is
available for approved conservation practices (see
"S.I.P."). In Florida, the program is administered by the
Florida Division of Forestry, IFAS Cooperative Extension
Service, Florida Game and Fresh Water Fish Commission, and
USDA Natural Resources Conservation Service.
Forest
type – A
group of tree species that, because of their environmental
requirements, commonly grow together. Examples of forest
types are the Douglas-fir/hem-lock type or the spruce/fir
type. In addition, a descriptive term used to group stands
with similar composition and development characteristics.
Forest
wetland –
an area characterized by woody vegetation over 20 feet
tall, where soil is at least periodically saturated with or
covered by water.
Form
class – A
measure of bole taper derived by dividing diameter inside
bark at a given height (usually 17.3 or 33.6 feet) by DBH,
times 100. These values often are entered when using
tree-volume tables.
Fragmentation
– The
breaking up of a large forest area into patches either by
natural processes or through management or conversion to
other land uses. Natural habitats may become separated into
isolated segments or “islands.”
See also Connectivity.
Free-grown
tree – A
tree that has always grown in the open with no competition
from adjacent trees.
Fungi
– Any
group of organisms that live in the soil and decompose dead
organic matter.
Ground
cover –
all herbaceous plants and low-growing shrubs in a forest or
open area.
Growing
space – The
availability of all the requirements a plant needs in order
to grow, including soil, light, water, nutrients,
CO2.
Growing
stock – All
the trees growing in a stand, generally expressed in terms
of number, basal area, or volume.
Habitat
– The
local environment in which a plant or animal naturally
lives and develops.
Habitat
diversity –
the variety of wildlife habitat features and types in a
specific area. Habitat diversity takes many forms –
the variety of plants and animals on a site; structural
diversity or the vertical arrangement of vegetation from
canopy to forest floor; horizontal diversity or the
distribution of habitat types across the landscape; and
temporal diversity or habitat changes over time. Generally,
areas with substantial habitat diversity will support more
wildlife species than areas with less habitat diversity.
See "wildlife habitat."
Habitat
type – Classification
of a land area according to dominant plant forms (usually
trees and shrubs) and physical characteristics. Can help to
indicate the biological potential of a site.
Hardwood
–
tree species in the angiosperm group (the flowering plants,
that produce seeds enclosed in a fruit). Hardwood trees are
characterized by broad leaves (as opposed to needles) and
are usually deciduous. See "softwood."
Harvest
– Removing
trees on an area to obtain an income or usable product.
Heart
rot –
fungus-caused decay of a tree's heartwood (interior wood).
Trees are infected when fungal spores enter tree wounds or
dead branch stubs, and encounter conditions favorable for
spore germination. See "conk."
Herbicide
– Any
chemical used to kills plants.
High-grading
–
A timber cutting method which removes the trees of highest
quality and leaves the specimens of lower quality to
continue growing. Generally considered poor forestry, it
returns quick profits at the expense of future productivity
and gradually degrades the genetic resource of a woodland
(see Low-grading).
Increment
–
See Annual
growth.
Increment
borer – A
hollow, auger-like instrument used to bore into the tree
trunk to remove a cylindrical cross section (core sample)
of wood. It is used to expose annual growth rings.
Indicator
species – A
plant or animal species whose presence in an area indicates
that certain specific habitat conditions prevail throughout
the area.
Insecticide
– Any
chemical used to kill insects. The term often is used
interchangeably with pesticide.
Integrated
Pest Management (IPM) –
the use of different techniques in combination to control
pests, with an emphasis on methods that are least injurious
to the environment and most specific to the particular
pest. For example, pest resistant plant varieties, regular
monitoring for pests, pesticides, natural predators of the
pest, and good stand management practices may be used
singly or in combination to control or prevent particular
pests.
Integrated
resource management – A
term used to indicate the simultaneous consideration of
ecological, physical, economic, and social aspects of
lands, waters, and resources in developing and carrying out
multiple-use, sustained-yield management.
Intermediate
trees –
See Crown
class.
Intolerant
species – Tree
species that are incapable of establishing or growing in
the shade of other trees.
Landscape
– A
large land area composed of interacting groups of
ecosystems, including all the physical and biological
aspects of such an area, regardless of ownership.
Landscape
configuration – The
pattern of forest stands, meadows, lakes, and other
features within a large area.
Landscape
connectivity –
See Connectivity.
Landscape
ecology – The
study of biological interactions across a large land area,
or watershed.
Litter
– the
uppermost layer of organic debris on a forest floor,
composed mainly of fresh or slightly decomposed leaves,
bark, twigs, flowers, fruits, and other vegetable
matter.
See Duff.
Live
crown ratio – The
percentage of the length of a tree stem supporting living
branches.
Low
fires – Fires
with a low flame height and low temperature that burn duff,
seedlings, saplings, and trees that are not fire-resistant.
Mature fire-resistant trees are scorched but generally not
killed by low fires.
Low-grading
–
The sound forestry practice in which the stems of lower
value trees are removed during thinnings to release more
promising crop trees (see High-grading).
Macroclimate
– The
climate of a large region as a whole, considered apart from
modifying irregularities of land and vegetation.
See also Microclimate.
Management
plan – A
written plan for the organized handling and operation of a
forest property. It usually includes data and practices
designed to provide optimum use of forest resources
according to the landowner’s objectives.
Mast
–
the flowers, fruits or seeds of plants, especially of trees
and shrubs, that are eaten by animals. Hard mast includes
hard-shelled seeds such as acorns and hickory nuts. Soft
mast includes flowers, and seeds with a fleshy cover, for
example berries, wild cherries and maple seeds.
Mature
forest – A
term generally applied in an economic sense to indicate a
forest that has attained harvest age.
Mature
tree – A
tree in a managed forest that has reached the size or age
for its intended use.
Mean
annual increment (MAI) – The
annual increase in size (volume) of a tree. Or the increase
in size (volume) of a stand at a certain age, divided by
that age in years.
Mensuration
– That
phase of forestry dealing with the measurement of volume,
growth, and development of individual trees and stands.
Microclimate
– The
climate of a small, specific area reflecting such local
differences as soil surfaces, vegetation, and atmospheric
characteristics.
Microsite
– An
environmental feature that is small in scale but unique in
character. Microsites often have a significant impact on
natural regeneration.
Mid-successional
– An
association of plant and animal species that replaces early
successional species, but is eventually replaced by climax
species in the absence of disturbance.
Mixed
conifers – Timber
stands characterized by a mixture of conifer species,
including ponderosa pine, lodgepole pine, Douglas-fir,
grand fir, western white pine, and western larch. A mixture
of forest types.
Mixed-species
stand – Forest
stands made up of more than one type of tree.
Montane
forests – Forests
that are mid-elevation and generally moister than foothill
forests, but not as cold as subalpine forests.
Mortality
– Death
of forest trees as a result of competition, disease, insect
damage, drought, wind, fire, and other factors.
Mulch
–
materials such as pine straw, wood chips, bark, and leaves
that are loosely spread on the soil surface to reduce water
loss and weed growth.
Multiple
use – Forest
land management for more than one purpose, such as wood
production, water, wildlife, recreation, forage, and
aesthetics.
Multi-storied
– Forest
stands containing trees of different heights.
Mycorrhizal
fungi – Fungi,
which form a symbiotic relationship with the roots of
certain trees, enabling those trees to extract more water
and nutrients from the soil.
Nutrients
– Chemical
substances necessary for plant and tree growth.
Nutrient
cycling – The
biological, geological, and chemical circulation of
inorganic elements such as nitrogen, phosphorus, and
potassium through the soil, living organisms, water, and
air, thus providing nutrients to animals and vegetation in
the process.
Obligate
species – A
species restricted to a particular environment or a
particular mode of life, such as a plant or animal found
only in a narrowly defined habitat, e.g., a tree cavity.
Old
growth – A
forest ecosystem containing old trees, usually over 125
years old, and associated plants and wildlife.
Organic
matter – Material
produced by plants and animals, such as leaves, branches,
bark, wood, hair, fur, and bones.
Overmature
– A
stand of trees that is older than normal rotation age for
the forest type.
Overstocked
– A
stand or forest condition, indicating more trees than
desired.
Overstory
– That
portion of the trees in a stand forming the upper crown
cover.
Overstory
retention – Leaving
some of the bigger trees in the stand to serve as seed
trees or shelterwoods for instance.
Pathology
– The
science that deals with diseases of forest trees, forest
stands, and products.
Photosynthesis
– The
process in trees and other plants changing air and water
into food using the sun’s energy.
Pioneers
– Shade-intolerant
species that are the first trees to invade freshly
disturbed sites.
Plant
association – A
vegetation community, in which the dominant species forms
the highest level in the hierarchy of plant species.
See also Climax
community.
Plantation
– A
reforested area established by planting trees.
Planting
stock – Seedling
trees ready for planting.
Population
– Organisms
(trees, shrubs, herbs, animals, insects) of common ancestry
that occupy a particular forest area.
Prescription
–
a schedule of activities for a stand or forest property
which, when carried out, should produce the outcome desired
by the landowner. Prescriptions have three elements –
(1) land-type classification – location, soils,
species, stocking, etc.; (2) activity schedule –
timing of operations, methods, etc.; and (3) projections of
growth and yield for current and subsequent stands.
Prescriptions can apply to individual stands and/or to the
entire forest property.
Preservation
–
As applied to wood –
Treating wood products with chemicals to prevent damage by
insects or decay.
In reference to land and resources –
Maintaining a natural environment undisturbed by human
influence.
Productivity
– Growth
per unit time.
Pruning
–
In forestry usage, the removal of branches from the lower
trunk of a tree to allow the stem to continue growing
without producing large or loose knots. This is an
expensive practice, but if done judiciously, can be a
valuable investment in the crop trees of certain species.
Walnut and white pine are the most often pruned trees.
Pure
stand – A
stand of trees of all one species.
Reforestation
– Reestablishing
a forest on an area where forest vegetation has been
removed.
Regeneration
– The
natural or artificial renewal of trees in a stand.
Reproduction
– Young
trees. The process of forest replacement or renewal that
may be introduced artificially by planting or naturally by
sprouting or self-seeding.
Residual
– Trees
left in a stand, after cutting, to grow until the next
harvest.
Resilience
– The
ability of a forest ecosystem to recover from a
disturbance.
Riparian
– Pertaining
to the area along the banks of a river, stream, or lake.
Riparian
ecosystem – An
ecosystem that is transitional between land and water
ecosystems. The soils, plants, animals, and other organisms
found in such an area.
Rotation
– The
number of years required to establish and grow trees to a
specified size, product, or condition of maturity.
Second
growth – Young
forests that originated naturally or were planted on the
site of a previous stand that was removed by cutting, fire,
or other cause.
Seed
year – A
year in which a given species produces a large seed crop.
Used in reference to trees that produce seed irregularly or
infrequently.
Seed
zone – Areas
that have similar climate and elevation conditions. Used to
specify where tree seed was collected and where trees from
such seed will probably grow successfully.
Seral
stage – A
phase of ecological development toward a more mature or
climax community.
See Climax
community; Successional stage.
Shade
intolerant – A
term applied to tree species that grow better in direct
sunlight than in the shade of other trees. The opposite of
shade tolerant. Examples include coastal Douglas-fir,
western larch, lodgepole pine, and red alder.
Shade
tolerance – A
tree’s capacity to develop and grow in the shade of,
and in competition with, other trees. Examples of highly
shade-tolerant species are western hem-lock, western
redcedar, and Pacific yew.
Shade
tolerant – A
term applied to tree species that grow better in the shade.
The opposite of shade intolerant. Examples include western
hemlock, western red-cedar, and pacific yew.
Shrub
– A
low growing perennial plant with a woody stem and low
branching habit.
Single-layered
canopy – When
the codominant trees in the stand are all about the same
height (an even-aged stand), the forest has a more or less
continuous single-layered canopy. Trees in the understory
usually are not numerous enough to make additional layers
of canopy.
Site
– An
area evaluated for its capacity to produce forest products.
Evaluation is based on combined biological, climatic, and
soil factors.
Site
class – A
grouping of similar sites that indicates relative
productivity. The common system for the Douglas-fir region
includes five site classes, in which Site I is the most
productive and Site V is the least productive.
Site
index – An
expression of forest site quality based on the height of
the dominant and codominant trees in the stand at a
specified age, usually 50 or 100 years.
Site
productivity – Growth
per unit time on a given site, determined by geologic and
climatic conditions.
Slope
– The
incline of the terrain usually expressed as the amount of
incline in feet over a hundred feet of horizontal distance.
Snag
–
a standing dead or dying tree that has lost most of its
branches, or the standing portion of a broken-off tree.
Snags provide cavities for nesting, perches, and feeding
sites for wildlife.
Softwood
–
A term applied to trees with needle-like leaves, many of
whose wood is softer than the wood of a majority of
broad-leafed trees. The term is roughly equivalent
to
gymnosperm,
evergreen,
and
coniferous and
is the opposite of
angiosperm and
deciduous.
Soil
texture – Proportion
of clay, silt, and sand in soil.
Specialists
– Plants
or animals that require specific conditions to grow and
reproduce.
Species
– A
group of organisms (plants or animals) very similar in
appearance, which can interbreed freely with each other but
not with other groups.
Species
composition – The
mixture of tree species in a stand within a forest.
Stand
– A
recognizable area of the forest that is relatively
homogeneous and can be managed as a single unit. Stands are
the basic management units of the forest. Stand types
include: –
All-aged – A
stand that supports trees of all ages and usually all
sizes. This stand type is rare. Contrast it with an
even-aged stand. –
Even-aged – A
stand in which trees are essentially the same age (within
10 to 20 years). –
Fully stocked – A
stand where trees effectively occupy all growing space, yet
ample room exists for developing crop trees. –
Mixed – A
stand that has more than one species in the main tree
canopy. –
Overstocked – A
stand that is overcrowded, thus reducing tree vigor.
–
Pole – A
stand in which most trees are 5 to 9 inches in diameter.
–
Pure – A
stand in which at least 80% of the trees belong to a single
species. –
Residual – The
stand that remains after cutting. –
Sawtimber – Most
trees in the stand are large enough in diameter (usually 10
to 12 inches DBH or larger) to be sawn into lumber.
–
Understocked – A
stand in which crop trees do not effectively occupy the
growing space. –
Uneven-aged – A
stand that supports trees of several age classes
(technically, more than two age classes).
Stand
condition – A
silvicultural classification used to describe the present
overall health of the stand, particularly in relation to
its need for treatment.
Stand
density – A
quantitative measure of stand stocking, or the number of
trees for a given area.
Stand
initiation phase – Following
a disturbance, plants regenerate the disturbed site.
Stand-replacement
fire – A
large fire that burns duff, seedlings, saplings, and mature
trees, leaving the site unoccupied by vegetation and at the
start of a successional cycle.
Stand
structure – Stages
in the natural development of a forest stand, which often
include distinct phases such as stand initiation, stem
exclusion, understory re-initiation, and old growth.
Stand
table – A
table by diameter classes of volume, basal area, or trees
per acre existing in a stand or expected to exist at a
certain time.
Stem
exclusion phase – After
several years, new individuals are not able to regenerate
within the stand. Some of the existing trees die. Survivors
grow larger and express differences in height and diameter.
Stewardship
Incentives Program (S.I.P. ) –
a program funded by the USDA Forest Service that provides
costshare assistance to private forest landowners for
approved conservation practices, such as the development of
a Forest Stewardship Management Plan, reforestation, forest
and agroforest improvement, soil and water protection,
riparian and wetland protection, and enhancement of aquatic
habitat, wildlife habitat and forest recreation. See
"Forest Stewardship Program."
Structure
–
the presence, size, and physical arrangement of vegetation
in a stand. Vertical structure refers to the variety of
plant heights, from the canopy to the forest floor.
Horizontal structure refers to the types, sizes, and
distribution of trees and other plants across the land
surface. Forest lands with substantial structural diversity
provide a variety of niches for different wildlife species.
Succession
– The
replacement of one plant community by another until
ecological stability is achieved.
See Climax
community; Plant association.
Successional
development – Where
a stand lies in the successional cycle between pioneer and
climax conditions.
Successional
stage – A
phase in the natural development of forest communities.
Over time, favorable conditions are reached for the
establishment of the next stage.
See Stand
structure.
Suppressed
trees – Trees
much shorter than the general level of the canopy. These
trees exhibit reduced growth rate and vigor.
Suppression
– When
a larger tree over-tops a smaller tree, permitting little
or no sunshine to reach the crown of the smaller tree and
retarding its growth.
Sustainability
– Forest
development that incorporates the means to maintain
biological diversity, resilience to stress, and ecosystem
health and integrity, in the context of the ability to meet
future as well as present human needs.
Sustained
yield – Management
of forest land to produce a relatively continuous flow of
timber or revenue.
Terrestrial
ecosystem – A
land-based ecosystem.
Tolerance
– The
ability of a tree to grow satisfactorily in the shade of or
in competition with other trees. Trees classified as
tolerant can survive and grow under continuous shade.
Transpiration
– Water
loss from leaves during growth and respiration.
Transplant
– A
very young tree or seedling lifted from a nursery seedbed
and replanted at the nursery.
Treatment
– Any
action in forest stands controlled by a silvicultural
prescription.
Tree
– A
woody plant having a well-defined stem, usually standing
over 30 feet high at maturity.
Tree
farm – A
privately owned woodland in which producing timber is a
major management goal. It may be recognized as a
“Certified Tree Farm” by the American Tree Farm
System.
Understory
– That
portion of the trees or other vegetation below the canopy
in a forest stand.
Understory
re-initiation phase – A
later stage in stand development when forest floor trees
and shrubs again regenerate and survive in the understory.
Uneven-aged
management – Managing
a forest by periodically harvesting trees of all ages to
maintain a broad age (or size) class distribution. The
forester maintains a greater number of trees in each
smaller age class than in the next older or larger class,
up to some maximum age. This type of management is not
common in the West.
See Selection
harvest.
View
shed – The
landscape seen from a particular viewpoint or along a
transportation corridor.
Virgin
forest – A
forest essentially uninfluenced by human activity.
Watershed
– An
area of land that collects and discharges water into a
single stream or other outlet. Also called a catchment or
drainage basin.
Watershed
analysis – The
study of how a particular drainage network functions. An
aspect of ecosystem management planning.
Wetlands
– Marshes,
swamps, and other water-saturated soils. These areas offer
important habitat for wildlife, significant support of
nutrient cycling in ecosystems, and protection against the
severity of storms and floods. Wetlands are among the lands
most vulnerable to destruction and conversion to other
uses.
Wildlife
corridors –
strips of trees, shrubs and understory vegetation that
provide cover and habitat for wildlife, and serve as travel
lanes for movement across open areas and between isolated
patches of habitat. They provide wildlife with access to
the different types of habitat they require, and can foster
re-colonization of forest fragments.
Wolf
tree –
a large, broad-crowned, excessively branchy tree which
occupies more space than is justified by its timber value,
although it may have high aesthetic and wildlife value.
Wolf trees often provide abundant cover and heavy mast
crops for animals.
Woodland
–
a forest with low tree densities, often defined as less
than 30% crown cover when trees are mature.
___________________________________________________________
Main Sources:
• Forest
Ecology in Washington,
WSU Cooperative Extension, EB1943.
• Terminology for Forest
Landowners,
WSU Cooperative Extension, EB1353.
• Terminology
of Forest Science Technology, Practice, and
Products,
Society of American Foresters (SAF).
• The
Dictionary of Forestry,
John A. Helms (editor), 1998.