Glossary


A

Abiotic
The nonliving components of the environment, such as air, rocks, light, water, temperature, etc.
Aerate
To mix air and water so that the oxygen content of the water is enhanced.
Aestivate
To go into a torpid state in which the body physiological parameters are not significantly reduced and responses to external stimuli are prompt.
Age classes
In forestry, intervals (commonly 10 years) into which the age range of a tree crop is divided; also the trees falling into such an interval. With animals, individuals in the same age range.
Agroforestry
A dynamic, ecologically-based natural resources management system that, through the integration of trees in farmland and rangeland, diversifies and sustains production for increased social, economic and environmental benefits for land users at all levels. For more information, see Landhelp.org's page on agroforestry.
Alfisols
An order in the USDA soil classification system which includes mineral soils characterized by umbric or ochric epipedons, arglillic horizons, and that hold water at less than 15-bars tension during at least 3 months when the soil is warm enough for plants to grow outdoors.
Alluvial Fan
A cone-shaped mass of sediments built by rivers or streams as they deposit materials carried from mountains onto more level ground.
Alluvial
Pertaining to inorganic material, such as sand, gravel, and rock, deposited by running water.
Alpine Zone
The elevational life zone above timberline, corresponding to the Arctic tundra, and having distinct types of low-lying plants. Found at about 11,500 ft in Central Colorado.
Anchor Chaining
A type of site preparation involving dragging a heavy ship anchor chain between 2 crawler-type tractors to remove or lessen competition from existing vegetation.
Animal Community
The species of animals supported by a combination of niches in a given area.
Annual
When referring to plants, those that complete their life cycle from seed to mature seedbearing plant in one growing season.
Apical Dominance
Inhibition of the growth of lateral buds by the terminal bud of a shoot resulting from auxins produced by the terminal buds.
Arborescent
Resembling a tree in growth, structure, or appearance.
Argillic Horizon
A mineral soil horizon that is characterized by the alluvial accumulation of layer-lattice silicate clays.
Aridisols
An order in the USDA soil classification system which includes mineral soils characterized by an aridic moisture regime, an ochris epipedon, and other pedogenic horizons but no oxic horizon.
Arid
Dry, receives little precipitation.
Asexual
Having no evident sex or sex organs; sex-less; pertaining to or characterizing reproduction involving a single individual, and without male or female gametes, such as binary fission, cloning, or budding.
Aspect
The compass direction toward which a slope faces.
Autotrophic stream
Major energy source is from within the stream.
Avian
Of, relating to, or derived from birds.


B

Bare-root
Seedling trees with their roots exposed; also refers to a method of planting seedlings in which the roots are bare.
Basal Area (of a tree)
The cross-sectional area of the trunk 41/2 feet above the ground; (per acre) the sum of the basal areas of the trees on an acre; used as a measure of forest density.
Bedding
The process of an animal lying down for rest.
Bedload Sediments
Inorganic particles too heavy to be carried in suspension which moves from stream current along the stream bed.
Biological Diversity or Biodiversity
The variety of life in all its forms and all its levels of organization. Biodiversity refers to diversity of genetics, species, ecosystems, and landscapes.
Biological Potential
The maximum production of a selected organism that can be attained under optimum management.
Biomass
The weight or total quantity of living organisms of one species per unit of space is called species biomass. The weight or total quantity of all the species in a community is called community biomass.
Biosphere
That portion of the earth's crust, waters, and surrounding air-layer which is inhabited by living organisms.
Biotic Community
An assemblage of plants, animals, and other living things in a given locality.
Biotic
Life or the act of living.
Biotrophic Levels
The feeding levels in a food chain or web.
Bloom
A proliferation of living algae and/or other aquatic plants on the surface of lakes or ponds.
Blowdown
Trees felled by high winds.
Board Foot
A unit for measuring wood volume in a tree, log, or board. A board foot is commonly 1 foot by 1 foot by 1 inch, but any shape containing 144 cubic inches of wood equals one board foot.
Bole
The trunk of a tree.
Breeding Display
A sexual ritual performed by birds or other taxa to solicit the attention of the opposite sex.
Brood Cover
Vegetative growth form and composition needed for the rearing of young ground-dwelling birds.
Brood Ranges
Geographical areas used for brood rearing by ground-dwelling birds.
Browse
The young twigs and leaves of woody plants consumed by wild and domestic animals.
Buck
To cut trees into shorter lengths, such as logs or cordwood.
Buffer Strip
A strip of vegetation that is left intact or managed to reduce the impact of a treatment or action in one area on another.
Burrow
A hole or tunnel dug in the ground by an animal.
Buteo
Any broad-winged, soaring hawk of the genus Buteo.
Butte
A hill that rises abruptly from the surroundings. The sides are steeply sloped or with cliffs, and the top is nearly flat.


C

Cacti
Plants adapted to dry conditions. Plural of cactus.
Caliper
A tool to measure the diameter of a tree.
Calving Area
The areas, usually on spring-fall range, where cows give birth to calves and maintain them during their first few days or weeks.
Cambium
In woody vegetation, the layer of cells that lies between the secondary xylem and secondary phloem cell layers; through a process of cell division, the cambium produces the secondary xylem and the secondary phloem that are also known, respectively, as the wood and the innermost living bark.
Cannibalistic
Refers to animals that eat their own kind.
Canopy Closure
The progressive reduction of space between tree crowns as they spread laterally; a measure of the percent of potenetial open space occupied by the collective tree crowns in a stand.
Canopy
The continuous cover formed by tree crowns in a forest.
Canyon
A deep, narrow gap or cleft in the earth caused historically by running water or glaciers.
Carnivore
An organism that depends largely on other animals as a source of nutrients.
Carnivorous
Of, or relating to carnivores.
Carrion
Dead and decaying flesh
Carrying Capacity
The maximum rate of animal stocking possible without inducing damage to vegetation or related sources; may vary from year to year because of fluctuating forage production.
Case-harden
In wood, characterized by compression in the outer layers and tension in the core, the result of too severe drying conditions; trees or logs charred on the outside are often case hardened.
Cavity Dwellers
Species of birds and mammals that depends on cavities in trees for their shelter and/or nesting.
Cavity Nesters
Wildlife species that nest in cavities.
Channel
An open conduit, either naturally or artifically created, which periodically or continuously contains moving water or which forms a connecting link between two bodies of water.
Charring
Burning or scorching the surface of woody material.
Chipping
The process of reducing large pieces of wood into small pieces of more of less uniform size by running the material through a chipper.
Cirque
A deep, steep-walled recess in a mountain, caused by glacial erosion at the head of a valley.
Cleaning Cuts
An operation in a young stand, not past the sapling stage, to: (1) free small trees, as in a plantation, from weeds, vines, or sod-forming grasses, and (2) provide better growing conditions by liberating crop trees from other individuals of similar age but of less desirable species or from which are overtopping or likely to overtop them.
Clearcutting
Removal of the entire standing crop of trees; in practice much unsalable material may be left standing.
Clearcut
The harvest of all the trees in an area. Clearcutting is used to aid tree species whose seedlings require full sunlight to grow well or wildlife species that require open areas for forage near forest edge.
Climax Community
Final or stable community in successional series.
Climax
The culminating stage in plant succession for a given site where the vegetation has reached a highly stable condition; and is self-perpetuating and in dynamic equilibrium with the physical habitat.
Clinometer
An instrument used to determine the height of a tree or angle of a slope.
Clone
A group of plants, growing in close association, derived by asexual reproduction from a single parent plant.
Closed Canopy
The condition that exists when the canopy created by trees or shrubs or both is dense enough to exclude most of the direct sunlight from the forest floor.
Coastal Plain
Large, nearly level areas of land near ocean shores.
Cobble
Naturally rounded stone larger than a pebble and smaller than a boulder.
Codominant Tree
A tree that extends its crown into the canopy and receives direct sunlight from above but limited sunlight from the sides. One or more sides of a codominant tree are crowded by the crowns of dominant trees.
Cold fire
A low intensity fire, usually characterized by moderately high fuel moisture content and little or no surface wind.
Coldwater Fish
Any fish which propagates and thrives in colder waters, usually less than 70 F, and doesn't tolerate warmer waters for extended periods of time, including chars, trout, salmon, grayling, and whitefishes.
Coliform Organism
Any of a number of organisms common to the intestinal tract of man and other animals whose presence in water is an indicator of pollution and of potentially dangerous bacterial contamination.
Collector
Aquatic insects that filter small food particles.
Colluvial Fan
A cone-shaped accumulation of rock fragments and other debris deposited at or near the base of cliffs or mountains by gravitational force.
Colonial Nesters
Birds that commonly nest in colonies.
Colony
A group of the same kind of animals or plants living together.
Commensalism
2 or more organisms living together in a mutually beneficial relationship.
Commercial Forestland
Any area capable of producing 20 cubic feet of timber per acre per year that has not been protected from such use by law or statute.
Communal Roost
An overnight resting place used over an extended period of time by a group of birds, usually of the same species.
Community Type
A generalized category comprising a number of similar units or stands of vegetation and including animal life.
Community
A group of one or more populations of plants and animals in a common spatial arrangement; an ecological term used in a broad sense to include groups of various sizes and degrees of integration.
Competition
When two or more organisms use the same resource.
Congregate
When animals group together in an area.
Coniferous Forest
A forest dominated by cone-bearing trees.
Coniferous
Pertaining to trees that bear cones.
Conifer
The most economically important order of the Gymno-spermae, comprising a wide range of trees within Coniferophytina (class Coniferopsida); Trees mostly evergreen that bear cones and have needle-shaped or scale-like leaves; timber commercially identified as softwood.
Consulting Forester
An independent professional who manages forests and markets forest products for private woodland owners. Consulting foresters do not have direct connections with firms that buy wood products, but are retained by woodland owners as their agents.
Consumers
Organisms that require organic substances and obtain them by living off other organisms.
Containerized Seedlings
Young trees growing in biodegradable receptacles in which they have developed.
Contrast
In wildlife management, the degree of difference in vegetative structure along edges where plant communitites meet or where successional stages or vegetative conditions within plant communities meet.
Control Line
An inclusive term for constructed or natural fire barriers; a fire edge treated to control a fire.
Cooperative Extension Service (CES)
The educational arm of the USDA that links university research to people who can benefit from it.
Cordwood
Small diameter or low quality wood suitable for firewood, pulp, or chips. Cordwood is not suitable for sawlogs.
Cover
Vegetation used by wildlife for protection from predators, or to ameliorate conditions of weather, or in which to reproduce; also a shortened version of "crown cover"
CPOM
Coarse particulate organic matter, coarse bits of detritus found within an aquatic ecosystem.
Crop Tree
A young tree of a desirable species with certain characteristics desired for timber value, water quality enhancement, or wildlife or aesthetic uses.
Crown (shrub)
The region of a seed plant at which stem and root merge.
Crown (tree)
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.
Crown-sprout
The ability of some plants to regrow after plant material above ground is removed by fire or other disturbances.
Crown Cover
The amount of canopy provided by branches and foliage of trees, shrubs, and herbs in a plant community. May be specified by species, kind of plant, or collectively.
Cruise
A forest survey used to obtain inventory information and develop a management plan.
Cruising Radius
The maximum distance an animal travels from a central point in its habitat; usually expressed in terms of time; daily, seasonal, or annual.
Cull Logs
Trunks of trees that have been cut and left during a timber harvesting operation because they are of inferior quality.
Cull Material
Any item of production relegated or rejected because it did not meet certain specifications.
Cultivate
Tilling or working the soil for the purpose of growing crops and other desired plants.


D

DBH
Tree diameter at breast height. This has traditionally been the "sweet spot" on a tree where measurements are taken and a multitude of calculations are made to determine things like growth, volume, yield and forest potential. Tree DBH is outside bark diameter at breast height. Breast height is defined as 4.5 feet (1.37m) above the forest floor on the uphill side of the tree. For the purposes of determining breast height, the forest floor includes the duff layer that may be present, but does not include unincorporated woody debris that may rise above the ground line.
Dead and Down Woody Material
All woody material, from whatever source, that is dead and lying on the forest floor.
Decadent
Deteriorating; when used in reference to forest stand condition, there are inferences for the loss of trees from the overstory and of the presence of disease, or indications of loss of vigor in dominant trees so that the mean annual increment is negative.
Deciduous
Shedding or losing leaves annually; the opposite of evergreen. Trees such as maple, ash, cherry, and larch are deciduous.
Decimating Factors
Causes of mortality in a wildlife population, i.e., hunting, parasites, disease, poison, starvation, and predation.
Deflector
A structure placed in a stream or river to create more favorable fish habitat by altering the direction of flow.
Defoliate
To remove leaves from a plant.
Dense
Thick or crowded closely together.
Den Tree
A tree with cavities suitable for birds or mammals to nest in.
Depositional Material
Matter deposited by either water or ice.
Detrimental
Having harmful effects.
Detritus
Leaf litter, twigs, and other particulate organic matter.
Dew
Water droplets condensed from the air onto cool surfaces such as leaves.
Diagnostic
Of or relating to diagnosis; identified with a species or situation.
Diameter at Breast High (DBH)
The standard diameter measurement for standing trees, including bark, taken at 4.5 feet above the ground.
Dimension Lumber
Hardwood dimension lumber is processed to be used whole in the manufacture of furniture or other products. Softwood dimension lumber consists of boards more than 2 inches thick but less than 5 inches thick. This wood is used in construction.
Dispersal
The movement of members of a population into or out of a habitat.
Dispersion
The pattern of distribution of individuals in an animal population; in the mathematical sense dispersion describes the probability of occurrence of such individuals in particular places.
Dissemination Distance
The distance seed is naturally dispersed or distributed from its point of origin.
Dissolved Oxygen
In contrast to the molecules of oxygen, along with hydrogen, of which water is physically constituted, is atmospheric oxygen that has been absorbed by water. Fish and other aquatic organisms depend upon dissolved oxygen.
Diversity Index
A number that indicates the relative degree of diversity in habitat per unit area, as in the Shannon or Simpsons indices of diversity.
Diversity
The relative degree of abundance of wildlife species, plant species, communities, habitats, or habitat features per unit of area.
Dominance
Condition in communitites or in vegetational strata in which one or more species, by means of their numbers, coverage, or size, have considerable influence upon or control of the conditions of existence of associated species.
Dominant
Plant species or species groups which, by means of their numbers, coverage, or size, influence or control the existence of associated species. Also, individual animals which determine the behavior of one or more other animals, resulting in the establishment of a social hierarchy.
Down material
Trunks and limbs of trees in various stages of decomposition found on the forest floor.
Dozing
A method of clearing woody vegetation by using a tractor with a front-mounted blade to push over individual trees or bushes.
Drought
The lack of normal precipitation for an extended period of time.
Dusting Area
A location where animals dust themselves.
Dusting
The process of rolling or exercising vigorously in dust or duff; in birds, has the function of aligning barbules and maintaining feathers.
Dynamic
Characterized by or tending to produce continuous change or advance.


E

Ecological Dominants
Organisms that exert a major controlling influence within a trophic level or a community by virtue of their numbers, size, production, or other attributes.
Ecological Niche
The role a particular organism plays in the environment.
Ecological Principles
Fundamental assumptions or laws that determine the existence and status of organisms within a community.
Ecological Succession
The transition of species within a given area through a definite ecological state; Through succession of species composition, grasslands can become tree-bearing forests.
Ecology
The study of interactions between organisms and their environment.
Ecosystem
An interacting natural system including all the component organisms together with the abiotic environment; occupying an arbitrarily defined volume of the biosphere.
Ecotone
A transition area between two distinct, but adjoining, communities.
Edge Effect
The increased richness of flora and fauna resulting from the mixing of 2 communities at an ecotone where they join. Also the effects (often negative) of increasing surface to volume ratio in habitats thereby reducing effective space for interior species.
Edge
The boundary between two ecological communities, for example, field and woodland. Edges may provide wildlife habitat for certain species. Consideration of an edge can reduce the impact of a timber harvest.
Elk Calving Habitat
A habitat used by elk for calving; usually located on spring-fall range in areas of gentle slope; contains both forage areas and hiding and thermal cover close to water.
Emphasis Species
Those animals which are favored in habitat management because they have certain attributes which meet the goals of the landowner or the agency having management responsibility, such as: those having sport, commercial, or special aesthetic values, those which are threatened or endangered, or a combination of these.
Endangered Species
Any species or subspecies in immediate danger of becoming extinct throughout all or a significant portion of its range.
Entisols
An order in the USDA soil classification system that includes mineral soils characterized by the absence of distinct pedogenic horizons within 39 inches of the soil surface.
Entries
Tree harvesting activities.
Environmental Stability
A degree of consistency in environmental parameters that tends to produce a balanced community.
Environment
The sum total of all the external conditions that may influence organisms. The surroundings that affect the growth and development of an organism.
Epicormic Branching
Branches that grow out of the main stem of a tree from buds produced under the bark. Severe epicormic branching increases knottiness and reduces lumber quality.
Epilimnion
The water layer overlying the thermocline of a lake.
Escape Cover
Usually vegetation dense enough to hide an animal; used by animals to escape from potential enemies.
Eurytopic species
Organisms with wide ranges of ecological tolerances that permit them to be widely distributed.
Eutrophication
Having waters rich in mineral and organic nutrients that promote a proliferation of plant life, especially algae, which reduces the dissolved oxygen content and often causes the extinction of other organisms.
Even-Aged Stand
A stand in which the age difference between the oldest and youngest trees is minimal, usually no greater than 10 to 20 years. Even-aged stands are perpetuated by cutting all the trees within a relatively short period of time.
Evergreens
Plants that retain foliage year round.
Excavate
To make a cavity or a hole.
Exclusion
Keeping something out of an area.
Exponential
Expressed in terms of a designated power of E, the base of natural logarithms.
Extension Forester
A Cooperative Extension Service professional who educates woodland owners on how they can effectively manage their forests.


F

Farm Services Agency (FSA)
The branch of the U.S. Department of Agriculture (USDA) that administers cost-sharing programs for such forestry practices as tree planting and timber stand improvement.
Fawning Area
An area, usually on spring-fall range, where does give birth to fawns and maintain them in their first few days or weeks.
Featured Species Management
A wildlife management strategy to produce relatively high numbers of selected wildlife species in particular places for particular purposes.
Felling
The cutting of standing trees.
Fertile
Rich in material needed to support plant growth.
Filamentous
Having filaments, or long thread-like appendages.
Final Cut
Generally, removal of the last trees left in a stand; more particularly, removal of the last seed bearers or shelter trees after regeneration is considered to be established under a shelterwood system.
Fissured
Fractured into narrow openings or cracks.
Floodplain
Land areas adjacent to streams that are subject to periodic flooding.
Flow regime
A combination of velocity and volume of water carried by a stream that determines channel characteristics and sediment load capacity.
Fluctuate
To vary, or rise and fall irregularly.
Flushing flow
A periodic, higher than normal volume of stream flow that serves the beneficial purpose of removing fine sediments from coarse-textured stream beds.
Food Chain
The path through which energy is transferred from plants to herbivores and then to carnivores.
Food Drift
Aquatic and terrestrial invertebrates carried downstream by the current.
Food Pyramid
A graphic portrayal of the flow of energy through a biotic community, using categories of food-consuming organisms as the strata in a triangular configuration.
Food Web
The interlocking of food chains.
Forage Fish
Nongame fish upon which many game fish rely as a major source of food.
Forage
Vegetation used for food by wildlife, particularly ungulate wildlife and domestic livestock.
Forb
Any herbaceous plant species other than those in the Gramineae, Cyperaceae, and Juncaceae families. Broad-leaved flowering plant, other than a grass or woody shrub.
Forester
A degreed professional trained in forestry and forest management.
Forest Fragmentation
The subdivision of large natural landscapes into smaller, more isolated fragments. Fragmentation affects the viability of wildlife populations and ecosystems.
Forestry Incentives Program (F.I.P.)
A Federal cost-sharing program that reimburses part of the costs landowners incur in completing certain forestry practices. The F.I.P. is administered by the Natural Resources Conservation Service.
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.
Forest Type Conversion
Alteration in the vegetative composition of a stand of trees resulting from the implementation of a planned effort.
Forest
A biological community dominated by trees and other woody plants.
FPOM
Fine particulate organic matter, fine bits of detritus found within an aquatic ecosystem.
Free water
Water that is not bound to any surface, particularly soil particles.
Frilling
The method of killing trees by inflicting a series of cuts around the bole and applying an herbicide to the wounds. Frilling or girdling can be used to reduce the density of a stand or kill individual trees that are undesirable for timber and/or chosen to provide standing dead trees (snags) for wildlife.
Frost Pocket
A low-lying, localized area in which the frost-free growing season is appreciably shorter than that of the immediately surrounding area.
Fruit
The ripened ovary or ovaries of a seed-bearing plant, together with accessory parts, containing the seeds and occurring in a wide variety of forms. An edible, usually sweet and fleshy form of such a structure.
Fuelwood
Living or dead trees, or portions thereof, suitable for burning as fuel.
Full Stocking
The stocking level (density) of a forest stand that yields maximum biologically possible growth rates; synonymous with optimum stocking.
Fungicide
A chemical substance that kills fungi.
Fungi
Plural of fungus; Any of numerous eukaryotic organisms of the kingdom Fungi, which lack chlorophyll and vascular tissue and reproduce sexually and asexually with the formation of spores. Fungi range in form from a single cell to a body mass of branched filamentous hyphae that often produce specialized fruiting bodies. The kingdom includes the yeasts, molds, smuts, and mushrooms and include species that exist as saprophytes or parasites of other plants and animals.


G

Game
Species of vertebrate wildlife hunted by man for sport.
Gene Pool
Narrowly, the genic material of a localized interbreeding population; broadly, the genic resources or materials of a species throughout its entire range.
Geomorphic
Of or like the earth or the configuration or shape of the earth's surface.
Girdling
A method of killing trees by cutting through the stem, thus interrupting the flow of water and nutrients. Girdling can be used to reduce the density of a stand or kill individual trees that are undesirable for timber and/or chosen to provide standing dead trees (snags) for wildlife.
Glaciation
The action of huge masses of moving ice formed from compacted snow.
Gleaner
One who gleans or picks up bit by bit.
Gleaning
A process of feeding, particularly by birds, in which food items are gathered from the surface of the foraging substrate.
Glean
To gather food in a systematic manner with a minimum of waste and unnecessary effort.
Gradient
The rise or fall of a ground surface expressed in degrees of slope.
Grain
Cereal grains for human consumption.
Granitic
Of, pertaining to, or derived from granite.
Grass-Forb Stage
1 of 5 forest structural stages, a successional stage dominated by grasses and forbs.
Grass
Relatively short plants typically having long narrow leaves and hollow, jointed stems.
Grazers
Aquatic insects that feed on attached algae or other aquatic plants.
Grit
Granular inorganic matter ingested by gizzard-equipped birds to facilitate the grinding of hard food items.
Ground water
Water within the earth that supplies wells and springs.
Group Selection
A modification of the selection system in which trees are removed in small groups rather than individually.
Growing Stock
All the trees growing in a forest or a specified part of it; generally expressed in numbers or volume.
Growth form, animal
The pattern of increasing and/or decreasing density an animal population exhibits over time.
Growth form, plant
Morphological categories of plants, such as trees, shrubs, and vines.
Growth Rings
The layers of wood a tree adds each season; also called annual rings. These rings frequently are visible when a tree is cut and can be used to estimate its age and growth rate.
Guild
A functional category used for combining species that overlap significantly in their utilization of a particular resource.


H

Habitat Component
A simple part, or a relatively complex entity regarded as a part, of an area or type of environment in which an organism or biological population normally lives or occurs.
Habitat Niche
The smallest unit of a habitat (the arrangement of food, cover, and water) that is occupied by an organism. Habitat niche refers to the physical space occupied by the organism while ecological niche refers to the organism's role.
Habitat
The area or environment where an organism or ecological community normally lives or occurs.
Hard Snag
A snag composed primarily of sound wood, particularly sound sapwood; generally merchantable.
Hardwoods
A general term encompassing broadleaf, deciduous trees.
Harvest
In forestry, the cutting, felling, and gathering of forest timber. May also refer to the hunting of game animals.
Hawking
The feeding behavior of birds wherein they catch insects in flight.
Hazard Reduction
A management action designed to reduce risk from a recognized combination of factors that may lead to injury or economic loss.
Heart Rot
Any rot in a tree confined to the heartwood, associated with fungi species; generally originating in a living tree.
Herbaceous
Relating to plants having little or no woody tissue.
Herbicide
A chemical substance used for killing plants.
Herbivore
An organism that eats plants.
Herpetofauna
An artificial grouping of animals that includes amphibians and reptiles.
Heterogeneity
A relative term used to express the degree of abundance of different species in an animal or plant community. Also used to describe genetic variability.
Heterotrophic stream
Major energy sources are produced outside the stream.
Hibernate
To go into a torpid state in which the body physiological parameters are drastically reduced and responses to external stimuli are gradual.
Hiding Cover for deer
Vegetation capable of hiding 90% of a standing adult deer from the view of a human at a distance equal to or less than 200 feet; generally, any vegetation used by deer for security or to escape from danger.
Hiding Cover for elk
Vegetation capable of hiding 90% of a standing adult elk from the view of a human at a distance equal to or less than 200 feet; generally, any vegetation used by elk for security or escape from danger.
High Grading
To remove all mature, good quality trees from a stand and leave inferior species and individuals. High grading should be distinguished from even-aged management in which mature and immature trees are removed to aid regeneration.
High Thinning
Synonymous with crown thinning.
Holistic
Emphasizing the importance of the whole and the interdependence of its parts.
Home Range
The area that an animal traverses in the scope of normal activities; not to be confused with territory.
Homogeneity
Degree of sameness.
Horizontal Diversity
The diversity in an area that results from the number of plant communities or successional stages or both; the greater the number, the greater the horizontal diversity.
Hot Fire
A high intensity fire, usually characterized by low fuel moisture content and high surface wind velocities.
Hydrarch Succession
Primary succession that is initiated in or at the margin of a lake, pond, or stream.
Hydrophilic
Of, relating to, or having a strong affinity for water.
Hydrophobic
Repelling, tending not to combine with, or incapable of dissolving in water.
Hypolimnion
The water layer underlying the thermocline of a lake.


I

Improvement Cuts
Cuttings made in a stand past the sapling stage for the purpose of improving its composition and character, by removing trees of less desirable species, form, and condition in the main crown canopy.
Inceptisols
An order in the USDA soil classification system which includes mineral soils characterized by one or more pedogenic horizons in which mineral materials other than carbonates or amorphous silica have been altered or removed but not accumulated to a significant degree.
Incubation period
The time interval between egg laying and hatching.
Indicator Species
Plants or animals whose physical presence denotes the presence of other species or environmental conditions not readily observed.
Induced Diversity Index
A number that indicates the relative degree of induced diversity in habitat per unit area produced by edges formed at the junction of successional stages or vegetative conditions within plant communities by direct human activities.
Induced Edge
An edge created between 2 successional stages or vegetative conditions within a plant community due to direct human activities.
Induced Opening
A clearing in forested or brushy areas created intentionally by man.
Inflow-outflow Ratio
The relationship between the volume of water flowing into a body of water to that being discharged.
Inherent Diversity Index
A number that indicates the relative degree of inherent diversity in habitat per unit area produced by plant community to plant community edges.
Inherent Edge
An edge that results from the natural meeting of 2 plant community types.
Insectivorous
An animal that eats insects.
Interior Basin
Land areas that are generally bowl-shaped and surrounded by hills and mountains.
Intermediate cuts
Cuttings made in a stand between the time of its formation and its major harvest.
Intermittent stream
A stream that ordinarily goes dry at one or more times during the year but sustains flows for some period.
Interpersion
The intermixing of plant species and plant communities that provide habitat for animals in a defined area.
Interspecific
Existing or arising between members of different species.
Intraspecific
Existing or arising between members of the same species.
Introduced Species
A nonnative species that was intentionally or unintentionally brought into an area by humans.
Irrigate
To supply cropland, parks, yards with water through the use of diversions, ditches, and pipes.


J

Juxtapose
To situate side by side; to place together.
Juxtaposition
The act of arranging stands in space.


K

Keystone Species
A species whose presence contributes to a diversity of life and whose extinction would consequently lead to the extinction of other forms of life. Keystone species help to support the ecosystem (entire community of life) of which they are a part.


L

Lacustrine soils
Refers to those soils that originated from sediments in lakes.
Lagomorph
Any of an order of gnawing animals having two pairs of incisors in the upper jaw, one behind the other, and comprising the rabbits, hares and pikas.
Landform
A feature of the earth's surface with distinctive form characteristics which can be attributed to the dominance of particular processes or structure in the course of its development and to which the feature can be clearly related.
Landing
A cleared area within a timber harvest where harvested logs are processed, piled, and loaded for transport to a sawmill or other facility.
Latilong study
An inventory of organisms based on their occurrence in relationship to latitude and longitude.
Layering
The positioning of vegetative strata within a plant community.
Leave strip
Stands of trees left standing between areas where trees have been removed.
Legume
A plant of the pea family (Leguminosae) that bears seeds in a pod.
Lek
A site where birds traditionally gather for sexual display and courtship.
Liberation cuts
Cuttings designed to release a young stand, sapling stage or younger, from overstory competition.
Limiting factor
The environmental influence through which the toleration limit of an organism is first reached, which acts, therefore, as the immediate restriction in one or more of its functions or activites or in its geographic distribution.
Litter
The uppermost layer of organic debris on a forest floor.
Littoral
Refers to shallow water in which aquatic vegetation can be present on the bottom.
Lopping and Scattering
Cutting up the tree branches or slash created by logging and spreading it more or less evenly over the ground without burning.
Lopping
After felling, the chopping of small trees and branches and tops of large trees so that the resultant slash will lie close to the ground and decay more rapidly.
Low thinning
A type of thinning that particularly favors the dominant trees by removing a varying portion of the other trees.


M

Macrospatial Heterogeneity
Geographical differences in plant or animal diversity in relationship to latitude or topographic relief.
Mammalian
of, relating to, or derived from mammals.
Management Indicator Species
Endangered and threatened species (or species of concern) identified on state and federal lists for the planning area.
Manipulate
Manage or influence to achieve desired results.
Marking Timber
Indicating by paint or other means which trees are to be cut or otherwise treated. It is advisable to mark trees to be harvested twice - once at eye level and once on the stump.
Mast
The nuts of forest trees suitable as food for livestock and wildlife.
Mature Stage
1 of 5 forest structural stages in which the stand is primarily composed of or dominated by mature trees in vigorous condition.
Maturity
The stage at which a tree or other plant has attained full development and is in full seed production.
McLeod
A combination hoe, rake and scraping tool used by Firefighters to remove plants and shrubs when building a fireline.
Meandering
Following a winding, intricate course.
Mechanical Thinning
Any thinning that selects the trees to be removed according to some simple, objective criterion.
Mesic
Refers to environmental situations characterized by moderately moist conditions.
Mesophytic
Refers to plants that grow under moderately moist environmental conditions.
Microclimate
The climatic conditions within a small or local habitat that is well defined.
Microenvironment
A small environment.
Microscopic
Too small to be seen by the unaided eye.
Microspatial Heterogeneity
Site specific differences in species diversity.
Midstory
The middle story of a three-story tree canopy.
Migration Corridor
A belt, band, or stringer of vegetation that provides completely or partially suitable habitat which animals follow during migrations.
Migration Route
A travel route used routinely by wildlife in their seasonal movement from one habitat to another.
Mixed-age Stand
A stand composed of trees of 2 or more ages.
Mixed Stand
A stand of trees in which less than 80% of the trees in the main crown canopy are of a single species.
Moldboard Plow
A type of plow that turns the soil completely upside down, burying all crop remains underneath.
Mollisols
An order in the USDA soil classification system which includes mineral soils chacterized by a mollic epipedon overlaying mineral material with a base saturation of 50% or more when measured at ph 7.
Monomer
A chemical compound that can undergo polymerization
Monotype
Made up of a single species.
Monotypic
Of, or pertaining to a single species.
Montane Zone
An elevational life zone extending from the foothills up to the subalpine zone.
Mop-up
The act of making a fire safe after it has been controlled.
Moraine
An accumulation of earth and stone carried and finally deposited by a glacier.
Mortality
The death or loss in a population from any cause.
Multi-tiered stands
Stands with 2 or more distinct tree layers in the canopy.
Multiple Use
A concept of land management in which a number of products or services are deliberately produced from the same land base.
Mutualism
An obligatory relationship between 2 species wherein both species benefit from the relationship.


N

Natality
The production of new animal life by a given animal population; Birth.
Natural Openings
Clearings in a forest or shrub area that are inherent because of site factors or that have been created by natural causes.
Natural Resources Conservation Service (NRCS)
The branch of the USDA that coordinates and implements soil conservation practices on private lands. The NRCS can provide woodland owners with detailed information about soil characteristics.
Natural Thinning
The mortality or loss of trees in a stand due to suppression by more vigorous growing individuals.
Non-persistent Pesticide
A pesticide having a short life or existence under natural conditions.
Non-serotinous Cones
Opposite of serotinous; opening at maturity without requiring heat to expose seeds.
Nongame
Wild vertebrates not commonly subject to sport hunting or fishing.
Nutrient Level
The degree of fertility.
Nutrient
Any substance that can be metabolized by an organism to give energy and build tissue; Nutritive substance required for plants and animals to grow and exist.


O

Obligate Association
An interspecific relationship in which one species is highly dependent on the other.
Obligate Exclusion
An interspecific relationship in which one species excludes another.
Old-growth Forest
The last stage in forest succession. An old-growth forest often has large individual trees, a multi-layered crown canopy, and a significant accumulation of coarse woody debris.
Old-growth Stage
1 of 5 forest structural stages dominated by over-mature trees.
Old-growth Stand
A forest stand that is past full maturity and showing decadence.
Open canopy
A canopy condition that allows large amounts of direct sunlight to reach the ground.
Outwash
Detritus, consisting mostly of gravel and sand, transported by the running water from a melting glacier and laid down in stratified deposits.
Overmature
The condition that exists after an even-aged stand reaches maturity and declines in vigor, health, and soundness.
Overstocked
The situation in which trees are so closely spaced that they compete for resources and do not reach full growth potential.
Overstory
The portion of the trees that form the uppermost canopy layer in a forest of more than 1 story.
Overturn
The sinking of surface water and rise of bottom water in a lake that results from changing temperatures that occur in the spring and fall wherever lakes are icebound in the winter.
Ovulation rate
Number of eggs available for fertilization in a given period of time.
Oxbow Lake
A crescent-shaped body of water that remains after a stream channel has been altered.


P

Palatability
The relish with which a particular species or plant part is consumed by an animal.
Parasite
Organism that attacks or lives at the expense of another organism.
Parent Material
Organic or inorganic material from which soil originates by a process of weathering and chemical decomposition.
Park
An open space all or partly surrounded by trees.
Partial Cuts
Any timber harvest that leaves live trees standing for some management purpose.
Particulate Matter
Minute particles of organic or inorganic materials.
Parturition
The act or process of giving birth.
Pathogen
Any agent that causes disease, especially microorganisms.
Pathological Age
A cutting time for trees determined on the basis of pathological factors.
Pellet group
A concentration of numerous particles of fecal material resulting from a single defecation.
Peninsula
A long, narrow projection of land into water.
Percolation
Downward flow or infiltration of water through the spaces between rocks or particles of soil.
Perennial
For streams, running water ordinarily present on a year round basis. For plants, a plant lasting for three seasons or more.
Persistent Pesticide
A chemical poison which doesn't decompose within 1 growing season or 1 year after application and is capable of being stored within the tissues of an organism and transferred from 1 organism to another through a food chain.
Pesticide
A substance that destroys pests.
Phase
A plant grouping resulting from site-differentiated variations within a plant association rather than time-differentiated occurrences.
pH
A notation designating acidity and alkalinity.
Plankton
Free-swimming or floating animal and plant life generally dependent upon water current for locomotion.
Plant Association
A grouping of plants that have reached dynamic equilibrium with the local environmental conditions and is equivalent to climax.
Plant Community
A vegetative complex unique in its combination of plants; A reflection or integration of the environmental influences on the site; denotes a general kind of climax vegetation.
Plant Formation
A broad level of plant classification which is primarily controlled by major climatic relations and is distinguished on the basis of physiognomy of life form of the dominants only, e.g., coniferous forests, deciduous forests.
Plant Region
A division of a plant formation that is similar throughout its extent in physiognomy and is generally controlled by regional climate, e.g., temperate xerophytic forest.
Plant Series
A division of a plant region that has specificity of physiognomy of its ecological structure and is generally characterized by 1 or 2 common climax dominant plant species, e.g., ponderosa pine forest.
Plateau
An elevated, relatively level expanse of land.
Playa
The level area at the bottom of a closed basin that is often covered with water from rain runoff and snow melt.
Pole-sapling stage
1 of 5 forest structural stages in which the dominant vegetation is trees that qualify as poles (generally 4 to 10" DBH) or saplings (generally 1-4" DBH).
Pole Stand
A stand of trees whose average dbh is between 4 and 10 inches.
Pole Timber
Trees 4 to 10 inches dbh.
Pole
A tree, from the time its lower branches begin to die until the time the rate of crown growth begins to slow and crown expansion is noticable.
Polymer
A chemical compound or mixture of compounds formed by polymerization and consisting essentially of repeating structural units.
Pool-riffle ratio
An expression of the length of a stream composed of pools in relation to that of riffles.
Pool
An area of stream that is deep and of low current velocity relative to the main stream.
Population
The aggregate of all units forming the subject of study. A community of individuals that share a common gene pool.
Potential Natural Vegetation (PNV)
The vegetation that would exist if humans were removed from the scene and the resulting plant succession were telescoped into a single moment.
Pothole
A sizeable, rounded, and often water-filled depression in land.
Precommercial Operations
Cutting in forest stands to remove wood too small to be marketed. Precommercial operations improve species composition and increase the quality, growth, and vigor of remaining trees.
Predator
Any animal that kills and feeds on other animals.
Preparatory cut
A light partial cut, made towards the end of the cutting rotation cycle in stands under shelterwood management.
Prescribed Burning
Skillful application of fire to natural fuels under conditions of weather, fuel moisture, soil moisture, etc. that allow confinement of the fire to predetermined areas to accomplish management objectives.
Prescribed Fire
Fire used as a management tool under specific conditions for burning a defined area.
Prescription
The formal written plan of action to carry out a silvicultural treament of a forest stand to achieve specific objectives.
Primary Cavity Nester
A species that excavates, digs or chips out cavities in wood to provide itself with a site for nesting, e.g., woodpecker.
Primary Productivity
The rate at which new organic material is created.
Primary Succession
Any ecological development of plant or animal life originating from a bare area.
Producers
Green plants that synthesize their own organic compounds from inorganic substances.
Prospectus
A document that describes the location of a property, indicates trees marked for cutting, and states that the timber will be sold in accordance with a suitable contact. A prospectus includes the number of trees marked, their diameter classes, and a volume.
Protocooperation
an interspecific relationship favorable to both species but not obligatory.
Pruning
The act of sawing or cutting branches from a living tree. In forest management, pruning is done to promote the growth of clear, valuable wood on the tree bole.
Pruning
The cutting away of unwanted material.
Pulpwood
Wood suitable for use in paper manufacturing.
Pure Stand
A stand of trees in which at least 80% of the trees in the main crown canopy are of a single species.


R

Railing
A method of clearing shrubby vegetation by dragging railroad rails through it with 2 large tractors.
Raptorial Birds
Pertaining to birds that are raptors.
Raptor
A predatory bird that catches and kills its prey with sharp claws or talons on its feet and tears flesh with a specialized hooked beak.
Regenerate
To renew a tree crop through artifical or natural means or both. Also to replace lost or damaged parts with new tissue.
Regeneration Cut
Any removal of trees intended to assist regeneration already present or to make regeneration possible.
Regeneration
The process by which a forest is reseeded and renewed. Advanced regeneration refers to regeneration that is established before the existing forest stand is removed.
Rejuvenate
To stimulate and return to youthful health and vigor.
Release Cuttings
Cuttings designed to free trees from competition by cutting or otherwise removing neraby vegetation.
Removal Cuts
The last cuttings made in stands under shelterwood.
Residual Stand
The trees remaining intact following any cutting operation.
Resilience
A measure of the ability of a system to persist in the presence of perturbations arising from weather, physical-chemical factors, other organisms, or humans.
Resprouting
The production of new plant growth from the root crown.
Rest-rotation Grazing
An intensive system of management whereby grazing is deferred on various parts of the range during succeeding years.
Richness
A measure of the relative degree or number of plant or wildlife species or both associated with particular habitat conditions.
Riffle
The faster moving portion of a stream.
Riparian
Of, pertaining to, or situated on the banks of a watercourse (as a river or stream).
Roller chopping
A method of clearing shrubby vegetation by pulling a large, water-filled drum with attached cutters through the vegetation.
Rotation
The planned number of years between the regeneration of a stand and its final cutting at a specified stage.
Rubble
Rough broken stone


S

Salmonids
Coldwater fishes of the family salmonidae, e.g., salmon and trout.
Salvage Cut
The removal of dead, damaged, or diseased trees to recover maximum value prior to deterioration.
Sanitation Cutting
The removal of dead or damaged trees or trees susceptible to death or damage.
Sapling
A tree at least 41/2 feet tall and up to 4 inches in diameter
Saturation Point
The maximum population density an optimum habitat for a species will support.
Scarify
To break up and loosen the surface of the ground; To etch, slit or soften the outer seed coat in order to speed germination.
Secluded
Removed or screened from view of other areas and disturbances.
Second-growth Stand
A group of trees that has been regenerated naturally.
Secondary Cavity Nester
Wildlife that occupies a cavity in a tree or snag that was excavated by another species.
Secondary Succession
Ecological development of a site that takes place following the destruction of part or all of the vegetation on the site.
Sedge
Any of numerous grasslike plants of the family Cyperaceae, having solid stems, leaves in three vertical rows, and spikelets of inconspicuous flowers, with each flower subtended by a scalelike bract.
Sedimentary Rocks
Rocks formed by the accumulation of sediment in water.
Sediment
Material suspended in liquid or air.
Seed Bearer
Any tree retained to provide seed for natural regeneration.
Seedbed
Soil prepared for planting of seed or natural reseeding.
Seed Cut
A cut designed to further open a shelterwood managed stand after the preparatory cut and before seeding takes place to provide the necessary light and heat required for regeneration.
Seedling
A young tree grown from seed from the time of germination until it becomes a sapling.
Seed Tree
A mature tree left uncut to provide seed for regeneration of a harvested stand.
Seed
The propagative part of the plant.
Selection Harvest
The harvest of individual trees or small groups of trees at regular intervals to maintain an uneven-aged forest. Selection harvests are used to manage species that do not need sunlight to survive.
Selection Thinning
A cut of the largest dominant trees and the poorest overtopped trees in effort to utilize the timber before dominant trees become wolf trees of low economic value and overtopped trees are lost to mortality.
Seral Stage
One in a series of steps in the process of ecological succession.
Serotinous Cones
Cones that remain closed without allowing dissemination of the enclosed seeds long beyond the time of maturation, often released by heat in fire-prone areas.
Shade-intolerant Plants
Plant species that do not germinate or grow well in shade.
Shade-tolerant Plants
Plants that grow well in shade.
Sheet Erosion
Loss or movement of soil in thin layers.
Shelterwood Harvest
The harvest of all mature trees in an area in a series of two or more cuts, leaving enough trees of other sizes to provide shade and protection for forest seedlings until they are well established.
Shoal
The shallow portion of a body of water usually characterized by light penetration to the bottom.
Shortgrasses
Grasses of short stature that grow on sites characterized by sparse rainfall.
Shredders
Aquatic insects that feed on leaves, twigs, and living or nonliving plant tissue.
Shrub-seedling Stage
1 of 5 forest structural stages in which the vegetation of the stand is dominated by shrubs or tree seedlings or both.
Shrub
A plant with persistent woody stems and relatively low growth form.
Sight Distance
The distance at which 90% or more of an adult elk or deer is hidden from the view of a human.
Silt
Material consisting of small granular particles of earth capable of being readily transported and desposited by water.
Silvicultural Treatment
Any activity designed to produce or improve a stand of trees to meet a predetermined objective.
Silviculture
The art and science of controlling the establishment, growth, composition, health, and quality of forests.
Single-storied Stand
A stand of trees in which the canopy is contained in 1 layer.
Single-tree Selection
A method of harvesting under an uneven-aged forest management system in which trees are individually selected for harvest. Also called individual selection.
Sinuosity Ratio
A comparison of the distance traversed by a segment of a stream channel with that of the straight-line distance of the segment.
Site Preparation
Treatment of an area prior to reestablishment of a forest stand. Site preparation can include mechanical clearing, burning, or chemical (herbicide) vegetation control.
Site
The combination of biotic, climatic, topographic, and soil conditions of an area.
Skidder
A rubber-tired machine with a cable winch or grapple used to drag logs out of the forest.
Skidding
The act of moving trees from the site of felling to a leading area or landing. Tractors, horses, or specialized logging equipment can be used for skidding. Skidding methods vary in their impact on soils and the remaining stands.
Skid Road or Skid Trail
A prepared road or trail used for pulling logs from the stump to the landing or yard.
Skyline Logging
A method of powered cable logging in which a heavy cable is stretched between 2 spar-trees or their equivalents in effort to move timber to a landing overhead.
Slash
Branches and other woody material left on a site after logging.
Slope
The degree that the land surface is inclined
Snag
A dead tree that is still standing. Snags provide important food and cover for a wide variety of wildlife species.
Soft Snag
A snag composed primarily of wood in advanced stages of decay and deterioration.
Softwood
Any tree in the gymnosperm group, including pines, hemlocks, larches, spruces, firs, and junipers. Softwoods often are called conifers although some, such as junipers and yews do not produce cones.
Spatial Heterogeneity
The diversity of organisms in relationship to space.
Species Richness Management
A wildlife management strategy where the goal is to produce a relatively high number of species per unit area.
Species Richness
A measurement or expression of the number of species of plants or animals present in an area.
Species
Related organisms that share the same characteristics and are capable of interbreeding and successfully reproducing the same kind of organism.
Sprout
A tree growing from a cut stump or previously established root system.
Spur Road
A short branch of a main timber haul road.
Stability
The ability of an ecosystem when changed from a steady state to develop forces that tend to restore it to its original condition.
Stagnated stand
A stand in which the growth of individual trees is much below potential because of crowding or high density of trees.
Stagnation
The process of the lessening of the growth rate of individual trees in a stand because of overcrowding.
Stand Density
The quantity of trees per unit area, usually evaluated in terms of basal area, crown cover and stocking.
Stand
A group of forest trees of sufficiently uniform species composition, age, and condition to be considered a homogeneous unit for management purposes.
Stenotopic Species
Organisms with low ranges of ecological tolerance that narrowly restrict their distribution.
Stewardship
The administration of land and associated resources in a manner that enables their passing on to future generations in a healthy condition
Stocking
The number and density of trees in a forest stand. Stands are often classified as understocked, well-stocked or overstocked.
Stratification
Division of a forest, or any ecosystem, into separate layers of vegetation that provide distinct niches for wildlife. See canopy, understory, and herbaceous vegetation.
Structural Stage
Any of several developmental stages of tree stands.
Stumpage
The value of standing trees in a forest.
Subalpine Zone
An elevational life zone extending from about 10,000 feet above sea level in central Colorado to timberline.
Subclimax
A stage in succession short of the climax community in which further development is inhibited by the influence of some factors other than climatic factors.
Subdominant
A component of a plant community, typically a species which, though locally dominant, exerts much less dominance than the widespread dominant does.
Substrate
With respect to aquatic situations, the bottom of the lake or stream.
Successional Stage
A stage or recognizable condition of a plant community that occurs during its development from bare ground to climax.
Succession
The natural replacement of one plant (or animal) community by another over time in the absence of disturbance.
Succulent
Having thick fleshy leaves that conserve moisture.
Suckering
to send out suckers.
Sucker
A shoot arising from below ground level, either from a rhizome or from a root.
Sun Scalding
Injury to bark and cambium caused by exposure of the tree stem to high temperatures from intense sunlight.
Supersaturated
An unstable condition in which a medium contains more of an element or substance in solution than would be the case under stable conditions.
Suppressed
A tree condition characterized by low growth rate and low vigor as a result of competition with overtopping trees. See overtopped.
Suppression Mortality
Death of plants caused by natural thinning.
Suspended sediment
Soil and other materials suspended in water.
Sustained Yield
An ideal forest management objective in which the volume of wood removed equals growth within the total forest.


T

Talus
The accumulation of broken rocks that occurs at the base of cliffs or other steep slopes.
Temperate Forest
A forest occurring in the temperate zone.
Temperate Zone
The portions of the earth in the northern and southern hemispheres that lie between the tropics and the polar circles.
Temperature Inversion
The atmospheric condition in which the air temperature increases with height, contrary to the usual condition in which the air temperature increases closer to the earth.
Terrain
The character or topography of the land.
Territorialism
A behavioral trait in which an animal defends a geographical area from intruders of the same or other species.
Territory
The area that an animal defends, usually during breeding season, against intruders of its own or other species.
Thermal Cover
Cover used by animals to ameliorate effects of weather.
Thermocline
The transition zone between the epilimnion and the hypolimnion.
Thermostratification
The process in which a lake separates into layers due to differing water temperatures.
Thinning
Felling of part of an immature crop or stand to accelerate growth in the remaining trees.
Threatened Species
A species or subspecies whose population is so small or is declining so rapidly that it may become endangered in all or a significant portion of its range.
Three-storied Stand
A stand of trees whose crown structure is divided into 3 distinct canopy layers.
Till
Materials carried by glaciers, ranging in size from large boulders down to silt, which are deposited in place when glaciers melt.
Timber Stand Improvement (T.S.I.)
Any practice that increases the value or rate of value growth in a stand of potential sawtimber trees. Pruning and thinning are considered T.S.I.
Topographic Features
Those natural physical terrain features that are commonly identified on topographic maps.
Total Diversity
The sum total of diversity within an area. The sum of induced and inherent diversity.
Toxic
Pertaining to poision.
Transitional
The process of changing from one form to another.
Transition Zone
An area on which 2 or more plant communities or successional stages within plant communities merge and which shows characteristics of all involved communities or stages.
Transpiration
The process by which water vapor passes from the foliage or other parts of a living plant to the atmosphere.
Transportation Corridor
A strip of land in which travel by humans is or can be accommodated.
Travel Corridor
A route followed by animals along a belt or band of suitable cover or habitat.
Travel Lanes
Areas of cover commonly used by animals moving from one location to another.
Tree Farm
A privately owned forest managed on a multiple use basis with timber production as an important management goal.
Tree
A plant that is usually more than 12 feet tall and has a single main woody stem with a distinct crown of leaves.
Trophic Level
Functional classification of organisms in a community according to feeding relationships.
Trophic Pyramid
A graphic portrayal of the biomass in different trophic levels within a biotic community.
Trophic Structure
Feeding relationships within the community that determine the flow of energy from plants to herbivores to carnivores.
Tuber
A swollen, fleshy, starchy end of an underground side shoot or stem, distinguished by their eyes, which sprout into plants with shoots and roots.
Two-storied Stand
A stand of trees whose crown structure is divided into 2 distinct canopy layers.


U

Understory
The level of forest vegetation beneath the canopy.
Undulating
A regular rising and falling or side to side motion.
Uneven-aged Management
A system of forest management in which stands are produced or maintained with an intermingling of trees that differ markedly in age.
Uneven-aged Stand
A group of trees of a variety of ages and sizes growing on a uniform site; also called all-aged stand.
Ungulate
A mammal with hooves.


V

Valley
An elongated lowland between mountains, hills, or other upland areas that often has a river or stream running through it.
Vascular plants
Plants containing a network of structures that carry or transport water (xylem) or nutrients (phloem).
Veneer Log
A high-quality log of a desirable species suitable for conversion to veneer (A thin surface layer, as of finely grained wood, glued to a base of inferior material). Veneer logs must be large, straight, of minimum taper, and free from defects.
Versatility Index
A figure indicating relative degrees of versatility between species in terms of the number of plant communities and successional stages used by the individual species for feeding and reproduction.
Vertical Diversity
The diversity in an area that results from the complexity of the above ground structure or layers of the vegetation.
Viable Population
A wildlife population of sufficient size to maintain its existence over time in spite of normal fluctuations in population levels.
Vigor
In plants and animals, refers to the capacity for strong growth and high survival.
Virgin Forest
An area of old-growth trees that has never been harvested by humans.


W

Warmwater Fish
Any fish that requires warm water in which to propagate.
Waste Water
The water that runs off cropland during irrigation. Also refers to sewage as spelled wastewater.
Water Bar
A shallow channel or raised barrier constructed diagonally across a road, trail or control line so as to lead water away.
Water Quality
Determined by a series of standard parameters; turbidity, temperature, bacterial content, pH, and dissolved oxygen.
Watershed
A region defined by patterns of stream drainage. A watershed includes all the land that contributes water to a particular stream or river.
Welfare Factors
Those elements within an animal's habitat that contribute to its well-being.
Wetlands
Those areas that are inundated by surface or groundwater with a frequency sufficient to support, and under normal circumstances does or would support, a prevalence of vegetation or aquatic life that requires saturated or seasonally saturated soil.
Wilderness
Lands designated by law as wilderness; An unsettled, uncultivated region left in its natural condition, especially a large wild tract of land covered with dense vegetation or forests.
Wildfire
An unplanned fire requiring suppression action.
Wildlife Habitat
The native environment of an animal. Habitats ideally provide all the elements needed for life and growth: food, water, cover and space.
Windfall
A tree uprooted or broken off by wind.
Windfirmness
Having the ability to withstand heavy wind.
Windrow
Slash, brushwood, etc. concentrated along a line so as to clear the ground between the lines.
Windthrow
A tree felled by wind. Windthrows, also known as blowdowns, are common among shallow-rooted species and in areas where cutting has reduced stand density.
Winterkill
The death of an organism caused by intolerable conditions during the winter period.
Wolf Tree
A dominant vigorous tree, generally of bad form, that occupies more growing space that its timber value warrants. Wolf trees may offer value to wildlife.


X

Xeric
Refers to environmental situations characterized by arid conditions.
Xerophytic
Refers to plants that grow under arid environmental conditions.


Y

Yarding
Transporting timber from the point of felling to a yard or landing.
Young stage
1 of 5 successional stages in which a stand of trees is dominated by trees that are no longer poles but have not yet reached maturity.


Z

Zooplankton
Free-swimming or floating animal plankton.



















































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