Adaptation. The condition of showing fitness for a particular environment, as applied to characteristics of a structure, function or entire organism; a modification of a species that makes it more fit for reproduction and/or existence under the conditions of its environment.

Aerie. A protected location on a cliff used by predatory birds as a site for rearing their young.

Age-class. A group of individuals of a species that have the same age.

Allelopathy. The harmful influence of one plant on another plant, as when one plant releases chemicals into the soil that inhibit the growth of other plants.

Annual. Occurring yearly or, as in annual plants, living for only one year.

Areal Cover. A measure of dominance that defines the degree to which above ground portions of plants cover the ground surface; it is possible for the total areal cover for all strata combined in a community or for single stratum to exceed 100 percent because: 1) most plant communities consist of two or more vegetative strata; 2) areal cover is estimated by vegetative layer; and 3) foliage within a single layer may overlap.

Association. A collection of units or parts into a mass or whole; for example, a group of animals, plants or both. A statement of physical proximity or grouping, without necessarily requiring or implying interactions between units of the group, in contrast to "community", which does. Similar or equivalent to "aggregation".

Autecology. Ecological study of a single organism or a single species.

Autotrophic. Making its own food by photosynthesis or requiring only inorganic chemicals for metabolic synthesis.

Basal Area. The cross-sectional area of a tree trunk measured in square inches, square centimeters, etc.; basal area is normally measured at 4.5 feet above ground level and is used as a measure of dominance; the most commonly used tool for measuring basal area is a diameter tape or a D-tape (then convert to basal area).

Bioaccumulation. The process by which organisms absorb chemicals or elements directly from their environment.

Biomagnification. The process by which chemicals or elements present in the environment become more and more highly concentrated in organisms that feed on plants or lower organisms that originally accumulate those chemicals or elements from the environment.

Biomass (also standing crop).

1. Summed mass or weight of individuals in one or more species, usually related to a defined area or volume.
2. Amount of substance in a population, expressed in material units, such as living or wet weight, dry weight, ash-free weight, nitrogen content, etc.

Biotic Community. A group of living organisms characterized by a distinctive combination of both animal and plant species in a particular habitat.

Browsed. Any tree with several centimeters of one or more limb tips, including but not restricted to, the tallest limb, bitten off by deer or other wildlife.

Brush Habitat. Includes a wide variety of plant and animal life dominated by and associated with coastal scrub and chaparral.

Bunch Grass. Any of a number of perennial grasses (family Gramineae) which grow in tight clumps and regenerate each year from deep roots.

Candidate Species. Any species or subspecies of bird, mammal, fish, amphibian, reptile, or plant that is being considered for listing as endangered or threatened but is not yet the subject of a proposed rule.

Canopy. Branches and leaves above ground or water.

Canopy Cover (of a stream). Vegetation projecting over a stream, including crown cover (generally more than 1 m above the water surface) and overhand cover (less than 1 m above the water).

Carrying Capacity. Maximum average number or biomass of organisms that can be sustained in a habitat over the long term. Usually refers to a particular species, but can be applied to more than one.

Chaparral. A plant community of drought-adapted shrubs, usually found in rocky and rapidly drained shallow soils.

Community. An association of living organisms having mutual relationships among themselves and to their environment and thus functioning, at least to some degree, as an ecological unit.

Consumptive Wildlife Use. Activities that involve harvest of wildlife, such as hunting and fishing.

Critical Habitat.

1. Specific areas within the geographic area occupied by a species at the time it is listed in accordance with the Endangered Species Act.
2. Specific areas outside the geographical area occupied by a species at the time it is listed if there is a determination that such areas are essential for conservation of the species.

Density.

1. Number of organisms or items per unit area or volume.
2. The number of individuals per unit area.

Diameter at Breast Height (dbh). The width of a plant stem (e.g., tree trunk) as measured at 4.5 feet above the ground surface.

Diversity Index. The relationship of the number of taxa (richness) to the number of individuals per taxon (abundance) for a given community.

Dominance. Refers to the spatial extent of a species; commonly the most abundant species in each vegetation stratum that, when ranked in descending order of abundance and cumulatively totaled, immediately exceeds 50 percent of the total dominance measure (e.g., areal cover or basal area) for the stratum, plus any additional species comprising 20 percent or more of the total dominance measure for the stratum.

Dominance Measure. The means or method by which dominance is established, including areal coverage and basal area; the total dominance measure is the sum total of the dominance measure values for all species comprising a given stratum.

Dominance Threshold Number. The number at which 50 percent of the total dominance measure for a given stratum is represented by one or more plant species when ranked in descending order of abundance (i.e., from most to least abundant); when this number is immediately exceeded, the dominant species for the stratum are realized.

Dominant Species. For each stratum, dominant species are those that, when ranked in descending rank order and cumulatively totaled, immediately exceed 50 percent of the total dominance measure, plus any additional species comprising 20 percent or more of the total dominance measure for the stratum.

Ecosystem.

1. An ecosystem is the dynamic and interrelating complex of plant and animal communities and their associated non-living environment.
2. The physical and climactic features and all the living and dead organisms in an area that are interrelated in the transfer of energy and material.
3. An interacting complex of a community and its environment functioning as an ecological unit in nature. Differs from "system" in being a more rigorous definition that encompasses and requires assumptions of energetics, ecological interactions, species adaptations and so forth.

Ecotype. Species or variety that, through natural selection, has adjusted to specific conditions of a locality.

Endangered Species. Any species which is in danger of extinction throughout all or a significant portion of its range.

Endemic. Native to a particular region.

Environment.

1. The complex of climatic, edaphic and biotic factors that act upon an organism or an ecological community and ultimately determine its form and survival.
2. CEQA defines environment as “the physical conditions which exist within the area which will be affected by a proposed project, including land, air, water, mineral, flora, fauna, noise, and objects of historic or aesthetic significance.”

Epiphyte. A nonparasitic plant that grows on a surface other than soil or sediment, usually on another plant.

Evapotranspiration. Loss of water by evaporation from the soil and transpiration from plants.

Evergreen (plant). Retaining its leaves at the end of the growing season and usually remaining green through the winter.

Exclosure. An area from which livestock or other animals are excluded.

Exotic. Not native to a given area; either intentionally transplanted from another region or introduced accidentally.

Exotic Species. Plant or animal species introduced into an area where they do not occur naturally; non-native species.

Faunation. The total animal life of a zone or area; the animal equivalent of vegetation.

Fern Allies. A group of nonflowering vascular plants comprised of clubmosses (Family Lycopodiaceae), small clubmosses (Family Selaginellaceae) and quillworts (Family Isoetaceae).

Flora.

1. The taxonomic (kinds) plant groups present in a given area.
2. A list or manual of all plant species that may occur in an area.

Foliage Volume. The space, expressed in cubic meters, occupied by a tree.

Forb. Generally, any herb that is not a grass.

Forbs. Broad-leaved herbs, in contrast to bryophytes, ferns, fern allies and graminoids.

Fragmentation of Habitat. Division of a large piece of habitat into a number of smaller, isolated patches.

Frequency Analysis. A method of evaluating vegetation in an area by establishing a transect and counting the occurrences of plant species at various sampling points along the transect.

Frequency of Occurrence. The number of times a given plant species occurs at sample points along a transect.

Functional Groups (ecology). Groups of organisms that obtain energy in similar ways. Autotrophic plants fix energy from sunlight. Fungi and bacteria decompose organic matter. Shredders chew large particles like tree leaves. Scrapers rasp periphyton and microbes from solid substrates. Collectors filter fine particles from the water or gather them from deposits.

Genetic Diversity. A property of a community of organisms of a certain species, in which members of the community have variations in their chromosomes due to a large number of slightly dissimilar ancestors; this property makes the community in general more resistant to diseases or to changing ecological conditions.

Graminoids. Grasses (Family Gramineae or Poaceae) and grasslike plants such as sedges (Family Cyperaceae) and rushes (Family Juncaceae).

Growing Season. The portion of the year when soil temperatures are above biologic zero (41 F) as defined by Soil Taxonomy; the following growing season months are assumed for each of the soil temperature regimes: 1) thermic (February-October); 2) mesic (March-October); 3) frigid (May- September); 4) cyric (June-August); 5) pergelic (July-August); 6) isohyperthermic (January-December); 7) hyperthermic (February-December); 8) isothermic (January-December); and 9) isomesic (January- December).

Growth. Height from ground level to top of tallest upstretched leaf at planting subtracted from height similarly measured at any time after planting.

Guild. Group of organisms that exhibit similar habitat requirements and that respond in a similar way to changes in their environment.

Habitat.

1. The physical location or type of environment in which an organism or biological population lives or occurs.
2. The place occupied by an organism, population, or community. It is the physical part of the community structure in which an organism finds its home, and includes the sum total of all the environmental conditions present in the specific place occupied by an organism . Often a habitat is defined to include a whole community of organisms.

Habitat Type. A land or aquatic unit, consisting of an aggregation of habitats having equivalent structure, function, and responses to disturbance.

Herb. Nonwoody (herbaceous) plants including graminoids (grass and grasslike plants), forbs, ferns, fern allies and nonwoody vines; seedlings of woody plants that are less than three feet in height are also considered herbs.

Herbivory. The consumption of herbaceous vegetation.

Host. The organism which serves as the primary source of food or shelter for another organism.

Indicator Plant. Plant species indicating some specific characteristic of a certain locality.

Invasive Species Non-native species disrupting and replacing native species.

Leaf Blight. Any of various diseases which lead to the browning and dropping of a plant’s leaves.

Limited Habitat. A habitat type that is rare or has been significantly reduced from its historical distribution, either locally or statewide, and is of special importance meeting the general life requirements of many wildlife species.

Limiting Factor. Environmental factor that limits the growth or activities of an organism or that restricts the size of a population or its geographical range.

Litter. The undecomposed plant and animal material found above the duff layer on the forest floor.

Macroalgae. Multicellular algae (green, blue-green and red algae) having filamentous, sheet or mat-like morphology.

Macrobenthos. Organisms (e.g., insect larvae) living in or on aquatic substrates and large enough to be seen with the naked eye.

Macrofauna. Animals large enough to be seen with the naked eye.

Macroinfauna. Animals living within aquatic sediments and large enough to be seen with the naked eye.

Macroinvertebrates. Invertebrates large enough to be seen with the naked eye (e.g., most aquatic insects, snails and amphipods).

Macrophyte.

1. Plants large enough to be seen with the naked eye.
2. Any plant species that can be readily observed without the aid of optical magnification, including all vascular plant species and bryophytes (e.g., Sphagnum spp.), as well as large algae (e.g., Chara spp., and Fucus spp.).

Mammal. “Mammal” means any wild or feral mammal or any part thereof, but not any wild, feral, or undomesticated burro.

Source: California Fish and Game Code.

Management Indicator Species. A species whose habitat requirements most reflect those of the species community in the habitat of concern, usually used to indicate habitat quality and to predict future conditions.

Mesic. Moderately wet, such as in locations near springs or with moderate rainfall, as opposed to hydric (wet) or xeric (dry).

Microbial. Pertaining to work by microorganisms to small to be seen with the naked eye.

Microhabitat. Specific combination of habitat elements in the place occupied by an organism for a specific purpose.

Morphological Adaptation. A structural feature that aids in fitting a species to its particular environment (e.g., buttressed bases, adventitious roots and aerenchymous tissue).

Morphological Features. Properties related to the external structure of soil (such as color and texture) or of plants.

Mycorrhiza. Symbiotic association between a fungus and (usually) the root of a higher plant.

Non-indigenous Species. Non-indigenous species (NIS) are those plants and animals that have been transported through human activities from their native ranges into new ecosystems where they did not evolve. Also known as exotic species, introduced species, and alien species.

Nonpersistent Vegetation. Plants that break down readily after the growing season; no evidence of previous year's growth at beginning of next growing season.

Old-growth Stand. Forest stand dominated by trees reaching natural senescence; the last stage in forest succession.

Overstory (and understory). Overstory is the larger, taller trees of growth which occupies a forest area and shades young trees, hardwoods, brush, and other deciduous varieties which are growing beneath the larger trees (i.e., understory).

Perennial (plant).

1. Living for many years.
2. A plant which lives for more than one year, dies back seasonally, and regenerates from surviving roots or stems.

Photoperiod. Recurring cycle of light and dark periods. The natural photoperiod is approximately 24 hours, and the ratio of light to dark hours slowly changes over the course of a year. In controlled experiments, the photoperiod is usually (but not necessarily) retained at 24 hours, and the light:dark ratio is typically constant.

Photosynthesis. Production of organic substances from carbon dioxide and water in the presence of light. Most photosynthesis occurs in green plant cells, where chlorophyll helps transform radiant energy into chemical energy.

Physiological Adaptation. A peculiarity of the basic physical and chemical activities that occur in cells and tissues of a species, which results in it being better fitted to its environment (e.g., ability to absorb nutrients under low oxygen tensions).

Pioneer Plants. Plants that colonize disturbed sites or raw mineral soils and ameliorate them for succeeding plants.

Plant Community. The plant populations existing in a shared habitat or environment.

Plant Succession. The development of a plant community from its initial stage to its climax stage.

Population. Organisms of the same species that occur in a particular place at a given time. A population may contain several discrete breeding groups or stocks.

Prevalence Index. A weighted average measure of the sum of the frequency of occurrences of all species along a single transect or as calculated for a plant community by averaging the prevalence index of all sample transects through the community.

Primary Production. Production of organic substances by photosynthesis; the quantity of material so produced per unit time.

Productivity.

1. Rate of new tissue formation or energy utilization by one or more organisms.
2. Capacity or ability of an environmental unit to produce organic material.
3. The ability of a population to recruit new members by reproduction.

Quadrat. Sample units or plots that vary in size, shape, number and arrangements, depending on the nature of the vegetation, site conditions and purpose of study.

Quantitative. A precise measurement or determination expressed numerically.

Range. The set of conditions throughout which an organism (e.g., plant species) naturally occurs.

Rare or Endangered Species. A species of animal or plant listed in: Section 670.2 or 670.5, Title 14, California Administrative Code; or Title 50, Code of Federal Regulations, Section 17.11 or Section 17.2, pursuant to the Federal Endangered Species Act designating species as rare, threatened, or endangered.

Relative Basal Area. An estimate of basal area for trees, such as produced by the Bitterlich sampling technique.

Reproductive Adaptation. A peculiarity of the reproductive mechanism of a species that results in it being better fitted to its environment (e.g., prolonged seed dormancy).

Root Sprout. A living shoot which grows from the root of a plant whose above-ground portion has been cut down.

Ruderal. Weedy vegetation growing on compacted, plowed, or otherwise distrubed ground and showing a preference for this type of habitat.

Sapling.

1. Strong, young tree plant, the stem of which has normal branch development from the bottom up.
2. Woody vegetation between 0.4 and 5.0 inches in diameter at breast height and greater than or equal to 20 feet in height, exclusive of woody vines.

Savanna. A type of woodland characterized by a very open spacing between its trees and by intervening areas of grassland.

Seedling. A young tree that is generally less than 3 feet high.

Sensitive Species.

1. Species that can only survive within a narrow range of environmental conditions and whose disappearance from an area is an index of pollution or other environmental change.
2. Those species which rely on specific habitat conditions that are limited in abundance, restricted in distribution, or are particularly sensitive to development.
3. Plant or animal species which are: 1) Federal listed or proposed threatened or endangered species, or candidate species; 2) bird species protected under the Migratory Bird Treaty Act; 3) species protected under State endangered species laws and regulations, plant protection laws and regulations, Fish and Game codes, or species of special concern listings and policies; or 4) species recognized by national, state, or local environmental organizations (e.g., the California Native Plant Society).

Shrub.

1. A woody perennial plant differing from a tree by its low stature and by generally producing several basal shoots instead of a single stem.
2. Woody vegetation usually greater than 3 feet but less than 20 feet tall, including multi-stemmed, bushy shrubs and small trees and saplings. Woody seedlings less than 3 feet tall are considered part of the herbaceous layer.

Shrub Vegetation (Bush). Community of shrubs; scrub.

Species Area Curve. The curve on a graph produced when plotting the cumulative number of plant species found in a series of quadrats against the cumulative number or area of those quadrats; it is used to determine the number of quadrats sufficient to adequately survey the herbaceous understory.

Species-specific. Applying only to a particular species; said of effects that vary depending on the species in question.

Stilted Roots. Aerial roots arising from the trunk and branches, presumably providing support to the plant.

Stolons. A creeping stem or runner with elongated internodes and reduced leaves, capable of taking root at some distance from the mother plant and developing into individual plants after the intermediate part has died off.

Stratum. A layer of vegetation used to determine dominant species in a plant community.

Symbionts. Plants living in symbiosis with other plants. Each of the partners seems to profit from the other one so that, for instance, higher (superior) plants show poor growth or , at least, little growth increment without their symbionts (mycorrhizae or nodule bacteria).

Symbiosis. Two organisms of different species (or genus) living in close association, one or both may benefit and neither is harmed.

Sympatric. Co-occurring in the same area.

Synecology. A subdivision of ecology that deals with the study of groups of organisms associated as a unit.

System. A group of related natural objects and/or forces within a defined zone; a regularly interacting or interdependent group of items forming a unified whole; a more general and less rigorous term than "ecosystem."

Tap Root. A deep plant root that evolved to tap into groundwater reserves, usually exhibiting less horizontal spreading than other types of roots.

Taxon. Any formal taxonomic unit or category of organisms: subspecies, species, genus, family, order, etc. (Plural: taxa.)

Threatened Species. Any species which is likely to become an endangered species within the foreseeable future throughout all or a significant portion of its range.

Transect. A line on the ground along which sample plots or points are established for collecting vegetation data and in many cases, soil and hydrology data as well.

Transpiration.

1. Passage of water vapor and other gases from a living body through membranes or pores; usually used to mean loss of water from leaves and other plant surfaces.
2. The process in plants by which water is released into the gaseous environment (atmosphere), primarily through stomata.

Tree. A woody plant 5 inches or greater in diameter at breast height and 20 feet or taller.

Trophic Level. Stage in a food chain or web leading from primary producers (lowest trophic level) through herbivores to primary and secondary carnivores (consumers- highest level).

Trophic Web. Feeding relationships in communities that determine the flow of energy and materials from plants to herbivores, carnivores and scavengers.

Unique Species. A biotic resource whose presence is unusual and of special interest due to extremities of range, special soil types, or unusual associations with other species.

Vascular (plant). Possessing a well-developed system of conducting tissue to transport water, mineral salts and foods within the plant.

Vegetation.

1. The plant growth forms that generally occupy a given area (e.g., forest, hydrophytes or chaparral).
2. The sum total of macrophytes that occupy a given area.

Vigor. Measure of change in plant growth or foliage volume through time after planting.

Wildlife Corridor. Linear spaces that connect the various areas of an animal’s habitat; links between feeding, watering, resting, and breeding places.

Wildlife Habitat. Area that provides a water supply and vegetative habitat for wildlife.

Xerophyte. A plant that grows in a dry environment such as the desert or chaparral.

Xerophytic. Adapted to survive in a region where access to water is limited.

Compiled by:
The Habitat Restoration Group
P.O. Box 4006
Felton, CA  95018
408/335-6800
email:  hrg@cruzio.com							
 URL:  http://www.cruzio.com/~hrg/
 

February 1996

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