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					              Glossary of Ecological Terms

This glossary was compiled to facilitate clarity and consistency in the use of
terms for the Landscape Ethic Committee of the Los Angeles and San Gabriel
Rivers Watershed Council. The glossary is a subset of the vast dictionary of
terms used by scientists across a number of fields in ecology to communicate
concepts clearly. A bibliography of sources for these terms is included at the end
of this document.

Abiotic factors. The non-living physical and chemical factors in an environment
      that affect ecological interactions (e.g. light availability, moisture
      availability, temperature, pH, etc.)

Association. Indicates a large assemblage of organisms in a particular area,
     with one or two dominant species; refers to any group of plants growing
     together and forming a small unit of natural vegetation. (see Community)

Biodiversity. Full range of variety and variability within and among living
      organisms, their associations, and habitat-oriented ecological complexes.
      Term encompasses ecosystem, species, and landscape as well as
      intraspecific (genetic) levels of diversity.

Biome. A biogeographic region; a major regional ecological community
     characterized by distinctive life forms and principal plant (terrestrial biome)
     and animal (marine biome) species.

Biotic factors. All living organisms and their effects, both direct and indirect, on
       other living things (ex. predator-prey relationships, poisonous plants,
       herbivores, etc.)

Chaparral. Refers to areas with broad-leaved evergreen shrubs found in
     climates with hot dry summers and mild wet winters.

Close. Adjacent or within pollen or seed dispersal range.

Colonization. Successful invasion of a newly created habitat; successful
      recruitment in gaps or vacant niches following disturbance.

Community. Any group of organisms belonging to a number of different species
    that co-occur in the same habitat or area and interact through trophic and
    spatial relationships; typically characterized by reference to one or more
    dominant species. (see Association)

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Composition. A list of species that make up a community, or any other
    ecological unit.

Core habitat. Center portions of large, undisturbed tracts of land occupied by
      interior species (as opposed to edge species).

Corridor. A connection between adjacent and similar habitats large enough to
      allow the movement of propagules across all biological resources to pass;
      connection includes both core and edge habitat; a natural or restored
      connection for a population of organisms to use in order to breed and/or
      remain contiguous.

Cover. Plant material, living (vegetative cover) and dead (litter cover), on the soil
      surface; the area of ground covered by vegetation of a particular plant
      species, which is usually expressed as a percentage.

Cultivar. A variety of plant produced and maintained through continued

Distribution. 1.) the spatial arrangement of organisms in a defined area- which
       fall into one of three categories: clumped, uniform, or random; 2.) the
       geographic area in which a species naturally occurs Syn: range; 3.) in a
       statistical sense, it is the total observed (or estimated) frequency of
       occurrence for the studied subject (or statistic).

Disturbance. Any relatively discrete event in time, either natural or human-
      caused that disrupts ecosystem, community, or population structure and
      changes resources, substrate availability, or the physical environment.
      Key descriptors are magnitude, frequency, size of area, and dispersion.

DTSC Ecological Risk Assessment. A procedure defined by the California
     Department of Toxic Substance Control (DTSC) that guides environmental
     professionals (not necessarily toxicologists or biologists) engaging in
     remediation and reclamation consulting activities. It may be required as
     part of a Preliminary Endangerment Assessment (PEA) of a contaminated

Ecology. The study of the interrelationships between living organisms and their

Ecosystem. The interacting system of a biological community and its non-living
     environmental surroundings.

Ecotone. The boundary or transition zone between adjacent communities or
     biomes; also known as edge.

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Ecotype. A genetic subdivision of a taxon with distinct physiological or
     morphological characteristics.

Edge effect. The effect exerted by adjoining communities on the population
     structure within the marginal zone (ecotone), which often contains a
     greater number of species and higher population densities than either
     adjoining community; also refers to processes that characterize habitat
     fragmentation and the concomitant creation of edge.

Endemic. Refers to a species that is not only native to a geographic area but is
     also restricted to that area or specific habitat.

Enhancement. Management technique (using removal of exotics, seeding,
     transplantation, fencing, watershed manipulations, etc.) that attempts to
     restore to predisturbance conditions areas that are only partially disturbed
     by human influence; alters a site for an improvement for a specific value.

Exotic species. Nonnative species that have established viable populations
      within a community; species present within a community that did not exist
      there before the influence of human activities. Refers to a species that is
      foreign to a geographic area and usually alienated from its natural
      competitors and predators.

Fitness. The relative competitive ability of a given genotype conferred by
      adaptive morphological, physiological or behavioral characters, expressed
      and usually quantified as the average number of surviving progeny of one
      genotype compared with the average number of surviving progeny of
      competing genotypes.

Fragmentation. Process by which habitats are increasingly subdivided into
     smaller units, resulting in their increased insularity as well as losses of
     total habitat area.

Garden. 1. A piece of ground for the cultivation of herbs, plants, fruits, flowers,
     etc.; it is usually close to the house. 2. A rich, well-cultivated spot of tract
     of country; an area of fertile, developed land. 3. A place for public
     enjoyment, planted with trees, flowers, etc., and often having special
     displays of animal or plant life.

Gene flow. Refers to the exchange of heritable traits in a population of
      organisms. Lack or low gene flow is considered detrimental because it
      limits variability (gene pool) which the population can use to overcome
      changing environmental conditions.

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Genetic contamination. Refers to the unintentional crossover of biologically
      engineered genes from one genus to another genus or from one species
      to another species within the same genus; inadvertent hybridization.

Genetic degradation. Deleterious change in a native taxon's gene pool due to
      addition of non-local genes. The gene source can be plants of--
             a) the same genus or species, but a non-local Californian taxon,
                 ecotype or cultivar;
             b) the same genus, but a foreign taxon.

Genetic diversity. The genetic diversity of a species, an ecosystem, or in fact
      anything living is a crucial indicator as to how life is coping over time in the
      environment that it exists in. The varied species' gene pool inevitably
      means there are a diverse number of permutations in the genes that the
      gene pool consists of. A diverse gene pool is deemed genetically diverse.

Genetic swamping. A phenomemon that is especially detrimental for plants
      whose natural populations have been impacted by human development
      where large, previously continuous "metapopulations" of species have
      been splintered into small, more or less isolated subpopulations. Small
      populations mean small gene pools. Cultivar pollen comes along,
      overwhelming (swamping) the species' already shrinking genetic base.
      Chance -- what researchers call genetic drift -- can take over, and more
      beneficial traits may be lost in the random recombination of genes that
      occurs during sexual reproduction. In species that don't typically grow in
      small, far-flung populations, so-called inbreeding depression, or
      interbreeding between closely related individuals, can drastically reduce
      genetic variation, causing still more reproductive problems for the plants
      and further reducing population size -- creating a downward spiral that has
      been termed "genetic meltdown."

Genus. A category in biological classification comprising one or more
     phylogenetically related, and morphologically similar species; a rank in the
     hierarchy of taxonomic classification forming the principal category
     between family and species.

Habitat. The locality, site and particular type of local environment occupied by
      an organism; includes food, water, shelter, cover, and the ability to raise

Habitat connectivity. A measure of connectedness in a habitat-oriented
      description of landscape elements.

Habitat creation. Establishment of a historic ecosystem on lands that did not
      previously support that system, or on severely altered sites.

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Habitat degradation. Decline in habitat quality that accompanies non-natural
      forms of disturbance.

Holland Vegetation Descriptions. Preliminary vegetation descriptions
      compiled by Robert Holland in 1986 to define terrestrial natural community
      types in California; adopted widely by regulatory agencies, such as,
      California Department of Fish and Game, U.S. Fish and Wildlife Service
      and the U.S. Army Corps of Engineers.

Horticulture. The art or science of cultivating fruits, flowers, and vegetables for
      specific human purposes; the cultivation of a garden.

Hybrid. Offspring of a cross between genetically dissimilar individuals; in
      taxonomy, often restricted to the offspring of the interspecific (between
      species) crosses.

Indigenous. Refers to a species that is native to a geographic area; plants that
      existed in an area prior to the 1600's, before Russian exploration. Syn:

Invasive. Refers to a species, not previously present in a plant community, that
      aggressively increases in abundance due to ecosystem disturbance or
      because it is an exotic species alienated from its competitors and

Island biogeography. The theory (developed by MacArthur and Wilson in 1967)
      that the number of species inhabiting an island is a function of island area
      and distance from the mainland, and is determined by the relationship
      between immigration (greater on larger and nearer islands) and extinction
      (greater on smaller islands).

Keystone species. Species on which a large number of species within a given
     community depend for survival.

Landscape. Ecological mosaic of specific ecosystems; "a kilometer-wide area
     where a cluster of interacting stands or ecosystems is repeated in similar
     form" (Godron and Formann); a complex of interacting ecosystems and

Landscaping. Manipulated ecosystem for cultural values such as aesthetics
     and recreational access

Linkage. A smaller or narrower connection between adjacent and similar
      habitats that allows the passage of some biological resources; examples
      include hedgerows, streams, irrigation ditches, and footpaths.

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Locally appropriate. Native plants whose habitat requirements match the
      locale's sun, soil and water parameters.

Locally native. A species that has arrived and inhabited an area (watershed)
      naturally, without deliberate assistance by man, or would occur had it not
      been removed through past management (by man). Some species are
      only native in particular regions. Differences in characteristics and
      adaptation to conditions occur more locally -- hence 'locally native'.

Mediterranean climate. A climate characterized by cool, wet winters and warm,
      dry summers.

Metapopulation. Series of populations (or subpopulations) with dynamic
     patterns of local extinctions, recolonizations; gene flow or migration
     among subunits provides characteristic evolutionary and ecological
     features that help avoid extinction of the entire (meta)population. A group
     of conspecific populations coexisting in time but not in space.

Mitigation. 1.) restoring, replacing, or creating ecological habitats (e.g.
      wetlands) in one area to compensate for loss of natural habitats in another
      area due to development. Syn: compensatory restoration 2.) avoiding,
      minimizing, or reducing ecosystem losses.

Mitigation Banking. Creates “mitigation credits” that can be purchased by
      developers in lieu of compensatory restoration. Allows accumulation and
      transfer of mitigation funding and actions among different projects.

Mitigation Banks. 1.) sites selected for habitat restoration or creation 2.)
      market-based banks that exchange “mitigation credits” on a development
      site for habitat restoration/creation requirements on another site.

Mycorrhizae. Largely symbiotic relationships between large and taxonomically
     diverse groups of fungi and vascular plants that allows for the uptake of
     water and minerals by the vascular plant, and for the uptake of sugars and
     carbohydrates from the vascular plant by the associated fungus.

Native plant. Indigenous; living naturally within a given area; used of a plant
      species that occurs at least partly in natural habitats and is consistently
      associated with certain other species in these habitats.

Natural. Independent of human activity; refers to predisturbance condition of a

Naturalized: refers to a previously exotic or foreign species, which has
      established in and conformed to an ecosystem.

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Niche. Ecological role of a species in a community conceptualized as the
      multidimensional space, of which the coordinates are the various
      parameters representing the condition of existence of the species, to
      which it is restricted by the presence of competitor species; sometimes
      used loosely as an equivalent of microhabitat in the sense of the physical
      space occupied by a species.

Non-persisting. A plant that will disappear from the landscape in less than three
     years without affecting the native vegetation or seed bank.

Non-point source (NPS) pollution. Pollution discharged over a wide land area,
     not from one specific location; diffuse pollution caused by sediment,
     nutrients, organic and toxic substances originating from land-use activities,
     carried to lakes and streams by surface runoff; contamination that occurs
     when rainwater, snowmelt, or irrigation washes off plowed fields, city
     streets, or suburban backyards. As this runoff moves across the land
     surface, it picks up soil particles and pollutants, such as nutrients and

Performance criteria. Series of defined issues that are the basis for judging
      success of a project.

Pest. Any animal or plant not valued by human society that usually overgrows or
      competes with valued animals or plants.

Phenotype. The visible characteristics of an organism.

Phenotypic plasticity. Variability in the physical appearance of individuals of
     the same species.

Phytoremediation. Direct use of living plants for in situ removal, containment,
      degradation, or rendering harmless contaminants in soil. It takes
      advantage of the unique and selective uptake capabilities of root systems,
      together with the translocation, bioaccumulation and contaminant
      storage/degradation abilities of the entire plant body. Plant-based soil
      remediation systems can be viewed as biological, solar-driven, pump-and-
      treat systems with an extensive, self-extending uptake network that
      enhances the ground ecosystem for subsequent productive use. There
      are several primary mechanisms by which plants clean up contaminants:
      phytoextraction, phytovolatilization, rhizofiltraton, phytostabilization,
      phytostimulation and phytoprecipitation.

Pollutant: A substance that occurs in the environment at least in part as a result
      of man's activities and has a deleterious effect on living organisms. Tests
      must be conducted to determine if there has been a regulatory defined
      release or, if the levels are naturally occurring. Pollutants may alter the

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       physical and chemical environment so as to affect the ability of organisms
       to survive at levels far below the regulatory action limits.

Population. A group of interbreeding organisms not separated by geographic
     barriers which would inhibit breeding between all individuals.

Propagules. Any part of an organism, produced sexually or asexually, that is
     capable of giving rise to a new individual; the minimum number of
     individuals of a species required for colonization of a new or isolated

Reclamation. Management techniques that attempt to reverse impacts to land
     caused by human disturbance and to bring back some form and function;
     altering an area to bring it to a healthy state similar to the original
     (predisturbance) ecosystem. Syn: replacement.

Reforestation. The replanting of trees on areas of land where forests have been
      cleared by felling or burning or by natural means. The planted forest has
      much less species diversity than the original forest.

Rehabilitation. Management techniques that seek to re-establish many
     components of the indigenous ecosystem; falls short of restoration.

Reintroduction. Placement of an individual, population, or species back into its
      former habitat after it has been extirpated from that habitat.

Remediation: The process of correcting environmental degradation. Syn:

Restoration. Altering an area in such a way as to reestablish an ecosystem’s
      structure and function, usually bringing it back to its original (pre-
      disturbance) state or to a healthy state close to the original; management
      techniques that attempt to enhance or bring back the natural
      predisturbance form and functions of a self-sustaining community or
      ecosystem; measures taken to return a site to predisturbance conditions.

Revegetate. Establish vegetation on disturbed lands.

Riparian. Refers to the banks of a stream or river, usually characterized by
      hydrophilic (water-loving) vegetation.)

Riparian Habitat. Areas adjacent to rivers and streams with a differing density,
      diversity, and productivity of plant and animal species relative to nearby

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Sawyer and Keeler-Wolf Vegetation Descriptions. California vegetation
     descriptions compiled in 1995; more detailed and quantitative than
     Holland descriptions.

Seed bank. The seeds that are present in, or on, the soil at the site.

Soil. The superficial weathered layers of the Earth's crust and any intermixed
       organic material.

Species. The basic unit of biological classification; in the hierarchy of biological
      classification the category below genus; a taxon of the rank of species.

Species richness. The absolute number of species in an assemblage or

Sterile. Incapable of successful sexual reproduction; infertile.

Subspecies. A genetically distinct geographic subunit of a species. A group of
     interbreeding natural populations differing taxonomically and with respect
     to gene pool characteristics, and often isolated geographically, from other
     such groups within a biological species and interbreeding successfully
     with these groups where their ranges overlap.

Sustainable. Capable of being self maintained.

Sustainable landscaping. A landscaping approach that seeks to minimize
      inflows to and outflows from a landscape. For example, a typical garden
      requires a number of resources for its construction - concrete, lumber,
      plants, compost, PVC irrigation pipe etc. Additional inputs are needed for
      the maintenance of the garden, such as water, fertilizer, fuel to operate
      power equipment, pesticides and herbicides. A garden also generates
      materials that may be harmful to the environment, such as lawn clippings,
      tree and shrub prunings (collectively referred to as "greenwaste"), polluted
      runoff of chemical-laden water and others. Sustainable landscaping
      attempts to reduce these inputs and outputs without sacrificing beauty,
      economy and ease of maintenance.

Taxon. A scientifically named organism (e.g., Nassella pulchra, Oenothera
     deltoides var. howellii, Lyonothamnus floribundus ssp. asplendifolius).

Toxicants. Pollutants that produce toxic effects based on exposure and

Trophic level. The sequence of steps in a food chain or food pyramid from
      producer to primary, secondary or tertiary consumer.

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Upland. 1.) terrestrial ecosystems located away from riparian zones, wetlands,
     springs, seeps, and dry washes 2.) ecosystems made up of vegetation not
     in contact with groundwater or other permanent water sources

Vegetation. The assemblage of plant species in a given area; also used as a
     general term for plant life.

Variability. Characteristics of living things differ between individuals of the same

Variety. A rank in the hierarchy of botanical classification; the principal category
      between species and form. An ambiguous term often used for any variant
      group within a species.

Watershed. The land area that drains water to a particular stream, river, or lake.
     It is a land feature that can be identified by tracing a line along the highest
     elevations between two areas on a map, often a ridge. Large watersheds,
     like the Mississippi River basin contain thousands of smaller watersheds.

Watershed Approach. A coordinated framework for environmental
     management that focuses public and private efforts on the highest priority
     problems within hydrologically-defined geographic areas taking into
     consideration both ground and surface water flow.

Watershed Area: A topographic area within a line drawn connecting the highest
     points uphill of a water intake into which overland flow drains.

Weed. Any plant growing where it is not wanted; any plant that proliferates on a
     disturbed site; any plant that is not valued by the human society and
     usually tends to overgrow or compete with valued flora.

Wetland. A general term for lowlands covered with shallow and sometimes
      temporary or intermittent waters. Syn: marsh, swamp, bog, wet meadow,
      slough, fen, river-overflow land.

Xeriscaping. A method of landscaping that uses drought-resistant plants that
      are well adapted to the local area.

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Callenbach, Ernest. 1998. Ecology: A Pocket Guide. University of California
      Press, Berkeley, Calif. 154 pp.

Fiedler, Peggy L., and Subodh K. Jain. 1992. Conservation Biology. Chapman
       and Hall, New York. 507 pp.

Keeton, W. T. and J. L Gould. 1986. Biological Science. W.W. Norton and
      Company. New York, NY. Pgs. 1175

Lincoln, R.J., G.A. Boxshall, P.F. Clark. 1992. A dictionary of ecology, evolution
       and systematics. Cambridge University Press, Cambridge. 298 pp.

SERCAL 1992. Revegetation/Restoration Planning: The Basics. Society for
    Ecological Restoration. November 1992.



( (Cultivar Crazy-
        Preserving the Genetic Heritage of Plants - Oxford Dictionary of Science

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