Forestry Terms - E -
ECOLOGICAL STATUS: The degree of similarity between the present Community and the potential natural community on a site. Ecological status is rated irrespective of management objectives. Ratings are based on the floristic similarity of the current vegetation to the potential natural community. The similarity can be expressed on a relative scale ranging from 0 to 100 with adjective ratings assigned as low, moderate or high similarity.
ECOLOGICAL TYPE (Habitat Type): A category of land having a unique combination of potential natural community; soil, landscape features, climate, and differing from other ecological types in its ability to produce vegetation and respond to management. Classes of ecological types include all sites that have this unique combination of components with the defined range of properties.
ECOLOGICAL UNIT: The map unit developed for an ECOLOGICAL TYPE or types. This unit often includes a complex of small and intricately associated ecological types too small to delineiate separately.
ECOLOGY - The science or study of the relationships between organisms and their environment.
ECOREGION CODE: The ecoregion code number in which the inventory/sample is located. Determined from Ecoregion, land surface form and hydrologic unit maps of the U.S.
ECOSYSTEM/COVER TYPE: The native vegetation ecological community considered together with non-living factors of the environment as a unit and, the general cover type occupying the greatest percent of the stand location. Based on tree or plant species forming a plurality of the stocking within the stand. May be observed in the field or computed from plot measurements.
EDGE - The transition between two different types or ages of vegetation.
EVEN-AGED -Stand of trees in which there are only small differences in age among the
individual trees.
EVEN-AGED MANAGEMENT - A forest management method in which all trees in an area are
harvested at one time or in several cuttings over a short time to produce stands that are
all the same age or nearly so. This management method is commonly applied to
shade-intolerant conifers and hardwoods.
EFFECTIVE ROOTING DEPTH: The depth of the soil that accounts for 80 percent of the roots.
EMBEDDEDNESS: A rating of the degree that larger substrate particles (boulder, rubble, or gravel) are surrounded or covered by fine sediment.
ENDANGERED or THREATENED SPECIES - A species is endangered when the total number of remaining members may not be sufficient to reproduce enough offspring to ensure survival of the species. A threatened species exhibits declining or dangerously low populations but still has enough members to maintain or increase numbers.
ENVIRONMENT - The interaction of climate, soil, topography, and other plants and animals in any given area. An organism's environment influences its form, behavior, and survival.
EQUIVALENT BASAL DIAMETER (EBD): The square root of sum of squared basal diameters (BD).
EROSION - The wearing away of land or soil by the action of wind, water, or ice.
EROSION SEVERITY: The degree of erosion taken place on the site. Classes include: Slightly eroded: Erosion has changed the soil enough to require only slight modification of management from that of the non-eroded soil; potential use and management remain generally the same. Most slightly eroded soils have class 1 erosion. Slightly eroded areas are not distinguished from non-eroded areas in most surveys.
- Moderately eroded: Erosion has changed the soil to such an extent that required management or the response to management differs in major respects from that of the non-eroded soil. Suitabilities for major uses such as range or forestry, and major engineering uses--are the same. Shallow gullies may be present. The word "moderately" is omitted from the name unless it is needed to differentiate between this phase and other eroded phases of the same soil.
- Severely eroded: Erosion has changed the soil so much that (1) the eroded soil is suited only to uses significantly less intensive than the non-eroded soil, (2) the eroded soil needs intensive management immediately or over a long period to be suitable for the same uses as the non-eroded soil, (3) productivity is reduced significantly, or (4) limitations for some major engineering interpretations are greater than on the non-eroded soil. Shallow gullies, or a few deep ones, are common in some places.
ESTABLISHED SEEDLINGS: Tree seedlings which are expected to survive and continue to grow over the next several years.
EVAPOTRANSPIRATION - The evaporation of water from the soil and the transpiration of water from the plants that live in that soil. Approximately one-quarter of a forest's annual rainfall returns to the air through evapotranspiration.
