1987 Wetland Delineation Manual - The Wetlands Regulation Center

Wetland Delination Manual, 1987 86
Range - As used herein, the geographical area in which a plant species is known to occur.
Redox potential - A measure of the tendency of a system to donate or accept electrons, which
is governed by the nature and proportions of the oxidizing and reducing substances contained
in the system.
Reducing environment - An environment conducive to the removal of oxygen and chemical
reduction of ions in the soils.
Relative density - A quantitative descriptor, expressed as a percent, of the relative number of
individuals of a species in an area; it is calculated by
Number of individuals of species A X 100
Total number of individuals of all species
Relative dominance - A quantitative descriptor, expressed as a percent, of the relative size or
cover of individuals of a species in an area; it is calculated by
Amount* of species A X 100
Total amount of all species
*The amount of a species may be based on percent areal cover, basal area, or height.
Relative frequency - A quantitative descriptor, expressed as a percent, of the relative
distribution of individuals of a species in an area; it is calculated by
Frequency of species A X 100
Total frequency of all species
Relief - The change in elevation of a land surface between two points; collectively, the
configuration of the earth's surface, including such features as hills and valleys.
Reproductive adaptation - A feature of the reproductive mechanism of a species that results in
it being better fitted to its environment (e.g. ability for seed germination under water).
Respiration - The sum total of metabolic processes associated with conversion of stored
(chemical) energy into kinetic (physical) energy for use by an organism.
Rhizosphere - The zone of soil in which interactions between living plant roots and
microorganisms occur.
Root zone - The portion of a soil profile in which plant roots occur.
25 February 1997 Environmental Techncal Services Co. 834 Castle Ridge Rd Austin, Texas 78746