Glossary 



Adaptation - The condition of showing fitness for a particular environment, as applied to char- 

 acteristics 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 



Adventitious roots - Roots found on plant stems in positions where roots normally do not oc- 

 cur. 



Aerenchymous tissue (Aerenchyma) - A type of plant tissue in which cells are unusually large, resulting in 

 large air spaces in the plant organ; such tissues are often referred to as spongy and usually provide in- 

 creased buoyancy. 



Aerobic - A condition in which molecular oxygen is a part of the environment. — 



Alfisols - Soils having significandy more clay in the B-horizon than in the A-horizon and high base status. 



Anaerobic - A condition in which molecular oxygen is absent (or effectively so) from the environment. 



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



Aqualfs - Soils with an aquic or peraquic moisture regime and having clay accumuladng in the B-horizon; 

 wet Alfisols. 



Aquents - Soils with an aquic or peraquic moismre regime and lacking distinct soil horizons in the subsoil; 

 wet Entisols. 



Aquepts - Soils with an aquic moisture regime and showing some soil development in the B-horizon; wet 

 Inceptisols. 



Aquic moisture regime - A moisture condition associated with a seasonal reducing environment that is vir- 

 tually free of dissolved oxygen because the soil is saturated by ground water or by water of the capillary 

 fringe, as in soils in Aquic suborders and Aquic subgroups. 



Aquods - Soils having an accumularion of iron, aluminum, and organic matter in the B-horizon in addition 

 to having an aquic moisture regime; wet Spodosols. 



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 veget- 

 ative strata; 2) areal cover is estimated by vegetative layer, and 3) foliage within a single layer may overlap. 



Disturbed condition - As used herein, this term refers to areas in which indicators of one or more character- 

 istics (vegetation, soil, and/or hydrology) have been sufficiently altered by man's activities or natural 

 events so as to make it more difficult to recognize whether or not the wetland identification criteria are met. 

 Artificial wedands - Wetiands created by the activities of man, either purposefully or accidentally. 



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). 



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