Relief - The change In elevation of a land surface between two points; collec- 

 tively, 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. 



Routine wetland determination - A type of wetland determination in which 

 office data and/or relatively simple, rapidly applied onsite methods are 

 employed to determine whether or not an area is a wetland. Most wetland 

 determinations are of this type, which usually does not require collection of 

 quantitative data. 



Sample plot - An area of land used for measuring or observing existing 

 conditions. 



Sapling/shrub - A layer of vegetation composed of woody plants <3.0 In. in 

 diameter at breast height but greater than 3.2 ft in height, exclusive of 

 woody vines. 



Saturated soil conditions - A condition in which all easily drained voids 

 (pores) between soil particles in the root zone are temporarily or permanently 

 filled with water to the soil surface at pressures greater than atmospheric. 



Soil - Unconsolidated mineral and organic material that supports, or is cap- 

 able of supporting, plants, and which has recognizable properties due to the 

 Integrated effect of climate and living matter acting upon parent material, as 

 conditioned by relief over time. 



Soil horizon - A layer of soil or soil material approximately parallel to the 

 land surface and differing from adjacent genetically related layers in physi- 

 cal, chemical, and biological properties or characteristics (e.g. color, 

 structure, texture, etc.). 



Soil matrix - The portion of a given soil having the dominant color. In most 

 cases, the matrix will be the portion of the soil having more than 50 percent 

 of the same color. 



Soil permeability - The ease with which gases, liquids, or plant roots pene- 

 trate or pass through a layer of soil. 



All 



