Organic matter availability structures of microbial biomass and their activity in Pachamalai Forested stream in Tamilnadu.

Microbial biomass (bacteria, fungi, algae) and the activity of extracellular enzymes used in the decomposition of organic matter among different benthic substrata over one hydrological year in a Pachamalai stream. Microbial heterotrophic biomass (bacteria plus fungi) except during short periods of high light availability in the spring and winter. Bacterial and fungal biomass increased with the decomposition of cellulose and hemicellulose compounds from leaf material. Later, lignin decomposition was stimulated in fine (sand, gravel) and coarse (rocks, boulders and cobbles) substrata by the accumulation of fine detritus. In the drought provoked an earlier leaf fall. The resumption of the water flow caused the weathering of riparian soils and subsequently a large increase in dissolved organic carbon and nitrate, which led to growth of bacteria and fungi.