These residues, borne by runoff, are converted to non-toxic compounds by microbial decomposition, oxidation, reduction, hydrolysis, solar radiation and other biodegrading forces at work in the soil and litter of the streamside forest. While scientists have long understood the biological processes at work in the streamside forest, additional data are necessary to fully quantify their importance with respect to pesticide degradation. The streamside forest acts as a sink by storing nutrients for extended periods of time The streamside forest can function as a sink when nutrients are taken up by plants and sequestered in plant tissue. Nitrogen and other nutrients may also be passed up the food chain when plant tissues are consumed by animals and converted to animal tissues. In wetter areas, nutrients in leaf litter can be stored for longer periods as peat.
Sediments filtered out by the streamside forest remain to become incorporated into the forest soil.
The streamside forest functions as a source when it provides energy to streams in the form of dissolved carbon compounds and participate organic detritus. These materials are critical to processes within the stream itself, helping to restore and maintain nature s equilibrium. They pass on this energy when they are, in turn, consumed by larger benthic fauna and eventually by fish. Thus the streamside forest functions as an important energy source for the entire aquatic food chain from headwaters to estuary. Simple removal of nonpoint pollutants is not enough to improve the quality of water resources.