Root systems of woody vegetation not only help stabilize banks, but supply cover for fish and aquatic insects. Forest litter is the basis of food in the stream ecosystem, being utilized by insects that are in turn prey for fish. Water Quality Recent studies have shown that riparian forests as narrow as 50 feet in width can completely remove excess nitrogen as it moves from farm fields through the forests to the adjacent stream. These forested areas also filter sediments and phosphorus, thereby acting as buffers to nutrient inputs to streams. The retention varies depending on width of forest, slope, and other factors.
Tree roots help stabilize streambanks by holding soil in place.
Riparian forests also lower flow velocities, causing sediment to settle out. The most important role of the riparian forest is the uptake and long-term storage of nutrients in its woody material. A major concern to the aquatic environment is the increased nutrients entering a watercourse during and after a harvest operation.