In an effort to quantify the extent of ecosystem degradation, stream ecologists have developed several techniques to assess the overall health of stream ecosystems. While many of these techniques examine species at the top of the food web, others are based on the most basic processes that fuel stream ecosystems. Organic detritus or particulate organic matter (POM) is used as a food source by lower trophic levels. One of the key effects of natural woody debris formations is enhancing retention of POM. Large woody debris formations trap leaf packs and twigs, and they retard flow, creating depositional zones.

Effects of large woody debris structures on retention of organic matter

Effects of large woody debris structures on flow