By Dixie Ward
Large woody debris creates important habitat for fish and other aquatic species.
Environmental scientists define “large woody debris” as trees, logs, rootwads, and large tree branches that fall into streams and interact with the water, sediment or organisms in the stream. It is an important resource for fish and wildlife.
In many watersheds, large woody debris is a main factor controlling the shape of the stream. When a large piece of wood enters and stays in a stream it can interact in many ways with flows of water, sediment and nutrients. For example, a log can cause high water flows to go down into the stream bed, scouring out a pool. The more wood that is present, the greater number of pools that will form. These pools are very important to fish and other aquatic organisms and the wood within these pools provide cover and shelter.
It also plays a significant role in aquatic food webs. This role ranges from trapping and storing organic matter to providing direct food sources and habitat for aquatic insects, such as mayflies, stoneflies and caddisflies. MRWA is currently working with the U.S. Forest Service on a wood restoration project to add large woody debris to existing instream habitat structures in Bigelow Creek, a stream that provides important spawning and rearing habitat for a community of migratory steelhead and resident brook trout and sculpin.