When I’m hiking a river or a stream in the summer I often curse all of the down trees and woody debris I have to scamper over or around. Who knew I should actually be thanking the woody debris?
According to an article by Dayle Wallien, “Large woody material (LWM) , including whole trees, limbed logs and rootwads, to forest streams can provide many benefits to fish. Scientists have now come to understand that in-stream LWM is ecologically important for a number of reasons:”
- LWM can help spawning gravels accumulate , by stopping the gravel from moving downstream;
- Pools can form behind LWM, which provide important juvenile rearing habitat, as well as habitat for all fish during periods of low-flows;
- LWM can help slow stream speed , which helps adult fish as they move upstream and shelters rearing juveniles from using too much energy fighting currents;
- LWM provide shade , offering pockets of cooler water, and can help to lower the temperature of an entire stream;
- LWM provides fish with refuge from predators ;
- LWM can help to stabilize banks, prevent erosion and decrease sediment movement that can harm downstream fish habitat;
- LWM is important to the aquatic food chain, because it traps organic matterand provides habitat for insects and invertebrates, which are both food for fish.
The next time you have to paddle around a downed tree or get scratched by a branch, remember, wood is good for fish habitat.