Have you ever gone fishing in a Cook Inlet creek and snagged your line on a pile of dead wood? While hooking this dead wood may be frustrating for fishermen, these old logs and branches -- called "large woody debris" by scientists -- are a critical part of any stream habitat. Their source is the flood plain of each stream or river.

Erosion along the waterway's winding channel may cause trees to fall into a stream; dead and fallen trees may also be washed into a stream system during large floods. Large pieces of wood deflect and concentrate the stream's current, scouring out pools that subsequently provide important cover and wintering habitat for trout and young salmon. Large woody debris also helps the stream retain and store organic material by trapping smaller pieces of wood, leaves from streamside trees and carcasses of spawned-out salmon. This organic matter feeds aquatic invertebrates, which are an important food source for trout and juvenile salmon.

The vast majority of spruce trees in the Anchor River basin have been killed by the current spruce bark beetle outbreak. What does this mean for the future of large woody debris in our local streams?

This fall, researchers from the University of Alaska Anchorage and the USDA State and Private Forestry organization of the USDA Forest Service began a study to determine what impact the bark beetle epidemic will have on future accumulations of large woody debris in the Anchor River basin. These scientists are measuring the density of trees next to the streams, surveying the stream habitat and monitoring spruce regeneration near streams to estimate the present abundance and future sources of large woody debris within the river basin. With their help, we will gain an appreciation for the "old dead wood" in our local waterways by better understanding the importance of woody debris in stream habitats.

To learn more about the Kachemak Bay Research Reserve, please visit www.kbayrr.org.

Coowe Walker is a watershed specialist at the Kachemak Bay Research Reserve.

Researchers Dan Rinella and Keith Boggs are leading the multi-year study of large woody debris in the Anchor River basin.