Effect of Forest Harvesting and Riparian Buffers on Headwater Stream Temperatures

Abstract

Headwater streams are small in size, but can be 80% of stream length. They have a high density in steep terrain and have a high biodiversity of invertebrates, amphibians and fish. However, they are very sensitive to landscape change, particularly timber harvesting in the Pacific Northwest. Timber harvesting exposes streams and results in a changed temperature environment. There are concerns that elevated headwater stream temperatures will negatively impact stream biota and have cumulative effects downstream. Many factors as well as harvesting affect stream temperatures including, air temperature, stream morphology, ground-water, riparian and basin vegetation condition, shade, aspect, sediment, windthrow and stream wood. Although larger streams lower in the watershed are protected by riparian buffers by law in Washington, small streams do not currently have the same level of protection.