Wildfire and Headwater Stream Productivity: Effects of Intense Fire on Food Subsidies to Downstream and Riparian Habitats in Eastern Washington

Frequent intense, stand-replacing wildfires have occurred throughout the western United States in recent years. Fish bearing streams and riparian areas receive food subsidies of invertebrates and detritus from headwater streams, however, little is known about how fire impacts these foodwebs. The objectives of this study are to examine the effects of forest fire on the source of these subsidies from headwater streams and quantify the effects of forest fire on the abundance and diversity of macroinvertebrate communities. Benthic, emergent, and drift samples of macroinvertebrates were taken from five streams with burned watersheds and five control streams once per month in summer 2004. Invertebrates are identified to family and measured to the nearest millimeter to determine biomass. Counts of individuals from June 2004 drift samples show that burned streams have ten times more drifting invertebrates than control streams. This research will provide timely information for riparian forest management in fire-prone regions of North America. Wildfires may be beneficial to aquatic habitats both in creating diverse habitat and conditions that support abundance and diversity of invertebrates and other organisms.