Monster Seminar JAM - Contrasting Effects of Anthropogenic vs. Natural Disturbances on the Flow of Resources Between Streams and Riparian Zones
Dr. Colden V. Baxter, Stream Ecology Center and Department of Biological Sciences, Idaho State University
Streams and riparian zones are closely linked by reciprocal flows of materials and organisms. Results from a combination of studies allow us to compare the effects of human-caused vs. natural disturbances on these resource fluxes. For example, research conducted in Japan suggests that disturbances like riparian deforestation, channelization, and non-native fish introduction can diminish the magnitude or alter the fate of invertebrate prey fluxes between stream and riparian food webs. Moreover, these reductions do not occur only via simple donor-recipient effects. Experimental results showed that reducing or altering the fate of the invertebrate flux in one direction triggered complex interactions that also dampened the reciprocal flux. In contrast, on-going studies in central Idaho suggest that a natural disturbance, wildfire, may serve to amplify the flow of resources between streams and riparian zones. Fire increases sunlight penetration, but may also increase terrestrial invertebrate and labile leaf litter input to streams. Any of these changes appear to fuel increases in aquatic insect emergence back to riparian zones. Such feedback loops are typical of complex, non-linear systems. Perhaps these patterns of dampening and amplification in reciprocal fluxes typify stream-riparian responses to anthropogenic vs. natural disturbances.
University of Washington
Date and Time:
May 11, 2006,
11:00 am - 12:30 pm