Tuesday, June 5, 2007 - 8:30 AM
95

Functional diversity of detrital inputs alter particulate organic matter dynamics in a forested headwater stream

Sue L. Eggert, Department of Entomology, University of Georgia, Athens, GA 30602, J. Bruce Wallace, Department of Entomology and Institute of Ecology, University of Georgia, Athens, GA 30602, Judy L. Meyer, Institute of Ecology, University of Georgia, Athens, GA 30602, and Jackson R. Webster, Department of Biological Sciences, Virginia Tech, 2119 Derring Hall, Blacksburg, VA 24061.

The functional diversity of leaf inputs (as defined by decay rates) to small streams can impact stream ecosystems through detritus quality and availability to consumers.  We examined the role of detrital complexity on ecosystem function by adding the same amount of three leaf species of various decay classes (fast, slow, mixed) over a 5-year period to a mesh-canopy covered stream at Coweeta Hydrologic Lab.  During two years each of fast and slow leaf addition, mean annual leaf standing crop in the treatment stream was lower than that in the reference stream (RIA, P<0.01).  Mixed leaf addition resulted in similar leaf standing crops in both streams.  Mean annual FBOM standing crops were similar between streams during each leaf addition period.  Minimum leaf standing crops in the treatment stream were 0.3, 7.8, and 6.2 g AFDM m-2 during summer months of fast, slow, and mixed leaf addition, respectively.  Minimum leaf standing crop in the reference stream was 54.0 g AFDM m-2, demonstrating the large difference in resources available for consumers in the treatment stream, particularly during years when only fast decay leaves were added.  Consumer production data will help determine the relative influence of resource quantity vs. quality in small forested streams.

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