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Communication at the NABS Annual meeting, Keystone, 2000
(277) SOURCES OF ORGANIC MATTER TO OVERLAND FLOW AND FLOODWATERS IN A DESERT WATERSHED.
J.W. Edmonds and N.B. Grimm. Department of Biology, Arizona State University, Tempe, AZ, 85287-1501
Temporal variability in organic matter and nutrient loading is high in desert streams. This variability is associated with spatial distribution of organic matter throughout the terrestrial landscape (uplands). Precipitation falls in discrete, patchy cells on the uplands: then overland flow is directed into rill networks before entering larger channels. Variation in precipitation and runoff location results in variable source inputs of organic matter. We identified 5 potential sources of organic matter to a Sonoran Desert stream, Sycamore Creek, then quantified organic matter quantity and chemical complexity and nutrient concentrations of each source. All sources were monitored during 15 rain events (8 of which resulted in mainstem floods) to determine the dominant contributors of organic matter. Bulk precipitation was high (7-8 mg/L) in dissolved organic carbon (DOC) and characterized by low organic matter chemical complexity, with no N content. In comparison, DOC concentrations, chemical complexity, and organic N content all increased dramatically during overland flow. Tributary inputs explained half of the DOC load; other sources appeared to be redissolution of dried material associated with channel sediments. Stable isotope analysis will be used to further identify the major contributors of organic matter to Sycamore Creek.
Presented at 11:15 AM on Thursday, June 1, 2000 in Organic Matter Processing II
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