Dr. John S. RichardsonUniversity of British Columbia, Professor Aquatic and Riparian Area Ecologyhttp://faculty.forestry.ubc.ca/richardson/jrichardson.html |
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Controls on organic matter decomposition in streams and effects on food webs. |
| Organic matter from terrestrial leaf litter provides a key resource to stream food webs. The rates at which organic material is decomposed or transported downstream are complex processes, potentially governed by local and regional drivers. Within-stream complexity, measured as the amounts of large and small wood, we find large differences in the amounts of detritus retained, but also higher rates of decomposition in areas with large wood resulting in much higher rates of production of invertebrates. In streams with forest canopies ranging from solely deciduous to solely coniferous, we find more than two-fold differences in the decomposition rates associated with canopy cover. Climate change models predict lower summer flows and we have experimentally addressed potential effects by using combinations of flow diversions and species knock-outs. As flows are reduced in small streams the rates of decomposition slow, and likewise as key detritivores are selectively removed decomposition rates slow and are not compensated for by other consumers. It is not clear how the degree of variation in detrital supply through the year might affect overall biodiversity and productivity as large pulses can leave longer-lived organisms without resources for long enough to lead to mortality. |
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Ort |
| 04.02.2010 15:00 Uhr Großer Hörsaal |
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