HR: 09:30h
AN: NB41B-05    [Abstracts]
TI: Spatial Variability of Leaf-litter Decomposition in Streams
AU: * Tiegs, S D
EM: scott.tiegs@eawag.ch
AF: EAWAG/ETH Swiss Federal Institute for Environmental Science and Technology, Limnological research Center, Kastanienbaum, CH-6047 Switzerland
AU: Akinwole, P O
EM: philips.akinwole@eawag.ch
AF: EAWAG/ETH Swiss Federal Institute for Environmental Science and Technology, Limnological research Center, Kastanienbaum, CH-6047 Switzerland
AU: Gessner, M O
EM: mark.gessner@eawag.ch
AF: EAWAG/ETH Swiss Federal Institute for Environmental Science and Technology, Limnological research Center, Kastanienbaum, CH-6047 Switzerland
AB: Most studies of leaf decomposition in streams quantify decomposition rates in single riffles or short stream reaches and so we still know little about how decomposition varies at larger spatial scales. We used a leaf-bag approach and a hierarchical experimental design to investigate decomposition across three spatial scales spanning five orders of magnitude. In each of four replicate fourth-order watersheds in the Black Forest of Germany we selected three third-order streams. Each of the 12 streams contained four replicate riffles in which we installed four coarse- and fine-mesh bags (384 bags in total). Mean decomposition rates were highly consistent among watersheds (a range of less than 3% across all four watersheds) for both mesh types. However, significant differences in mean decomposition rates were observed among streams and riffles in coarse-mesh bags. Decomposition rates in fine-mesh bags did not vary at any spatial scale. This discrepancy between mesh types suggests that patchy distribution of invertebrate feeding accounts for observed differences in decomposition whereas the more homogeneous distribution of microbes made microbial decomposition highly predictable. These results show that 1) variability of leaf decomposition depends on scale and 2) microbial decomposition responds differently to a change in scale than decomposition involving invertebrates.
DE: 9901 NABS Student Award - Basic Research
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly