HR: 11:15h
AN: NB42A-04    [Abstracts]
TI: Effect of Elevated Etmospheric CO₂ on Litter Breakdown in a Stream
AU: * Schindler, M
EM: markus.schindler@eawag.ch
AF: EAWAG - Swiss Federal Institute for Environmental Science and Technology, Seestrasse 79, Kastanienbaum, LU 6047 Switzerland
AU: Gessner, M O
EM: mark.gessner@eawag.ch
AF: EAWAG - Swiss Federal Institute for Environmental Science and Technology, Seestrasse 79, Kastanienbaum, LU 6047 Switzerland
AB: Climate change scenarios predict a continuing increase in atmospheric CO₂ concentration in the future. One potentially important effect on plants is an increase in leaf lignin concentration, which in turn is critically important in controlling breakdown rates of leaves. Given the power-function type relationship between leaf lignin concentration and breakdown rate, breakdown of leaf species with a low lignin concentration is expected to respond sharply to CO₂-induced changes in litter quality, whereas species with high concentrations should be insensitive. To test this hypothesis, we conducted a litter-bag experiment with leaves from six deciduous species differing in litter chemistry which were collected from trees exposed to either elevated or ambient CO₂ levels. The 12 types of leaves were enclosed in coarse-mesh and fine-mesh bags and placed in a softwater mountain stream in November 2004. The bags were retrieved after 7 weeks and leaf mass loss determined. Consistent with our hypothesis, our preliminary results suggest that leaves subjected to elevated CO₂ concentration showed indeed an overall tendency to decompose more slowly, with the CO₂ effect being greatest for the species decomposing most rapidly.
DE: 9901 NABS Student Award - Basic Research
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly