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Communication at the NABS Annual meeting, Keystone, 2000
(249) ELEVATED ATMOSPHERIC CO2-INDUCED CHANGES IN LEAF LITTER CHEMISTRY: EFFECTS ON IN SITU AQUATIC MICROBIAL ACTIVITY AND LEAF DECOMPOSITION RATES.
K.A. Wahtera1, N.C. Tuchman1, and R.G. Wetzel2. 1Department of Biology, Loyola University Chicago, 6525 N. Sheridan Rd., Chicago, IL. 60626, 2Department of Biological Sciences, University of Alabama, Tuscaloosa, AL., 35487 USA
Trembling Aspen saplings were exposed to either elevated (72 kpa) or ambient (36 kpa) levels of atmospheric CO2 to evaluate the hypothesis that CO2-induced changes in the chemical quality of leaf litter will alter in situ decomposer utilization and leaf decomposition rates. Aspen litter, grown under conditions of elevated CO2 (ELEV), had both higher C:N ratios (56:1) and lignin content (64.8 mg/g leaf) than ambient-grown leaves (AMB: C:N=28.1; 55.7 mg lignin/g leaf). 30 leaf packs of each CO2 treatment were placed into a headwater stream (Emmett Co., MI.) in September 1999 for four months. AMB litter decomposed 10% faster than ELEV in the first 30 days (AMB: 53 %R; ELEV: 58.6 %R). Additionally, microbial respiration was 30% lower on ELEV litter (ELEV: 0.86 mg O2/g leaf/hr; AMB: 1.36 mg O2/g leaf/hr). These early differences, however, were masked after 60 days of exposure in the stream. Preliminary macroinvertebrate data indicates a lower abundance of both CPOM and FPOM detritivores on ELEV litter. ELEV litter supported 30% and 39% fewer leaf-shredding invertebrates after 30 and 60 days of exposure. In addition, 70% and 60% fewer filter-feeding invertebrates were found on ELEV litter after 60 and 90 days exposure respectively.
Presented at 9:15 AM on Thursday, June 1, 2000 in Organic Matter Processing I
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