HR: 1340h
AN: B33E-1075    [Abstracts]
TI: APEX, the Alaska Peatland Experiment: an Experimental Approach to Peatland Carbon Cycling at the Bonanza Creek LTER Site
AU: * Turetsky, M
EM: mrt@msu.edu
AF: Department of Plant Biology, Michigan State University, East Lansing, MI 48823
AU: Millar, N
EM: millarn@msu.edu
AF: Department of Plant Biology, Michigan State University, East Lansing, MI 48823
AU: Conlin, M R
EM: conlinmo@msu.edu
AF: Department of Plant Biology, Michigan State University, East Lansing, MI 48823
AB: Peatlands cover only 3-5 % of the world's land surface but store 30 % of the world's soil carbon (C) pool. Globally, peatlands are situated predominantly in boreal and subarctic regions that will experience some of the most dramatic warming under greenhouse induced climate change. Water table position is a strong control on peatland C emissions to the atmosphere, although the recalcitrant nature of moss litter might stabilize near surface organic matter in many northern peatlands. In the winter of 2005, we initiated a large scale experiment in a moderately rich fen near the Bonanza Creek LTER site in central Alaska (APEX: www.apex.msu.edu). The goal of our project is to understand vegetation and C cycling processes under altered water table and soil thermal regimes. We established three water table plots (control, raised, lowered), each about 120 m² in area, using drainage ditches to lower the water table by 5-10 cm and solar powered pumps to raise the water table by about 5 cm. Within each water table plot, we constructed replicate open top chambers (OTCs) to passively increase surface temperatures by about 1 ° C.

Our first year of monitoring showed rapid changes in both plant and microbial activity across our experimental treatments. Net ecosystem exchange of CO₂ was greater in the control plot than in the other water table plots (p=0.002; df 2; F=6.56), likely due to vegetation shifts under altered water tables. Ecosystem respiration (dark CO₂ fluxes) varied across the warming treatments (p=0.001; df 1; F=20.21; warming: 4.65 ± 0.13; no warming: 3.91 ± 0.12 μmol CO₂ m^-2 s^-1) but did not differ across the three water table plots (p>0.05). This may indicate relatively rapid changes in microbial activity in response to warming treatments. Similarly, CH₄ fluxes varied by a warming × water table interaction (p=0.02; df 2; F=2.17), with the greatest fluxes in the raised plot with warming (11.76 ± 2.71 μmol CH₄ m^-2 min^-1) and the lowest fluxes in the lowered plot without warming (3.69 ± 1.01 μmol CH₄ m^-2 min^-1). These results show that peatland C fluxes will respond quickly to changes in climate, and are controlled by interactions between vegetation structure, hydrology, and soil temperatures in boreal regions.
UR: http://www.apex.msu.edu
DE: 0428 Carbon cycling (4806)
DE: 0475 Permafrost, cryosphere, and high-latitude processes (0702, 0716)
DE: 0497 Wetlands (1890)
SC: Biogeosciences [B]
MN: Fall Meeting 2005