Scaling soil CO2 and CH4 fluxes in heterogeneous northern forest landscapes.
Peter
Weishampel, University of Minnesota, weish004@umn.edu
(Presenting)
Jennifer
King, University of Minnesota, jyking@umn.edu
Randall
Kolka, USDA/Forest Service, rkolka@fs.fed.us
In developing landscape-level carbon budgets, we measured fluxes of CO2 and CH4 from soils of forests and wetlands in the Marcell Experimental Forest (MEF) and the Chequamegon National Forest (CNF) during the 2005 growing season. At MEF, CO2 efflux from peatland cover types (6.1 Mg ha-1) was lower than that from forested and non-forested upland cover types (7.9 and 10.1 Mg ha-1, respectively). MEF uplands were a slight sink for CH4 (-0.005 kg C ha-1 d-1), and peatlands were a substantial source (0.31 kg C ha-1 d-1). As peatlands account for approximately 20% of the cover types at MEF, this site acted as a net source of CH4 during the measurement period. At the CNF, we sampled 7 different field sites representative of vegetation cover classes and forest management regimes in the region. CO2 efflux was lowest at an open bog site (2.9 Mg C ha-1) and highest in a 5 year clearcut (7.8 Mg C ha-1), with the flux from other wetland types, a mature forest, and a young clearcut ranging from 5.4-6.8 Mg C ha-1). Net CH4 flux also varied with site, with the mature hardwood site, the older clearcut, and the coniferous wetland acting as sinks for (-1.2, -1.3, and - 0.7 kg C ha-1 respectively), and the younger clearcut, the alder swamp, the bog, and the sedge fen acting as sources (3.7, 0.9, 2.7, and 19.8 kg C ha-1 respectively). Site differences appear to be directly related to differences in temperature, moisture and vegetation.