HR: 10:35h
AN: B42B-02 INVITED     [Abstracts]
TI: Permafrost And Vegetation Dynamics In Peatlands: Implications For CO$_{2}$ and CH$_{4}$ Exchange
AU: * Christensen, T R
EM: torben.christensen@nateko.lu.se
AF: GeoBiosphere Science Centre, Physical Geography and Ecosystems Analysis, Lund University, Solvegatan 12, Lund, 22362 Sweden
AU: Johansson, T
EM: torbjorn.johansson@nateko.lu.se
AF: GeoBiosphere Science Centre, Physical Geography and Ecosystems Analysis, Lund University, Solvegatan 12, Lund, 22362 Sweden
AU: Malmer, N
EM: nils.malmer@planteco.lu.se
AF: Department of Ecology, Plant Ecology and Systematics, Lund University, Solvegatan 37, Lund, 22362 Sweden
AU: Akerman, J
EM: jonas.akerman@nateko.lu.se
AF: GeoBiosphere Science Centre, Physical Geography and Ecosystems Analysis, Lund University, Solvegatan 12, Lund, 22362 Sweden
AU: Crill, P
EM: patrick.crill@geo.su.se
AF: Department of Geology and Geochemistry , Stockholm University, Stockholm, 106 91 Sweden
AU: Mastepanov, M
EM: mikhail.mastepanov@nateko.lu.se
AF: GeoBiosphere Science Centre, Physical Geography and Ecosystems Analysis, Lund University, Solvegatan 12, Lund, 22362 Sweden
AU: Str”m, L
EM: lena.strom@nateko.lu.se
AF: GeoBiosphere Science Centre, Physical Geography and Ecosystems Analysis, Lund University, Solvegatan 12, Lund, 22362 Sweden
AU: Svensson, B
EM: bosvetem@althea.tema.liu.se
AF: TEMA Vatten, Link”ping University, Sweden, Linkoping University, Linkoping, 581 83 Sweden
AU: Friborg, T
EM: tfj@geogr.ku.dk
AF: Geographical Institute, Oster Voldgade 10 Copenhagen University, Copenhagen, 1353 Denmark
AU: Svensson, S
AF: GeoBiosphere Science Centre, Physical Geography and Ecosystems Analysis, Lund University, Solvegatan 12, Lund, 22362 Sweden
AB: Ecosystems along the 0 degree C mean annual isotherm are arguably among the most sensitive to changing climate. When the temperature goes from below to above 0 degree C for more than two subsequent years permafrost moves out of equilibrium with the climate and starts thawing. This in itself provide an early warning of a warming climate while the permafrost melting at the same time has serious implications for hydrology, vegetation composition and ultimately ecosystem functioning. Peatlands underlain by permafrost emit significant amounts of the important greenhouse gas methane (CH$_{4}$) to the atmosphere and act as a moderate CO$_{2}$ sink. These CH$_{4}$ emissions are intimately related to temperature and hydrology, and alterations in permafrost coverage, which affect both of those, have dramatic impacts on the emissions. Using a variety of data and information sources from the same region in subarctic Sweden we show that mire ecosystems are subject to dramatic recent changes in the distribution of permafrost and vegetation. These changes are most likely caused by a warming, which has been observed during recent decades. The derived vegetation maps of the central part of the Stordalen mire (15 ha) clearly show a decadal change in vegetation composition between 1970-2000. The areal extension of dry elevated ombrotrophic areas has decreased by 11-36% or expressed in hectares, an approximate loss of 1 to 3 hectares. Accordingly dwarf shrub vegetation with a high abundance of bare peat and lichens in the bottom layer and associated species in the field layer are now less abundant on the mire. During the same time period the total CO$_{2}$ and CH$_{4}$ flux changed by 1-11% (sink) and 19-66% (source) respectively. When calculating the flux as total C-equivalents, using IPCC's GWP (Global Warming Potentials) for CH$_{4}$ at the 100-year timescale, it shows that the mire in 2000 has a 14-31% greater radiative forcing on the atmosphere.
DE: 1890 Wetlands
DE: 1615 Biogeochemical processes (4805)
DE: 0315 Biosphere/atmosphere interactions
DE: 0400 Biogeosciences
SC: Biogeosciences [B]
MN: 2004 AGU Fall Meeting