HR: 1340h
AN: B23D-1576    [Abstracts]
TI: The Importance of Vertical Heterogeneity in Soil Organic Matter for Determining Soil Respiration and Carbon Sequestration With Global Ecosystem Models
AU: * Braakhekke, M C
EM: Maarten.Braakhekke@bgc.mpg.de
AF: Max Planck Institute for Biogeochemistry, Hans Knoell Str 10, Jena, 07745, Germany
AU: * Braakhekke, M C
EM: Maarten.Braakhekke@bgc.mpg.de
AF: Wageningen University, Earth ystem Science Chair, P.O. Box 47, Wageningen, 6700 AA, Netherlands
AU: Reichstein, M
EM: Markus.Reichstein@bgc.mpg.de
AF: Max Planck Institute for Biogeochemistry, Hans Knoell Str 10, Jena, 07745, Germany
AU: Kruijt, B
EM: Bart.Kruijt@wur.nl
AF: Wageningen University, Earth ystem Science Chair, P.O. Box 47, Wageningen, 6700 AA, Netherlands
AU: Beer, C
EM: Christian.Beer@bgc.mpg.de
AF: Max Planck Institute for Biogeochemistry, Hans Knoell Str 10, Jena, 07745, Germany
AU: Kabat, P
EM: Pavel.Kabat@wur.nl
AF: Wageningen University, Earth ystem Science Chair, P.O. Box 47, Wageningen, 6700 AA, Netherlands
AB: A major shortcoming of many current global models simulating soil carbon processes is the lack of consideration for the non-uniform vertical distribution of soil organic matter (SOM). By treating the soil as a homogeneous ´bucket´ of carbon, with constant properties and dynamics in time and depth, a number of processes and interactions are ignored which can strongly affect biochemical cycles in the soil and the whole ecosystem. Firstly, when root and microbial respiration do not occur close to the soil surface, the gradient of temperature, moisture and oxygen availability should be considered in order to correctly determine the CO2 production and efflux. Secondly, carbon sequestration often occurs in the deep soil (Rumpel et al., 2002), either because recalcitrant SOM fractions are transported downward or because of unfavorable conditions at depth. The latter reason includes a lack of fresh energy-rich litter, which is related to the so-called ‘priming' effect (Fontaine et al., 2004), referring to the increase of old SOM decomposition when fresh litter is added. We propose that ignoring vertical heterogeneity in soil can lead to errors in predictions of global models and present the first results of a new soil-process model which includes the vertical heterogeneity of organic matter, temperature and moisture, as well as the mechanisms leading to carbon stabilization in the subsoil. This model is to be applied at a global scale, in global ecosystem models. We show that in many cases the vertical heterogeneity of SOM has an important effect on the carbon cycling in soil and should not be ignored.
DE: 0414 Biogeochemical cycles, processes, and modeling (0412, 0793, 1615, 4805, 4912)
DE: 0428 Carbon cycling (4806)
DE: 0486 Soils/pedology (1865)
DE: 1622 Earth system modeling (1225)
SC: Biogeosciences [B]
MN: 2007 Fall Meeting