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CR5.1 | Thawing permafrost - stabilization versus decomposition of organic matter?
Thawing permafrost - stabilization versus decomposition of organic matter?
Convener: Christian Beer | Co-conveners: Carsten W. Mueller, Georg Guggenberger
About 800 Pg soil carbon has been frozen for centuries to millennia. A large fraction of it is assumed to be thawed due to climate change in the near future. A rapid mineralization of this carbon to carbon dioxide or methane will directly alter the global carbon cycle resulting in positive feedback mechanisms that even accelerate climate change. However, permafrost-affected soils and the organic matter stored within are distributed heterogeneously with depth and across ecosystems. Is such thawing organic matter accessible to microorganisms and vulnerable to microbial decay, and hence will it be decomposed fast? Will a large part of it be stabilized at mineral surfaces or in soil aggregates, or will stabilization processes known from temperate soils be rather ineffective? Furthermore, what is the effect of hydrological changes to carbon mineralization or stabilization, particularly with respect to energy constraints of microorganisms? What will be effects of changing vegetation functions to soil organic matter dynamics? This session invites papers that investigate decomposition versus stabilization of thawing permafrost or active layer-organic matter. Contributions may be based on laboratory experiments, field observations, or modelling from the process level to the global scale.