Soil Organic Carbon – an Old Story with a New Future.

Soil organic carbon (SOC) dynamics in wildland soils is not a new topic in soil science, but has gained renewed interest in the context of carbon sequestration for the mitigation of greenhouse gas emissions. Pedogenesis has long used principles of SOC transport, storage, and stabilization, as well as their biotic and abiotic controls; but this knowledge has been slow to permeate current SOC and climate change models. Also, various SOC fractionation schemes have remained limited in elucidating the fate of C entering the soil via foliar litterfall and rhizodeposition. Understanding how SOC from above- vs belowground sources is stabilized is critical for management practices aimed at increasing long-term SOC storage.  There is ample evidence that SOC dynamics in the mineral soil do not mimic those in the forest floor and that they are subject to different control mechanisms.  It would also appear that intrinsic SOC chemistry is less important in causing differences in SOC stabilization among vegetation types than are soil properties and the interaction between SOC fluxes and the mineral soil matrix. The challenge is to apply these new research findings on SOC dynamics and stabilization to practical carbon accounting schemes.