Climate induced changes to soil structure can alter biogeochemical cycling of carbon

Wednesday, 17 December 2014: 11:20 AM
Teamrat A Ghezzehei, Chelsea L Arnold and Asmeret Aseafaw Berhe, University of California Merced, Merced, CA, United States
There is a lot we know about how carbon is cycled in the soils of different ecosystems, but this understanding is often limited our knowledge of the current conditions of the soil. What happens when the structure of the soil changes? We have found that climate induced changes to soil structure can shift when and where carbon is decomposed especially in soils that are hydrologically-dependent such as permafrost and wetlands. As soils experience drying past their historic limit of dryness, the irreversible changes in soil structure with consolidation can significantly alter the distribution of soil moisture and subsequently the ability of microorganisms to decompose available carbon. Instead of seeing a rapid and significant loss of carbon that would normally be associated with drying in these soils, the change in soil structure and reduction of porosity can potentially buffer carbon loss as drying progresses. This occurs as the smaller pores stay saturated during the consolidation process. This can have large implications for the future of the arctic permafrost as thawing progresses with a warming climate, in addition to natural drying of wetland regions.