Processes driving soil CO2 temporal variability in Antarctic Dry Valleys

The polar deserts of the McMurdo Dry Valleys, Victoria Land, Antarctica, are among the most hostile places on Earth, where terrestrial biota is limited to small patches of hospitable land. Carbon dioxide (CO2) soil surface flux has been used to estimate the rates of biological activity in hospitable areas, but researchers have also observed CO2 fluctuations at sites with low biological activity, including strong negative fluxes suggestive of an abiotic sink for CO2. To better characterize the biotic and abiotic controls on soil surface CO2 flux, and their relative contributions to variability, we designed and executed a long-term monitoring experiment in four of the McMurdo Dry Valleys. This experiment used automated temporal monitoring of both CO2 efflux, and soil concentrations, at sub-diel timescales. In general, the fluxes we observed were well under