Background/Question/Methods   The McMurdo Dry Valleys of Antarctica are a polar desert ecosystem within the LTER network and host simple biotic communities lacking vascular plants and vertebrates. In this cold and arid environment availability of liquid water is a primary constraint over soil biota. Our research seeks to understand the influence of seasonal snow melt on soil organisms and biogeochemical cycling. During November 2009-January 2010 eighteen snow packs from multiple locations in two valleys were identified and monitored to characterize snow ablation dynamics and associated influences on soil processes over multiple spatial scales. Surface soils under and adjacent to snow packs were sampled 3 times over the summer as ablation occurred to capture the variation in soil properties in subnivian and exposed environments.

Results/Conclusions   Snow packs had significant influences over soil physical properties (i.e. temperature, soil water and salinity), which were correlated with invertebrate diversity and abundance, microbial biomass, nitrogen mineralization and nitrate mobility. Ongoing analyses address the influence of snow packs on the spatial dynamics of soil communities and nitrogen cycling. These results will provide insights to the influence that seasonal snow dynamics may have on soil biodiversity and related ecosystem functioning in a region characterized by a variable and changing climate.