The legacies of waxing and waning connectivity in a polar desert ecosystem

Background/Question/Methods - As the largest ice-free area of Antarctica, the McMurdo Dry Valleys are a mosaic of open soils, stream channels, alpine/piedmont glaciers, and permantently ice-covered closed basin lakes. Given the cold (-18 degC annual mean air temp) and dry (<5cm snow water equivalent annually) climate, it has been long recognized that this system is particularly sensitive to physical forcing factors (e.g., warm summers generating increased glacial melt). Two critical physical processes that are responsible for significant vectors of energy and matter across this landscape are streamflow, which occurs for 6-10 weeks in the austral summer, and aeolian transport, which primarily occurs during strong down valley Fohen wind events. How important are these two vectors to ecosystem function? What are the dynamics of these processes across space and time?

Results/Conclusions - We measure meteorology at 12 locations across the landscape and streamflow, stream chemistry, temperature, and electrical conductivity at 17 gauges since 1993. For ~10 years, we also measured sediment transport in passive collectors to evaluate transport and deposition rates. Here we compare and contrast the frequency and strength of these two transport vectors across 20+ years of record, with an emphasis on connecting landscape features and accompanying transfers of mass and matter. Whereas streams are in general more consistent vectors of transport, streamflow occurs only during the summer. Alternatively, aeolian transport is far less predictable, and short-lived (few days), its breadth across the landscape provides the opportunity for much greater transport across the landscape if only briefly.