Increased Connectivity in a Polar Desert Resulting from Climate Warming: McMurdo Dry Valley LTER Program
The McMurdo Dry Valleys (MDV) is a polar desert on the coast of East Antarctica, a region that has not yet experienced the climate warming that is now occurring elsewhere. The McMurdo Dry Valleys Long Term Ecological Research (MCMLTER) project has documented the ecological responses of the glacier, soil, stream and lake ecosystems in the MDV to a cooling trend that occurred from 1986 to 2000, which was associated with the depletion of atmospheric ozone. In the past decade, warming events with strong katabatic winds occurred during two summers and the resulting high streamflows and sediment deposition changed the dry valley landscape, possibly presaging conditions that will occur when the ozone hole recovers. Based upon observations over the past decade and predictions of future warming in Antarctica, the overarching hypothesis of the MCMLTER project is that climate warming in the McMurdo Dry Valley ecosystem will amplify connectivity among landscape units leading to enhanced coupling of nutrient cycles across landscapes, and increased biodiversity and productivity within the ecosystem. In our research, contemporary patterns in ecological connectivity in the MDV are examined and used as a basis for predictions of future changes. Warming in the MDV is hypothesized to act as a slowly developing, long-term press of warmer summers, upon which transient pulse events of high summer flows and strong katabatic winds will be overprinted. Four specific hypotheses address the ways in which pulses of water and wind will influence contemporary and future ecosystem structure and function. Dramatic increases in connectivity are projected to occur in the next century, e.g. the closed basin lakes of Taylor Valley will likely rise and may begin to coalesce. The MCMLTER project has extended the spatial scale to include the more southerly Miers and Garwood Valleys, where thermokarst erosion is now underway. Because windborne transport of biota is a key aspect of enhanced connectivity from katabatic winds, new monitoring includes high-resolution measurements of aeolian particle flux. Importantly, integrative genomics are employed to understand the responses of specific organisms to the increased connectivity. The project includes a novel environmental history component that will use environmental history which examines interactions between human activity, scientific research, and environmental change in the MDV over the past 100 years. In much the same way as the simplicity of the MDV ecosystems makes the area an ideal location for exploring ecological theory, the simplicity of the area’s human history – in terms of its short timeframe and the small number of people involved – makes it an excellent location for integrating the theory and practice of environmental history with the ecological research of the LTER network.