COS 23-5
Antarctic terrestrial ecosystems abide: Changes in soils, lakes and streams of the McMurdo Dry Valleys as the cooling trend ends

Tuesday, August 11, 2015: 9:20 AM
321, Baltimore Convention Center
Michael N. Gooseff, INSTAAR, University of Colorado, Boulder, CO
John E. Barrett, Biological Sciences, Virginia Tech, Blacksburg, VA
Byron J. Adams, Department of Biology and Evolutionary Ecology Laboratories, Brigham Young University, Provo, UT
Peter T. Doran, Department of Geology and Geophysics, Louisiana State University, Baton Rouge, LA
Andrew Fountain, Portland State University, Portland, OR
W. Berry Lyons, The Ohio State University, Columbus, OH
Diane M. McKnight, INSTAAR, University of Colorado, Boulder, CO
John Priscu, Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, MT
Eric R. Sokol, Biological Sciences, Virginia Tech, Blacksburg, VA
Cristina Takacs-Vesbach, Biology, University of New Mexico, Albuquerque, NM
Martijn Vandegehuchte, School of Global Environmental Sustainability, Colorado State University, Fort Collins, CO
Ross A. Virginia, Environmental Studies Program, Dartmouth College, Hanover, NH
Diana H Wall, Department of Biology, School of Global Environmental Sustainability, Colorado State University, Fort Collins, CO

Ecosystems are significantly influenced by their physiography, geographic setting, and climate. The McMurdo Dry Valleys (MDV) experienced a decadal cooling trend in mean annual (-0.7°C/decade) and austral summer (-1.2°C/decade) air temperatures, and increasing solar radiation (+8.1 W/m2/decade) from 1986 to 1999.  The MDV ecosystem responded with decreases in soil invertebrate populations, glacial meltwater generation, chlorophyll-a content in stream algal mats and lake water columns, lake levels, and lake primary productivity, and increases in lake ice-cover thickness.  In the 2001-02 austral summer, the highest flow season since 1993 occurred as a consequence of several weeks of warm, cloud-free weather.  In the decade since, mean summer air temperatures have stabilized at cool temperatures (no trend 2003-2011, mean of -4.2°C, variance of 0.15°C). We now seek to determine how the MDV ecosystem responds since the end of the cooling trend.


Coincident with the summer air temperature stability, responses observed to be coincident with the cooling trend have ceased (no patterns in soil invertebrate populations, stream algal mat chl-a), reversed (stream algal mat biomass, lake level rise, lake ice thinning, lake primary production), and some have become more pulsed (meltwater production). These changes in ecosystem properties since the 2001-02 summer further demonstrate the primary control of climate on this ecosystem, and also indicate the differential responses to climate for communities in each landscape unit.