Wednesday, August 5, 2009

PS 43-28: Back to the Future: Re-sampling old research sites to assess changes in arctic plant community composition in Barrow, Alaska

Sandra Villarreal, University of Texas at El Paso, David R. Johnson, University of Texas at Arlington, Craig E. Tweedie, Systems Ecology Lab, University of Texas at EL Paso, Robert Hollister, Grand Valley State University, and Patrick J. Webber, Michigan State University.

Background/Question/Methods Arctic ecosystems are undergoing significant changes due to persistent climate change.  To determine the consequences of a changing climate, there is a need to better understand biotic responses are occurring at various scales in the Arctic.  In particular, plant communities are responding to these environmental changes with shifts in species abundance and diversity.  Vegetation plays a key role in primary productivity, nutrient cycling, surface energy budget, and trophic interactions at all levels in the Arctic.  This study focuses on documenting changes in arctic plant communities by re-sampling 34 former International Biological Program (IBP) sites established in Barrow, Alaska in 1971.  Sampling sites consist of a 1m x 10m plot of vegetation. Cover assessment for each species was done by visual estimation.   Vegetation plots were chosen to best represent the various plant microcommunities of the tundra at Barrow, Alaska.  Much of the tundra at Barrow is characterized by polygonal rims and troughs.  Changes in the elevation between these landscape factors are associated with changes in active layer, and can be important definers of moisture regimes and thus, plant communities.  Here we describe patterns of change within these communities, and physical factors that might be determinants and drivers of change in particular communities. 

Results/Conclusions Data from the 2008 re-sampling effort in Barrow indicates that plots with higher moisture tended to have greater shifts in species abundance and diversity.  In contrast, drier communities showed the least amount of change.  By documenting change that has occurred at a decadal time scale, we can further understand how plant communities will behave in the future.  This has important implications on how Arctic terrestrial landscapes can alter the Earth systems through biotic or abiotic feedbacks.   


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