1. Ecotypic Variation and the Response of Tundra Plants to Climate Change Ned Fetcher 1, Cynthia Bennington 2, James B. McGraw 3, Milan Vavrek 4, Kelli Cummings 1, and Gaius R. Shaver 5 1 Wilkes University, 2 Stetson University, 3 West Virginia University, 4 Glenville State College, 5 Marine Biological Laboratory Transplanting was done by slicing whole tussocks from the soil below the moss layer. Then tussocks were transported to the other sites and inserted into holes left by removal of other tussocks to be transplanted. Because E. vaginatum has an annual root system, this technique was less disruptive than for other species. Local tussocks were also transplanted within each garden. Ten tussocks were transplanted from each site to each garden. Tiller growth was monitored by haphazardly selecting tillers, and counting the number of new leaves as well as the total number of green leaves. These data were combined to produce an index of tiller size by multiplying the number of green leaves times the length of the longest leaf, which is highly correlated with the leaf mass per tiller (Fetcher 1985). Map of northern Alaska showing location of experimental gardens at Eagle Creek (EC), No Name Creek (NN), Coldfoot (CF), Toolik Lake (TL), Sagwon (SAG) and Prudhoe Bay (PB). The Continental Divide separates southern and northern ecotypes of Eriophorum vaginatum. Response of tiller size index (length of the longest leaf x no. of green leaves) for six populations of E. vaginatum in 1983, 1993, and 2010 to a latitudinal gradient in northern Alaska. The effect of environment is shown by mean values for each garden while the effect of genotype is shown by the lines showing the response of each population. These graphs show that the populations south of the Brooks Range (EC, NN, CF) are more responsive to the environmental gradient than populations on the North Slope (TL, SAG, PB) (Fetcher and Shaver 1990). Plants form the base of Arctic tundra food webs and are the determinants of terrestrial primary productivity in the Arctic. Given this central role, the response of tundra plants to climate change will have regional and global implications. This project examines the role of ecotypic differentiation, i.e., local adaptation of plants to the environment, in modulating and potentially limiting the response of a plant species to climate change. In 1980, a reciprocal transplant experiment was set up to examine ecotypic differentiation in the tussock- forming sedge Eriophorum vaginatum along a latitudinal gradient. The experiment demonstrated strong genetic differentiation between populations of this widespread, abundant Arctic plant species. Since 1980 the Arctic climate has warmed significantly, and these temperature changes, along with associated changes in the soil environment, have caused measurable changes in Arctic plant communities. In 2009 and 2010 we re-censused the experiment to ask whether climate change has already resulted in a ‘mismatch’ between ecotypes and their original environment. Questions Are the original differences between populations of E. vaginatum from south and north of the Brooks Range maintained after 27 years? Because of the warmer climate, do the southern ecotypes show improved performance relative to 27 years ago? Eagle Creek No Name Creek Coldfoot Toolik Lake Sagwon Prudhoe Bay Tussock of Eriophorum vaginatum from Toolik Lake at the Eagle Creek garden showing early senescence in mid-August, 1982. Conclusions The original differences between northern and southern ecotypes of Eriophorum vaginatum appear to be maintained after 30 years. At some gardens there appears to be significant “home team advantage” whereby the native ecotype has greater survival than the alien ecotype. There seems to be little evidence that the southern populations have an advantage as a result of recent warming on the North Slope. Kelli Cummings and Cynthia Bennington measuring tiller size index on BP oil field at Prudhoe Bay. Students in the background are measuring photosynthesis. Acknowledgements Funding was provided by NSF grant #0908936. Additional support was provided by the Arctic Long Term Ecological Research program, funded by the National Science Foundation, Division of Environmental Biology. Literature Cited Fetcher, N. 1985. Effects of removal of neighboring species on growth, nutrients, and microclimate of Eriophorum vaginatum. Arctic and Alpine Research 17:7-17. Fetcher, N., and G. R. Shaver. 1990. Environmental sensitivity of ecotypes as a potential influence on primary productivity. American Naturalist 136:126-131. Survival of tussocks from southern (EC, NN, CF) and northern populations (TL, SAG, PB) at five gardens in 2009. Prudhoe Bay garden was not censused in 2009. Survival of both northern and southern ecotypes was high at Eagle Creek and Toolik Lake. At No Name Creek and Coldfoot the southern ecotypes had greater survival, while at Sagwon the northern ecotypes had greater survival. Caitlin Peterson (Stetson University) at the Eagle Creek garden. Methods Tussock Survival Tiller Size