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Jennifer Liebig ACF Abstract FY12

"Finding Grouping Schemes to Better Predict Tundra Response to Warming"

International Polar Year (IPY) 2012: From Knowledge to Action

Arctic plant communities are changing in response to warming due to global climate change. Responses to warming are not homogeneous across species or functional groups. To predict how tundra vegetation will change as warming continues, we examined the response of plants to experimental warming at four sites established in the mid-1990s as part of the International Tundra Experiment (ITEX). The change in cover in response to warming was assessed individually for each species, and then these data were lumped into different grouping schemes based on traits that could potentially be used to predict response. The four ITEX sites are in northern Alaska, where there is a wet meadow site and a dry heath site in Barrow (71°172443N 156°452593W) and a wet meadow site and a dry heath site in and in Atqasuk (70°2840N 157°25253W). Each consists of 24 experimental plots warmed by passive open-topped warming chambers and 24 control plots. The cover of plant species was sampled using a point-frame method in 2007 and 2008. A two-way ANOVA was used to compare difference in cover among groups between the warmed and control plots. If the groups within a grouping scheme responded significantly differently to the warming treatment (i.e., there was an interaction between warming treatment and grouping scheme), then that grouping scheme was considered useful for predicting change in tundra communities. Of the grouping schemes used for this analysis, some were based on geographic distribution, such as distribution zones defined by Young 1971, some were based on phenology of the species, such date of flower opening as observed in these sites, and some were based on other morphological and life history traits, such as the wintering state of buds as defined by Sørensen 1971. The usefulness of an individual grouping scheme varied from site to site. Overall, the geographic grouping schemes were the best predictors of change in plant cover in response to warming and the phenological grouping schemes were the least successful. These grouping schemes are useful for increasing our understanding of how and why community composition is changing; however, a more complex grouping system that combines different traits is needed to more fully understand and better predict the response of Arctic plant species to warming.