Associate Professor University of Minnesota St. Paul, Minnesota, United States
Abstract: Background/Questions/Methods (199/200 words) Future climate change (increased warming and drought) could alter prairie dominance and diversity. Plant species differ greatly in their ability to tolerate climate extremes, and species that are particularly sensitive to warming and drought may be lost. Tallgrass prairies are historically biodiverse and many, including those we study here, are dominated by Andropogon gerardii, a highly productive warm-season (heat-tolerant) grass which may be relatively insensitive to drought. However, the separate and combined effects of warming and drought on both dominant species and plant diversity have rarely been studied experimentally. We addressed the following questions: (1) will A. gerardii remain dominant when drought is combined with warming? (2) will warming, drought, or their combined effects cause species loss in these same plant communities? We sought to answer these questions using a long-term field experiment at Cedar Creek Ecosystem Science Reserve where warming, drought, and warming+drought treatments were applied in subplots (n=128) of main plots (n=32) seeded at three levels of plant species richness (1, 4, & 16 species). Each year, we harvested, dried, and weighed biomass at the species level to assess treatment effects on plant communities. Here we present results from the fourth year of the experiment.
Results/Conclusions (147/200 words)
We found that under ambient conditions, A. gerardii consistently exhibited the most biomass of any species (mean: 140.63 g/m2). A. gerardii also remained dominant compared to other species (p < 0.005) and although its dominance was not significantly affected by other treatments, it did decrease slightly with drought (- 3%) and increased with both warming (+ 21%) and warming+drought (+ 40%). Additionally, warming alone led to a marginally significant reduction in species richness, measured by the effective number of species (p=0.071). Overall, our findings highlight the ability of a dominant species to withstand the predicted effects of climate change. We also find that warming may be a stronger driver of species loss compared to drought in this particular ecosystem. This research aids in our understanding of community structure responses to predicted climate change and can inform land management efforts in a warmer and drier future.
