Integrating physiological threshold experiments with climate modeling to project mangrove range limits

Friday, 19 December 2014
Kyle C Cavanaugh1,2, James Kellner3, Susan Cook-Patton2, Park Williams4, Candy Feller2 and John Parker2, (1)University of California Los Angeles, Geography, Los Angeles, CA, United States, (2)Smithsonian Environmental Research Center Edgewater, Edgewater, MD, United States, (3)Brown University, Ecology and Evolutionary Biology, Providence, RI, United States, (4)Lamont -Doherty Earth Observatory, Palisades, NY, United States
Due to limitations of purely correlative species distribution models, there is a need for more integration of experimental approaches when studying impacts of climate change on species distributions. Here we used controlled experiments to identify physiological thresholds that control poleward range limits of three species of mangroves found in North America. We found that all three species exhibited a threshold response to extreme cold, but freeze tolerance thresholds varied among species. From these experiments we developed a climate metric, freeze degree days (FDD), which incorporates both the intensity and frequency of freezes. When included in distribution models, FDD was a better predictor of mangrove presence/absence than other temperature-based metrics. Using 27 years of satellite imagery, we linked FDD to past changes in mangrove abundance in Florida, further supporting the relevance of FDD. We then used downscaled climate projections of FDD to project poleward migration of these range limits over the next 50 years.