title: Integrating physiological threshold experiments with climate modeling to project mangrove species' range expansion.
abstract: Predictions of climate-related shifts in species ranges have largely been based on correlative models. Due to limitations of these 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 the frequency of freezes. When included in distribution models, FDD accurately predicted mangrove presence/absence. Using 28 years of satellite imagery, we linked FDD to observed changes in mangrove abundance in Florida, further exemplifying the importance of extreme cold. We then used downscaled climate projections of FDD to project that these range limits will move northward by 2.2-3.2 km yr(-1) over the next 50 years.
authors.affiliation: Department of Geography, University of California, Los Angeles, 1255 Bunche Hall, Box 951524, Los Angeles, CA, 90095, USA; Smithsonian Environmental Research Center, Smithsonian Institution, Edgewater, MD, 21037, USA; Department of Ecology and Evolutionary Biology, Brown University, Providence, RI, 02912, USA.
authors.forename: Kyle C
authors.initials: KC
authors.lastname: Cavanaugh
authors.forename: John D
authors.initials: JD
authors.lastname: Parker
authors.forename: Susan C
authors.initials: SC
authors.lastname: Cook-Patton
authors.forename: Ilka C
authors.initials: IC
authors.lastname: Feller
authors.forename: A Park
authors.initials: AP
authors.lastname: Williams
authors.forename: James R
authors.initials: JR
authors.lastname: Kellner
mesh_terms: D000220:Adaptation, Biological / Q000502:physiology*; D032407:Avicennia / Q000502:physiology*; D057231:Climate Change; D029764:Combretaceae / Q000502:physiology*; D003710:Demography; D005431:Florida; D005615:Freezing; D005843:Geography; D008962:Models, Theoretical; D011157:Population Dynamics; D043982:Rhizophoraceae / Q000502:physiology*; D063809:Satellite Imagery; D013045:Species Specificity; D053833:Wetlands
keywords: Avicennia germinans; Laguncularia racemosa; Rhizophora mangle; climate change; ecological thresholds; freeze tolerance; range expansion; species distribution modeling