Site: Coweeta LTER

Ecologists have long been interested in how patterns of species distribution and diversity shift with changing climates, a concern that has spiked as the reality of rapid global climate change becomes increasingly apparent. Knowing whether certain species are threatened by shifting climate patterns is important for planning management activities and predicting how ecosystem functions can change in the future.

Coweeta researchers in the southern Appalachians, a global hotspot of biodiversity for lungless Plethodontidae salamanders, are especially concerned about the fate of these small but important creatures that play critical roles in terrestrial and stream processes. Because Plethodontidae salamanders are lungless and breathe through their moist skin, they are especially sensitive to shifts in temperature and precipitation. In order to predict how salamander populations will be affected by climate change, researchers modeled the population distribution under several different climatic future scenarios. They found, even using the most conservative assumptions about climatic shifts, that suitable habitat would likely contract by at least 20% by 2020.

These results are significant for a number of reasons. Firstly, it explicitly demonstrates that the salamander population of southern Appalachia is in danger of significant reduction and possible extinction of some species, and that this will likely have a significant impact on stream and terrestrial ecosystem processes. Secondly, this study predicts measurable declines in species diversity and abundance as early as 2020, in contrast to the majority of modeling efforts that focus on projections further into the future (2050 and beyond). These predictions present a unique opportunity for Coweeta researchers to use model outputs as testable hypotheses about species responses to climatic shifts. Though the models are strong in their ability to predict salamanders’ reactions to climatic shifts alone, in reality the ability of salamanders to disperse and follow suitable climatic habitat will also hinge on relationships with other species that might also be affected by climatic changes, and on geographical barriers to dispersal such as urban development or the presence of warmer, drier valleys for those that live at higher elevations. The long term climate and salamander abundance data at the Coweeta LTER, combined with the opportunity to test model outputs many years into the future, makes this an incredibly opportunity to study long term biotic shifts in response to climate change.

Graph for
Effect of latitude and Maxent threshold on projected percent climatic habitat loss by 2020, 2050, and 2080 for 35 plethodontid species currently found in the southern Appalachian region of the Coweeta LTER. Presented are percent suitable climatic habitat losses relative to current climate distribution model for two Maxent thresholds (‘strict’ = solid points with a solid regression line and dark grey 95% confidence bands; ‘liberal’ = hollow points with a dashed regression line and light grey 95% confidence bands). Darkest shading indicates regions of overlap between ‘strict’ and ‘liberal’ confidence bands
Milanovich 2010