Validating Predictions from Climate Envelope Models

David N Bucklin,Frank J Mazzotti,James I Watling,Laura A Brandt,Carolina Speroterra,Raphaël Arlettaz,Stephanie S Romañach

doi:10.1371/journal.pone.0063600

Abstract

Climate envelope models are a potentially important conservation tool, but their ability to accurately forecast species’ distributional shifts using independent survey data has not been fully evaluated. We created climate envelope models for 12 species of North American breeding birds previously shown to have experienced poleward range shifts. For each species, we evaluated three different approaches to climate envelope modeling that differed in the way they treated climate-induced range expansion and contraction, using random forests and maximum entropy modeling algorithms. All models were calibrated using occurrence data from 1967–1971 (t1) and evaluated using occurrence data from 1998–2002 (t2). Model sensitivity (the ability to correctly classify species presences) was greater using the maximum entropy algorithm than the random forest algorithm. Although sensitivity did not differ significantly among approaches, for many species, sensitivity was maximized using a hybrid approach that assumed range expansion, but not contraction, in t2. Species for which the hybrid approach resulted in the greatest improvement in sensitivity have been reported from more land cover types than species for which there was little difference in sensitivity between hybrid and dynamic approaches, suggesting that habitat generalists may be buffered somewhat against climate-induced range contractions. Specificity (the ability to correctly classify species absences) was maximized using the random forest algorithm and was lowest using the hybrid approach. Overall, our results suggest cautious optimism for the use of climate envelope models to forecast range shifts, but also underscore the importance of considering non-climate drivers of species range limits. The use of alternative climate envelope models that make different assumptions about range expansion and contraction is a new and potentially useful way to help inform our understanding of climate change effects on species.

Highlights

IntroductionBecause the effects of increasing greenhouse gas are expected to exacerbate climate change over the course of the twenty-first century and beyond [1], models are an important tool for anticipating potential future effects of climate change and identifying proactive mitigation and adaptation strategies
Climate change is one of the major conservation issues of the twenty-first century
All 12 species have been suggested to have shifted their range in response to changing climate, static AUC values were higher than projected AUC values for at least one algorithm in nine out of 12 species (Table 1), suggesting that not all range shifts are consistent with a climate change model

Summary

Introduction

Because the effects of increasing greenhouse gas are expected to exacerbate climate change over the course of the twenty-first century and beyond [1], models are an important tool for anticipating potential future effects of climate change and identifying proactive mitigation and adaptation strategies. Climate envelope models (CEMs) establish species-climate relationships that can be extrapolated in space and time [2]. Because climate is one of the major filters determining broad patterns of species distribution [3], [4] and because models can be constructed using relatively simple statistical models and data inputs [2], CEMs have become a widely-used tool for forecasting climate change effects on species distributions [5], [6]. We use independent data on changes in the distribution of selected breeding birds in North America from 1967–71 to 1998–2002 to evaluate the ability of three alternative models, including one with no climate change, to correctly classify species and absence

Methods

Results

Conclusion