Patchy range retractions in response to climate change and implications for terrestrial species conservation

Abstract

Context Efforts to adapt conservation to climate change often focus on facilitating range shifts to higher latitudes, by enhancing landscape capacity for poleward expansion. The need to protect populations at trailing edges of species distributions, and how and where to do so, has received less attention. Objectives We assess how population declines caused by variation over space and time in exposure to climate change can necessitate conservation adaptation to climate change throughout species’ geographic ranges. We propose approaches for conservation in landscapes where species are vulnerable. Methods We synthesize primary literature relating to recent landscape-scale changes to species distributions to identify evidence for patchy patterns of climate-driven decline. We use this evidence to propose a framework to adapt terrestrial species conservation. Results Patchy retractions occur throughout species ranges as environmental heterogeneity results in spatial variation in climate and rates of climate change, whereas equatorward range margins are often not the first place to exceed climatic limits. Furthermore, climate effects on fitness, survival and reproduction interact with habitat quality, creating both localized extinction hotspots and climatically resilient microrefugial landscapes across species ranges. Conservation can benefit from the identification of vulnerable versus microrefugial landscapes, and implementation of targeted interventions. Conclusions A focus on expansions and retractions at broad latitudinal range margins risks overlooking declines throughout species’ distributions. Understanding fine-resolution ecological responses to the climate can help to identify resilient microrefugial landscapes, and targeted management to promote cooler or more stable conditions can complement facilitation of broader-scale range shifts.