Identifying refugia from climate change

Abstract

This article highlights how the loose definition of the term ‘refugia’ has led to discrepancies in methods used to assess the vulnerability of species to the current trend of rising global temperatures. The term ‘refugia’ is commonly used without distinguishing between macrorefugia and microrefugia, ex situ refugia and in situ refugia, glacial and interglacial refugia or refugia based on habitat stability and refugia based on climatic stability. It is not always clear which definition is being used, and this makes it difficult to assess the appropriateness of the methods employed. For example, it is crucial to develop accurate fine‐scale climate grids when identifying microrefugia, but coarse‐scale macroclimate might be adequate for determining macrorefugia. Similarly, identifying in situ refugia might be more appropriate for species with poor dispersal ability but this may overestimate the extinction risk for good dispersers. More care needs to be taken to properly define the context when referring to refugia from climate change so that the validity of methods and the conservation significance of refugia can be assessed.

Detecting microrefugia in semi-arid landscapes from remotely sensed vegetation dynamics

“…These included measures of topographic features, hydrologic features, and granite outcrops (Table 1). Topographic variation is often considered to produce favorable microclimates that support microrefugia (Ashcroft, 2010;Dobrowski, 2011) and several topographic variables were developed (Table 1). In arid areas, water availability is expected to drive the distribution of microrefugia.…”

“…There exists much uncertainty over how to identify refugia within landscapes to target management spatially (Ashcroft, 2010). Putative refugia (micro-and macrorefugia) are typically located using simple heuristics, most commonly that areas with high topographic heterogeneity are likely to function as refugia (Ashcroft, 2010;Carroll et al, 2017;Dobrowski, 2011).…”

“…There is growing interest in developing fine-scale grids of micro-or topo-climate, often with ~30 m pixels, via downscaling techniques Dingman et al, 2013;McCullough et al, 2016) or interpolation from dense sensor arrays (Ashcroft, 2010;Frey et al, 2016) to identify microrefugia. An important source of uncertainty is that different measures and different methodological choices identify different sites as candidate refugia (Ashcroft, 2010;Ashcroft et al, 2012;Carroll et al, 2015Carroll et al, , 2017.…”

Ecosystem greenspots pass the first test

“…There is ongoing debate about terminology (Rull 2009;Stewart et al 2010;Keppel et al 2011), with differences primarily based on spatial and temporal scale. Irrespective of the terminology used, refugia are necessarily specific to the type of disturbance (Berryman and Hawkins 2006) and the species of interest (Ashcroft 2010). The actual area required for populations to persist in situ will vary with the intensity and duration of the disturbance, and the life history attributes of the species.…”

“…Recent research has focussed on identifying topographically driven micro-climates as potential climate change refuges (Ashcroft et al 2009(Ashcroft et al , 2012Ashcroft 2010;Dobrowski 2011). Landscape genetics and phylogeographic analyses are also being used to identify the locations of historical refugia (Hugall et al 2002;Carnaval et al 2009;Scoble and Lowe 2010).…”