A novel approach to quantify and locate potential microrefugia using topoclimate, climate stability, and isolation from the matrix

Abstract

Ramp, D. (2012). A novel approach to quantify and locate potential microrefugia using topoclimate, climate stability, and isolation from the matrix. Global Change Biology, 18 (6), 1866-1879. A novel approach to quantify and locate potential microrefugia using topoclimate, climate stability, and isolation from the matrix AbstractEcologists are increasingly recognizing the conservation significance of microrefugia, but it is inherently difficult to locate these small patches with unusual climates, and hence they are also referred to as cryptic refugia. Here we introduce a new methodology to quantify and locate potential microrefugia using fine-scale topoclimatic grids that capture extreme conditions, stable climates, and distinct differences from the surrounding matrix. We collected hourly temperature data from 150 sites in a large (200 km by 300 km) and diverse region of New South Wales, Australia, for a total of 671 days over 2 years. Sites spanned a range of habitats including coastal dune shrublands, eucalypt forests, exposed woodland ridges, sheltered rainforest gullies, upland swamps, and lowland pastures. Climate grids were interpolated using a regional regression approach based on elevation, distance to coast, canopy cover, latitude, cold-air drainage, and topographical exposure to winds and radiation. We identified extreme temperatures on two separate climatic gradients: the 5th percentile of minimum temperatures and the 95th percentile of maximum temperatures. For each gradient, climatic stability was assessed on three different time scales (intra-seasonal, intra-annual and interannual). Differences from the matrix were assessed using a moving window with a 5 km radius. We averaged the Z-scores for these extreme, stable and isolated climates to identify potential locations of microrefugia. We found that our method successfully predicted the location of communities that were considered to occupy refugia, such as rainforests that have progressively contracted in distribution over the last 2.5 million years, and alpine grasslands that have contracted over the last 15 thousand years. However, the method was inherently sensitive to the gradient selected and other aspects of the modelling process. These uncertainties could be dealt with in a conservation planning context by repeating the methodology with various parameterizations and identifying areas that were consistently identified as microrefugia. Disciplines Medicine and Health Sciences | Social and Behavioral Sciences Publication DetailsAshcroft, M. B., Gollan, J. R., Warton, D. I. & Ramp, D. (2012). A novel approach to quantify and locate potential microrefugia using topoclimate, climate stability, and isolation from the matrix. Global Change Biology, 18 (6), 1866-1879. AbstractEcologists are increasingly recognising the conservation significance of microrefugia, but it is inherent difficult to locate these small patches with unusual climates, and hence they are also referred to as cryptic refugia. Here we introduce a new methodology to quantify an...

Microrefugia, Climate Change, and Conservation of Cedrus atlantica in the Rif Mountains, Morocco

“…To maximize the probability of long-term survival of Atlas cedar we suggest (1) that all the modern remaining microrefugia should be protected from human activities, and in particular to protect seedlings at the upper treeline limit; (2) the climate stability and suitability in all microrefugia should be evaluated (Hylander et al, 2015) through continuous climate monitoring, using climate data loggers (Ashcroft et al, 2012) and collecting climate time series from sites as close as possible to microrefugia; (3) perform an exhaustive DNA survey, using different genetic markers (Petit et al, 1998) for evaluating the genetic diversity, the risk of extinction, and to further prioritize populations for conservation, and (4) sites identified as potentially favorable microrefugia under conditions of 2,100, but presently unoccupied by Atlas cedar, should become recipients of seeds or seedlings. Ultimately, we should consider some artificial gene introgressions between the microrefugia so that we can improve heterozygosity and the capacity of that hybridized generation to adapt in situ (Wolf et al, 2001;Fady et al, 2003;Soliani et al, 2012).…”

“…Such climate scenarios are expected to have a major impact on Mediterranean biodiversity hotspots (Malcolm et al, 2006). One approach to evaluate the pertinence of the modern microrefugia for the conservation of Atlas cedars is to quantify the local topoclimate in each microrefugium, using data loggers, and compare them with the regional climate (Ashcroft et al, 2009(Ashcroft et al, , 2012. The spatial resolution of the climate data used in the present work does not allow us to evaluate the impact of a local climate on a specific microrefugium.…”

Beyond exposure, sensitivity and adaptive capacity: a response based ecological framework to assess species climate change vulnerability

“…Past work has described migration, tolerance, evolutionary adaptation, and extinction as the range of species responses to climate change [16,26]. We expand on these species responses by considering an increasingly clear and distinct microrefugia response [27][28][29], and by dropping extinction as a response, as it is effectively the consequence of a lack of response. In this ecologicallybased formulation, species vulnerability is the degree to which a species is unable to exhibit any of the four responses necessary for persistence: 1) the migration response, in which a species follows (in a biogeographical sense) its moving climatic limits through dispersal and establishment in new areas where its niche becomes available [30][31][32]; 2) the microrefugia response, when the niche of a species persists in locations that retain suitable climate characteristics [27,[33][34][35] within a greater area that becomes unsuitable at the macro-climatic scale; 3) the toleration response, a situation when climate shifts fit within a species niche breadth [36][37][38][39]; 4) and the evolutionary adaptation response, when a species alters its niche to withstand changes in climate through natural selection [40,41].…”

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

“…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.…”