Improving forecasts of arctic-alpine refugia persistence with landscape-scale variables

Abstract

Refugia, sites preserving conditions reminiscent of suitable climates, are projected to be crucial for species in a changing climate, particularly at high latitudes. However, the knowledge of current locations of high-latitude refugia and particularly their ability to retain suitable conditions under future climatic changes is limited. Occurrences of refugia have previously been mainly assessed and modelled based solely on climatic features, with insufficient attention being paid to potentially important landscape-scale factors. Here, climate-only models and 'full' models incorporating topo-edaphic landscape-scale variables (radiation, soil moisture and calcareousness) were developed and compared for 111 arcticalpine plant species in Northern Fennoscandia. This was done for both current and future climates to determine cells with resilient climatic suitability harbouring refugia. Our results show that topographic and edaphic landscape-scale predictors both significantly improve models of arctic-alpine species distributions and alter projections of refugia occurrence. Predictions of species-climate models ignore landscape-scale ecological processes and may thus provide inaccurate estimates of extinction risk and forecasts of refugia where species can persist under a changing climate.

Rocky habitats as microclimatic refuges for biodiversity. A close-up thermal approach

“…The climatic niche or our two relict plants, for example, would have been impossible to model with standard climatic models because they do not account for microhabitat complexity and topography-driven patterns of temperatures and other important environmental attributes. Spatially fine resolution species distribution models yield more realistic scenarios (Randin et al, 2009), and a new generation of climatic models including topographic heterogeneity and other ecological variables are evidencing that fine-scale variation in temperatures is important in reducing species range retractions and extinction risks due to climatic change (Slavich et al, 2014, Maclean et al, 2015, Niskanen et al, 2017, Suggit et al, 2018. The survival of a very rare plant in the Alps, for example, could only be explained by the existence of topoclimatic microrefugia (Patsiou et al, 2014).…”

Drivers of high-latitude plant diversity hotspots and their congruence

“…czerepanovii) and alpine tundra above the tree-line in the north (Sormunen et al 2011, le Roux et al 2012. See Niskanen et al (2016aNiskanen et al ( , 2016b for further details on the study area.…”

Persistence of arctic-alpine flora during 24,000 years of environmental change in the Polar Urals

“…Arctic-alpine plants are considered to be at greater risk of habitat loss and local extinction under future climate change than plants of lower elevations 1–3 . Yet model simulations and predictions at larger scales often fail to account for the importance of local-scale factors that control plant distributions 4,5 , and it may be that extinction probabilities have been overestimated. Indeed, observed extinction rates on mountain tops have been low, despite climate warming over the past century 6,7 .…”

“…At the same time, compressed vertical and horizontal gradients enable species to track their bioclimatic niches effectively as climate changes 13,14 . Most evidence that mountain regions function as long-term refugia or safe sites is, however, indirect, being based on contemporary observation and/or modelling 3,5,15 .…”