Improving Refugia Identification by Combining Landscape and Species-Based Approaches

A burrowing owl keeps an alert eye on anything that moves around its burrow.
Source: Unsplash, Public Domain

Identifying and protecting climate change refugia — areas relatively buffered from climate change that can help species persist in a warming climate — is increasingly important for conservation planning. Until recently, the approaches used to identify refugia at broad scales mainly focused on landscape features and climate conditions. However, new research shows that including approaches that look at species-specific tolerances for climatic change can provide unique information that other methods miss, highlighting the importance of asking “refugia for what?” when prioritizing refugia. Using complementary ways to map climate change refugia provides a more complete understanding of regional refugia, inviting more tailored management actions to protect these habitats for biodiversity in a changing climate.

The ability of an area to serve as a climate change refugium for biodiversity depends on the following factors: the physical landscape, the amount of climate change experienced and the range of climate conditions that species can tolerate. There are several approaches used to understand an area’s refugium potential, each of which is based on one or more of these factors. Environmental diversity approaches look at the range of climate, soil and landscape features that provide variable climate conditions and can serve as small-scale refugia (i.e., deep valleys, steep slopes), while climatic exposure approaches look at areas where projected climatic changes are relatively small. Climate tracking approaches, which can be species-neutral (relying on information about climate and landscape variation) or species-based (relying on species-specific needs), look at the distance and connectivity between areas that are currently suitable for species and new locations that will be suitable in the future. 

To better understand the spatial similarities and differences between refugia identified with these approaches, Northwest Climate Adaptation Science Center-funded researchers Julia Michalak (University of Washington) and colleagues used existing refugia data from across North America to compile overlapping refugia maps, allowing regional patterns of refugia to emerge. They were then able to look at the landscape characteristics within these patterns to understand what factors are driving similarities and differences in areas where refugia were identified. They found that although only 7% of the study area was classified as potential refugia using all three approaches, 86% of the study area was classified as refugia using at least one of the three approaches. This discrepancy shows that certain approaches for identifying refugia are more relevant in particular regions. 

The findings also show that species-based approaches add another layer of information that is important to identifying refugia, since they account for the conditions that a species can tolerate, which the other measures may under- or overestimate. When divided by habitat group, species-based approaches identified the greatest diversity of regions. For example, considering refugia for grassland birds, a very vulnerable species group, identifies areas omitted by other approaches. These results further emphasize that using multiple, complementary refugia mapping approaches offers a more complete picture of the refugia potential of an area. 

Until now, the approaches used to identify refugia mainly focused on landscape and climate conditions. New research emphasizes the importance of focusing refugia management on specific conservation targets and incorporating species-specific approaches, to provide more nuance that can improve conservation planning in a changing climate.

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