Distribution and protection of climatic refugia in North America

Abstract

As evidenced by past climatic refugia, locations projected to harbor remnants of present-day climates may serve as critical refugia for current biodiversity in the face of modern climate change. We mapped potential climatic refugia in the future across North America, defined as locations with increasingly rare climatic conditions. We identified these locations by tracking projected changes in the size and distribution of climate analogs over time. We used biologically derived thresholds to define analogs and tested the impacts of dispersal limitation with 4 distances to limit analog searches. We identified at most 12% of North America as potential climatic refugia. Refugia extent varied depending on the analog threshold, dispersal distance, and climate projection. However, in all cases refugia were concentrated at high elevations and in topographically complex regions. Refugia identified using different climate projections were largely nested, suggesting that identified refugia were relatively robust to climate-projection selection. Existing conservation areas cover approximately 10% of North America and yet protected up to 25% of identified refugia, indicating that protected areas disproportionately include refugia. Refugia located at lower latitudes (≤40°N) and slightly lower elevations (approximately 2500 m) were more likely to be unprotected. Based on our results, a 23% expansion of the protected-area network would be sufficient to protect the refugia present under all 3 climate projections we explored. We believe these refugia are high conservation priorities due to their potential to harbor rare species in the future. However, these locations are simultaneously highly vulnerable to climate change over the long term. These refugia contracted substantially between the 2050s and the 2080s, which supports the idea that the pace of climate change will strongly determine the availability and effectiveness of refugia for protecting today's biodiversity.

Climate change likely to reshape vegetation in North America's largest protected areas

“…Most PAs in North America, including the 22 we examined, are situated in mountainous highelevation terrain (Michalak, Lawler, Roberts, & Carroll, 2018) that currently supports extensive alpine communities. Most PAs in North America, including the 22 we examined, are situated in mountainous highelevation terrain (Michalak, Lawler, Roberts, & Carroll, 2018) that currently supports extensive alpine communities.…”

“…Projected changes vary geographically as expected, with an overall trend toward vegetation associated with warmer or drier climates (or both). Most PAs in North America, including the 22 we examined, are situated in mountainous highelevation terrain (Michalak, Lawler, Roberts, & Carroll, 2018) that currently supports extensive alpine communities. Where it currently exists, alpine cover may be replaced by coniferous forest, given suitable soil conditions, which is consistent with expected upward tree-line shifts in mountainous environments (Harsch, Hulme, McGlone, & Duncan, 2009).…”

“…Conversely, if a strong range expansion is indicated, managers could consider strategies to facilitate natural colonization of associated species (i.e., realign). Conservation strategies to facilitate the ability for species to persist, adapt, and migrate across this matrix, might include expanding the sizes of PAs, creating new areas that conserve critical refugia (Michalak et al, 2018), and connecting habitats along species' migratory routes (Carroll, Parks, Dobrowski, & Roberts, 2018). Whether species' ranges remain stable, contract, or expand, it is likely that PAs will remain important for conservation under a changing climate (Johnston et al, 2013).…”

“…All PAs, including the large and iconic PAs we studied, interact within a surrounding matrix of unprotected lands, where natural vegetation is increasingly becoming fragmented or reduced (Piekielek & Hansen, 2012). Conservation strategies to facilitate the ability for species to persist, adapt, and migrate across this matrix, might include expanding the sizes of PAs, creating new areas that conserve critical refugia (Michalak et al, 2018), and connecting habitats along species' migratory routes (Carroll, Parks, Dobrowski, & Roberts, 2018). Future work based on the climate analog model could inform such efforts by integrating more species specific information (e.g., dispersal distance), identifying areas important for species movement among PAs (sensu Littlefield, McRae, Michalak, Lawler, & Carroll, 2017) or critical refugia (sensu , and by including habitat fragmentation impacts (Batllori et al, 2017).…”

Network‐ and distance‐based methods in bioregionalization processes at regional scale: An application to the terrestrial mammals of Iran

“…As such, identification of climate regions, i.e. areas with geographically distinct climatic patterns, can help defining priority areas for protection of climatic refugia or evolutionary processes (Brito et al, 2016;Michalak, Lawler, Roberts, & Carroll, 2018). Bioregions and climate regions can serve as conservation units and provide a framework for regional biodiversity conservation planning.…”