Natural and cultural areas that will remain similar to what they are today -- despite climate change -- need to be identified, managed and conserved as "refugia" for at-risk species, according to a study published today in PLOS ONE.
The study, authored by a large, collaborative group of resource managers and researchers including USGS and Department of the Interior Climate Science Center scientists, sets out, for the first time, specific steps to help identify and manage these more resilient and climate-stable havens for plants, animals and fishes.
"These are places that will be protected from climate change, at least relative to the land around them," said lead study author Toni Lyn Morelli, a USGS research ecologist with the Northeast Climate Science Center. "Management actions can then reduce other stressors, like disturbance or invasive species, so these areas can act as short-term sanctuaries for species of conservation concern and other important natural and cultural resources."
The authors distinguish refugia from smaller, more transient places that offer plants and animals protection from exposure and disturbance. By contrast, the refugia concept was historically used to describe areas where plants and animals were geographically isolated, such as in the ice ages, when such isolation saved them from extinction, Morelli pointed out.
"Natural resource managers are trying to help species adapt to climate change, looking for places where they can make a difference," added Morelli. "Since they can't act on everything, everywhere, we can use the refugia concept to highlight more climate-resistant areas that could help populations remain in place despite warming and changing precipitation."
The authors detailed steps, challenges and opportunities for managing refugia. For example, it is hard to imagine protecting climate change refugia for wolverines, with single individuals ranging over hundreds of kilometers. However, wolverines might benefit from a focus on snow refugia because they require minimum levels of snowpack for den sites that could potentially be managed. ?
Another example they cited is freshwater refugia for cold-water-dependent species such as salmon. Cold groundwater that flows into streams and rivers via deep aquifers buffered from regional air temperatures can support cold, sustained streamflows in regions where water temperatures might become too warm or stream flows too low otherwise.
The authors wrote that "such large, cold, connected river networks are recognized as regional strongholds for imperiled fish populations facing increasing pressures from climate warming and other stressors."
Morelli and colleagues point out that unlike historical climate fluctuations, current global greenhouse gas levels are likely to exceed any seen in the past, so climate change refugia identified today will probably not offer long-term solutions for stressed species. But when coupled with management strategies, they could serve as reservoirs of genetic material, for example.
"There is a great need for such a strategy," the authors wrote. "Over 80 percent of U.S. national parks are already at the extreme warm end of their historical temperature distributions, indicating that ongoing and future changes in the same direction will transcend temperatures that they experienced over the last century," they added.
Ultimately, said Morelli, a mix of strategies, including conducting management actions across areas with a range of climate vulnerabilities, might be the most effective way forward.
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