Wildlife in Southeast will need help to survive global warming

Some species of turtles in North America will be hard-pressed to survive global warming. bberwyn photo.
Some species of turtles in the Southeast will be hard-pressed to survive global warming without help.  @bberwyn photo.

New study IDs climate connectivity corridors that can help plants and animals move

By Bob Berwyn

Natural habitat in the eastern half of the U.S. has been so fragmented by roads, farms and cities that many plants and animals won’t be able to survive global warming without a lot of help.

That means thinking about the concept of climate connectivity, according to a new study that aims to give policy makers tools to consider climate change for development and conservation planning.

The research, reported June 13 in the Proceedings of the National Academy of Sciences, shows how creating climate-specific movement corridors could give many species a better chance to survive the warming expected in the coming decades.

The research is important because scientists know that, in response to past climate change, plants and animals have moved on the landscape. But never before has the world’s climate shifted as fast as right now — which means many species won’t be able to move without help.

The study tries to address a complex, multi-layered challenge that includes current habitat fragmentation, at natural areas that ahven’t been impacted by humans, and how all that will change as global temperatures continue to warm.

“We need to consider what will be suitable habitat in the future,” said co-author Joshua Lawler, a University of Washington professor of environmental and forest sciences. That means trying to anticipate how warming will affect habitat that may be OK now, but won’t be suitable in 30 years.

The species most vulnerable to climate change are those that can’t move very far, have specific habitat needs, and don’t like crossing barriers like roads or fields. That includes amphibians with limited ranges, like frogs and salamanders endemic to the Southern Appalachians that are sensitive to changes in moisture and temperatures, Lawler said. Small mammals that can’t disperse very far, and plants that rely on animals to disperse seeds are also in that category, he said.

“It is well-known that many species require relatively intact areas of suitable habitat in order to carry out essential processes such as foraging, reproduction, dispersal and migration,” said Nate Nibbelink, director of the Center for Integrative Conservation Research at the University of Georgia. “As the climate changes, species will have to track changing temperature and moisture conditions in order to survive,” said Nibbelink, who was not directly involved in the study.

“An important contribution of this work is that it helps us (ecologists and managers) prioritize limited funding for research and habitat restoration efforts, by focusing on areas of the US where it will have the biggest impact on improving connectivity of habitat corridors for species,” he said. ”

“There’s a huge diversity of amphibian species with specific habitat needs, and climate change is going to push them from coastal regions up to mountain regions,” said co-author Jenny McGuire, a research scientist in the School of Biology at the Georgia Institute of Technology.

“They need to move inland. They truly need corridors to traverse agricultural fields … I think of it in part as facilitating the speed at which they can move across the landscape, and at high enough densities, to survive,” McGuire said. “If we really start to be strategic about planning to prevent biodiversity loss, we can help species adjust effectively to climate change.”

McGuire and her collaborators set out to determine the practicality of that kind of travel and test whether these human initiatives could improve migration to cooler areas. Using detailed maps of human impact created by David Theobald at Conservation Partners in Fort Collins, Colorado, they distinguished natural areas from areas disturbed by human activity across the United States. They then calculated the coolest temperatures that could be found by moving within neighboring natural areas.

“A lot of these land areas are very fragmented and broken up,” McGuire said. “We studied what could happen if we were to provide additional connectivity that would allow species to move across the landscape through climate corridors. We asked how far they could actually go and what would be the coolest temperatures they could find.”

The study goes beyond simply issuing warnings about impacts. Co-authors Tristan Nuñez from the University of California Berkeley, Lawler at the UW, Brad McRae from the Nature Conservancy created detailed maps showing the easiest pathways across climate gradients and human-disturbed regions to connect natural areas.

In future work, the researchers hope to examine individual species to determine which ones are most likely to struggle with the changing climate, and which areas of the country are likely to be most impacted by conflicts between humans and relocating animals.

“We see a lot of species’ distributions really start to wink out after about 50 years, but it is tricky to look at future predictions because we will have a lot of habitat loss predicted using our models,” McGuire said. “Change is perpetual, but we are going to have to scramble to prepare for this.”

The study also found that, in general, the western U.S. provides greater temperature ranges and fewer human interruptions than eastern landscapes, allowing plants and animals there to move toward more hospitable climates with fewer obstacles. Only 2 percent of the eastern U.S. provides the kind of climate connectivity required by species that will likely need to migrate, compared to 51 percent of the western United States.

Improving connectivity would require rehabilitating forests and planting natural habitats adjacent to interruptions such as large agricultural fields or other areas where natural foliage has been destroyed. It could also mean building natural overpasses that would allow animals to cross highways, helping them avoid collisions with vehicles.

Not only will animals have to move, but they’ll also need to track changes in the environment and food, such as specific prey for carnivores and the right plants for herbivores. Some birds and large animals may be able to make that adjustment, but many smaller creatures may struggle to track the food and climate they need.

“A lot of them are going to have a hard time,” said McGuire. “For plants and animals in the East, there is a higher potential for extinction due to an inability to adapt to climate change. We have a high diversity of amphibians and other species that are going to struggle.”

Some of the areas eyed in the study include the coastal plains from Louisiana through Virginia, which could be a bottleneck for species trying to move north away from rising temperatures and sea levels.

In future work, the researchers hope to examine individual species to determine which ones are most likely to struggle with the changing climate, and which areas of the country are likely to be most impacted by conflicts between humans and relocating animals.

“We see a lot of species’ distributions really start to wink out after about 50 years, but it is tricky to look at future predictions because we will have a lot of habitat loss predicted using our models,” McGuire said. “Change is perpetual, but we are going to have to scramble to prepare for this.”

On a hopeful not, life is more resilient than we think,” she said. Past interglacial cycles saw huge climate change that weren’t accompanied by mass extinctions, she said. “Life is resilient, but only if it’s allowed to be resilient, if  speices moving across the landscape can find little refugia,” she said.

The main message that comes out of the paper is that we’ve really fragmented the landscape, but that there is some hope that we can restore the connectivity,” Lawler said. “But even if we do add those corridors, the landscape is still going to highly fragmented. If we want those species to survive, we’re going to have to slow climate change as much as we can.”

The research was supported by the U.S. National Park Service and by the Packard Foundation.

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One thought on “Wildlife in Southeast will need help to survive global warming

  1. Only the very strongest invasive species will survive invading a previously occupied niche, and all during species aren’t going to move on at the same time and speed. Yes connectivity is very important, but species loss will be the tale of my grandchildren’s lifetimes. Perhaps artificial preservation will help, zoos and seed banks and the like, but crawling isn’t going to get any group to safety.it is too early to just “transplant” species, we humans haven’t faced up to it for our own survival, even.

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