By Matt Miller, senior science writer
Imagine you’re on a long hike, and you are trying to get to a valley on the other side of a mountain. Do you take a gentle trail that leads you easily around it? Or do you hike straight up the mountain, braving waist-deep snow, frigid wind, slick rocks and risk of death?
It really isn’t much of a decision, is it?
Animals take similar routes when they migrate and roam. A mule deer or a lynx won’t waste calories or risk its life by taking a precarious route. To survive and thrive, they need relatively easy paths to move to feeding, breeding and resting areas.
Now animals face a new reason to move: climate change. As vegetation and climactic conditions change, many species will need to move to new ranges.
But how do they get to these new habitats? Will they find an easy route, or will they have to risk roads, inhospitable terrain, housing developments and other dangerous paths?
Questions like these are at the heart of what ecologists call connectivity: the degree to which a landscape allows wildlife to move from one place to the next. A well-connected landscape is one where animals can move easily. In a disconnected landscape, populations and habitats become isolated from each other.
A new paper published in Conservation Biology by Tristan Nuñez and colleagues from the Washington Wildlife Habitat Connectivity Working Group provides a simple and straightforward method for land managers to account for species shifting their ranges in response to climate change, and to protect and restore land accordingly.
To date, a lot of work on climate change connectivity has emphasized combining complex models, each containing lots of uncertainty: uncertainty about future CO2 emissions, uncertainty about how local climates will change, uncertainty about how vegetation and habitat will respond, and uncertainty about how species’ ranges will track those changes.
“This paper strips away a lot of that complexity,” says Brad McRae, Nature Conservancy ecologist and one of the coauthors of the paper. “Our premise is this: Areas that are cooler today will be relatively cooler tomorrow. Species will have to move to cooler areas. Conservationists will need to connect warm areas to cool areas while avoiding barriers like roads and housing developments.”
And not just connect them, but also do it along the gentlest climate gradient while avoiding barriers. In other words: Not sending animals over icy mountain peaks, through hot valleys, or through shopping malls.
If an agency was looking at where to restore or protect habitat, it could now focus on routes that allow wildlife to easily access higher-elevation habitats.
Over the past century, many wildlife species have already shifted range by moving upward in both elevation and latitude. This research allows land managers to plan for that.
The Nature Conservancy developed a tool, called Climate Linkage Mapper, which automates the entire process the researchers used, making it very easy for land managers to replicate.
“A lot of the literature calls for land managers to incorporate connectivity for climate change into their planning, but doesn’t suggest feasible ways to actually do this,” says McRae. “Managers can actually use this approach. We are now focused on getting this tool into their hands.”
The tool was developed in Washington state, where the Washington Wildlife Habitat Connectivity Working Group has been researching and developing tools that help land managers make the best decisions possible on connectivity.
Already those tools are being used by numerous federal and state agencies to connect forests, arid lands, and other habitats around the state.
“One of the ways animals will react to climate change is to adjust their ranges,” says McRae. “But what if they couldn’t get there? When our tools are applied, they will allow animals to move to new ranges and habitats.”
Nuñez, TA, Lawler, JJ, McRae, BH, Pierce, DJ, Krosby, MB, Kavanagh, DM, Singleton, PH and Tewksbury, JJ. (2013). Connectivity Planning to Address Climate Change. Conservation Biology. doi: 10.1111/cobi.12014
Opinions expressed on Cool Green Science and in any corresponding comments are the personal opinions of the original authors and do not necessarily reflect the views of The Nature Conservancy.