A new tool for identifying potential broadscale wildlife dispersal pathways amongst the most natural and connected lands in the western United States. Assuming that wildlife prefer dispersing and migrating through natural lands, not highly human modified lands, we asked: If we are to conserve the existing potential for wildlife movement amongst and between undisturbed lands at the national scale, what are the pathways along which that movement would best occur? In partnership with Dr. David Theobald at Colorado State University, we developed a method for answering this question, and the result is a map of what we call Wild LifeLines. Wild LifeLines depict potential dispersal pathways in the US that emphasize the least human modification and highest existing connectivity of natural condition lands. They help identify which places should be conserved as new cores and linkages to secure landscape capacity for broad-scale wildlife movement, and which modified lands should be prioritized for restoration. Wild Lifelines is a powerful new expression of places and pathways that are important for connectivity preservation projects with the goals of mitigating habitat fragmentation, providing for the dispersal of wide-ranging species, and facilitating adaptation to climate change.
Click here to download a White Paper explaining Wild LifeLines in greater detail, with more maps. We are currently preparing a technical paper about the methodology, for submission to a science journal. The following is a summary article written from the White Paper:
WILDLANDS NETWORK ANNOUNCES WILD LIFELINES
A new approach to conservation planning
As our nation and continent are rapidly modified in order to benefit the well-being of human interests in commerce, livestock production, farming, resource exploitation, real estate development, and border security, it is imperative that we quickly identify the most critical lands and the natural pathways between them to help ensure continued resilience of biodiversity. In response to this challenge, Wildlands Network, in conjunction with Dr. David Theobald, presents a new conservation map called Wild LifeLines ™. This innovative planning tool helps identify key areas where landscape fragmentation must be avoided because of these areas’ relative importance to national-scale landscape permeability for wildlife movement.
Over the years conservation biologists have refined various methodologies for identifying wildlife corridors. Typically, this involves picking a species of concern and choosing several “patches” of habitat. A computer model is then asked to figure out the best pathways to get from one patch to another, based on the particular needs and behavioral ecology of that species. The model also can be asked to identify those pathways that best avoid certain features such as roads, housing developments, and open fields, that might be dangerous for the animal to pass through. The result is a map of the “least cost,” or safest and most efficient, pathways for that animal.
This process has yielded vital information for land managers and conservation activists; however, it is slow, expensive, and requires gathering enormous amounts of information. Given that conservation is now challenged by the speed of “development” and climate disruption, an additional, larger scale approach is required to understanding what places we must protect so wildlife can move across the landscape. Inspired by Colorado State University researcher David Theobald’s recent work to develop a “naturalness metric” for the United States, Wildlands Network formulated an idea for just such an approach.
In essence, Dr. Theobald was putting together layers of information about the degree of modification of lands, traffic volume flows, housing densities, and other elements. Subsequent analysis led to the creation of a map of the U.S. that colored the country according to how much naturalness was left. The Wildlands Network science team saw naturalness as a proxy for what ecologists call “permeability,” or the degree to which the landscape still allows movement by wildlife. They then asked, “If we are to conserve the existing potential for wildlife movement across the landscape at the national scale, what are the pathways along which that movement would best occur according to Dr. Theobald’s map?
Assuming that wildlife movement will be least restricted across “natural” areas and most restricted across “human-modified” areas, Wildlands Network began working with Dr. Theobald to provide a broad scale look at landscape connectivity based on landscape naturalness, freed from the constraints of a focus on any particular individual species or habitat type. What developed was a novel modeling approach best explained by analogy.
Imagine rain falling equally across the top of a mountain. It begins to run down-slope; as enough water gathers, a headwater stream forms, and begins to incise into the surface. Headwater streams merge to form second-order streams, and so on, until the flows converge to form a river, which is the accumulation of all flows. As water flows across the surface of the mountain it follows paths of least resistance. Imagine now that “resistance” is human modification of the land. If animals are “dropped" like rain equally across the nation and are then constrained to “flow” across the country from the Canadian to Mexican border avoiding human-modified areas, where would they go? Where would pathways converge?
The result is a map of what we call Wild LifeLines™. Similar to what could be envisioned as wildlife circulatory system or human bypass map, it is a pattern representing the most efficient “flow” patterns across the landscape if following lands of least modification, or highest degree of naturalness.
The thicker “arteries” represent convergences of flow paths, and represent the highest amount of existing connectivity. A cell’s naturalness value and its position relative to national-scale naturalness values determine the relative importance of a location. Thinner secondary and tertiary lines represent the best ways for wildlife to get to primary arteries.
Our analysis is not influenced by the protected status or ownership of lands. Although protected areas are important elements of conservation reserve systems, they are not sufficient due to their isolation, and their utility is uncertain in the face of climate disruption. There are many lands outside of protected areas, both private and public, which will become increasingly important elements in a national conservation system. The Wild LifeLines map helps identify them.
We expect that refinements will be made based on more detailed data for local areas, and will incorporate specific needs for well-known species through “focal species” and least-cost modeling efforts. Once we obtain comparable data for Canada and Mexico, we can further refine the specific location of pathways connecting beyond the U.S.
Wild LifeLines, a complementary tool to conservation network planning methodologies, helps large-landscape conservation initiatives identify which proposed new core and linkages should be prioritized if the goal is to contribute to protection of existing connectivity at broad scales. It also provides general guidance and priorities for locating potential highway crossing structure projects; assists land trusts in assessing which of their opportunities would best contribute to the larger context; and it can guide preferred locations for restoration projects. Lastly, and of urgency, Wild LifeLines indicates many of the most valuable pathways to conserve for climate change adaptation, given that wildlife will be forced to undertake large-scale range shifts over the next decades.
We’d like to thank the following for contributing to this project: Dr. Kevin Crooks, Dr. Sarah Reed, Conner Bailey, Kurt Menke, and the Spine of the Continent Steering Committee. For more information and maps, please visits our website.
|Wild LifeLines White Paper.pdf||13.89 MB|
"To my mind, these live oak-dotted hills fat with side-oats grama, these pine-clad mesas spangled with flowers, these lazy trout streams burbling along under great sycamores and cottonwoods, come near to being the cream of creation."