Broad-scale connectivity in the American Great Plains

How connected are the American Great Plains?  Although the region conjures up images of vast stretches of uninterrupted grasslands, the reality is that agriculture and urban development have chopped up the landscape so that it no longer maintains high connectivity.  In a recent study, Cushman and colleagues have set out to tackle this question, focusing on three species of conservation concern that inhabit the region: swift fox (Vulpes velox), lesser-prairie chicken (Tympanuchus pallidicinctus), and massasauga rattlesnake (Sistrurus catenatus).  The focus of the study was less on defining small, well-defined linear pathways, but rather looking at broad-scale landscape patterns and describing the landscape surrounding an individual as a gradient of quality habitat.  Using resistant kernel and least-cost path approaches, their aim was to determine the extent of connectivity, identify key connectivity hotspots, and examine how well protecting connectivity for one species could protect another.  By focusing on the Great Plains Landscape Conservation Cooperative (GPLCC) region, they were able to conduct one of the largest scale connectivity modeling efforts to date.

One key finding was that a species’ dispersal ability plays a larger role than its landscape resistance in determining connectivity.   While this implies that species with large dispersal abilities, such as lesser-prairie chickens and swift fox, may fare better than those with low dispersal abilities, such as massasauga rattlesnakes, large gaps between core habitats may still be problematic if strong linkages aren’t planned for and maintained.  In addition, there was little overlap between different species’ connectivity, with less than 10% of connected habitat useful for all three species studied.  With so little overlapping connectivity, it may be difficult to use “umbrella” species, and adaptive management plans may need to consider individual species more specifically in terms of dispersal and distribution.  Despite the uncertainties still inherent in most connectivity modeling, these results show a useful example of how broad-scale, spatially explicit modeling can inform conservation strategies over a large region such as the Great Plains.