Reimagining the American West to Reach Half-Earth

National parks in the United States require improved connectivity to maintain resilience in the midst of climate change. Additionally, biodiversity losses and encroaching human-modifications are widely documented inside parks and outside their greater ecosystems. Conservationists have called for big, bold, and innovative strategies to complete and connect protected areas, which includes parks and wilderness areas. E.O. Wilson and others have stated that setting aside 17% of land units, which is suggested by the Aichi target 11 of the Convention on Biological Diversity, is not enough to halt species losses and that we must set aside half of the Earth as a protected area network. The protected area network must be permeable to allow for species movements; however, this is difficult amidst heavy human encroachment. Here, I combined two studies to provide insights into priorities for maintaining connectivity of national parks at the scale of greater park ecosystems across the contiguous United States (U.S.) and reimagined the protected area network in the American West to reach half-earth. In the first study, I used ArcGIS to develop a coarse-scale greater ecosystem model (GEM) to evaluate the permeability of national parks and their surrounding landscapes. Since much is unknown about species’ behavioral responses to human encroachment, the GEM model used one variable “wildness” and three potential species responses. Previous greater ecosystem models are species and habitat-suitability specific, and therefore, are difficult to compare across the continent. Since wildness has been evaluated on a national level, I concluded that the GEM model can be used across the continent to evaluate protected areas’ greater ecosystems. Secondly, the GEM model could aid the National Park Service’s Inventory and Monitoring program outside parks’ administrative boundaries. Thirdly, the GEM model can analyze ecosystem representation and the conservation status of a parks’ greater ecosystems. By ranking protected areas to determine conservation priorities and identifying the most intact wildlands, protected area expansions can be evaluated to complete a vital protected area network. In the second study, I used ArcGIS to model an innovative conservation strategy and evaluate if two scenic trails in the national park system could serve as green infrastructure for continental wildlife corridors over the next century. In cities, green infrastructure, such as parks and greenways, are employed as a climate mitigation and adaptation strategy. Therefore, on a continental scale I used Beier’s two-kilometer wildlife corridor method (2018) and buffered the Pacific Crest Trail (PCT) and the Continental Divide Trail (CDT) to analyze if a trail corridor held three vital conservation values for wildlife corridors: wildness, connectivity and diversity. To determine the feasibility of using my model in the field and to inform policy on if new land acquisitions or designations are needed, I also calculated the conservation status and land management that the trails traversed. The PCT and the CDT corridors were both found to be remarkably wild and connected when compared to other land units in the U.S. Eighty-six percent of the PCT and 87% of the CDT were in the top 50% of the most wild and connected landscapes. Secondly, many of the ecosystems along the proposed corridor are already represented in the American reserve. Thirdly, both the PCT (99.96%) and CDT (94.96%) follow the route of the best corridor values in the U.S. and match the forward centrality models for the next 100 years. Fourthly, the public already owns 90% of the land the corridors traverse and land units that are not permanently protected (12%) are managed by two primary agencies: The U.S. Forest Service (USFS) and the Bureau of Land Management (BLM). Therefore, it is recommended that these scenic trails become re-designated as “critical wildlife corridors” and act as an anchor for the protected area network. These two studies seek to provide a vision and road map to meeting Wilson’s half-earth in the American West where wildlands are well represented and 40% of land units are publicly owned. By anchoring our protected area network with the largest intact public wildlands in America and using existing green infrastructure (i.e. scenic trails) as continental wildlife corridors, we have the opportunity to meet a big bold conservation target of preserving 50% of landmass in the West by 2050.