Climate change in the Pacific Northwest is expected to increasingly favor the spread of invasive annual grasses, alter water availability and increase fire return intervals, leaving many native plant species with diminished and degraded habitat ranges. Motorized recreation is increasingly popular in the region and can amplify these threats by proliferating off-road trails, aiding the dispersal of invasive plants and increasing human-caused fire ignition risk in remote areas. Developing management strategies to minimize recreation impacts requires data about where they occur and how they are spreading. This data is often lacking and can be difficult and expensive to collect, especially at large spatial scales.
The purpose of this project is to provide baseline data about the locations and extent of motorized trails in southwestern Idaho and to quantify their proliferation over recent decades. This will be done by digitizing trails in high-resolution satellite imagery, and ground truthing to confirm findings. Digitizing efforts will focus on the Owyhee Front, a popular area with many trails, around long-term monitoring sites for Mulford’s Milkvetch (Astragalus mulfordiae), a rare and threatened plant endemic to southwestern Idaho and eastern Oregon that is a conservation priority for local land management. Mulford’s milkvetch grows on sandy desert slopes that are popular for motorized recreation, putting its habitat at heightened risk. The data from this project will be used to create maps identifying motorized trail hotspots for targeting trail management efforts and communication materials for land managers and the public about the local proliferation and impacts of motorized trails. Future directions for this work include a cumulative impacts assessment to investigate the interacting effects of land use, invasive plants and climate change on the decline of Mulford’s Milkvetch in the Owyhee Front.