To mitigate worsening fire severity in the western United States, forest managers are increasingly thinning tree stands to reduce available fuels. These treatments have the potential to disrupt the movements and habitat of Pacific marten (Martes caurina), who prefer multistory, dense conifer vegetation. We analyzed the movements from 32 GPS-collared martens within Lassen National Forest, between 2010 and 2019, to provide actionable recommendations to managers looking to lessen the impacts of forest-thinning treatments on martens. We categorized each stand in the study area by structural complexity: complex (i.e., dense), simple managed (i.e., thinned dense stands), simple (i.e., thinned or naturally sparse), and open (i.e., little or no cover canopy). We found that martens selected territories comprising a few large complex and simple managed stands and many small simple and open stands. Within their territories, they preferred large complex and simple managed stands; however, preference between the four stand types was indiscernible at smaller patch sizes. This indicates that complex and simple managed patches of these smaller areas could be good targets for fuel-thinning treatments. With additional analyses, we offer forest managers guidelines for area, shape, and location of thinned stands that minimize disruption of marten habitat.

Smith Freeman is a PhD student in the Conservation Sciences program at the University of Minnesota. Her research focuses on the movement ecology of gray wolves in northern Minnesota and Pacific marten in northern California and Oregon. Additionally, Smith contributes to the development of the animal tracking analysis platform, MoveApps and created the R package mixedSSA to make fitting integrated step-selection analyses easier. She is co-advised by Dr. John Fieberg and Dr. Joseph Bump.