Pinyon-juniper removal has long-term effects on mammals

Removing tree cover is a common forest management practice, and pinyon-juniper woodlands in the western United States have been the focus of tree reduction efforts for decades. The scale and intensity of tree removal practices are expected to increase as technology advances and as land managers are tasked with meeting multiple objectives, including fire prevention and habitat enhancement for livestock and wildlife of conservation concern. However, the long-term consequences of pinyon-juniper removal on animal communities are virtually unknown. The objectives of this study were to assess whether mammal habitat use differs between reference pinyon-juniper woodlands and stands that were mechanically disturbed by chaining more than 40years ago, and to determine if these differences are associated with particular habitat characteristics. We used remotely triggered wildlife cameras to evaluate differences in mammal habitat use of historically chained sites (n=22) and reference sites (n=22) in northwestern Colorado. Our results demonstrate marked differences in habitat use between chained sites and reference woodlands for most detected mammal species. Bobcat, mountain lion, American black bear, golden-mantled ground squirrel, and rock squirrel all showed a negative response to historically chained sites, indicating long-term effects of tree removal on these species. In contrast, habitat use of chipmunk, mountain cottontail, and coyote did not differ between chained and reference sites. For most species, habitat use was influenced by specific vegetation characteristics, such as proportion of tree cover, which could be factored into management decisions. By understanding the long-term consequences of tree removal for diverse mammal species, we are better equipped to adapt forest management practices to benefit species of both economic and conservation concern.