Managing for adaptive capacity: thinning improves food availability for wildlife and insect pollinators under climate change conditions

A trait-based approach was developed to assess impacts of management practices on the adaptive capacity of ecosystems using impacts of overstory density and thinning on understory vegetation components related to wildlife habitat. The relationship between overstory basal area and understory vegetation for species grouped by traits that reflect food availability for wildlife (i.e., the production of flowers, fleshy fruit, and palatable leaves) was characterized in thinned and unthinned stands at seven Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) forests in western Oregon 6 years following thinning. Lower overstory densities and thinnings were associated with a higher likelihood of selected ecosystem functions, specifically the provision of food for wildlife, as evident by higher cover of flowering, fleshy fruit and palatable leaf producing species. Within these functional groups, thinning increased cover of drought-, fire-, and heat-tolerant species, which suggests that these ecosystem functions are more likely to be maintained under climate change conditions. The responses of species groups appear to be driven by the sensitivity of species to resource availability and to physical disturbances associated with thinnings.