Enhancing avian production on Department of Defense managed forest lands with appropriate management
U.S. Department of Defense installations in the mid-Atlantic region provide habitat for a number of bird species that are of conservation concern. Management of these habitats for the benefit of bird species is one objective among many within the greater military mission. Approximately 65 % of the DoD land in this region supports upland forest including pine plantations. These forests are managed for training activities, buffers between training areas and public lands, and economical benefits of timber harvest. Pine plantations cover 9,330 ha (23,045 acres) of DoD installations in the mid-Atlantic and account for nearly 10% of all forested upland areas. Although specific silvicultural techniques vary with factors such as forest yield (e.g., pulpwood, fiber, or saw-timber), planting trees at high densities and clear-cutting stands on relatively short rotation schedules (20-25 yrs) is a common practice in the region. Pine plantation management creates a specific age class distribution that differs in scale and frequency from disturbances in natural landscape, truncates succession and prevents development of some characteristics associated with old-growth forests, and prevents development of understory and mid-story vegetation that is common in mid successional forests. The influence of stand age and management of pine plantations was investigated to provide habitat recommendations to increase the capacity of DoD installation to support bird populations. Stand age had a significant influence on species richness and total bird density. Total bird density generally declined as stands aged and formed a closed canopy. Thinning of pine plantations resulted in positive density responses for many species. Thinning reduces the number of pine trees, opens the canopy, and allows regrowth of understory vegetation. As a result, thinning extends the use of pine plantations of early successional species that depend on shrubby habitat and promoted use of stands by forest species as well. Implementing thinning as a management tool for pine plantations can increase the capacity of DoD installations in the mid-Atlantic to support bird populations by 20 %. Thinning allows a greater number of species use a greater length of time across the entire rotation cycle (i.e., from planting until final harvest). Over 5 rotations, thinning pine plantations can support 1,900,000 more pairs of birds compared to management regimes that do not include thinning.