Combining conservation value with conservation filters to guide forest management for avian biodiversity

Abstract

Maintaining richness and diversity of bird species on forest landscapes has long been a major theme in sustainable forest management. However, effects of management decisions on species diversity are uncertain because of difficulties in accounting for all species simultaneously. Utilizing a diversity contribution approach, we applied an integrated coarse filter-mesofilter conservation strategy to inform avian biodiversity conservation in the western Upper Peninsula of Michigan, USA. Diversity contribution is a measure of relative contribution of a given area to regional species diversity based on species richness and distinctiveness, with region defined according to the study design. At the coarse filter level, we compared and ranked forest types by bird conservation value based on proportional representation of high-contribution sampling plots (sampling plots in the top 25% of diversity contribution) relative to proportional representation in the dataset. At the mesofilter level, we identified how plot-level compositional and structural attributes affected diversity contribution within forest types. We found that forest types less common in the dataset, such as cedar and upland conifer, had the highest bird conservation value, while the most common forest type (northern hardwoods) provided the greatest number of high-contribution plots. Stand-level attributes that increased structural complexity, such as higher densities of large trees, saplings, and snags, or lower basal area, tended to increase the likelihood of being a high-contribution plot within a given forest type. However, the importance and effect of different attributes varied among forest types. Our novel application of the conservation filter strategy provides a way to identify high priority forest types for avian conservation, and create stand-level prescriptions for increasing avian conservation value. Given data on forest inventory and bird community composition, managers can use this application as a planning tool in the face of uncertainty about how management decisions affect larger-scale avian biodiversity.