A Decision Support Tool: Integrating Wildlife Occupancy Models with Stand Projections

Abstract

With the increase in consumptive trends of wood products there is greater push for ecosystem management. Ecosystem management is a process that aims to conserve major ecological services and restore natural resources while meeting the socioeconomic, political and cultural needs of current and future generations, and more efficient natural resource management. Forests provide natural resources for consumption; however, they also support wildlife and provide many other ecosystem services. Therefore, it is increasingly common that natural resource managers are asked to balance multiple objectives on a single property. The main objective of this study was to show how the theoretical outcomes from growth and yield models and wildlife occupancy models could be combined to give land managers an idea of what to expect before management is executed. A growth and yield model, the Forest Vegetation Simulator (FVS), is used for stand projection. The resulting stand structures are input into species-specific wildlife occupancy models to estimate probability of occurrence. A simplified example from the Barbour Wildlife Management Area in Alabama is used to illustrate this approach. Area managers wish to convert existing mixed loblolly pine-hardwood stands into an open-canopy, fire maintained, longleaf pine ecosystem. Though species specific occupancy models are used here for simplification, other species or objectives can be used for other properties. Three management scenarios were projected 100-years into the future: no treatment; immediate conversion through clearcutting, site preparation, and planting at three different densities; and long-term conversion through single-tree selection. Regression models were developed to predict reproductive and ground cover, variables not projected by FVS which are important parameters for occupancy of species. At five-year intervals, projected stand structure was input into occupancy models developed for four species of migratory songbirds; wood thrush, pine warbler, yellow-breasted chat, and prairie warbler. Stand structure varied through time for each of the scenarios, but there was little difference between reproductive cover and ground cover between scenarios. The pine warbler was predicted to occupy stands under both the no management and single-tree selection scenarios throughout the entire projection period. Under the even-aged management scenarios, the pine warbler has a probability of use between 80 and 100% throughout the projection cycle. The yellow-breasted chat’s probability of use varies between management scenarios. The wood thrush has less than a 30% probability of use under any management scenario. The prairie warbler has the highest probability of use in the even-aged scenarios over time, but will still use the other management scenarios between 20 to 30% of the time. While there seems to be little difference in the probability of use between management scenarios for each species, there is still predictive power for this decision support tool. Only three management alternatives were simulated in this example. There are an infinite number of other possible alternatives that were not reviewed here. By integrating these two models (stand projection and habitat occupancy) a unique tool is available for land managers to gauge the efficacy of their management plans while also developing a timeline of predicted forest structure that can be compared with future inventory for use in adaptive management.