Integrating wildlife habitat into a constrained optimization strategy on state-owned timberlands in North Carolina

Abstract

Integrating wildlife management goals into forest planning presents multiple complex challenges. Forest growth and yield models that use different metrics than the habitat suitability models wildlife managers use to estimate habitat quality for wildlife species. Moreover, integrating wildlife habitat requirements into forest management planning requires future forest conditions to be linked quantitatively to the habitat requirements of specific wildlife species. Further, for a methodology to gain widespread acceptance, the analytical platform it is constructed on must be readily available to forest planning practitioners. We used a modified Delphi method to qualitatively relate measured or predicted values within parameterized ranges of 11 vegetation structure and composition metrics (table 1) to the potential of a forest stand to provide habitat for 16 focal wildlife species (table 2). We chose predictive metrics from traditional timber inventory data (e.g., stand and stock data) and simulated outcomes across a 50-year horizon using the Forest Vegetation Simulator. We quantitatively related predicted conditions in a given forest stand to its potential to provide habitat for a combination of the selected focal species using an index derived from the metrics relevant to the focal wildlife species (tables 3, 4, 5, 6). We integrated the index values as accounting variables in a linear programming framework using the Woodstock Optimization Studio (the standard platform for planning analysis in the forest industry worldwide), which allows them to be tracked over the 50-year model horizon, constrained, or optimized directly as part of the model’s objective function. We applied the model to study area of 49,453 hectare across 2,836 timber stands on public lands managed by the North Carolina Wildlife Resource Commission and evaluated the trends in the harvest scheduling, habitat index values, and revenue under 13 formulations of the objective function maximizing habitat (MAX HABITAT) and revenue objectives (MAX CASHFLOW). By scheduling more thinning treatments, index values under the habitat formulation increased faster and higher than those realized under the maximized revenue formulation, which scheduled more final harvest treatments to maximize undiscounted cashflows across the modelled horizon. In the case study, production possibilities analysis indicated worthwhile gains could be achieved for revenue objectives with minimal impacts to wildlife habitat objectives (fig. 1).

Parent Publication

• Sixth Forest Vegetation Simulator Conference; 2023 March 7-9; Fort Collins, CO

Citation

Phillips, Casey E.; Roise, Joseph P.; Moorman, Christopher E.; Cook, Rachel L.; Parajuli, Rajan; Jordan, Christopher. 2024. Integrating wildlife habitat into a constrained optimization strategy on state-owned timberlands in North Carolina. In: Shaw, John D; Battaglia, Mike A.; Castle, Mark, [comps.]. Sixth Forest Vegetation Simulator Conference; 2023 March 7-9; Fort Collins, CO. Proceedings RMRS-P-81. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. p. 45-49.