Integrating harvest scheduling and reserve design to improve biodiversity conservation

Abstract

Reserve establishment and strategic harvest planning are two longstanding but often separate approaches to conserving biodiversity in working landscapes. Our paper unites these fields and explores how ecological characteristics of landscapes influence conservation outcomes, with a particular consideration of tropical forests. We used an integer programming model to compare the performance of different management designs on simulated landscapes with different species diversity values and degrees of conspecific spatial aggregation. We explored three classes of reserve and harvest plans: optimal, random, and fixed-pattern (the last of which is most common in tropical forest management). Optimal designs (and performance criteria) were rooted in the Optimized Floating Refugia strategy, a new approach to landscape-level forest management that assumes local extinctions will occur and seeks to facilitate recolonization for as many species as possible via strategic spatiotemporal planning. We found several interesting interactions between harvest planning and reserve establishment. On landscapes with ecological characteristics resembling those of tropical forests (high species diversity and high conspecific aggregation), strategic harvest plans with no reserves saved more species than fixed-pattern, aggregated harvest plans with over 20 percent of stands set aside as reserves. Our findings also suggest an important rule of thumb: less aggregated harvest plans lead to fewer extinctions than more aggregated harvest plans. Overall, we found that the integration of harvest planning and reserve design led to novel insights, and that the divergence in absolute performance between different management regimes (but not the ordinal ranking) was highly dependent on the ecological characteristics of the landscape.