Assessing the Efficacy of a Large-Scale Habitat Conservation Plan in Western Washington, USA

Habitat conservation plans (HCPs) under the US Endangered Species Act have become an important conservation tool. For over two decades, the Washington State Department of Natural Resources (WDNR) has managed much of the state's forested lands under one of the largest and longest-running single-entity HCPs in existence, seeking to integrate timber harvest and other social–ecological values mostly related to structurally complex, older forest habitats. Here, we examine trends in older forest conditions on western Washington WDNR-managed lands relative to HCP expectations, using publicly available spatial datasets to compare trends in older forest area and connectivity before (1986–1999) and after (1999–2017) HCP implementation. Trends in both attributes changed markedly between the pre- and post-implementation periods, varying strongly with management intensity. Since 1999, total older forest area (i.e., that meeting structural index/ indicator thresholds) saw little net change (-38 ha·yr-1, totaling -685 ha) across approximately 624,000 ha, but shifted spatially from WDNR's most intensively managed lands (-843 ha·yr-1) to conservation-designated lands such as riparian (+552 ha·yr-1) and mixed (with both harvest and habitat objectives) upland (+253 ha·yr-1) areas. Similarly, older forest connectivity declined on lands primarily managed for timber but increased on all other lands managed less intensively. So far, the decades since HCP implementation largely have been a time of landscape reorganization—positioning the landscape consistent with HCP intentions to meet timber objectives while developing older forest habitat in designated areas into the future. This work illustrates a method to evaluate policy implementation and the likelihood of achieving HCP expectations over time. Key Points We examined outcomes to date of one of the largest, longest-running forest Habitat Conservation Plans (HCP) in existence (western Washington State-managed forestlands). Under the plan, overall older forest area has changed little but its abundance and connectivity have increased where intended (conservation-oriented areas). The first approximately two decades of HCP implementation have been a time of reorganization, repositioning the landscape toward long-term objectives.