Leveraging historical spy satellite photographs and recent remote sensing data to identify high conservation value forests

High conservation value forests (HCVF) are critically important for biodiversity and ecosystem service provisioning, but face manifold threats. Where systematic HCVF inventories are missing, such as in parts of Eastern Europe, these forests remain largely unacknowledged and therefore often unprotected. Here, we propose a novel, transferable approach for detecting HCVF, based on integrating historical spy satellite images, contemporary remote sensing data and information on current anthropogenic pressures. Using Romania as a pilot-study, we mapped forest continuity (1955-2019), canopy structural complexity, and anthropogenic pressures, and identified a large area (738,000 ha) of HCVF. More than half of this area is susceptible to current anthropogenic pressures and lacks formal protection. By providing a framework for broad-scale HCVF monitoring, our approach facilitates integration of HCVF into forest conservation and management. This is urgently needed to achieve the goals of the European Union's Biodiversity Strategy to maintain valuable forest ecosystems. This article is protected by copyright. All rights reserved.