Cumulative and component impacts of the human footprint on remotely sensed biodiversity indicators using dissimilarity to high integrity reference states

• Quantifies ecological dissimilarity using remote-sensing derived biodiversity indicators as a proxy for forest integrity. • Demonstrates that anthropogenic pressures significantly influence forest structural integrity, but not functional integrity. • Employs a robust matching technique to ensure comparisons are made against suitable high-integrity forest analogs. • Provides a scalable methodology for identifying high-integrity forest ecosystems for conservation and restoration. Forests with high ecological integrity are fundamental for biodiversity conservation and provide integral ecosystem services. These forests have natural or near-natural ecosystem structure, function, and composition. Anthropogenic pressures such as habitat loss, overexploitation of natural resources, and land use changes are leading to the degradation or loss of high-integrity forests. As a result, assessing forest integrity over large areas is increasingly important for a range of conservation initiatives. In this study, we used remote sensing-derived forest structural and functioning metrics alongside a high-quality reference state to calculate ecological dissimilarity as a proxy for ecological integrity. We examined stand-level integrity and focused on forest structural attributes such as canopy height, cover, complexity, and biomass, as well as the Dynamic Habitat Indices, which summarize annual energy availability relevant for biodiversity. We further refined our reference states by using coarsened exact matching to ensure our comparisons were drawn from suitable protected analogs. We applied these methods to Vancouver Island, Canada, where we assessed the distance, in structural and functional space, to matched high-integrity forests found in the island’s oldest and largest protected area. We also assessed how individual and cumulative anthropogenic pressure affect the ecological integrity of forests on the island. We found that mean forest structural dissimilarity increased from 0.79 to 1.61 under high levels of anthropogenic pressure (ANOVA; p < 0.001), while functional dissimilarity was not impacted by any anthropogenic pressure (ANOVA; p > 0.05). This indicates that anthropogenic pressures were observed to directly influence forest canopy characteristics, and less so energy availability. For individual pressures, we found that built environments, harvesting, and population density influenced structural dissimilarity (ANOVA; p < 0.05), while roads did not influence structural dissimilarity (ANOVA; p > 0.05). These methods for identifying high-integrity forests can be used to identify areas to be prioritized for protection or restoration, which in turn progresses towards the Kunming-Montreal Global Biodiversity Framework’s goal of 30 % of all ecosystems protected, while focusing on high-integrity ecosystems.