Quantifying conservation outcomes in Indigenous peoples’ lands across the tropics

Biodiversity loss and climate change represent some of the biggest challenges humanity currently faces, with habitat loss as the biggest proximate driver. Area-based conservation is a key conservation policy and recent international conservation targets aimed for at least 30% of terrestrial, inland water, and of coastal and marine areas to be effectively conserved and managed through protected areas and other effective area-based conservation measures, recognising Indigenous and traditional territories, by 2030. While the effectiveness of protected areas (PAs) in achieving conservation outcomes has received much research attention in recent years, there still remains a gap in a global-scale understanding for Indigenous lands (ILs). Focusing on tropical forests, as globally important biomes for biodiversity and climate change mitigation, this thesis quantifies three metrics of conservation outcomes on ILs, PAs, the spatial overlap of protected areas and Indigenous lands (PIAs), and non-protected areas across the tropical Americas, Africa, and Asia. In Chapter 2, I examined deforestation and forest degradation rates from 2011-2019 using propensity score matching and generalised linear mixed models. I found that deforestation was reduced by 16.8-25.9% and degradation reduced by 9.1-18.4% on ILs compared to non-protected areas across tropical regions, while differences compared to PAs varied between regions. In Chapter 3, I sought to investigate forest integrity using the Forest Landscape Integrity Index which incorporates observed pressures, inferred pressures, and lost connectivity, and long-term human land-use intensity using the Anthromes dataset. Across tropical regions, forest integrity was highest and land-use intensity the least in PIAs, but varied in ILs between regions compared to non-protected areas. In Chapter 4, I assessed 11,872 forest-dependent vertebrate species’ Area of Habitat and compared species richness, extinction vulnerability, and range-size rarity inside and outside Indigenous peoples’ lands. At least 76.8% of tropical amphibians, birds, mammals, and reptiles had range overlaps with ILs, with an average range overlap of ~25%. Most countries in the Americas had higher species richness in ILs than outside, whereas most countries in Asia had lower extinction vulnerability scores in ILs, and more countries in Africa and Asia had slightly higher range-size rarity in ILs. Taken together, the thesis reveals the contributions that Indigenous peoples’ lands make towards tropical conservation, in terms of reducing habitat loss, maintaining habitat quality, and providing vital habitat for forest-dependent vertebrate diversity. Supporting and including Indigenous peoples in conservation target-setting and planning is not only socially just, it is likely vital to the success of achieving the Kunming-Montreal targets.