Variation in the costs and ecological benefits of tropical natural forest regeneration

Natural regeneration is a cost-effective alternative to tree planting for restoring degraded and converted tropical forests, contributing to climate mitigation and biodiversity recovery. However, global variation in its costs and benefits remains poorly quantified, limiting the ability of restoration programmes to strategically leverage its full potential. Here, we assess this variation by integrating data on costs and ecological benefits across the tropics, spanning 7.49 million km² of land with biophysical potential for natural forest regeneration. If completely regenerated, this additional forested area could accumulate approximately 9.57 Gt C over 30 years and reduce the overall extinction risk of forest-dependent species by about 31% relative to baseline. We show that Indonesia, Madagascar, Philippines, México, and Malaysia have the largest areas with high carbon and biodiversity benefits at low costs, which we refer to as ‘holistic hotspots’ for natural regeneration. We find that cost-effective areas with high carbon or high biodiversity benefits alone show different spatial patterns from holistic hotspots. These tradeoffs in achieving both benefits reduce the area of holistic hotspots to 9.67% of the entire study region. The cost-benefit maps we provide can enable decision-makers to improve their spatial planning and investment to achieve their forest restoration goals.File descriptions: fig2_PNR_categories.tif — spatial distribution of cost–benefit categories for the potential of natural regeneration (main text Figure 2). sup_fig2_extinction_risk_forest_dependent.tif — reduction in extinction risk for forest-dependent species from natural regeneration. sup_fig3_extinction_risk_broader_species.tif — reduction in extinction risk for the broader set of species with forest in their area of habitat. sup_fig7_sensitivity_opp.tif — opportunity-cost sensitivity analysis. sup_fig8_sensitivity_natural_break.tif — sensitivity analysis using Jenks natural breaks as the classification method. sup_fig13_max_rate_annual_carbon.tif — cost–benefit categories using the maximum annual carbon accumulation rate. sup_fig15_threatened_species_categories.tif — cost–benefit categories using IUCN threatened-species richness. sup_fig16_country_level.tif — cost–benefit categories normalised at the country level. sup_fig19_broader_species_categories.tif — cost–benefit categories using the reduction in extinction risk of species whose area of habitat includes forest.