A newly published study identifies where and when to protect forests with the goal of protecting the maximum number of additional plant species over a 50-year period. The greatest return on investment would come mostly from forest conservation within Melanesia (around New Guinea), South and Southeast Asia, the Anatolian peninsula (Turkey), northern South America and Central America. Many of the highest-conservation-priority areas fall within lower-income tropical countries, so substantial international funding is likely needed to conserve and restore forests. An estimated 80% of the planet’s biodiversity lies within Indigenous peoples’ territories, and securing Indigenous communities’ land rights can be an equitable, low-cost, and effective way to protect the environment.