The cascading effects of biodiversity decline on human well-being present a pressing challenge for sustainable development. Conservation efforts often prioritize safeguarding specific species, habitats, or intact ecosystems but overlook biodiversity’s fundamental role in providing Nature’s Contributions to People (NCP) in human-modified landscapes. Here, we systematically review 154 peer-reviewed studies to estimate the minimum levels of (semi-)natural habitat quantity, quality, and spatial configuration needed in human-modified landscapes to secure functional integrity essential for sustaining NCP provision. We find that the provision of multiple NCP is threatened when (semi-)natural habitat in the landscape falls below an area of 20%–25% for each km2. Five NCP almost completely disappear below a level of 10% habitat. The exact quantity, quality, and spatial configuration of habitat required depends on local context and specific NCP. Today, about two-thirds of human-modified lands have insufficient (semi-)natural habitat, requiring action for NCP regeneration. Our findings serve as a generic guideline to target conservation actions outside natural areas.
Biodiversity is rapidly declining, affecting benefits critical to human well-being, including food production, water quality, climate regulation, and recreation spaces. This decline is particularly challenging in urban and agricultural areas significantly modified by humans but where reliance on biodiversity’s benefits is nevertheless high. We assess the minimum level of (semi-)natural habitat needed in human-modified landscapes to support the supply of these benefits. We find that biodiversity’s capacity to pollinate crops, regulate pests and diseases, maintain clear water, and limit soil erosion significantly declines when habitat area falls below 20%–25% per km2. This same limit applies in urban areas to maintain recreation spaces for people. We find that approximately two-thirds of agricultural and urban areas globally fall below this level. This broad target can be used in urban and agricultural areas to manage and regenerate ecosystem functions to enhance human well-being.