How do trees outside forests contribute to human wellbeing? A systematic review from South Asia

Trees have emerged as a key focus of global environmental policy. Several programs promote planting of trees outside forests (ToF), in places such as farms and grazing lands, due to the potential of trees to provide a wide variety of benefits to people and nature. Yet, our knowledge of human well-being outcomes of ToFs is limited, especially in South Asia. In this systematic literature review, we examine multidimensional human wellbeing outcomes of a wide range of ToF practices in rural landscapes of South Asian countries; including Bangladesh, India, Nepal, Pakistan and Sri Lanka. Relying on six databases, we uncover a large body of research in 325 articles considered for this review. Articles from Bangladesh and India dominate our review, with 71% of the studies. Further, two ToF systems, tree and forest gardens and multipurpose trees on farms, were the most commonly studied, accounting for approximately 43% of the dataset. About 62% of publications reported increases in incomes, representing economic wellbeing, 34% and 36% of publications reported an increase in material wellbeing (access to biomass and fuelwood respectively), and 10% in dietary diversity. ToF systems also created opportunities for vocational training. Trade-offs include negative and mixed outcomes on people's sense of agency, political voice, and social equity in particular with afforestation and monoculture plantation projects in which governmental agencies took leadership or influential roles. Some research designs were weak and it was unclear whether the studied tree-based systems reflect the actual distribution of tree-based systems in South Asia. This review offers useful insights to guide ongoing and future tree-based natural-climate solutions projects in the region and worldwide to ensure ecological security and human wellbeing are well considered. It also points to areas where future research is needed.