The human well-being outcomes of tree plantations in sub-Saharan Africa: A reassessment of evidence using longitudinal subnational-year data

Several globally driven endeavors endorse tree plantations as an intervention for resource restoration, with assumptions of socio-economic outcomes as co-benefits. Yet, evidence of such co-benefits remains questionable and unclear. Focusing on sub-Saharan Africa (SSA), we empirically reassess the effectiveness of tree planting and species diversity in tree plantations on Gross National Income (GNI) per capita, Human Development Index (HDI), and International Wealth Index (IWI). We use multi-way fixed effects instrumental variables on subnational-year panel data on tree plantations in the first-level administrative subdivisions of 12 SSA countries for the years 1992–2016. We find that dedicating more land to tree plantation over a three- to five-year period raises IWI by more than a third and GNI per capita by a substantial annual amount of 205 to 395 USD. We also find positive effects of tree species diversification in plantations (tree crops and planted forests) on GNI per capita and IWI. However, there is no evidence of HDI increments due to tree planting programs. Our findings remain consistent across different specifications, and a mediation analysis stresses that the impacts of tree plantations are led by men's employment opportunities outside the agricultural sector. We conclude that restoration efforts heavily based on tree planting activities can improve economic well-being outcomes, with heterogeneity across locations and genders, when tree species planted are diversified and successfully grown over time.