Determinants of Forest Recovery from Local to Regional Scales

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In recent years, there has been a surge of interest worldwide in promoting rapid and widespread reforestation. Across the planet, 30% of forests have been cleared and another 20% degraded, leading to biodiversity loss, climate change, and decline in other critical ecosystem services. In response to these issues, the Bonn Challenge has set the ambitious goal of reforesting 350 million hectares of land by 2030. But while scientists and practitioners have been very successful at restoring small areas of land, the science of how to scale restoration up to such large areas is still lacking. To scale up reforestation, we first need a better understanding of what factors promote the quickest and best forest recovery. Land-use history, the type and location of remnant forest in the landscape, and biophysical factors matter, but the relative importance of these is not clear. Moreover, how we assess recovery depends on what aspect we measure; trees can grow back quickly, but the biodiversity that characterized the original forest can take much longer to recover. Beyond biodiversity, reforestation promises to restore a suite of other ecosystem services. Key among these is carbon, and many reforestation projects, financed through carbon credits or aiming to restore timber for local use, prioritize the quick growth of biomass. But how does prioritizing one ecosystem service impact others? While our understanding of the temporal dynamics and interactions among ecosystem services is still nascent, the few existing studies suggest that non-linear responses and long-term trade-offs are common as ecosystem services change at differential rates.To address these challenges, here I am proposing to: (1) use satellite imagery to examine spatial patterns and drivers of reforestation at the regional scale; (2) at the local scale, assess the relative effects of land-use history, restoration type, and landscape context on different measures of forest recovery through time; (3) determine the trade-offs and synergies among ecosystem services and biodiversity as forests recover; and (4) scale up these results to develop models prioritizing reforestation at the regional scale. Fieldwork will be conducted in two countries, Malawi, in sub-Saharan Africa, and Ecuador; both countries have high rates of deforestation, large numbers of forest-dependent peoples, and have been planting millions of trees annually to meet their ambitious reforestation commitments.The results of this study will help elucidate general principles of forest recovery at the plot and regional levels and develop software approaches for prioritizing reforestation across landscapes. The ambitious restoration targets across the planet are a remarkable opportunity to restore ecosystem function but require well-informed and thoughtful approaches to ensure success at the plot to landscape levels and beyond.