Determinants of Forest Recovery from Local to Regional Scales

近年来，世界各地对促进迅速和广泛重新造林的兴趣激增。在全球范围内，30%的森林已经被砍伐，另有20%的森林退化，导致生物多样性丧失、气候变化和其他关键生态系统服务的下降。为了应对这些问题，波恩挑战赛制定了到2030年重新造林3.5亿公顷的雄心勃勃的目标。但是，尽管科学家和实践者已经非常成功地恢复了小面积的土地，但如何将恢复规模扩大到如此大的区域的科学仍然缺乏。*为了扩大植树造林，我们首先需要更好地了解哪些因素促进了最快和最好的森林恢复。土地利用历史、残存森林在景观中的类型和位置以及生物物理因素都很重要，但这些因素的相对重要性尚不清楚。此外，我们如何评估恢复取决于我们衡量的方面；树木可以迅速恢复，但以原始森林为特征的生物多样性可能需要更长的时间才能恢复。除了生物多样性，植树造林还有望恢复一系列其他生态系统服务。其中的关键是碳，许多通过碳信用融资或旨在恢复木材供当地使用的重新造林项目，优先考虑快速增长的生物质。但是，确定一项生态系统服务的优先顺序对其他生态系统服务有何影响？虽然我们对生态系统服务之间的时间动态和相互作用的了解仍处于萌芽阶段，但现有的少数研究表明，随着生态系统服务以不同的速率变化，非线性反应和长期权衡是常见的。*为了应对这些挑战，我建议：(1)利用卫星图像检查区域尺度上重新造林的空间格局和驱动因素；(2)在地方尺度上，评估土地利用历史、恢复类型和景观背景对不同森林恢复措施随时间的相对影响；(3)随着森林的恢复，确定生态系统服务和生物多样性之间的权衡和协同作用；(4)扩大这些结果，以制定在区域范围内优先重新造林的模型。将在撒哈拉以南非洲的马拉维和厄瓜多尔这两个国家进行实地工作；这两个国家的森林砍伐率很高，有大量依赖森林为生的人民，每年都在种植数百万棵树，以履行其雄心勃勃的重新造林承诺。*这项研究的结果将有助于阐明在地块和区域一级恢复森林的一般原则，并开发软件方法，以便在不同景观之间优先考虑重新造林。全球范围内雄心勃勃的恢复目标是恢复生态系统功能的绝佳机会，但需要消息灵通和深思熟虑的方法，以确保在地块到景观层面和更远的地方取得成功。

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.