The End of the Amazon Carbon Sink? (AMSINK)

亚马逊碳汇的终结？

• 批准号: NE/X014347/1
• 负责人: Oliver Phillips
• 金额: $ 104万
• 依托单位: University of Leeds
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FX014347%2F1
• 关键词: End; Amazon; Carbon; Sink; AMSINK

How forests respond to climate change and the increasing concentration of carbon dioxide in the atmosphere affects the course of climate change itself. The response of these ecosystems thus determine how much humanity needs to reduce greenhouse gas emissions to keep global heating within agreed limits. Understanding these is especially critical for the Amazon due to its huge importance for Earth's climate. While the need to know is urgent, the challenge is enormous. Satellites, planes, experiments and models all help, but long-term, tree-by-tree measurements in many sites are essential to understand how forests are accelerating or slowing the rate of climate change.So far intact Amazon forests have provided a huge 'sink' for carbon, slowing climate change. But a decade ago there were already signs this had weakened with tree death rates increasing, partly as a result of severe droughts. Projections suggest the sink may now be finished. If so we have lost a key ally in stabilising Earth's climate. But with no ground analysis since 2011 a big gap between knowledge and projection has opened up. The forecast is based on old measurements, has large uncertainty, and crucially fails to account for the huge natural variability of forests. AMSINK will resolve this. It uses ambitious new measurements, analysis and integration to discover how and why South American forests are changing, where and why they are able to resist climate change, and what the future holds. In short to understand the dynamics and destiny of this critical system.Our central idea is that the biomass carbon sink depends on the fundamental nature of forests - their climate, nutrients, soil water, species and diversity, and turnover rate - so that in many places net uptake of carbon may persist well beyond simple predictions based on climate-change. For example, while we know that scarce nutrients limit forest growth and droughts kill trees, (1) one third of the Amazon has relatively-rich soils where nutrients may allow long-term growth increases and (2) up to half is prone to waterlogging so some drying could benefit trees by aerating the soil, while (3) tree resistance to drought is likely to vary greatly with species.To know what is happening to S American forests, where and why therefore requires a huge, integrated and ambitious measurement effort. We must look widely at many forests for a long time. We need holistic science.To make this possible AMSINK takes three key steps. First we will unite 15 forest plot networks, each examining different locations and aspects of change across tropical S America, to create a connected 'team-of-teams' spanning 8 million km2 of forest. Second we will enrich these, with comparable nutrient, moisture and species drought-sensitivity measurements across the networks. Third, for the most valuable long-term Amazon plots we will take careful consistent tree-by-tree monitoring into the mid-2020s. In total AMSINK will integrate 1000 plots into a globally standardized framework and track more than half-a-million trees for up to 62 years. It will analyse these to discover the distribution, dynamics and trend of the biomass carbon sink to 2026, determine its drivers, and test our hypotheses of forest resistance to climate change. Our new findings will be applied to forecast future growth, mortality and carbon trends across the region, providing critical insights for national policy-makers, global agreements & fellow scientists.In all AMSINK makes the first continent-scale integrated measurement and analysis of how nature controls the long-term climate-change sensitivity of tropical forests and their carbon balance. It replaces projection with new measures to 2026, novel insight into which sink processes are changing where, critical understanding of why, and new constraints on how their future will unfold. It delivers exceptional scientific value for UK taxpayer support and vital, timely discoveries for policy-makers.

森林如何应对气候变化以及大气中二氧化碳浓度的增加影响到气候变化本身的进程。因此，这些生态系统的反应决定了人类需要减少多少温室气体排放，以将全球变暖保持在商定的限度内。了解这些对亚马逊地区来说尤其重要，因为它对地球气候非常重要。虽然迫切需要了解，但挑战是巨大的。卫星、飞机、实验和模型都有帮助，但在许多地点进行长期的逐树测量对于了解森林是如何加速或减缓气候变化的速度至关重要。迄今为止，完好的亚马逊森林为碳提供了巨大的“汇”，减缓了气候变化。但十年前，随着树木死亡率的上升，部分原因是严重的干旱，已经有迹象表明这种情况已经减弱。预计水槽现在可能已经完工。如果是这样，我们就失去了一个稳定地球气候的关键盟友。但自2011年以来没有地面分析，知识和预测之间的巨大差距已经打开。这一预测是基于旧的测量结果，具有很大的不确定性，关键是未能考虑到森林的巨大自然变异性。AMSINK将解决此问题。它使用雄心勃勃的新测量，分析和整合来发现南美洲森林如何以及为什么正在变化，它们在哪里以及为什么能够抵抗气候变化，以及未来会发生什么。我们的中心思想是，生物质碳汇取决于森林的基本性质--气候、养分、土壤水分、物种和多样性，以及周转率--因此，在许多地方，碳的净吸收可能会持续下去，远远超出基于气候变化的简单预测。例如，虽然我们知道稀缺的养分限制了森林的生长，干旱会杀死树木，但（1）三分之一的亚马逊地区土壤相对丰富，养分可能会允许长期生长增加，（2）多达一半的地区容易发生水涝，因此一些干燥可以通过使土壤通气而使树木受益，而（3）树木对干旱的抵抗力很可能因物种而异。2要知道南美森林发生了什么，在哪里以及为什么发生，需要一个巨大的，综合的和雄心勃勃的测量工作。我们必须长期广泛地观察许多森林。我们需要全面的科学。为了使这成为可能，AMSINK采取了三个关键步骤。首先，我们将联合15个森林地块网络，每个网络都检查南美洲热带地区的不同位置和变化方面，以创建一个跨越800万平方公里森林的连接“团队”。第二，我们将丰富这些数据，在整个网络中进行可比的营养、水分和物种干旱敏感性测量。第三，对于最有价值的长期亚马逊地块，我们将在20世纪20年代中期采取谨慎的逐树监测。AMSINK总共将把1000块土地纳入一个全球标准化框架，并对50多万棵树木进行长达62年的跟踪。它将分析这些数据，以发现到2026年生物质碳汇的分布，动态和趋势，确定其驱动因素，并测试我们对森林抵抗气候变化的假设。我们的新发现将被应用于预测整个地区未来的增长、死亡率和碳趋势，为国家政策制定者、全球协议和同行科学家提供重要的见解。总之，AMSINK首次对自然如何控制热带森林的长期气候变化敏感性及其碳平衡进行了大陆尺度的综合测量和分析。它取代了预测到2026年的新措施，对汇过程在哪里发生变化的新见解，对原因的批判性理解，以及对未来如何发展的新限制。它为英国纳税人的支持提供了卓越的科学价值，并为政策制定者提供了至关重要的及时发现。