UNDERSTANDING AND SCALING VULNERABILITY OF NEOTROPICAL AMAZON AND TRANSITIONAL FORESTS TO ALTERED FIRE REGIMES

了解和衡量新热带亚马逊和过渡森林对火情变化的脆弱性

• 批准号: NE/W00058X/1
• 负责人: Immaculada OliverasMenor
• 金额: $ 84.31万
• 依托单位: University of Oxford
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2022
• 资助国家: 英国
• 起止时间: 2022 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FW00058X%2F1
• 关键词: UNDERSTANDING; SCALING; VULNERABILITY; NEOTROPICAL; AMAZON

SUMMARYThe Amazon is the most important biome of South America, harbouring extraordinarily high levels of biodiversity and providing important ecosystems services. This biome is particularly notable for evolving independently from fire and in a moist, warm climate. In recent decades, altered fire regimes and an increasingly hotter and drier climate has pushed this key biome towards ecological thresholds that will likely lead to major losses in biodiversity and ecosystem services. Similarly, the ecotonal forests at the Amazon-Cerrado transition are unique ecosystems in terms of form and function, but they may be the first to suffer large-scale tree mortality and species loss due to the combined effects of increased anthropogenic disturbance, altered fire regimes and a drier climate. Vulnerability of fire and droughts are closely intertwined in Amazonian and transitional forests because fires in this region only occur when there is water stress and a human ignition source. Thus, drought increases vulnerability to fire, but we do not yet understand the magnitude and spatial variation of these vulnerabilities. Once a forest burns there is immediate tree mortality, but recent evidence also shows a significant time-lagged mortality that can last for decades, becoming an important carbon source. However, the mechanistic processes that lead to time-lagged tree mortality in this myriad of forest ecosystems encompassing the Amazon biome and the Amazon-Cerrado transition are still poorly understood. We also lack knowledge on how these processes might vary spatially across the biome and its transition. A better understanding of the mechanisms that lead to tree mortality after fires and droughts is needed to design future policies that emphasise nature-based solutions including restoration and natural regeneration. This proposal presents a multi-level approach that aims at deciphering the mechanisms that underly vulnerability to fire and time-lagged post-fire mortality across the tropical forests in Amazon and Amazon-Cerrado transition. To achieve this aim, we will quantify fire vulnerability at three different scales and link them through an upscaling approach. First, we will identify the ecological mechanisms, reflected through functional traits, that explain why individuals and species die after fires occur. For this, we will focus on poorly understood traits that can be related to fire and/or hydraulic functioning. Second, at the community scale, we will examine how vegetation structure, community traits and microclimate affect the probability to burn, through an intensive characterisation of different vegetation types with multispectral and light detection and ranging (LIDAR) imagery. Third, we will use our our unique ground-dataset on functional traits, vegetation structure and moisture dynamics, and the latest state-of-art remotely sensed information on structure and water stress to predict the vulnerability of the Amazon forests and Amazon-Cerrado transitional forests. This information will be directly applicable for the detection of sensitive hotspots (areas particularly vulnerable to fire) through satellite products. We will deliver quantifiable early-warning metrics of ecosystem vulnerability to fire that can be mapped and incorporated into fire management policies. This is a revised version of a NERC proposal that was rejected with a score of 7 by the NERC Panel in July 2020, and we have carefully addressed the Panel's comments. Specifically, we have clarified the methodology and we have reformulated the hypotheses, so they address vulnerability to fire and not drought fire-interactions.

亚马逊是南美洲最重要的生物群落，拥有极高的生物多样性，并提供重要的生态系统服务。这种生物群落特别值得注意的是，它独立于火和潮湿温暖的气候而进化。近几十年来，火灾状况的改变和日益炎热和干燥的气候已将这一关键生物群落推向生态阈值，这可能导致生物多样性和生态系统服务的重大损失。同样，亚马逊-塞拉多过渡地带的生态过渡带森林在形式和功能方面都是独特的生态系统，但由于人为干扰增加、火灾状况改变和气候干燥的综合影响，它们可能是第一个遭受大规模树木死亡和物种损失的生态系统。在亚马逊和过渡森林中，火灾和干旱的脆弱性密切交织在一起，因为这一地区的火灾只有在缺水和人为火源的情况下才会发生。因此，干旱增加了对火灾的脆弱性，但我们还不了解这些脆弱性的程度和空间变化。一旦森林被烧毁，树木会立即死亡，但最近的证据也表明，树木的死亡率有很大的时滞，可以持续几十年，成为一个重要的碳源。然而，机械过程，导致滞后的树木死亡率在这无数的森林生态系统，包括亚马逊生物群落和亚马逊塞拉多过渡仍然知之甚少。我们也缺乏关于这些过程在生物群落及其过渡中如何在空间上变化的知识。需要更好地了解火灾和干旱后导致树木死亡的机制，以设计未来的政策，强调基于自然的解决方案，包括恢复和自然再生。该提案提出了一个多层次的方法，旨在破译亚马逊和亚马逊-塞拉多过渡区热带森林火灾脆弱性和火灾后时间滞后死亡率的机制。为了实现这一目标，我们将在三个不同的尺度上量化火灾脆弱性，并通过升级方法将它们联系起来。首先，我们将确定生态机制，通过功能特征反映，解释为什么个人和物种在火灾发生后死亡。为此，我们将重点关注与火和/或液压功能相关的知之甚少的特征。第二，在社区规模，我们将研究如何植被结构，社区特征和小气候影响的概率燃烧，通过密集的表征不同的植被类型与多光谱和光探测和测距（激光雷达）图像。第三，我们将利用我们独特的功能特征、植被结构和水分动态地面数据集，以及最新的结构和水分胁迫遥感信息，预测亚马逊森林和亚马逊-塞拉多过渡森林的脆弱性。这一信息将直接用于通过卫星产品探测敏感热点（特别易受火灾影响的地区）。我们将提供可量化的生态系统火灾脆弱性预警指标，这些指标可以绘制并纳入火灾管理政策。这是NERC提案的修订版本，该提案于2020年7月被NERC小组以7分拒绝，我们已经仔细处理了小组的意见。具体来说，我们已经澄清了方法，我们已经重新制定了假设，所以他们解决火灾的脆弱性，而不是干旱火灾的相互作用。