A global understanding of forest-savanna transitions

全球对森林-稀树草原转变的理解

• 批准号: 2890074
• 金额: --
• 依托单位: University of Edinburgh
• 依托单位国家: 英国
• 项目类别: Studentship
• 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=studentship-2890074
• 关键词: global; understanding; forest; savanna; transitions

Savannas dominate the tropics, and often occur in areas which could be forest, given the rainfall and soils. Why savannas are where they are, and how that might change under climate change has long preoccupied scientists, but a general understanding has yet to be developed. Remote sensing offers a way to address this problem, and new data sets from lidar and radar sensors in particular, have the potential to describe and explain savanna-forest transitions globally. Given the importance of these ecosystems for local people, carbon cycling and biodiversity, this understanding is vital for responding to the climate and biodiversity crises. In this PhD you will use these new remote sensing data and machine learning to understand how and why savannas transition into forests and how this is changing. You will map and classify the world's savanna-forest transitions and test what determines their location and temporal stability. Theoretical models suggest that both gradual and abrupt transitions between savannas and forest can occur, depending on the traits of trees. However, in the real world, it is not clear why in some places, gradual transitions occur, whilst in other, there is a mosaic of sparse savanna and closed forest. Nor do we understand how stable these patterns will be under climate change, changes to herbivory (such as the loss of elephants) and CO2 fertilisation. Filling these gaps in our knowledge is important because savannas are thought to be particularly sensitive to climate change: they are expected to both be a globally important carbon sink, and to change rapidly as CO2 fertilisation allows trees to outcompete grasses. Which factors control savanna[1]forest boundaries, and how these factors will respond to climate change and other environmental changes, will therefore be vital for the future of savannas.

稀树草原占主导地位，并且考虑到降雨和土壤，通常发生在可能是森林的地区。为什么稀树草原在哪里，以及在气候变化下可能会发生变化的方式，长期以来一直关注科学家，但尚未建立一般的理解。遥感提供了一种解决此问题的方法，尤其是LiDAR和RADAR传感器的新数据集具有描述和解释全球稀树草原 - 森林过渡的潜力。考虑到这些生态系统对当地人的重要性，碳循环和生物多样性，这种理解对于应对气候和生物多样性危机至关重要。在此博士学位上，您将使用这些新的遥感数据和机器学习来了解稀树草原如何以及为什么过渡到森林以及如何改变。您将绘制和分类世界上的稀树草原 - 森林过渡，并测试决定其位置和时间稳定性的因素。理论模型表明，根据树木的特征，可以发生稀树草原和森林之间的逐渐和突然过渡。但是，在现实世界中，尚不清楚为什么在某些地方，逐渐过渡发生，而在另一个地方，有稀疏的稀树草原和封闭的森林。我们也不了解这些模式将在气候变化，食草动物（例如大象的损失）和二氧化碳受精的变化下稳定。在我们的知识中填补这些空白很重要，因为稀树草原被认为对气候变化特别敏感：预计它们都是全球重要的碳汇，并且随着二氧化碳施肥允许树木胜过草的草。因此，哪些因素控制稀树草原[1]森林边界，以及这些因素将如何应对气候变化和其他环境变化，因此对于Savannas的未来至关重要。