Collaborative Research: The Role of Spatial Interactions in Determining the Distribution of Savanna and Forest

合作研究：空间相互作用在确定稀树草原和森林分布中的作用

基本信息

批准号：
1614978
负责人：
Richard Durrett
金额：
$ 10.72万
依托单位：
Duke University
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2016
资助国家：
美国
起止时间：
2016-09-01 至 2019-08-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1614978&HistoricalAwards=false
关键词：
Collaborative Research Role Spatial Interactions

项目摘要

Ecologists have long emphasized climate as primary factor determining ecosystem dynamics at large scales, but the relationship between climate and vegetation is not always deterministic. Where vegetation-environment feedbacks are significant (e.g.,in savannas), predicting responses to climate can be especially difficult. Recent work suggests that feedbacks with fire may make savannas much more common than they would be were their distributions solely determined by climate; as a result, savanna and forest responses to global change may thus be drastic, sudden, and difficult to foresee. However, existing work does not explain why savanna is spatially aggregated with savanna and forest with forest -- a pattern that indicates that spatial processes may also play a role in determining ecosystem responses to climate. Here the investigators will consider the impacts of those spatial interactions between savanna and forest on their distributions and on their potential responses to climate and land-use change, both in the past and into the future.The investigators have identified three hypotheses to explain the spatial aggregation of savanna and forest: H1) that savanna and forest are bistable, and that spatial structure in initial conditions (as a result of past climate) determines their distributions, H2) that savanna and forest are bistable, but that spatial processes within savanna (e.g., fire spread) result in spatially structured distributions, and/or H3) that nearest neighbor interactions between savanna and forest change their distributions on long time scales, impacting their long-term stability. These hypotheses are variously supported in the empirical literature, and existing work has not attempted to disentangle these processes. Results will allow the research team to generate informed theoretical and empirical predictions about the past and future distribution of savanna and forest globally. The proposed work will also generate novel mathematical results. Possible outcomes of theoretical, spatial-stochastic models include a) savanna and forest coexistence in landscapes, b) forest exclusion by savanna, c) savanna exclusion by forest, or d) alternative stable states in biome savanna/forest dominance. The last outcome would be unlikely in a homogeneous spatial stochastic model, where the winning biome is decided by the direction of movement of the biome boundary (i.e., the front), but most closely resembles real biome distributions. Spatial stochastic model results will be reconciled with observations using theoretical and simulation modeling.

生态学家长期以来一直强调气候是决定生态系统动力学大规模生态系统动态的主要因素，但是气候与植被之间的关系并不总是确定性的。如果植被 - 环境反馈很大（例如，在稀树草原中），预测对气候的反应可能特别困难。最近的工作表明，用火的反馈可能使稀树草原比仅由气候决定的分布更为普遍。结果，稀树草原和森林对全球变化的反应可能是剧烈，突然且难以预见的。但是，现有的工作并不能解释为什么Savanna与Savanna和Forest与Forest进行空间汇总 - 这种模式表明，空间过程也可能在确定生态系统对气候的响应中发挥作用。在这里，调查人员将考虑萨凡纳和森林之间的空间互动对它们的分布以及对气候和土地利用变化的潜在反应的影响。森林是可行的，但是稀树草原内部的空间过程（例如，火灾蔓延）导致空间结构化的分布，//或H3），萨凡纳和森林之间最近的邻居相互作用在长期尺度上改变了它们的分布，从而影响了它们的长期稳定性。这些假设在经验文献中得到了不同的支持，现有工作并未试图解散这些过程。结果将使研究团队能够对全球稀树草原和森林的过去和未来分布产生明智的理论和经验预测。拟议的工作还将产生新的数学结果。理论上的空间模型的可能结果包括a）景观中的稀树草原和森林共存，b）Savanna的森林排除，c）森林中的稀树草原排除，或者d）在Biome Savanna/Forest统治中的替代稳定州。在均匀的空间随机模型中，最后的结果不太可能，在这种模型中，获胜的生物群落是由生物群落边界（即前部）运动方向决定的，但最类似于实际的生物群落分布。空间随机模型结果将与使用理论和仿真建模的观测值对待。