Collaborative Research:The Role of Ecomorphodynamic Feedbacks in Barrier Island Response to Climate Change

合作研究：生态形态动力反馈在障壁岛应对气候变化中的作用

• 批准号: 1324973
• 负责人: Laura Moore
• 金额: $ 38.27万
• 依托单位: University of North Carolina at Chapel Hill
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-08-15 至 2017-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1324973&HistoricalAwards=false
• 关键词: Collaborative; Research; Role; Ecomorphodynamic; Feedbacks

Climate-change-induced sea level rise and increases in storm intensity will affect barrier islands worldwide. The traditional view of barrier island evolution considers only changes in environmental conditions (such as sea level rise, changes in storms) and physical processes (such as the transport of sand), and predicts that barrier islands will respond to climate change gradually. However, recent work suggests that biological factors involving vegetation and interactions, or feedbacks, between vegetation and physical processes are also important in shaping islands and determining how they will respond to changing conditions in the future. For example, anticipated climate-change induced shifts in the geographic ranges of dune-building grasses may increase the vulnerability of islands to storms by changing the shape and height of protective dunes. And, just as interactions between vegetation and physical processes can build dunes (via sand trapping by dune-building grasses) they can also hinder, and even prevent, dune-building by maintaining areas of low elevation. Such feedbacks may cause gradual changes in environmental conditions to produce rapid changes in barrier island evolution, which would make human adaptation difficult. This project will allow us to better understand the processes that are important in determining how barrier islands will change in the future and the conditions under which the important processes and interactions will likely lead to rapid, rather than gradual changes in island behavior. This project will test a hypothesis that ecomorphodynamic feedbacks have the potential to amplify the effects of climate change on barrier island evolution, causing a nonlinear response to gradual changes in forcing, i.e., tipping points at which barrier islands rapidly convert from a high-relief, stable, ecologically diverse state to a low-relief, rapidly migrating, ecologically homogenous state. Through integrated numerical modeling and ecological experiments in the undeveloped barrier system of the Virginia Coast Reserve (VCR) LTER this project will address critical questions including: How do vegetation and physical processes interact in the formation and evolution of barrier island topography? How do overwash events affect topographic recovery and colonization of vegetation following storms? What is the role of ecomorphodynamic feedbacks in topographic recovery following storms? What combinations of factors lead to tipping points in the transition between high-relief and low-relief states as a result of nonlinearities in the ecomorphodynamic system? How are ecomorphodynamic feedbacks altered by climate change and what is the role of feedbacks in the transition between states?

气候变化引起的海平面上升和风暴强度的增加将影响全世界的堰洲岛。传统的堰洲岛演化观只考虑环境条件（如海平面上升、风暴的变化）和物理过程（如沙的移动）的变化，并预测堰洲岛将逐渐对气候变化作出反应。然而，最近的研究表明，涉及植被和植被与物理过程之间的相互作用或反馈的生物因素在塑造岛屿和决定它们如何应对未来不断变化的条件方面也很重要。例如，预计气候变化引起的造沙草地理范围的变化可能会改变沙丘的形状和高度，从而增加岛屿对风暴的脆弱性。而且，正如植被和物理过程之间的相互作用可以形成沙丘（通过造沙草捕获沙子）一样，它们也可以通过保持低海拔地区来阻碍甚至阻止沙丘的形成。这种反馈可能引起环境条件的逐渐变化，从而产生堰洲岛进化的快速变化，使人类难以适应。这个项目将使我们更好地了解在决定堰洲岛未来将如何变化的重要过程，以及在哪些重要过程和相互作用可能导致岛屿行为迅速而不是逐渐变化的条件。该项目将检验一个假设，即生态形态动力学反馈有可能放大气候变化对堰洲岛演变的影响，导致对强迫逐渐变化的非线性响应，即堰洲岛从高起伏、稳定、生态多样化状态迅速转变为低起伏、快速迁移、生态同质状态的临界点。通过在弗吉尼亚海岸保护区（VCR） LTER未开发的屏障系统中进行综合数值模拟和生态实验，该项目将解决关键问题，包括：植被和物理过程如何在屏障岛地形的形成和演变中相互作用？冲过事件如何影响风暴后的地形恢复和植被定植？生态形态动力学反馈在风暴后地形恢复中的作用是什么？由于生态形态动力学系统的非线性，哪些因素的组合导致高起伏和低起伏状态之间转变的临界点？生态形态动力学反馈是如何被气候变化改变的？反馈在不同状态之间的转换中起什么作用？