Collaborative Research: Network Cluster: The Coastal Critical Zone: Processes that transform landscapes and fluxes between land and sea

沿海沼泽是保护脆弱和极具价值的生态系统的基本环境。它们是控制地球表面条件并帮助维持生命的临界区的组成部分。沿海沼泽提供了至关重要的服务，如碳储存和去除营养物质和污染物，否则这些物质就会进入海洋。海平面上升正在扩大这些环境，但咸水也在进入，破坏林地，破坏农田。幽灵森林和被盐碱破坏的农田是世界海岸线上这些生态变化的鲜明指标，这些变化可能会对土地利用和经济产生不利影响。不那么明显，甚至可能更重要的是，水和化学循环的同时变化正在改变沿海临界区的功能。这项研究项目将量化在变化的沿海临界区发生的过程以及与之相关的陆海边缘元素循环、通量和储存的变化。该项目将解决海平面上升可能如何改变海陆边界的自然“管道”及其对沿海生态系统的影响等重要问题。研究结果将有助于决策者和利益相关者规划未来的环境变化。该项目将量化控制沿海临界区水文、生态、地貌和生物地球化学变化的耦合过程和反馈，以及海平面上升将如何转化为海陆边缘元素的循环、通量和储存的变化。海平面上升通过风暴和潮汐将盐分和洪水前锋推向内陆(快速过程)，同时逐渐抬高地下水位(缓慢过程)。该系统的复杂性，以及其强烈的水文瞬变(如潮汐、风暴)、紧密耦合的生态系统和生物地球化学马赛克以及人类的影响，使得沼泽-高地过渡的功能和反应难以表征和预测。该项目的主要假设涉及：(1)沿海临界区转变的主要快速和缓慢的水文驱动因素；(2)生态变化驱动地貌演变的景观反馈；以及(3)盐碱化和氧化还原转变改变营养物质和碳的循环、迁移和封存的生物地球化学反馈。这些过程在沼泽毗邻森林高地和农田的地区有所不同。这些假说将通过跨学科的实地观察、实验和建模来解决，这些观察、实验和建模完全整合了大西洋中部海岸的三个地点，以及成对的沼泽-森林和沼泽-农业地点。每个地点的森林和农业地点在水文、地球化学和生态方面存在重大差异，预计对海平面上升的反应也不同。该项目解决了确定沿海临界区的景观如何应对海平面上升以及如何将临界区研究应用于制定政策和行动以减轻影响的迫切需要。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Coastal marshes are essential environments that preserve a fragile and highly valuable ecosystem. They are an integral part of the Critical Zone that regulates the conditions at the Earth’s surface and helps sustain life. Coastal marshes provide crucial services such as carbon storage and removal of nutrients and contaminants that would otherwise make their way to the ocean. Rising sea level is expanding these environments, but salt-water is also moving in, destroying woodlands, and damaging farm fields. Ghost forests and salt-damaged farm fields are stark indicators of these ecological changes along world coastlines that can adversely affect land use and economies. Less apparent, and perhaps even more important, are the concurrent changes in water and chemical cycling that are altering the functioning of the coastal Critical Zone. This research project will quantify the processes that occur in the changing coastal Critical Zone and associated alterations in cycling, fluxes, and storage of elements at the land-sea margin. The project will address important questions about how sea-level rise may alter the natural “plumbing” that occurs at the land-sea boundary and its implications with respect to coastal ecosystems. The results will assist decision-makers and stakeholders in planning for future environmental changes. This project will quantify the coupled processes and feedbacks that govern the hydrological, ecological, geomorphological, and biogeochemical transformations in the coastal Critical Zone and how rising sea level will translate to changes in cycling, fluxes, and storage of elements at the land-sea margin. Sea-level rise pushes salt and inundation fronts inland via storms and tides (fast processes) while gradually elevating the water table (slow processes). The complexity of the system, with its strong hydrologic transience (e.g. tides, storms), tightly coupled ecosystem and biogeochemical mosaics, and human influences, make functioning and response at the marsh-upland transition difficult to characterize and predict. The governing hypotheses of this project address (1) the major fast and slow hydrological drivers of coastal Critical-Zone transition, (2) the landscape feedbacks in which ecological change drives geomorphological evolution that feeds back into hydrological and biogeochemical processes, and (3) biogeochemical feedbacks in which salinization and redox shifts alter cycling, mobility, and sequestration of nutrients and carbon. These processes differ between areas where the marsh abuts forested uplands versus agricultural land. The hypotheses will be addressed through interdisciplinary field observations, experiments, and modeling that are fully integrated across three locations along the mid-Atlantic coast with paired marsh-forest and marsh-agriculture sites. The forested and agricultural sites at each location represent major differences in hydrology, geochemistry, and ecology, and are expected to respond differently to rising sea level. This project addresses pressing needs to determine how landscapes in the coastal Critical Zone may respond to sea-level rise and how Critical-Zone research can be applied to developing policies and actions to mitigate the effects.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.