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而宝贵的生态系统的重要环境。它们是关键地带的组成部分，关键地带调节着地球表面的条件，帮助维持生命。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，否则它们就会进入海洋。不断上升的海平面正在扩大这些环境，但海水也在涌入，破坏了林地，破坏了农田。幽灵森林和盐渍农田是世界海岸线生态变化的鲜明标志，这些变化可能对土地利用和经济产生不利影响。不太明显，但可能更重要的是，水和化学循环的同步变化正在改变沿海临界带的功能。这个研究项目将量化发生在变化的沿海临界带的过程，以及与之相关的海陆边缘元素循环、通量和储存的变化。这个项目将解决一些重要的问题，比如海平面上升如何改变海陆边界的自然“管道”，以及它对沿海生态系统的影响。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带水文、生态、地貌和生物地球化学转变的耦合过程和反馈，以及海平面上升将如何转化为陆海边缘元素循环、通量和储存的变化。海平面上升通过风暴和潮汐（快速过程）推动内陆的盐和淹没前沿，同时逐渐提高地下水位（缓慢过程）。该系统的复杂性，加上其强烈的水文瞬变性（如潮汐、风暴）、紧密耦合的生态系统和生物地球化学拼合物以及人类影响，使得沼泽-高地过渡的功能和响应难以表征和预测。本项目的主要假设涉及：(1)沿海临界带过渡的主要快速和缓慢水文驱动因素；(2)生态变化驱动地貌演变的景观反馈，地貌演变反馈给水文和生物地球化学过程；(3)生物地球化学反馈，盐碱化和氧化还原变化改变循环、流动性和营养物质和碳的封存。这些过程在沼泽毗邻森林高地和农田的地区有所不同。这些假设将通过跨学科的实地观察、实验和建模来解决，这些观察、实验和建模将在大西洋中部海岸的三个地点进行全面整合，并配有成对的沼泽森林和沼泽农业地点。每个地点的森林和农业遗址在水文、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关键地带景观如何应对海平面上升以及如何将关键地带研究应用于制定政策和行动以减轻影响的紧迫需求。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值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.