Collaborative Research: Engineering salt marsh restoration to maximize denitrification - elevation and species interactions

1438092（Mortazavi）和1438235（Ortmann）。沿海湿地只占所有湿地面积的一小部分，但却很独特，因为它们也容纳了世界上很大一部分人口。沿海沼泽生态系统与人类居住和工业有着动态的联系，人类对这些生态系统的影响可能相当大。这种耦合的人类-沼泽系统具有重要的意义，因为沼泽提供了理想的生态系统服务，如营养过滤，洪水控制和碳封存。由于这些服务和城市化造成的沼泽地损失，恢复沼泽地已成为沿海管理的一个重要工具。氮的去除是湿地的一项重要功能，它通过减轻水体富营养化而对海岸带生态系统的可持续性做出贡献。目前，沼泽地的建设与假设，反硝化作用将有助于显着的N去除一旦植被到位，然而，研究表明，只有一些理想的生态系统服务恢复这样的努力。具体的信息是从沼泽恢复文学，这可以用来工程沼泽，更有效地去除氮缺失。本研究针对这一问题，旨在阐明物种特性和湿地海拔对恢复后湿地生态系统氮素去除能力的影响，为湿地生态系统的可持续发展和氮素去除最大化提供指导。为了实现这一目标，该项目解决了以下假设：（一）在灯心草romerianus的N去除率高于互花米草沼泽（物种效应），（二）存在一个最佳的沼泽表面海拔的N去除最大化（海拔效应），和（三）在这个最佳的海拔，沼泽将是最有弹性的营养增加（响应升高的N输入）。这些假设将在该领域以及与外地介观生态系统在亚拉巴马沿海沼泽超过三年的时间。这种方法使我们能够操纵沼泽表面海拔相对于平均海平面，以确定最佳条件下去除氮。项目结果将用于制定沼泽工程项目的具体准则，以确保氮的去除，一个重要的生态系统服务，是最大限度的。此外，更好地了解植被海拔微生物群落的相互作用，提供有关在沿海沼泽氮循环的基础知识，将实现。研究结果的综合将提供必要的数据，为恢复策略提供信息，包括沉积物补贴和物种选择，以优化氮的去除，从而减轻富营养化，通过工程湿地。沿海沼泽提供重要的生态系统服务，如过滤沉积物、减缓洪水和保护内陆发展免受周期性风暴的影响，并为具有重要商业价值的资源提供营养和栖息地。这项研究意义重大，因为它将有助于推进我们对复杂生态系统的理解，并将帮助我们改进工程沼泽提供的生态系统服务（即N去除）的最大化。在该项目期间收集的数据将立即适用于执行沼泽重建项目的沿海管理人员和团体。评估结果将分发给当地利益攸关方，包括土地管理者、地方政府决策者和居民。为了将这些发现置于更广泛的背景下，将开发可用于多芬岛海洋实验室教育和推广（E O）计划的教材，该计划被称为探索厅计划（DHP），这是墨西哥湾北方最大的沿海科学E O计划之一。

1438092 (Mortazavi) and 1438235 (Ortmann). Coastal wetlands represent a small fraction of all wetland areas, but are unique as they also host more than a significant fraction of the world's population. Coastal marsh ecosystems are dynamically linked to human dwellings and industry, and the impact humans have on these ecosystems can be considerable. This coupled human - marsh system has important implications, as the marshes provide desirable ecosystem services such as nutrient filtering, flood control, and carbon sequestration. Because of these services and the loss of marshes through urbanization, restoration of marshes has become an important tool in coastal management. Nitrogen (N) removal is an important service of marshes, which contributes to the sustainability of coastal ecosystems by mitigating eutrophication. Currently marshes are constructed with the assumption that denitrification will contribute significantly to N removal once vegetation is in place; however, studies suggest that only some of desirable ecosystem services are restored by such efforts. Specific information is missing from marsh restoration literature, which could be used to engineer marshes that are more effective at N removal. This research specifically addresses this issue.The primary objective of this research is to elucidate the impact of species identity and marsh elevation on the N removal capacity of restored marsh ecosystems to provide guidance in the engineering of sustainable marsh ecosystem which also maximize N removal. To achieve this objective the project addresses the following hypotheses: (i) rates of N removal in Juncus romerianus are higher than in Spartina alterniflora marshes (species effect), (ii) there exists an optimum marsh surface elevation where N removal is maximized (elevation effect), and (iii) at this optimal elevation, the marsh will be most resilient to increased nutrients (response to elevated N input). These hypotheses will be addressed in the field as well as with field-mesocosms in Alabama coastal marshes over a three-year period. This approach enables us to manipulate marsh surface elevation with respect to mean sea level to identify optimum conditions for N removal. Project results will be used to develop specific guidelines for marsh engineering projects to ensure N removal, an important ecosystem service, is maximized. Furthermore, a better understanding of the vegetation-elevation-microbial community interactions, providing fundamental knowledge about N cycling in coastal marshes, will be achieved. The synthesis of results from the research will provide the necessary data to inform restoration strategies, including sediment subsidy and species selection, to optimize N removal, and thus mitigate eutrophication, by engineered marshes. Coastal marshes provide important ecosystem services such as filtering sediments, moderating flooding and protecting inland developments from periodic storms, and provide nutrition and habitat for commercially important resources. The research is significant because it will help advance our understanding of a complex ecological system, and will help us refine efforts for maximizing an ecosystem service (i.e. N removal) provided by engineered marshes. The data collected during this project will be immediately applicable to coastal managers and groups carrying out marsh reconstruction projects. Results will disseminated to the local stakeholders including land managers, local government decision makers, and residents. To place the findings in a broader context, teaching material will be developed that can be used by the education and outreach (E&O) program of the Dauphin Island Sea Lab, known as the Discovery Hall Programs (DHP), one of the largest coastal science E&O programs in the northern Gulf of Mexico region.