Ecogeomorphological consequences of climate and human-driven mangrove expansion into salt marshes

红树林--热带海岸常见的木本植物--由于冬季气温变暖而向北扩展。沿着墨西哥湾北方海岸，特别是路易斯安那州南部，红树林开始取代沿海沼泽草。这可能会产生积极的结果，因为红树林可能比沼泽草更有效地稳定沉积物，并降低该地区沼泽损失的速度（称为路易斯安那州的海岸危机）。由于红树林殖民化的潜在积极影响，路易斯安那州的一些利益攸关方已开始通过一项名为圣伯纳德教区黑红树林种植项目的基层倡议种植红树林。在这个项目中，调查人员将i）量化红树林在减少波浪侵蚀沼泽边缘方面的有效性，ii）确定促进种植红树林生存的技术，iii）预测未来红树林的分布。这些信息将直接有利于圣伯纳德教区、路易斯安那州沿海和墨西哥湾北方的沿海管理人员。利益攸关方将通过一个正式的咨询委员会参与，该项目的结果将通过市政厅会议传达。调查人员将与当地高中合作，扩大他们的环境科学课程。他们还将通过一个移动的手机应用程序启动一个公民科学红树林扩张监测计划，旨在向公众宣传植物生态和海岸侵蚀。 通过遥感分析和实地研究相结合，调查人员建议量化红树林的无约束生态工程潜力，以减少沼泽边缘侵蚀率，特别是，改变沉积物和土壤建设动态沿着海岸线，更广泛。他们将确定的条件，促进红树林扩大在细尺度上，这是假设与沼泽边缘撤退释放的沉积物，并量化的生态地貌变化，发生从沼泽草到红树林的植被转移。实地操作实验将测试种植红树林存活和生长的最佳策略（例如，增加沉积物和去除植被）。将建立一个数值模型来检验关于沼泽边缘侵蚀、垂直加积和红树林定居之间反馈的假设。他们将使用一个新开发的模型作为决策支持工具，对各种气候（SLR和冬季冻结）和管理（种植频率和位置）情景下的沼泽侵蚀和红树林分布进行概率预测。尽管该项目的重点是路易斯安那州，但红树林扩张的问题与全球低纬度沿海地区有关。该奖项反映了NSF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。

Mangroves – woody plants generally found on tropical coasts – are expanding northward due to warmer winter temperatures. Along the northern Gulf of Mexico coast, and especially in southern Louisiana, mangroves are starting to replace coastal marsh grasses. This could have a positive outcome as mangroves may be more effective than marsh grasses at stabilizing sediment and reducing the extremely rapid rate of marsh loss in the region (known as Louisiana’s Coastal Crisis). Because of the potential positive impact of mangrove colonization, some stakeholders in Louisiana have started planting mangroves through a grass-roots initiative called the Saint Bernard Parish Black Mangrove Planting Project. For this project the investigators will i) quantify the effectiveness of mangroves at reducing marsh edge erosion by wave attack, ii) identify techniques that promote the survival of planted mangroves, and iii) predict future mangrove distribution. This information will directly benefit coastal managers in Saint Bernard Parish, in coastal Louisiana, and in the northern Gulf of Mexico. Stakeholders will be involved through a formalized advisory board, and the results of this project will be communicated through townhall meetings. The investigators will work with the local high school and expand their environmental science curriculum. They will also start a citizen-science mangrove-expansion-monitor-program through a mobile phone application, aimed at informing the general public about plant ecology and coastal erosion. Through a combination of remote sensing analysis and field-based research, the investigators propose to quantify the unconstrained ecological engineering potential of mangroves to reduce marsh edge erosion rates, specifically, and change sediment and soil building dynamics along the shoreline, more broadly. They will identify the conditions that promote mangrove expansion at the fine scale, which is hypothesized to be linked to sediment released by marsh edge retreat, and quantify the ecogeomorphic changes that occur with a vegetation shift from marsh grass to mangrove. Field manipulation experiments will test the best strategies for planted mangrove survivorship and growth (e.g., sediment addition and vegetation removal). A numerical model will be developed to test hypothesis on feedbacks between marsh edge erosion, vertical accretion, and mangrove colonization. They will use a newly developed model as a decision-support tool to produce probabilistic predictions of marsh erosion and mangrove distribution under various climatic (SLR and winter freezes) and management (planting frequency and location) scenarios. Despite the project being focused on Louisiana, the issue of mangrove expansion is relevant for low latitude coastal areas globally.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.