Productivity, stability, and geomorphological evolution of New England salt marshes: Plum Island case study

新英格兰盐沼的生产力、稳定性和地貌演化：普拉姆岛案例研究

• 批准号: 0617209
• 负责人: Brad Murray
• 金额: $ 12.07万
• 依托单位: Duke University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-07-01 至 2009-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0617209&HistoricalAwards=false
• 关键词: Productivity; stability; geomorphological; evolution; New

Coastal salt marshes are well recognized for their important ecological functions and societal values, providing great value as habitat and nursery grounds for commercially important fin and shellfishes, and as storm abatement. The Nation is currently losing much of its coastal marsh habitat. Several factors, including changes in sea-level-rise rates, influence salt-marsh growth and decline. However, changes in sediment supply caused by changing terrestrial land uses may have dominated the evolution of New England salt marshes in recent centuries. This project involves examination of sediment layers to investigate the hypothesis that the existing extensive marshes in this region developed recently and rapidly, in response to the increased sediment yield associated with colonial deforestation. If this hypothesis is true, it is possible that in this region (which now has less sediment washing off of reforested and developed landscapes) marshes are presently maintaining a precarious balance, relying on the continued sediment-trapping and stabilizing influences of marsh grasses. The vegetation influence helps the marsh surface gain elevation so that it does not disappear as sea level rises. However, accelerating rising sea level increases the amount of water that floods into and out of the marshes with the tides, increasing tidal currents and tending to cause erosion in the channel networks that intertwine through tidal marshes. Preliminary experiments with a simplified computer model suggest that if vegetation is disturbed in a marsh subjected to high rates of sea-level rise and/or reduced sediment delivery, this erosion could spread laterally, irreversibly converting marsh to open water. This project will employ field observations to further develop the model, and use it to explore how marshes and tidal networks evolve as vegetation influences, tidal currents, sea-level rise, and changing land use/sediment supply all interact. The results will have considerable broader impact across both scientific subdisciplines (ranging from landscape evolution to strictly ecological studies) and societal issues (ranging from storm abatement to land-use management).

沿海盐沼因其重要的生态功能和社会价值而得到广泛认可，为商业上重要的鳍类和贝类提供了栖息地和育苗地，并为减少风暴提供了巨大的价值。美国目前正在失去大部分沿海沼泽栖息地。有几个因素，包括海平面上升速率的变化，影响着盐沼的生长和下降。然而，近几个世纪以来，陆地土地利用变化引起的沉积物供应变化可能主导了新英格兰盐沼的演变。该项目包括检查沉积层，以调查该地区现有的广泛沼泽最近迅速发展的假设，以应对与殖民森林砍伐有关的沉积物产量增加。如果这一假设是正确的，那么在这个地区（现在从重新造林和开发的景观中冲走的沉积物较少），沼泽目前可能维持着一种不稳定的平衡，依赖于沼泽草持续的沉积物捕获和稳定作用。植被的影响有助于沼泽表面升高，因此它不会随着海平面的上升而消失。然而，海平面的加速上升增加了随潮汐流入和流出沼泽的水量，增加了潮汐流，并容易导致潮汐沼泽交织的水道网络受到侵蚀。用一个简化的计算机模型进行的初步实验表明，如果在海平面上升速度快和/或沉积物输送减少的沼泽中，植被受到干扰，这种侵蚀可能会横向扩散，不可逆转地将沼泽转变为开阔水域。该项目将采用实地观测进一步发展模型，并利用它来探索沼泽和潮汐网络如何随着植被影响、潮流、海平面上升和不断变化的土地利用/沉积物供应相互作用而演变。研究结果将对科学分支学科（从景观演变到严格的生态学研究）和社会问题（从减少风暴到土地使用管理）产生相当广泛的影响。