LTREB: Long-term Changes in Experimental Salt Marsh Plots: Effects of Chronic Eutrophication and Sea Level Rise.

氮富集和海平面上升是沿海生态系统（包括盐沼）生态变化的主要和加剧因素。我们建议在马萨诸塞州东部大Sippewissett沼泽的实验地块中定义慢性富营养化和海平面上升的长期影响和相互作用。自1970年以来，我们一直在10米半径范围内绘制植被和海拔图，实验施肥了4种剂量的氮。初步数据显示，由于富营养化和海平面上升，在形式、覆盖、生物量和空间分布方面持续发生长期变化。在我们33年的研究中，海平面上升了12-14厘米，在未富集的地块上，低沼泽植被以牺牲高沼泽植被为代价扩张。相比之下，在施肥的地块，增加的氮供应刺激了高沼泽植物的生长，这些植物的厚茅草增加了有机质的积累，有利于从洪水中捕获沉积物颗粒，从而抵消了淹没。我们假设氮供应的增加和海平面的上升改变了不同种类沼泽植物之间竞争成功的方向，并迫使长期的相互作用彻底改变了盐沼植物和依赖动物群落的空间配置和组成。对这些地块的持续研究提供了一个无与伦比的机会，可以了解全球河口发生的慢性氮富集和海平面上升的相互作用如何重构盐沼生态系统。我们还将上传和分析这些地块的大量过去数据记录，以发表长期影响，并与其他研究人员分享。

Nitrogen enrichment and sea-level rise are major and intensifying agents of ecological change in coastal ecosystems, including salt marshes. We propose to define long-term effects and interactions of chronic eutrophication and sea-level rise within experimental plots in the Great Sippewissett marsh in Eastern Massachusetts. Since 1970, we have been mapping vegetation and elevation within 10 m radius plots experimentally fertilized with 4 dosages of nitrogen. Preliminary data show continuing long-term shifts in form, cover, biomass and spatial distribution due to both eutrophication and sea-level rise. In un-enriched plots low marsh vegetation expanded at the expense of high marsh vegetation in response to the 12-14 cm sea-level rise during the 33 years of our studies. In fertilized plots, in contrast, increased nitrogen supply stimulated growth of high marsh plants whose thick thatch increased organic matter accumulation and favored capture of sediment particles from flooding water, thus countering submergence. We hypothesize that increased nitrogen supply and rising sea-level alter direction of competitive success among different species of marsh plants, and force long-term interactions that thoroughly reshuffle spatial disposition and composition of swards of salt marsh plants, and dependent animal communities. Continuing study of these plots offers an unmatched opportunity to understand how the interaction of chronic nitrogen enrichment and increased sea-level rise that is occurring in estuaries world-wide will restructure salt marsh ecosystems. We will also upload and analyze the extensive past data record for these plots for publication of long-term impacts, and sharing with the other researchers.