In response to current threats to salt marshes, there are increasing efforts to restore these vital coastal ecosystems and promote their resilience to global change drivers. Unfortunately, the economic cost associated with assessing the effectiveness of restoration is prohibitive and more information is needed about the trajectory and timing of restoration outcomes to improve restoration practices. Microbial communities provide essential salt marsh functions so assessing the degree to which microbial communities in restored marshes resemble reference marshes can serve as a proxy indicator for the potential return of microbial function. We studied a recently restored marsh located on Cape Cod, MA, USA, by examining shifts in the microbial community and sediment edaphic properties in three habitats of a degraded oligohaline marsh, both before and after restoration of tidal flooding and in comparison with three nearby S. alterniflora reference marshes that never had flow restrictions. We hypothesized that the microbial community would respond rapidly to the restoration and that over time these communities would be indistinguishable from reference marsh communities. We found that soil edaphic characteristics shifted along a trajectory of recovery toward the reference marshes, with increases in salinity and decreases in soil organic matter, percentage of carbon, and percentage of nitrogen. The microbial communities in all three habitats within the restored marsh were different from reference marshes, and both the prokaryotic and fungal communities within P. australis and Typha sp. habitats became more similar to reference marshes (similarities increasing from an average of 5 to 16% for prokaryotes and 3 to 10% for fungi) during the first 2 years after restoration. In that same time period, by contrast, there was no return of the native marsh vegetation. These results suggest that shifts in microbial community structure occur prior to shifts in marsh vegetation and may facilitate the successful revegetation of restored marshes. Understanding the recovery trajectory of marshes during restoration and the role that microbes play in promoting the long-term sustainability of these habitats is essential; these results suggest that microbial communities respond rapidly and in a positive direction to restoration efforts.

中文翻译：

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微生物对被动盐沼恢复的反应

为了应对当前对盐沼的威胁，人们正在加大力度恢复这些重要的沿海生态系统，并增强其对全球变化驱动力的适应力。不幸的是，与评估修复效果相关的经济成本令人望而却步，需要更多有关修复结果的轨迹和时机的信息以改善修复实践。微生物群落提供了基本的盐沼功能，因此评估恢复后的沼泽中微生物群落类似于参考沼泽的程度可以作为微生物功能潜在回报的替代指标。我们通过研究退化的盐沼沼泽地三个生境中微生物群落的变化和沉积物的浮游特性，研究了位于美国马萨诸塞州科德角的最近恢复的沼泽地，从未有流量限制的互花米草参比沼泽。我们假设微生物群落将对恢复做出快速反应，并且随着时间的推移，这些群落将与参考沼泽群落无法区分。我们发现，土壤盐分特征沿恢复轨迹向参考沼泽移动，盐分增加，土壤有机质，碳含量和氮含量下降。恢复的沼泽内所有三个生境中的微生物群落均不同于参考沼泽，而澳大利亚对虾和香蒲内的原核和真菌群落sp。在恢复后的最初两年中，生境变得与参考沼泽更加相似（原核生物的相似度从平均5％增加到16％，真菌相似性从3％增加到10％）。相比之下，在同一时期，原生沼泽植被没有恢复。这些结果表明，微生物群落结构的变化先于沼泽植被的变化发生，并且可能促进恢复的沼泽的成功植被恢复。了解沼泽在恢复过程中的恢复轨迹以及微生物在促进这些生境的长期可持续性中的作用至关重要；这些结果表明，微生物群落对修复工作迅速做出了积极响应。