Habitat fragmentation is known to be one of the leading causes of species extinctions, however few studies have explored how habitat fragmentation impacts ecosystem functioning and carbon cycling, especially in wetland ecosystems. We aimed to determine how habitat fragmentation, defined by habitat area and distance from habitat edge, impacts the above-ground carbon cycling and nutrient stoichiometry of a foundation species in a coastal salt marsh. We conducted our research in a salt marsh in the Mid-Atlantic United States, where the foundation grass species Spartina patens is being replaced by a more flood-tolerant grass, leading to highly fragmented habitat patches. We quantified decomposition rates, live biomass, and litter accumulation of S. patens at patch edges and interiors. Additionally, we measured relevant characteristics (e.g., habitat area, elevation, microclimate) of S. patens patches. Habitat edge effects, and not habitat area effects, had distinct impacts on ecosystem functioning. Habitat edges had less litter accumulation, faster decomposition rates, a warmer and drier microclimate, and lower elevations than patch interiors. Patches with low elevation edges had the fastest decomposition rates, while interiors of patches at any elevation had the slowest decomposition rates. Notably, these impacts were not driven by changes in primary production. Habitat fragmentation impacts the above-ground carbon cycling of S. patens in coastal wetlands by altering litter decomposition, but not primary production, through habitat edge effects. Future research should investigate whether this pattern scales across broader landscapes and if it is observable in other wetland ecosystems.

中文翻译：

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栖息地边缘效应减少了沿海盐沼的垃圾堆积并增加了垃圾分解

众所周知，栖息地破碎化是物种灭绝的主要原因之一，但很少有研究探讨栖息地破碎化如何影响生态系统功能和碳循环，尤其是在湿地生态系统中。我们旨在确定由栖息地面积和与栖息地边缘的距离定义的栖息地破碎如何影响沿海盐沼中基础物种的地上碳循环和营养化学计量。我们在美国中大西洋的一个盐沼中进行了研究，那里的基础草种 Spartina patens 被一种更耐洪水的草所取代，导致栖息地斑块高度分散。我们量化了斑块边缘和内部的 S. patens 的分解率、活生物量和凋落物积累。此外，我们测量了相关特征（例如，S. patens 斑块的栖息地面积、海拔、小气候）。栖息地边缘效应，而不是栖息地面积效应，对生态系统功能有明显的影响。与斑块内部相比，栖息地边缘的垃圾堆积较少，分解速度较快，小气候更温暖干燥，海拔较低。具有低海拔边缘的补丁的分解速度最快，而任何海拔的补丁内部的分解速度最慢。值得注意的是，这些影响并不是由初级生产的变化驱动的。栖息地破碎化通过栖息地边缘效应改变凋落物分解而不是初级生产，从而影响沿海湿地 S. patens 的地上碳循环。