Sea-level rise is leading to the migration of marshes into coastal forests throughout North America. Marsh migration represents a primary mechanism for marsh survival in the face of sea-level rise and leads to a fundamental reorganization of vegetation communities. Yet, the ecological implications of these changes remain unknown. To evaluate the effect of marsh migration on ecosystem function, we compared habitat, primary production, vertical accretion, nutrient cycling, and carbon accumulation between new and old salt marsh on Goodwin Island (Virginia, USA) where salt marsh is migrating landward into rapidly retreating coastal forest. Using historical imagery and radioisotopic dating of sediment cores, we determined marsh age (< 3 to approximately 616 years) across the landscape. We found that salt marsh functions generally depended more on elevation and/or landscape position than marsh age. Primary production and nutrient cycling (%C and %N soil content) did not vary significantly with marsh age. Accretion and carbon accumulation rates varied predictably with elevation in old marsh but not in new marsh. Instead, trends in soil formation were controlled by the colonization of Phragmites australis, a dominant plant in migrating marsh-forest boundaries along the Atlantic Coast. Vegetation zonation patterns were more clearly defined in old marsh, indicating that habitat types take time to develop. However, these vegetation differences did not translate to consistently different ecological functions. These observations suggest that marsh migration does not lead to permanent differences in ecological functions between new and old marsh, rather ecological functions will converge as new marsh ages.

海平面上升导致沼泽迁移到整个北美的沿海森林。面对海平面上升，沼泽迁移是沼泽生存的主要机制，并导致植被群落的根本重组。然而，这些变化的生态影响仍然未知。为了评估沼泽迁移对生态系统功能的影响，我们比较了古德温岛（美国弗吉尼亚州）新旧盐沼的栖息地、初级生产、垂直增长、养分循环和碳积累，这里的盐沼正在向陆上迁移并迅速退缩。沿海森林。使用沉积物核心的历史图像和放射性同位素测年，我们确定了整个景观的沼泽年龄（< 3 到大约 616 年）。我们发现盐沼功能通常更多地取决于海拔和/或景观位置，而不是沼泽年龄。初级生产和养分循环（%C 和 %N 土壤含量）不随沼泽年龄而显着变化。旧沼泽地的吸积和碳积累率随海拔的升高而变化，而新沼泽地则不然。相反，土壤形成的趋势是由殖民化控制的芦苇，一种沿大西洋海岸迁移沼泽森林边界的优势植物。古老沼泽中的植被分区模式更明确，表明栖息地类型需要时间发展。然而，这些植被差异并没有转化为始终不同的生态功能。这些观察结果表明，沼泽迁移不会导致新旧沼泽之间生态功能的永久性差异，而是随着新沼泽年龄的增长，生态功能会趋同。