Vegetation dieback and recovery may be dependent on the interplay between infrequent acute disturbances and underlying chronic stresses. Coastal wetlands are vulnerable to the chronic stress of sea-level rise, which may affect their susceptibility to acute disturbance events. Here, we show that a large-scale vegetation dieback in the Mississippi River Delta was precipitated by salt-water incursion during an extreme drought in the summer of 2012 and was most severe in areas exposed to greater flooding. Using 16 years of data (2007–2022) from a coastwide network of monitoring stations, we show that the impacts of the dieback lasted five years and that recovery was only partial in areas exposed to greater inundation. Dieback marshes experienced an increase in percent time flooded from 43% in 2007 to 75% in 2022 and a decline in vegetation cover and species richness over the same period. Thus, while drought-induced high salinities and soil saturation triggered a significant dieback event, the chronic increase in inundation is causing a longer-term decline in cover, more widespread losses, and reduced capacity to recover from acute stressors. Overall, our findings point to the importance of mitigating the underlying stresses to foster resilience to both acute and persistent causes of vegetation loss.

植被枯死和恢复可能取决于不常见的急性干扰和潜在的慢性胁迫之间的相互作用。沿海湿地容易受到海平面上升的长期压力，这可能会影响其对急性干扰事件的敏感性。在这里，我们发现密西西比河三角洲的大规模植被枯死是由 2012 年夏季极端干旱期间盐水入侵造成的，并且在遭受更严重洪水的地区最为严重。使用来自沿海监测站网络的 16 年数据（2007 年至 2022 年），我们发现枯萎病的影响持续了五年，并且在遭受更大洪水影响的地区仅部分恢复。枯死沼泽的洪水泛滥时间百分比从 2007 年的 43% 增加到 2022 年的 75%，同期植被覆盖和物种丰富度下降。因此，虽然干旱引起的高盐度和土壤饱和引发了严重的枯死事件，但洪水的长期增加正在导致覆盖范围的长期下降、更广泛的损失以及从急性应激源中恢复的能力下降。总体而言，我们的研究结果指出了减轻潜在压力以增强对植被丧失的急性和持续原因的恢复力的重要性。