Storm surge, not wind, caused mangrove dieback in southwest Florida following Hurricane Irma

Mangroves buffer inland ecosystems from hurricane winds and storm surge. However, their ability to withstand harsh cyclone conditions depends on plant traits and geomorphology. Using airborne lidar and satellite imagery collected before and after Hurricane Irma, we estimated that 62% of mangroves in southwest Florida suffered canopy damage, with largest impacts in tall forests (>10 m). Mangroves on well-drained sites (83%) flushed new leaves within one year after the storm. In poorly-drained sites, Irma triggered one of the largest mangrove diebacks ever recorded (10,760 ha), primarily affecting low elevation and interior mangrove areas dominated or co-dominated by A. germinans (73%). Our results show storm surge and ponding caused dieback, not wind. Identifying and monitoring vulnerable, low-lying coastal areas is essential to mitigate mangrove dieback from future storms.