Prolonged coastal inundation detected with synthetic aperture radar significantly retarded functional recovery of mangroves after major hurricanes.

Context: Hurricanes are major threats to coastal mangrove ecosystems. Inundation has been implicitly reported to associate with mangrove damages and mortality. However, there have been no spatial statistical analyses of the impact of inundation on mangrove recovery at landscape scales. Objectives: Our objectives are to detect spatiotemporal patterns of inundation after major hurricanes and to explore explicitly the role of inundation in mangrove recovery at landscape scale. Methods: Using C-band Synthetic Aperture Radar images, we detected the spatiotemporal pattern of surface flood and derived the spatial distribution of inundation depth under mangrove canopies based on surrounding surface flood and elevation along northern Puerto Rico coasts after major hurricanes in 2017. Based on the Enhanced Vegetation Index, we derived the short-term hurricane impact and the recovery ratio from 2018 to 2021, and analyzed the impact and the recovery of mangrove greenness by means of spatial error models. Results: The identification of surface flood reached very high accuracy. The severe impact is significantly explained by greater gust windspeed during the hurricane and lower elevation. More importantly, retarded mangrove greenness recovery is significantly explained by severer impacts, longer and deeper inundation, and heavier hurricane rainfall. Conclusions: Spatiotemporal heterogeneity in flood depth plays a significant and essential role in mangrove recovery and delayed mortality after major hurricanes. The derived flood depth turns out to be a better explanator of mangrove recovery than elevation, which highlights importance of landscape hydrology and topography with respect to mangrove response and restoration after major hurricanes. [ABSTRACT FROM AUTHOR]