Dataset: Ordered Mortality of Mangroves under Extreme Flooding in a Tropical Microtidal Estuarine Lagoon in China

The field investigation was conducted in January 2012, three months after the flooding event. We established two transects near the Longxi Bridge (site A and B; Fig. 1c), where the dominant species in the study area, C. tagal, was prevalent. Each transect was divided into zones with a width of 5 meters, and in each zone, we set up three 5 × 5 square meters plots for mangrove plant surveys (Fig. 1g). Site A and Site B underwent the same surveys, differing only in the length of the transects. The relative elevation of each sample plot was measured relative to the seaward edge of the fringe forest (i.e., the elevation of the seaward edge was set to 0; Fig. 1g). Elevation data in each plot were measured using the five-point method, and the average elevation of the three plots within each zone (15 measurements in total) was calculated as the average elevation for the entire zone. In each plot, we recorded the species and health status of every tree. The health status assessment, conducted by the same author, categorized trees into four levels based on their condition: healthy, acceptable, compromised, and dead. These categories were assigned values (healthy = 3, acceptable = 2, compromised = 1, dead = 0). Trees with more than 50% fresh leaf cover were considered healthy, while those with 20-50% fresh leaf cover were deemed acceptable. Compromised trees had a fresh leaf cover between 0% and 20%, while trees without any fresh leaves were considered dead. Additionally, in the middle zone of site A, we recorded the height of each tree within three plots. Since C. tagal often grows densely, we could only measure the height of a few individuals at the edges using a height rod. Therefore, researchers were trained to estimate tree height. All height estimates were made simultaneously by the same volunteer. Additionally, we selected three healthy living individuals of C. tagal from each zone and randomly chose five branchlets from each plant to count the number of leaves and propagules. Since there were fewer than three surviving C. tagal in the lowest elevation areas, all available trees were sampled. Additionally, in areas where Avicennia marina, Rhizophora apiculata, and Scyphiphora hydrophyllacea were clustered, we recorded the height and health status of many individuals, using the same methods as for C. tagal. The number of surveyed individuals for these three species was 97, 1572, and 778, respectively.