Diversity and assemblage of mangroves along the carigara bay in Leyte, Philippines

Abstract

The paper presents a detailed ecological investigation of mangroves (trees and palm) along Carigara Bay in Leyte, Philippines by comparing the diversity, vegetation structure, species composition, and indicator species among forest types (riverine and fringe) and zones (landward, middleward, and seaward/along water) as well as by examining their relationships with environmental variables. A total of 22 mangrove species, belonging to 12 families were documented wherein the most abundant was Sonneratia alba, followed by Nypa fruticans, then by Avicennia rumphiana. It was found that the diversity (Shannon-Wiener) of riverine mangroves (0.94 ± 0.07; 1.20 ± 0.04) was significantly higher than the fringe at the middleward and seaward/along the water (p < 0.001). In the fringe mangrove forests, the mangrove species Aegiceras corniculatum was associated with the middleward zone, and Camptostemon philippinensis, Aegiceras floridum, Rhizophora mucronata, Sonneratia alba, and Lumnitzera littorea were associated with the seaward zone, whereas landward zone of fringe and all the zones in riverine were generally associated by species with low to optimum salt tolerances such as Nypa fruticans, and Avicennia rumphiana as the most abundant. As well, a total of 14 mangroves have been identified as indicator species. Lastly, mangrove species can be generally classified as riverine and fringing based on the environmental factors explaining their distributions, and it has been found that soil porosity, water content, soil salinity, and distance from the sea or river’s edge were the most significant environmental factors that determine diversity patterns.