Stand structure, tree species diversity, and leaf morphological plasticity in Xylocarpus mekongensis Pierre among salinity zones in the Sundarbans, Bangladesh

Abstract

Stand structure, diversity, and plasticity of leaf morphology of Xylocarpus mekongensis were investigated among saline zones in Bangladesh Sundarbans. Stand structure and species diversity were assessed in 27 sample plots (20 m× 20 m) covering 1.08 ha of forest. A total of 11 species were recorded. Out of them, 7, 6, and 9 species were found in fresh water, moderate, and strong saline zone, respectively. Species dominance in terms of importance value showed Heritiera fomes > Excoecaria agallocha > Bruguiera sexangula > Xylocarpus mekongensis in fresh water zone; H. fomes > E. agallocha > Avicennia officinalis > Ceriops decandra in moderate saline zone. E. agallocha > Sonneratia apetala > H. fomes > C. decandra in strong saline zone. Species diversity decreased from fresh water to strong saline zone. The findings showed a wide range of leaf morphological plasticity of all the parameters within and among saline zones. Leaf index, plasticity index, and specific leaf area were maximum in fresh water zone than of others. The findings of PCA revealed clear evidences of plastic behavior of leaf morphological parameters. Thus, the plasticity of leaf morphology might contribute as an influential biological signs of forthcoming climate change events. • We investigated the effect of saline zone on stand structure and diversity on mangrove species in the Sundarbans. • We also investigated leaf index, leaf plasticity index, and specific leaf area among saline zones of Bangladesh Sundarbans. • Tree species diversity decreased from fresh water zone to strong saline zone. • Xylocarpus mekongensis showed high level of leaf morphological plasticity within and among saline zones.