Ecological influences on regeneration dynamics in the sundarbans, Bangladesh: Exploring biotic and abiotic factors across time and space

Abstract

Natural regeneration is critical for sustaining mangrove ecosystems, particularly the Sundarbans, the world's largest mangrove forest. This study assessed the impacts of biotic and abiotic factors on regeneration dynamics, examining spatial variations across salinity zones and temporal changes (2010–2020) using data from 30 permanent sample plots (PSPs) established by the Mangrove Silviculture Division, Bangladesh Forest Research Institute. We found that the biodiversity of the Sundarbans remained relatively stable over time, with a high Müeller-Dombois Similarity Index and low Bray-Curtis Dissimilarity Index across years and zones. However, salinity variations influenced species composition. The study also revealed a decline in the dominance of Heritiera fomes and an increase in the abundance of Excoecaria agallocha (showed habitat expansion) over time while both species maintained a high importance value. The total biomass growth from living (77.84 Mg/ha) and newly established trees (14.39 Mg/ha) was low, while the biomass loss (81.79 Mg/ha) from the dead trees was significant. Furthermore, our analysis indicated that abiotic factors, including salinity, siltation, and soil pH, had minimal influence on plant functional traits, but changes in basal area notably affected biomass dynamics. These findings provide insights into the regeneration trends of the Sundarbans and guide the formulation of policies to manage this unique ecosystem sustainably.