M. N. I. Khan and U. Berger
Department of Forest Biometry and Systems Analysis, Institute of Forest Growth and Computer Sciences, Technical University Dresden, Germany
Along with the global depletion of mangrove ecosystems due to over-exploitation and other anthropogenic activities, sea level rise due to climate change may exert a potential impact to the salinity regimes in mangrove ecosystems. Sundarbans mangrove forest in Bangladesh shows distinctive vegetation composition in three salinity zones, e.g., fresh water, oligohaline and polyhaline zones, as the forest partially receives upland fresh water flow by the Ganges. Information on mangrove succession and the ecological processes behind it is still little known because of absence of long term monitoring data in this regard. Nevertheless, such information is important in understanding ecosystem processes and in analyzing forest planning and management options.
In this study, we evaluated the impact of different salinity regimes and inter-and-intra- specific competition on vegetation composition in Sundarbans and analysed the results in the light of succession, based mainly on simulated data and empirical data as well. For the purpose of simulation experiments, the KiWi mangrove model was parameterized in this study to a South Asian as well as tropical mangrove forest (Sundarbans) for the first time and it was found suitable to extract information on vegetation dynamics. The most dominant four mangrove species (Heritiera fomes Buch.-Ham.; Excoecaria agallocha L.; Ceriops decandra (Griff.) Ding Hou; Sonneratia apetala Buch.-Ham) were taken into account for this study. We used the simulation model to understand how species-dependent growth rate, salt tolerance and shade tolerance lead to the observed patterns in horizontal and vertical forest structure in Sundarbans. Our study will enrich scientific knowledge on mangrove structure and dynamics, which in turn will help building the adaptation measures to mitigate the adverse impacts posed by sea level rise to Sundarbans.
Key words: KiWi model, mangrove succession, simulation experiment, slat tolerance, shade tolerance