A mangrove community along the oligohaline zone of the Sundarbans Reserve Forest (SRF), Bangladesh was selected to study stand structure, biomass accumulation, and carbon storage. Field data were measured from six plots of 2400 m 2 at three different locations. Species diversity and species wise contribution to total biomass carbon (TBC) were also analyzed. Heritiera fomes has maintained its dominance (53.8%, relative density) of the stand. The mean above-and below-ground biomass carbon stock of the mangrove community was 76.8 Mg ha¡1 and 41.1 Mg ha ¡1 , respectively. Avicennia officinalis contributed the highest TBC accumulation. Individuals of different mangrove species having diameter 9.99 cm constituted more than 72% of the mangrove stand but contributed less in carbon accumulation, representing only 15.6% of the TBC. While individuals having diameter in the 10-56 cm range constituted only 28% of stand density but contributed to high carbon accumulation, representing 84.4% of the TBC. Mangrove communities growing along the oligohaline zone of the SRF show high species richness and carbon stock, indicating their ecological significance, This needs to be considered in future decision making processes for the area as well as in understanding the role of SRF on mitigating the effects of climate change.

Litterfall production and litter decomposition are the principal factors for controlling the functions of mangroves to store and cycle carbon and nutrients within the ecosystem. We analyzed the litterfall production, its seasonality, patterns and changes of mass loss, carbon, and nitrogen content of litterfall decomposition in different locations as well as different position of decomposition bags in Sundarbans Reserve Forest (SRF). Total annual litterfall production was 1005.9 ± 7.0 g m À2 yr À1 and leaves being the principal contributor of all the studied location throughout the study period. During the decomposition experiment, the litterfall lost 20% of its original mass in the first 60 days, and this loss continued to 50% of its original weight by the end of the experiment (196 days). There was not significant difference in the mass loss at different positions or sites during the experiment period. Monthly mean total carbon and nitrogen mass in litterfall accounted for 344.6 ± 28.7 kg ha À1 and 8.7 ± 0.7 kg ha À1 , respectively. The pattern for nitrogen content showed increasing trend throughout the experiment period. Mangrove communities growing along the oligohaline zone showed higher nutrient concentration than other mangrove areas indicating their ecological significance and also efficiently retain C and N.

A large number of mangrove species are growing in the Sundarbans Reserve Forests (SRF), Bangladesh, yet little is known about their phenology. The aim of the present study was to understand the phonological patterns such as leaf emergence, leaf fall, flower buds, flowers, and propagules maturation, in the mangrove Bruguiera sexangula using litterfall data. This study was conducted at Karamjol and Ghagramari areas of SRF, Bangladesh and using litterfall data over two (2) years. Leaf and stipule litterfall occurred throughout the years, with distinct seasonal patterns. New leaf production was significantly correlated with monthly day length. Mean total litterfall was 18.75 Mg ha À1 yr À1 , with the largest component being vegetative organs (68.4%). Flowers and propagules litterfall were highest in summer and rainy season, respectively. Kendall's coefficient of concordance, W, revealed that flower and propagule were significantly concordant during the study years. Flowers and propagules litterfall were significantly influenced by monthly day length and rainfall, respectively. The development of propagule could be affected by the climate during the development and the number of flowers etc. The average development period from flowers to propagules was around 4 months. B. sexangula did not show any correlation between leaf emergence and reproductive organs production.

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The study of vegetative and reproductive phenology through litterfall collection of mangrove species is vital for mangrove management and restoration in climate change situation. This study was carried out to investigate vegetative and reproductive phenological pattern of Heritiera fomes using litterfall data in the Sundarbans, Bangladesh for a period of 24 months. Leaf and stipule litterfall released throughout the year with a distinct periodic pattern. Vegetative litterfall (981.9-1211.3 g/sq m/yr) contributed 59.3% of total litterfall (1791.1-1907.3 g/m/yr). The order of vegetative litterfall was leaf > branch > stipule. Peak flowering and mature fruit litterfall were noticed in April (1.52 times of mean monthly flower production) and July (1.56 times of mean monthly production), respectively. Analysis of variance (ANOVA) showed significant difference (p < 0.05) among monthly litterfall productions, whereas t-test showed no significant difference (p > 0.05) of litterfall production between two successive years during study periods. Vegetative and flower litterfall were significantly influenced by maximum wind speed, mean monthly temperature and day length. On the contrary, mature fruits were significantly correlated with rainfall.