Relationship Between Hydrological Characteristics and Plant Successions in the Mangrove Forest Sundarbans in Bangladesh (original) (raw)
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Status of major floral species of Indian Sundarban mangrove system.pdf
Relative abundance and Shannon-Weiner species diversity index of true mangrove species were estimated in 10 sampling stations of Indian Sundarbans during 2013. The mangrove patches in the selected stations were categorized into a 4-point scale depending on the values of Shannon-Weiner species diversity index. The health of the mangrove forest as per our constructed 4-point scale was found to be regulated primarily by anthropogenic factors, although in station like Sagar South, the natural erosion may be the key player in determining the mangrove floral diversity.
This study was conducted in the Sundarbans Mangrove Reserve Forest, Bangladesh by utilizing the stratified systematic sampling technique covering 55 compartments to determine the plant species composition, richness and diversity in relation to spatial habitats and salinity. A total of 61,189 individuals from 59 families comprising 135 genera with 182 species, and across all size classes of trees from 1.5-m height and above and other plant groups were enumerated and identified. There were five noteworthy collections of endangered status under the IUCN Red List category. Leguminosae and Gramineae were the two most dominant families by species while Sterculiaceae and Euphorbiaceae dominated by having large number of individuals. Simpson's and Shannon's indices of diversity registered moderate values due to high abundance of few species in the study site. High diversity of the streamsides and low salinity areas influenced the diversity of the entire Sundarbans. Species accumulation curves for different tree size classes showed irregular accumulation, while in the case of plants the accumulation was quite steep and continued to rise upward indicating high species richness compared to tree species. Multivariate cluster analysis and Principal Component Analysis (PCA) illustrated the effect of salinity in species distribution. The results are compared with past studies in the Sundarbans. This study suggests integration of biodiversity information with the existing Integrated Resource Management Plan in order for better planning and management of the biodiversity in the Sundarbans.
Tree diversity as affected by salinity in the Sundarban Mangrove Forests, Bangladesh
Bangladesh Journal of Botany, 2012
A botanical expedition to the Sundarban Mangrove Forests (SMF) in March, 2010 was made to study the tree diversity and their abundance as affected by salinity gradient. In six quadrats of 25m × 25m each, distributed in all four Ranges, a total of eight tree species were recorded. A maximum number of five species occurred in relatively low saline sites. Tree zonation dynamics of the forests along salinity gradient revealed an increase in the number of Ceriops decandra (goran), a salt tolerant plant in the north-eastern parts of the SMF which was dominated by Heritiera fomes (sundri), a freshwater loving plant in 1960's. Highest importance value index (IVI) was recorded for C. decandra, which was present in all sites, except Moroghodra, a freshwater zone in Nalianala (Khulna) Range. Comparison of the Landsat images of Nalianala and Chandpai Ranges during 1989, 2000 and 2010 revealed a decreased tendency of dominance of H. fomes in the two Ranges but increased tendency of Bruguiera sexangula (kankra), Excoecaria agallocha (gewa) and Sonneratia apetala (keora). Total tree cover in 2010 decreased by about 3% from that of 1989. The changes in the tree composition have been attributed to increased salinity. The changes in the physiography and tree composition of the two Ranges between 2000 -1989 were considerable.
Hydrologic monitoring and analysis in the Sundarbans mangrove ecosystem, Bangladesh
Journal of Hydrology, 2007
The unique habitat of the Sundarbans mangrove ecosystem is dependent upon the hydrological regime. Therefore, a comprehensive study to understand the hydrologic behaviour and the changes that have taken place due to anthropogenic activities in and around the area is fundamental to the management of natural resources and environment. In the past, ad hoc and uncoordinated efforts were made due to the inherent inaccessibility and high cost of data collection. The present article documents the results of the hydrologic monitoring, modelling and analysis in the Sundarbans. The study results show that the annual maximum tidal range has increased by about 0.75 m in the eastern and central parts during the last two decades. About 60% area remains in higher salinity condition (>20 ppt) for at least 1.5 months in a year. Organic pollution in the waterways is within the Environmental Quality Standard (EQS) of Bangladesh with the average Dissolved Oxygen (DO) of 5.99 mg/L. Total Ammonia, Nitrate (NO 3-N) and Phosphate (PO 4-P) level are present in sufficient quantity for the aquatic life to survive and are within EQS limit. Lead and Chromium occasionally exceed EQS limit especially along the large barge routes in the western part. The data and information presented in the paper will serve as a baseline for future hydrological and environmental studies.
Undergrowth species diversity of Sundarban mangrove forest (Bangladesh) in relation to salinity
ecology.uni-hohenheim.de, 2008
Undergrowth species diversity was investigated by random quadrat method. Ordination and Shannon-Wiener diversity index were produced by the CANOCO program and Cluster analysis was done by the SAS (Statistical Analylitical System, sixth version) program. 48 undergrowth species were recorded in the Sundarban mangrove forest belonging to the dominant families such as Fabaceae (Cynometra ramiflora, Dalbergia spinosa, Derris trifoliata), Poaceae (Myriostachya wightiana, Porteresia coarctata), Palmae (Nypa fruticans, Phoenix paludosa), Acanthaceae (Acanthus ilicifolius), Pteridaceae (Acrostichum aureum), Myrsinaceae (Aegiceras corniculatum), Rhizophoraceae (Rhizophora mucronata, Bruguiera gymnorrhiza). On the basis of frequency distribution of undergrowth vegetation data sets six undergrowth species were found to be dominant and widely adapted to the various salinity conditions in different zones of Sundarban mangrove forest, which were frequently occurring in most of the sites and quadrats such as Acanthus ilicifolius, Acrostichum aureum, Derris trifoliata, Vitis trifoliata, Sarcolobus globosus and Phoenix paludosa. The ordination of undergrowth species was assessed between environmental variables (salinity and pH) and undergrowth species. The ordination of undergrowth species revealed that some species are more saline tolerant, closely associated and widely distributed in the Sundarban mangrove forest like Derris trifoliata, Acanthus ilicifolius, Nypa fruticans, Sarcolobus globosus, Dalbergia spinosa, Flueggia virosa, Pandanus foetidus and Phoenix paludosa. It is interesting to note that salinity is a vital factor for the development of undergrowth species. It can also be concluded that the rich diversity of undergrowths of healthy individuals might be indicative of the healthy mangrove forest of the low saline zone area and poor diversity of undergrowths, as well as their stunted growth might be indicative of the ill mangrove forest of high saline zone area.
Salinity intrusion affecting the ecological integrity of Sundarbans Mangrove Forests, Bangladesh
International Journal of Conservation Science, 2017
The raising of the sea causes salinity intrusion into fresh water zones such as river, lake, floodplain and other lowlands. Salinity intrusion in the Mangrove forest is a continuous process. However, due to the increasing salinity ecological integrity of the Sundarbans have been largely affected. The compositional and functional aspects of flora and fauna have been changing at a great deal. The objective of this study is to delineate the changes of the structure and composition of the Sundarbans Mangrove Forest due to excess salinity intrusion and how salinity affect its biodiversity, wildlife habitat and other ecosystem components. This study reviewed related literature gathered through an extensive survey of various websites and the secondary data obtained from various departments with necessary modifications. The land use maps collected from the Bangladesh Forest Department were interpreted to achieve an elaborate classification of forest type and its gradual change with increasi...
Mangrove species distribution and water salinity: an indicator species approach to Sundarban
Journal of Coastal Conservation, 2017
The present study attempts to reveal the impact of salinity on mangrove species in terms of species distribution, and their trend of adapting to salinity changes. The study considers the mangrove species of entire Sundarban encompassing India and Bangladesh. The mangrove species distribution depends on a great deal on the salinity regime. Each mangrove species has optimal salinity range for its preferred habitat. This preference, as well as its tolerance level, may alter with the changing environmental regime. Based on this hypothesis, a few indicator species have been identified according to the preferred salinity. Ceriops and Avicennia have been identified as high salinity indicator species which are found in high frequency in the polyhaline zones, whereas Nypa and Heritiera are recognized as low salinity indicator species which show high abundance in oligohaline to mesohaline zones. Exoecaria and Bruguiera, the medium salinity indicator species, are found almost everywhere but are most abundant in the mesohaline zones. This study will help in evaluating the adaptive capacity of mangroves and also could build a functional relationship between their occurrences as indicator species with respect to the salinity.
Journal of Tropical Biodiversity and Biotechnology
The status of natural seedlings near localities in the Sundarbans Mangrove Forest was assessed through a stratified random sampling method to observe seedling composition and diversity, importance value index, family importance value, and species evenness. A total of 63 sample plots of 3,990 m2 area were surveyed in three natural and anthropogenic influenced salinity zones of Sundarbans. A total of 16,166 seedlings of 15 species under 12 families were found. Family Euphorbiaceae showed the highest (59.59%) family relative density and Rhizophoraceae presented the highest (20%) family relative diversity Index (FRDI). The maximum family importance value (FIV) showed by Euphorbiaceae (66.26) and the maximum importance value index (IVI) of species has been observed in Excoecaria agallocha (114.74). Excoecaria agallocha showed the highest relative density (59.6%) and relative abundance (39.87%) where the highest relative frequency (15.27%) was observed by Heritiera fomes. The mean stem d...
REGENERATION STATUS OF MAJOR MANGROVE SPECIES IN THE SUNDARBAN MANGROVE FOREST OF BANGLADESH
Natural regeneration can potentially play a major role in large-scale landscape restoration in mangrove areas of Bangladesh Sundarban. Both, biological and physical factors can affect the establishment and early stages along the development of trees. This study examined the response of natural regeneration of major mangroves species in the Sundarban. We recorded appearing of seedlings of different mangrove species in 30 permanent sample plots (PSP) of 400 m 2. The average number of seedlings appearing from 2000 to 2009 were recorded 36,363/year/ha although recruitment densities varied considerably among different parts of the forests. Heritiera fomes, Excoecaria agallocha, Ceriops decandra and other species together constituted 38.45%, 27.81%, 16.98% and 16.78% of the recruits (three months old seedlings) respectively. As well as the average number of seedlings appearing from 2010 to 2016 was found 31,752/year/ha. Heritiera fomes, Excoecaria agallocha, Ceriops decandra and other species together constituted 33.94%, 24.61%, 17.52% and 23.93% of the recruits (three months old seedlings) respectively. There is no statistically significant difference at the 5% level in the seedlings recruitment between the years 2000 to 2009 and 2010 to 2016. If adequate natural regeneration is not established by the end of the fourth growing season, then an alternative regeneration method may be implemented. Chronology of regeneration data revealed that natural regeneration is promising for the Sundarban mangrove forest to ensure a rich stocking in the future if other factors remaining favorable. Introduction The Sundarban, covering about one million ha in the delta of the rivers Ganga, Brahmaputra and Meghna is shared between Bangladesh (60%) and India (40%), and is the world's largest coastal wetlands. The area experiences a tropical monsoonal climate with an annual rainfall of 1,500 – 2,000 mm. Enormous amount of sediments carried by the rivers contribute to its expansion and dynamics. Salinity gradients change over a wide range of spatial and temporal scales. The biodiversity includes about 350 species of vascular plants, 250 fishes and 300 birds, besides numerous species of phytoplankton, fungi, bacteria, zooplankton, benthic invertebrates, mollusks, reptiles, amphibians and mammals. Species composition and community structure vary east to west and north to south, and along the hydrological and salinity gradients. Natural regeneration is the process by which the forest is naturally renewed; it is based on the recruitment of young plants deriving from seeds/propagules. Natural regeneration can successfully occur only if a sufficient amount of " growing space " is available for seed germination and subsequent growth of seedlings. Canopy trees strongly determine the understory light regime and tend to reduce the growing space for the recruitment of young trees into the canopy layer, thus consolidating their dominance. In natural mangroves, the onset of regeneration processes depends on