Salinity intrusion affecting the ecological integrity of Sundarbans Mangrove Forests, Bangladesh (original) (raw)
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SALINTY INTRUSION AFFECTING THE ECOLOGICAL INTEGRITY OF SUNDARBANS MANGROVE FORESTS, BANGLADESH
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 increasing salinity. Observations at the periphery of Sundarbans explore the effect of salinity on the population, livestock, aquatic species and the paddy fields. We used ArcGIS 9.3 to visualize the salinity prone zones, the boundary of administrative zones and the forest type to identify the causes and intensity of the issues, and to suggest the appropriate mitigating measures. The study states that the salinity intrusion causes the reduction of fresh water availability in Sundarbans. As a result, fresh water loving species are replaced by the species of the saline zone. Most of the areas are found with the small and bushy typed species that reduce biomass in comparison with their standard volume. The study reveals the effects of salinity intrusion in the Sundarbans Mangrove Forest which may affect its compositional, structural and functional integrity. Long-term and short-term policies are recommended to resolve the issues.
Dominant species losing functions to salinity in the Sundarbans Mangrove Forest, Bangladesh
Elsevier, 2022
Globally, mangrove forests are deteriorating due to several natural and anthropogenic factors such as sea level rise, habitat fragmentation, over-exploitation, pollution, etc. Sea-level rise-driven salinity would influence the functional activity of dominant species by declining their structure and functions, which is not well understood. Therefore, we tried to understand the increased salinity impact on the structures and functions of two identified dominant mangrove species (i.e., Excoecaria agallocha and Heritiera fomes) in the Sundarbans Mangrove Forest (SMF), Bangladesh. We test our hypothesis that salinity significantly retards the functions of dominant species structure and functions by evaluating two consecutive years of inventory data from 60 permanent sample plots (100 m 2 each) established in three distinct salinity zones in the SMF. The study revealed that structural parameters of dominant species such as tree height, diameter at breast height (DBH), and basal area decreased in higher saline zones than in less saline zones. E. agallocha and H. fomes stored more biomass and carbon in less saline and moderate saline zones compared to high saline zone. Besides, functional variables such as aboveground biomass carbon and total biomass carbon decreased with salinity for both dominant species. This study demonstrated that salinity shapes dominant species by declining their height, DBH, growth, etc., which indicates salinity is a critical discriminating variable for losing species' stand structures and functions. This information is critica to determine the physiological response of dominant species across the globe, which is crucial to predicting future climate change impacts such as sea-level rise.
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.
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.
AACL Bioflux, 2010
The Sundarban forest, located in the southwest of Bangladesh, is one of the largest continuous blocks of mangrove forests in the world. This mangrove forest ecosystem in Bangladesh is now in captious position. Negative natural and anthropogenic impacts and overexploitation of natural resources have caused severe damage to the ecosystem. Growing human population with few alternative livelihood opportunities poses a serious threat to the mangrove forest. The rapidly expanding shrimp farming industry is a significant threat to the mangrove forests of Bangladesh. Due to illegal cutting, encroachment of forest areas and illegal poaching of wildlife, the mangrove forest is losing biodiversity in an alarming rate. This forest ecosystem also has become vulnerable to pollution, which may have changed the ecosystem's biogeochemistry. Further threats arise from global climate change, especially sea level rise. This study seeks to identify the root causes of deterioration of the Sundarban mangrove forest in Bangladesh. It also recommends the application of sustainable management strategies covering needs for an advanced silvicultural system, improvement of scientific research as well as conservation measures.
Trends of Sundarbans Mangroves Biodiversity Declination in Bangladesh
Academia letters, 2022
The mangrove biodiversity declination is a source of concern to researchers around the world. The biodiversity of the Sundarbans is declining day by day like all the forests of Bangladesh. This study will provide you with a brief overview of the significant surveys of the Sundarbans from 1892 to 2016. It will also be possible to find out the reasons behind the destruction of biodiversity in the Sundarbans. A brief suggestion of what steps we should take to protect biodiversity is discussed.
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.
The Sundarbans is situated in the Ganges transboundary catchment which is known as the single largest mangrove ecosystems in the world and covers 10,000 km² between Bangladesh and India. Since the diversion of Ganges water at Farakka Barrage in India from early 1975, salinity level has increased drastically in the south western part of Bangladesh. Due to reduction of fresh water flow urban drinking water supply, industrial production, agriculture, fisheries, navigation, hydromorphology and mangrove wetlands ecosystems have been affected. Urban area both surface and groundwater have become unfit for human consumption. In the consequences about 0.170 million hectares (20.4%) of new land, and almost 27 small towns have been affected by various degrees of salinity during the last three decades. The saline front defined by 6 dS/m iso-haline has penetrated up to 173 km north from the coast. The salinity has exceeded the recommended level 1 dS/m for potable water. It is a new threat to supply quality drinking water to the small towns in the south western region in Bangladesh. The dominant mangrove Heritiera fomes and Ceriops decendra species are affected by top dying disease which is recognised as key management concern. The Fourier Polynomial water salinity models on Sundarbans rivers are showing the cycling increasing behaviour. The findings of this study a potential contribution for making comprehensive management plan are for urban water supply, and protection of the mangrove wetlands ecosystems in the Sundarbans region.
Archives of Applied Science Research, 2013
In estuarine areas of the mangrove forest of Sundar bans, surface water salinity variations through tid es, seasons and spaces were studied in a comprehensive way for the first time along with dilution efficiencies and extent of salinity exposure. Since Sundarbans is influenced b y several numbers of rivers in a criss-crossed way, the entire area has been divided as western sector (under Hoog hly, Saptamukhi and Thakuran rivers respectively), the middle sector under Matla and Bidya river (MB estuary) and eastern areas influenced by Gosaba, Harinbhanga, Jand Raimangal rivers (GHJR estuary). Study revealed tha t unlike western sectors, the tidal variations of salinity in other areas were less with negligible salinity difference (1.4 to 2.0 psu) between high and low tides. In co ntrast, pronounced seasonal variations of salinity were enc ountered (9.34 to 30.83 psu) in the region. The mos t parts of the Sundarban attained almost equal level of salinity i n monsoon (12.0 to 14.0 psu) an...