Tree diversity as affected by salinity in the Sundarban Mangrove Forests, Bangladesh (original) (raw)
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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.
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...
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...
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.
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.
Abstarct This study involves an analytical investigations into the critical appreciation’s of the relationship between hydrological characteristics and plant successions in the Sundarbans Mangrove Forests in Bangladesh. In this study attempts have been taken to examine the relationship between the major floral species of the Sundarbans and the hydrological parameter. For the present study some major patches of the forests have been selected as the study area. Scientific statistical sampling methods were followed in selecting these areas. In order to achieve the objectives of the study, hydro-graphical charts and satellite imageries were used to show the different aspects of plant successions and hydrological influence in the study areas. The results of the statistical tests suggest that there are both positive and negative relations in the role of hydrology on the floral situation in the Sundarbans. Some part of the study area are comparatively less saline than that of others. This is happening due to discharge of the Ganges-Brahmaputra river system. This hydrological characteristics plays a vital role in changing the floral distribution of the Largest Mangrove Forest of the World. Key Words : Mangrove forest, Sundarbans, salinity, hydrological parameters, Bangladesh
Salinity: A Primary Growth Driver of Mangrove Flora
The biomass of three dominant mangrove species (Sonneratia apetala, Avicennia alba and Excoecaria agallocha) in the Indian Sundarbans, the designated World Heritage Site was evaluated to understand whether the biomass vary with spatial locations (western region vs. central region) and with seasons (pre-monsoon, monsoon and post-monsoon). The reasons for selecting these two regions and seasons are the contrasting variation in salinity. Although several other environmental variables do have impact on mangrove growth and survival, but their uniformity in these two sectors has lead us to nullify and ignore their regulatory roles. Among the three studied species, Sonneratia apetala showed the maximum biomass followed by Avicennia alba and Excoecaria agallocha. We also observed that the biomass varied significantly with spatial locations (p<0.05), but not with seasons. The variation may be attributed to different environmental conditions to which these forest patches are exposed to. Volume 2018; Issue 02
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.
Dendrochronologia, 2020
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