Showing papers on "Heritiera fomes published in 2021"

Species-Level Classification and Mapping of a Mangrove Forest Using Random Forest—Utilisation of AVIRIS-NG and Sentinel Data

Abstract: Although studies on species-level classification and mapping using multisource data and machine learning approaches are plenty, the use of data with ideal placement of central wavelength and bandwidth at appropriate spatial resolution, for the classification of mangrove species is underreported. The species composition of a mangrove forest has been estimated utilising the red-edge spectral bands and chlorophyll absorption information from AVIRIS-NG and Sentinel-2 data. In this study, three dominant species, Heritiera fomes, Excoecaria agallocha and Avicennia officinalis, have been classified using the random forest (RF) model for a mangrove forest in Bhitarkanika Wildlife Sanctuary, India. Various combinations of reflectance/backscatter bands and vegetation indices derived from Sentinel-2, AVIRIS-NG, and Sentinel-1 were used for species-level discrimination and mapping. The RF model showed maximum accuracy using Sentinel-2, followed by the AVIRIS-NG, in discriminating three dominant species and two mixed compositions. This study indicates the potential of Sentinel-2 data for discriminating various mangrove species owing to the appropriate placement of central wavelength and bandwidth in Sentinel-2 at ≥10 m spatial resolution. The variable importance plots proved that species-level classification could be attempted using red edge and chlorophyll absorption information. This study has wider applicability in other mangrove forests around the world.

Leaf morphological plasticity in three dominant tree species in the Sundarbans mangrove forest of Bangladesh in different salinity zones

Abstract: Mangrove tree species show plasticity in their leaf morphological traits in different salinity zones. However, leaf morphological plasticity and its causes in different salinity zones are incompletely understood. To understand the mechanism of plasticity, this study investigated the responses of three dominant tree species Sundri (Heritiera fomes), Gewa (Excoecaria agallocha) and Goran (Ceriops decandra) of the Sundarbans to the salinity gradients. A total of 17 leaf parameters were measured and quantified. All collected data were analyzed using univariate and multivariate statistical tools to investigate leaf morphological plasticity. A wide range of phenotypic plasticity was observed in all leaf parameters studied among the salinity zones of the Sundarbans. One-way ANOVA and Tukey’s posthoc test revealed significant differences (P < 0.05) in all leaf parameters among the salinity zones and confirming that there was a high degree of phenotypic plasticity among the salinity zones of the Sundarbans. Petiole length (PL), leaf area (LA) and leaf length/petiole length (LL/PL) showed high level of plasticity among the salinity zones of the Sundarbans for each species of Sundri, Gewa and Goran. Plasticity index (PI) was developed in this study for each species studied. High level of phenotypic plasticity in these leaf traits reflects fitness of these species to different saline environments. Our results provide clear evidence that all the leaf parameters measured for three tree species viz., Sundri, Gewa and Goran effectively utilizes a plastic strategy in different salinity zones in the Sundarbans. Morphological trait plasticity could serve as powerful biological indicators to predict the shift of leaf morphology in upcoming environmental change events like sea level rise and reduction of fresh water flow from upstream.

Litterfall assessment and reproductive phenology observation in the Sundarbans, Bangladesh: A comparative study among three mangrove species

Abstract: Bangladesh has the single largest mangrove forest in the world, which is under threat from catastrophic disturbance and anthropogenic pressure. The study investigated monthly reproductive litterfall and correlated with climatic factors from March 2016 to February 2018. We applied circular statistics to detect seasonal trends of reproductive litterfall of Heritiera fomes, Xylocarpus mekongensis and Bruguiera sexangula in the Sundarbans. Although flower and fruit fall of H. fomes and X. mekongensis occurred for a specific period. But B. sexangula continued throughout the year. Flower fall of all three species peaked during March. Fruit fall of H. fomes, and X. mekongensis peaked during July and August respectively and the propagule fall of B. sexangula peaked during July. The highest proportion of flower fall was recorded in B. sexangula (2.13 ± 0.29 Mg ha−1year−1) followed by X. mekongensis (1.23 ± 0.07 Mg ha−1year−1) and H. fomes (1.06 ± 0.09 Mg ha−1year−1). But the highest fruit fall was recorded in H. fomes followed by X. mekongensis and B. sexangula. Annual flower and fruit fall were significantly different (p

Anti-Bacterial, Anti-Diarrheal, and Cytotoxic Activities of Edible Fruits in the Sundarbans Mangrove Forest of Bangladesh

Abstract: This study evaluated anti-bacterial, anti-diarrheal, and cytotoxic activities of ten edible fruits (Aegiceras corniculatum, Avicennia officinalis, Bruguiera gymnorrhiza, Ceriops decandra, Heritiera fomes, Nypa fruticans, Phoenix paludosa, Sarcolobus globosus, Sonneratia caseolaris, and Xylocarpus mekongensis) in the Sundarbans mangrove forest of Bangladesh. Highest antibacterial activity was shown for ethanol:methanol (1:1) extracts of S. caseolaris (2 mg/disc), which demonstrated inhibition zones of 16.7, 17.0, 14.7, 15.7, and 15.7 mm against Escherichia coli, Klebsiella sp., Shigella boydii, Shigella sonnei, and Staphylococcus aureus, respectively. In mice with castor oil-induced diarrhea, S. caseolaris extract (250 mg/kg body weight) showed the highest inhibition (87.7%) and delayed the onset time (273 min) of diarrheal episodes, followed by A. corniculatum extract (inhibition, 83.6%; delayed onset time, 187.4 min). S. caseolaris and A. corniculatum fruit powders were successively fractionated into n-hexane, diethyl ether, chloroform, ethanol, and methanol. Antidiarrheal activity significantly increased with increasing polarity of these fractions. In brine shrimp lethality assay, S. globosus extract demonstrated the highest cytotoxicity (59.2 μg/mL), followed by H. fomes (74.1 μg/mL) and C. decandra (116.7 μg/mL); however, lowest cytotoxicity was shown for A. corniculatum, A. officinalis, and S. caseolaris extracts. Mice treated with A. corniculatum extract did not experience any acute toxicity. These results demonstrate that S. caseolaris and A. corniculatum fruits have potential to treat diarrhea and may act as useful nutraceuticals.

Does coal fly ash influence the growth of mangroves

Abstract: A 1320-Megawatt capacity coal-fired power plant is establishing near the Ecologically Critical Area of the Sundarbans, Bangladesh. This power plant will generate 0.71 million tons of coal fly ash annually. Most of the previous studies concentrated on the soil amelioration and growth and yield of agricultural crops. However, this study investigated the effects of coal fly ash on the seedling growth (collar diameter, height, and biomass) of the major tree species (Bruguiera sexangula, Excoecaria agallocha, Heritiera fomes, and Xylocarpus mekongensis) of the Sundarbans, as well as to assess the nutrient (N, P, and K) partitioning in their parts (leaf, stem, and roots). Mangrove soil and coal fly ash were mixed to get seven treatments say T0, T1, T2, T3, T4, T5, and T7, which contained 0%, 5%, 10%, 20%, 30%, 40% and 50% of fly ash (w/w) respectively. A significant (p

Exploration of Rhizospheric Microbial Diversity of the Indian Sundarbans: A World Heritage Site

Abstract: The mangrove cover of the Indian Sundarbans has reduced drastically by over 40% from the year 1776 to 2020. This has led various true mangrove species such as Sonneratia griffithii Kurz to become critically endangered, Heritiera fomes Buch. Ham. to be classified as endangered and Ceriops decandra Ding Hou, Aegialitis rotundifolia Roxb. and Phoenix paludosa Roxb. to be classified as near threatened. The factors affecting vegetation are both ecological and anthropogenic. From the ecological point of view, the tilting of the Bengal basin tectonically has resulted in the accumulation of excess saltwater in the Indian Sundarbans while most of the freshwater is being received in the Bangladesh side of the mangrove belt. As a result major stenohaline species are depleting. From the anthropogenic standpoint, forests are not only being cleared for dwelling but also for agricultural land use. Replantation programs over the years have not been sustainable as the nature of natural succession has not been maintained while planting of the seeds and seedlings in the tidal inundation zones, and as a result even the pioneering species have not been able to survive. We have identified core microbiomes from rhizospheric assemblages of several mangrove plants of which data from few ferns and two true mangroves are discussed here. Results of our analysis indicate that core microbiomes are plant specific and do not depend on sites of collection. Even core microbiomes are discernible for environmental soil niches as well. These data suggest that future replantation schemes require the microbiome niche to be maintained if successful restoration is to be achieved either in the form of suitable site-specific plantations or microbial consortium-based supplementations.

Climate Change Impact on Sundarbans: Challenges for Mitigation Strategies

Abstract: The Sundarbans, the largest single block of tidal halophytic mangrove forest, has been facing increased challenges due to the combined effects of natural and anthropogenic disturbances. Climate change coupled with anthropogenic disturbances poses a great threat to the existence of this mangrove. Many regions of the world are affected by climate change, but Sundarbans is one of the highest affected regions due to high level of salinity, sedimentation, and land erosion. The salinity is increasing day by day due to frequent cyclones, sedimentation, and brackish tiger prawn cultivation. The increased salinity is jeopardizing the ecosystems of Sundarbans and poses more risk than any other stressors. The study aims to assess the impact of salinity on the pioneer and indicator plant species in terms of species distribution and the coping capacity with the increased salinity. Primary data was collected from 30 sample plots which were fresh swamp and fresh–brackish swamp in the past. Secondary historical data was collected from the Forest Department to understand the natural dynamics. It was found that the fresh swamp forests disappeared from their historical range. The pioneer species, Heritiera fomes, and the indicator species Nipa fruticans and Phoenix pelludosa are being replaced by the invasive species and highly salt-tolerant Avicennia marina. An immediate action is required to stop tiger prawn culture and to restore the government-owned canals from the encroachers.

Growth and Yield of Avicennia Officinalis (Baen) L. And Heritiera Fomes (Sundri) Buch. Ham. Plantations Established From Plus Tree Seeds in the Western Coastal Belt of Bangladesh

Abstract: Abstract not available Asiat. Soc. Bangladesh, Sci. 46(2): 209-214, December 2020