Showing papers on "Heritiera fomes published in 2016"

Photo-mediated green synthesis of silver and zinc oxide nanoparticles using aqueous extracts of two mangrove plant species, Heritiera fomes and Sonneratia apetala and investigation of their biomedical applications.

Abstract: Green synthesis by using biological agents has been a simple and effective approach for the synthesis of various forms of nanoparticles. The present investigation was intended to synthesis Ag-NPs and ZnO-NPs under photo-condition using the aqueous extracts of two mangrove plants namely Heritiera fomes and Sonneratia apetala and evaluate their potential biomedical applications. The formation of nanoparticles in aqueous solution of H. fomes and S. apetala under exposure to sun light was validated by change in color and formation of monodispersed NPs with a narrow particle size distribution. Fourier transform infrared spectroscopy (FT-IR) reveals the presence of Oxime and other heterocyclic compounds to be the most probable compounds responsible for the reduction and stability of nanoparticles in the solutions. The synthesized NPs displayed moderate free radical scavenging properties. The anti-inflammatory potential of ZnO-NPs was recorded to be comparatively higher than that of Ag-NP with 79% and 69.1% respectively. The Ag-NPs with unique properties of inhibiting α-amylase (91.14% and 89.16%) were found to be significantly high indicating its antidiabetic property. The synthesized NPs showed varied zone of inhibition (9-16mm) against the tested microbial pathogens. The synthesized nanoparticles possess strong biological activities in terms of antioxidant, anti-inflammatory, antidiabetic and antibacterial, potentials which could be utilized in various biological applications by the cosmetic, food and biomedical industries.

Are we failing to protect threatened mangroves in the Sundarbans world heritage ecosystem

Abstract: The Sundarbans, the largest mangrove ecosystem in the world, is under threat from historical and future human exploitation and sea level rise. Limited scientific knowledge on the spatial ecology of the mangroves in this world heritage ecosystem has been a major impediment to conservation efforts. Here, for the first time, we report on habitat suitability analyses and spatial density maps for the four most prominent mangrove species - Heritiera fomes, Excoecaria agallocha, Ceriops decandra and Xylocarpus mekongensis. Globally endangered H. fomes abundances declined as salinity increased. Responses to nutrients, elevation, and stem density varied between species. H. fomes and X. mekongensis preferred upstream habitats. E. agallocha and C. decandra preferred down-stream and mid-stream habitats. Historical harvesting had negative influences on H. fomes, C. decandra and X. mekongensis abundances. The established protected area network does not support the most suitable habitats of these threatened species. We therefore recommend a reconfiguration of the network to include these suitable habitats and ensure their immediate protection. These novel habitat insights and spatial predictions can form the basis for future forest studies and spatial conservation planning, and have implications for more effective conservation of the Sundarbans mangroves and the many other species that rely on them.

Mapping Long-Term Changes in Mangrove Species Composition and Distribution in the Sundarbans

Abstract: The Sundarbans mangrove forest is an important resource for the people of the Ganges Delta. It plays an important role in the local as well as global ecosystem by absorbing carbon dioxide and other pollutants from air and water, offering protection to millions of people in the Ganges Delta against cyclone and water surges, stabilizing the shore line, trapping sediment and nutrients, purifying water, and providing services for human beings, such as fuel wood, medicine, food, and construction materials. However, this mangrove ecosystem is under threat, mainly due to climate change and anthropogenic factors. Anthropogenic and climate change-induced degradation, such as over-exploitation of timber and pollution, sea level rise, coastal erosion, increasing salinity, effects of increasing number of cyclones and higher levels of storm surges function as recurrent threats to mangroves in the Sundarbans. In this situation, regular and detailed information on mangrove species composition, their spatial distribution and the changes taking place over time is very important for a thorough understanding of mangrove biodiversity, and this information can also lead to the adoption of management practices designed for the maximum sustainable yield of the Sundarbans forest resources. We employed a maximum likelihood classifier technique to classify images recorded by the Landsat satellite series and used post classification comparison techniques to detect changes at the species level. The image classification resulted in overall accuracies of 72%, 83%, 79% and 89% for the images of 1977, 1989, 2000 and 2015, respectively. We identified five major mangrove species and detected changes over the 38-year (1977–2015) study period. During this period, both Heritiera fomes and Excoecaria agallocha decreased by 9.9%, while Ceriops decandra, Sonneratia apelatala, and Xylocarpus mekongensis increased by 12.9%, 380.4% and 57.3%, respectively.

Climatic Signals in Tree Rings of Heritiera fomes Buch.-Ham. in the Sundarbans, Bangladesh.

Abstract: Mangroves occur along the coastlines throughout the tropics and sub-tropics, supporting a wide variety of resources and services. In order to understand the responses of future climate change on this ecosystem, we need to know how mangrove species have responded to climate changes in the recent past. This study aims at exploring the climatic influences on the radial growth of Heritiera fomes from a local to global scale. A total of 40 stem discs were collected at breast height position from two different zones with contrasting salinity in the Sundarbans, Bangladesh. All specimens showed distinct tree rings and most of the trees (70%) could be visually and statistically crossdated. Successful crossdating enabled the development of two zone-specific chronologies. The mean radial increment was significantly higher at low salinity (eastern) zone compared to higher salinity (western) zone. The two zone-specific chronologies synchronized significantly, allowing for the construction of a regional chronology. The annual and monsoon precipitation mainly influence the tree growth of H. fomes. The growth response to local precipitation is similar in both zones except June and November in the western zone, while the significant influence is lacking. The large-scale climatic drivers such as sea surface temperature (SST) of equatorial Pacific and Indian Ocean as well as the El Nino-Southern Oscillation (ENSO) revealed no teleconnection with tree growth. The tree rings of this species are thus an indicator for monsoon precipitation variations in Bangladesh. The wider distribution of this species from the South to South East Asian coast presents an outstanding opportunity for developing a large-scale tree-ring network of mangroves.

Dynamics of mangrove diversity influenced by climate change and consequent accelerated sea level rise at Indian Sundarbans

Abstract: Sundarbans, the largest contiguous mangrove forest of the world, regularly bears the brunt of numerous cyclones/storm surges. The frequencies of these disasters are ever increasing, in wake of the twin predicaments of sea level raise and climate change. This temporal study (2008-2013) at Jharkhali Island, delve into the dynamics of mangrove community in response to seasonal and yearly alterations in river-water salinity, due to the severe cyclone AILA (2009) and sea level raise. Raise in water salinity accentuates the abundance of salt tolerant species with physiological and phenological adaptations (Avicennia marina, Suaeda maritima) and decreased abundance of salt sensitive mangroves (Rhizophora mucronata). Exclusion of few mangrove species (Aglaia cuculata, Brownlowia tersa, Heritiera fomes, Kandelia candel and Nypa fruticans) is also evident, facilitating the proliferation of resistant, opportunistic and invasive flora (Clerodendron inerme, Derris trifoliata and Phoenix paludosa). Solutions have also been suggested in the light of the modern conservation paradigm.

Cambial dormancy induced growth rings in Heritiera fomes Buch.- Ham.: a proxy for exploring the dynamics of Sundarbans, Bangladesh

Abstract: Cambial marking experiment and cambial activity analysis offer strong evidence on existence of annual growth rings in Heritiera fomes and revealing the potential of dendrochronological applications in Bangladesh mangroves. Despite enormous significance in coastal protection, biodiversity conservation and livelihood support to the local communities, mangrove ecosystems have been continuously degrading mainly due to anthropogenic disturbances and climate change. Time series based on dated tree ring is an option to identify the causes of forest dilapidation. In this study, we investigated the structure and periodicity of the growth ring in Heritiera fomes, the flagship tree species of the Bangladesh Sundarbans, combining cambial marking experiment and cambial activity analysis. Distinct growth rings were found which are delineated by a band of marginal parenchyma, predominantly one cell wide but up to three and occasionally interrupted with fiber. Of the 13 trees with cambium marking experiment, one growth ring was found in each tree during a year. The dormant cambium was characterized by the abrupt boundary between xylem and cambial zone, absence of enlarging or differentiating cambial derivatives, lower number of cambial cells and thicker radial walls in cambial cells. Growth ring anomalies, i.e., wedging and partially missing rings were also found. In most of the cases, the lower part of the eccentric discs had low radial increment (<0.75 mm) and therefore the growth ring in that area merged with previous one and produced wedging or partially missing ring. However, the existence of annual rings suggests its great potential for future dendrochronological applications to reveal the dynamics of vegetation and climate in Sundarbans.

Diversity of Arbuscular Mycorrhizal Fungi in Different Salinity of Mangrove Ecosystem of Odisha, India

Abstract: A study was carried out to assess the species diversity of arbuscular mycorrhizal AM fungi in different salinity zones of Bhitarkanika mangroves of Orissa India Sixteen sites of Bhitarkanika mangrove areas were surveyed for the collection of roots and soil samples Seedlings of mangrove species were tested for AM colonization through root clearing and staining technique Soil samples were treated separately for the mineral analysis through wet oxidation techniques and spore multiplication by pot culture methods Wet sieving and decantation technique was followed for the isolation of AM spores from soil AM spores were identified on the basis of morphological characteristics by following the INVAM manual The physio chemical analysis of soil indicated its deficiency in phosphorus which decreases Kg ha with increase in salinity The genus Glomus is most dominant and has presence across all saline zones A total of AM species belonging to five genera namely Glomus Acaulospora Gigaspora Scutellospora and Enterophospora were recorded from three salinity zones of Bhitarkanika mangrove ecosystem The soils of lower salinity contained maximum number of AM species nos than the high salinity zones nos The decreased number of AM species in high salinity may be due to low phosphorus content and lack of suitable host plant also Among eighteen mangrove species from different salinity zones analyzed for mycorrhizal colonization in their root system Sonneratia apetala Heritiera fomes Excoecaria agallocha Derris heterophylla Bruguiera gynmorrhiza Avicennia officinalis Aglaia cucullata and Aegiceras corniculatum were found to be mycorrhizal This is first report on diversity of AM species in different salinity zones of Bhitarkanika mangroves of Orissa India

Germination Eco-Physiology and Plant Diversity in Halophytes of Sundarban Mangrove Forest in Bangladesh

Abstract: The eco-physiology of germination of two halophyte species and plant community types of different ecological zones (Oligohaline, Mesohaline, and Polyhaline zones) were studied. Xylocarpus mekongensis showed an increasing trend in germination at 5 ppt NaCl salinity and decreased with a further increase in the salinity (15 ppt). Heritiera fomes showed more than 80% germination under natural conditions with healthy seedlings but died at the end of winter due to lack of freshwater supply. Plant community types of halophytes of different ecological zones from Sundarban mangrove forest were identified and changes were discussed. Dominant plant species of the ecological zones and the nature of adaptation were evaluated. Formation of consociation in the Polyhaline zone and also to a lesser extent in the Mesohaline zone of the halophytes was observed. In contrast, the Oligohaline zone exhibited a mixed plant community. Seasonal variations in soil salinity (conductivity) in the river water from selected locations showed strong variation and was several times higher in the Oligohaline zone at the end of the winter season (March) than the monsoon season, which is due to the non-availability of a freshwater supply from upstream through the Ganges River. Seedlings of Sonneratia apetala planted (monoculture) in the Oligohaline zone in the experimental plot showed 96% establishment and vigorous growth within 3 years. Plant species from the quadrats of circular plots of 2 m radius were recorded and diversity was measured by H′, the Shannon–Wiener Index. Ecological diversity was measured based on rarefaction of the actual samples. The diversity values showed a correlation with the ecological conditions. The rarefaction methodology was compared with a number of diversity indices using identical data and was found to be influenced by sample size. The abundance of species, ranked from most to least abundant (in geometric series), was also calculated. The data were also analyzed with the log series and the Q statistic to bring plant diversity to a sharper focus. The result indicated a strong diversity of the halophytes of Sundarban mangrove forest. Plant succession pattern and plant composition of the three ecological zones were evaluated.