Showing papers on "Heritiera fomes published in 2000"

Testing patterns of zonation in mangroves: scale dependence and environmental correlates in the Sundarbans of Bangladesh

Abstract: Summary1 Associations between abiotic variables and patterns of species distribution and abundance are a major preoccupation of community ecologists. In many habitats, this association is manifest in discrete zones of vegetation. 2 We used statistical methods to examine tree species distribution patterns in relatively undisturbed regions of the Sundarbans of Bangladesh. We tested the hypothesis that mangroves occur in discrete zones with respect to elevation. These data were gathered with explicit attention to local and regional differences in edaphic characteristics so that species-environment relationships could be analysed at several spatial scales. 3 Correlations were also assessed between mangrove species composition and edaphic variables that co-vary with elevation, i.e. salinity, field capacity, cation exchange capacity, percentage silt, and mangrove physiognomic category (slope, basin, levee and flat). 4 Quantitative statistical analysis using randomization techniques failed to detect species zonation along any of 33 individual 200-m transects, within 1-km2 blocks, or within 1200-km2 regions. 5 Canonical correspondence analysis relating edaphic variables to species distributions accounted for a total of only 24% of the variance in species composition. 6 Our data suggest that the absence of zonation in the Bangladesh Sundarbans reflects the underlying biology of the system and is not an artefact of long-term human disturbance.

Rooting response in stem cuttings from five species of mangrove trees : effect of auxins and enzyme activities

Abstract: An experiment was conducted to optimise rooting in stem cuttings of the mangrove tree species Bruguiera parviflora, Cynometra iripa, Excoecaria agallocha, Heritiera fomes and Thespesia populnea. Cuttings were girdled or non-girdled and treated with the auxins indole-3-acetic acid (IAA), indole-3-butyric acid (IBA) and naphthalene-acetic acid (NAA) and amylase, IAA-oxidase, peroxidase and polyphenol oxidase activities were measured. The best rooting performance (in terms of root number) was in stem cuttings of E. agallocha followed by C. iripa and H. fomes when treated with IBA + NAA. IAA and IBA combinations were more effective in T. populnea and B. parvifolia. Variations in rooting response were markedly reflected in amylase, IAA-oxidase, peroxidase and polyphenol oxidase activities. Sharp increases in amylase and polyphenol-oxidase activities were associated with enhanced rooting in E. agallocha, C. iripa and H. fomes. On the contrary, lowered IAA-oxidase and peroxidase activities favoured rooting in T. populnea and B. parviflora. A higher number of roots occurred in pre-girdled cuttings in comparison to non-girdled cuttings.

The Sundarbans: a unique wilderness of the world.

Abstract: The Sundarbans, natural mangrove forests of Bangladesh covers an area of 577,000 ha. It is the largest single tract of mangrove forest in the world. The members of the family Rhizophoracae do not dominate the tree vegetation of the Sundarbans. Heritiera fomes and Excoecaria agallocha are the two most extensively occurring tree species in the forest and they are members of Sterculiaceae and Euphorbiaceae respectively. The forest is very rich in biodiversity and supports different species of about 334 plants, 120 fishes, 35 reptiles, 270 birds and 42 mammals. The Sundarbans is the only habitat of the famous Royal Bengal Tiger and estuarine crocodile. The Sundarbans, natural mangrove forests of Bangladesh cover an area of 577,000 ha, of which 401,600 ha is land and remaining 175,400 ha are under the water in the forms of river, canals and creeks of width varying from a few meters to several kilometers. The interconnected network of waterways makes almost every corner of the forest accessible by boat. Unlike most mangrove forests, the members of the family Rhizophoracae do not dominate the tree vegetation of the Sundarbans. Heritiera fomes and Excoecaria agallocha are the two most extensively occurring tree species in the forest and they are members of Sterculiaceae and Euphorbiaceae respectively. The forest is very rich in biodiversity. The Sundarbans play an important role in the economy of the southwestern region of Bangladesh as well as in the national economy. It is the single largest source of forest produce in the country. The forest provides raw material for wood based industries. In addition to traditional forest produce like timber, fuelwood, pulpwood etc., large scale harvest of non wood forest products such as thatching materials, honey, bees-wax, fish, crustacean and mollusk resources of the forest takes place regularly. The vegetated tidal lands of the Sundarbans also function as an essential habitat, nutrient producer, water purifier, nutrient and sediment trap, storm barrier, shore stabilizer, energy storage unit and aesthetic attraction. The Sundarbans is named after the principal tree Sundri (Heritiera fomes) found in it. Another opinion is that it is derived from the words ‘Samunder Ban’ meaning sea forests. It may also derived from the word ‘Sundar,’ meaning beautiful, because the forest is beautiful to look at (Choudhury 1968). The Sundarbans is of unique scientific and biological interest and offers rare opportunities for ecotourism, biological research and conservation education. Some areas in the forest have been earmarked as protected in the form of wildlife sanctuary. No forestry operations are carried out in these areas, which support a rich concentration of wildlife as well as vegetation, which has not been disturbed for decades. The forest was recognized as an important resource base about five centuries ago and actual scientific management of the forest was initiated more than 120 years ago. This is very significant because even today mangroves are not considered as a viable resource base in a number of countries of Asia, Africa and tropical Latin America. For its outstanding natural value the World Heritage Committee of UNESCO inscribed the Sundarbans of Bangladesh in the World Heritage list by their 21st session in 1997 and accordingly the Government of the People’s Republic of Bangladesh declared the Sundarbans as World Heritage site in December 1997 (Nuruzzaman and others 1999). This paper describes the vast wilderness of the Sundarbans, its economic and social importance and the need for integrated management and research. Legal Status____________________ During the Mughal period (1203-1538), the local kings leased the forests of the Sundarbans out. The history of changes in legal status boasts a number of unique features including the distinction of being the first mangrove forest in the world to be brought under scientific management. The area was mapped by the Surveyor General as early as 1764 following soon after proprietary rights were obtained from the Mughal Emperor, Alamgir II, by the East India Company in 1757. Systematic management of this forest tract started in the 1860s after the establishment of a Forest Department in the Province of Bengal, in India. The first Forest Management Division to have jurisdiction over the Sundarbans was established in 1869. The Sundarbans was declared a reserved forest in 1875-76, under the Forest Act, 1965 (Act VIII of 1965). The first management plan was written for the period 1893-98. (Hussain and Acharya 1994; UNDP 1998). Physiography __________________ The Sundarbans along the Bay of Bengal has evolved over the millennia through natural deposition of upstream sediments accompanied by intertidal segregation. The physiography is dominated by deltaic formations that include innumerable drainage lines associated with surface and subaqueous levees, splays and tidal flats. There are also marginal marshes above mean tide level, tidal sandbars and islands with their networks of tidal channels, subaqueous