A Half-yearly Peer Reviewed Journal of Bangladesh Forest Research Institute
Kraft pulping, in spite of its wide practice, suffers from some serious disadvantages, such as the odour problems, lower pulp yield and high investment requirements. To overcome these difficulties considerable efforts have already been made. In this paper, feasibilities of alternative methods to kraft pulping have been examined and discussed.
A kraft mill, even by utilizing the best available technology, cannot be made completely odour-free. However, there are several sulphide-free and non-sulphur pulping methods. Among these, sodaanthraquinone (AQ) pulping process seems to be promissing.
The most practised chemical to-day is the kraft process. 95% of the present production of chemical 74 Pulp yield can be increased by using polysulphide, H2S or AQ in the cook. The first two are used exclusively in kfraft cooking, and so the odour problem cannot be overcome. AQ on the other hand, is also suitable in a sulphur-free cook which eliminates the odour problem of the pulp mill. Soda-AQ pulping is more suitable with hardwoods.
There is an ample opportunity of reducing the investment cost in a kraft mill by replacing the conventional recovery furnace with alternative devices now under development or by eliminating some of the steps in the recovery cycle. There are also possibilities of eliminating the causticizing step and the lime kiln in any alkaline pulping process by replacing NaOH with disodium borate in cooking or by introduction of TiO2, Fe2O or ilmenite (FcO. TiO2) in the recovery stage.
Seedlings of Pinus caribaea var. hondurensis planted at Keochia Silvicultural Research Station, Chittagong in 1972 reached an average height of 14.0 m and started bearing fruits in 1982. The trees flowered during the months of January- February and cones ripened in August- September of the same year. Some seeds were hand-picked from two selected trees in 1982 and the seeds were extracted from the cones by exposing them in the sun. Germination experiment was carried out with them. The seeds were first tested by floatation process with 85% ethyl alcohol for finding out the empty seeds. After the test, 220 mature seeds were sown in polybags filled up with forest top soil. An appropriate quantity of chemical fertilizer was also applied. The tops of the bags was filled up with mycorrhizal soil collected from pine plantation. Out of 220 seeds 97 seeds germinated (44%). The growth rate was fair in the nursery and in the field their performance was encouraging. 70 seedlings out of 97 germinated ultimately survived (72%).
Based on availability and strength properties, eight indigenous species were selected as alternatives to Garjan for use as railway sleepers.
The sleepers were put to service test in the main track of the Bangladesh Railway. The performance of seven of them has been found satisfactory
and, therefore, are recommended for use as railway sleepers.
Loranthaceac includes semiparasitic plants which are known as mistletoes. In Bangladesh mistletoes attack a large number of hosts, viz., Gamar, Teak, Sal, Mango, Jackfruit and many ornamental plants. In the country 15 species under 7 genera of Loranthaceae have been recorded and their distribution have been discussed. The important hosts of mistletoes have been listed. A critical review on the biology and control of mistletoes has been presented. Attention has been drawn to generate adequate studies for appropriate control of the parasites in our context.
A small population of crab-eating macaque was located in the Whykheong region of the Cox’s Bazar Forest Division. The population is greatly threatened due to rapid expansion of shrimp cultivation in the area. The population status, food habit and distribution so far studied are presented in this paper. The possibilities of rehabilitating this species in other areas of Bangladesh have also been discussed.
Albizia falcataria Fosberg is a fast-growing exotic tree species. It was introduced into Bangladesh as a shade tree in the tea gardens. Diameter-height, age-diameter, age-height relationships and the growth pattern of the species have been investigated. At the end of the 8th year the MAI has been found to average about 31.0 m3/ha The total merchantable wood yield, excluding the branch wood and brush wood (5 cm top dia), at the end of 8th year has been found to be 248 m3/ha. Data collected from the Bangladesh Forest Research Institute Campus at Chittagong showed that the MAI was about 33 m3/ha. The total calculated yield from the same site was 402m3/ha at the end of the 10th growing season. The preliminary growth curves indicate that the rotation-age would be more than 10 years.
Grasses such as Blue panic, Guinea grass, Green panic, Rhodes grass, Signal grass, three cultivars of Buffel grass, two cultivars of Setaria and Legumes like Centro, Greenleaf desmodium, Highworth dolichos, Rongai dolichos, Archer dolichos, Tinaroo glycine, Siratro, Cook stylo, Schofield stylo, Endeavour stylo, Townsville stylo, Verano stylo were grown at six Silvicultural Research centres of Bangladesh to study their herbage production. Among grasses Signal grass, Guinea grass, Green panic and the cultivars of Setaria produced higher amount of herbage in comparison to other grasses. Legumes like Schofield stylo, Cook stylo, Endeavour stylo, Townsville stylo and Verano stylo produced higher yields of herbage in comparison to other legumes. These promising fodder grasses and legumes have important bearings on multiple land use in agriculture as well as in forestry.
Nominal 100 micron thick, 1 cm wide and 10 cm long radial/ longitudinal Pinus nigra microtome sections were dried and treated with dimethyl dichlorosilane in the vapour phase. The same experiment was repeated with previously water-leached specimens. The chlorosilane readily reacted with wood hydroxyl groups to form silyl cellulose. The silanation product was quite resistant to the effects of prolonged water leaching and is quite durable too.
2×2 cm radial-tangential 6 mm thick transverse wafer specimens of the same species were treated in both vapour and liquid phases. Water repelling effectiveness of the specimens were measured by time to half swell (Tj). ‘
Silanation by both vapour and liquid phases slows down the sorption process by over 70 times the normal process. The maximum equilibrium swelling is also brought down to 72.5% in the case of liquid phase and 75.0% in the liquid and vapour phase respectively. Conventional water repellents slow down the rate of water uptake but do not change the total sorption. This establishes the superiority of silanation over conventional water repellents in decreasing the maximum equilibrium swelling of wood in contact with moisture.
Diseases of 6 to 12 month old seedlings of Bokul, Debdaru, Jam, Kajubadam, Kumvi, Mohua, Sal and Shimul were recorded from Rasulpur Forest Nursery, Modhupur in 1974. Symptoms of the diseases have been briefly noted. Fungi were isolated from diseased seedlings, pathogenicity tests carried out in vitro on detached young leaves were the basis for ascertaining seven fungal and one algal pathogens. The extent of occurrences of the diseases was also recorded.
Garjan (Dipterocarpus turbinatus) is one of the most important species growing in the natural forests under Cox’s Bazar, Chittagong and Chittagong Hill Tracts forest divisions. Attempts were made to establish Garjan plantations since 1923 and from the last decade more attention has been directed to raise Garjan plantation on wider areas. The prospects of these plantations have been studied in this paper in order to aid planners in fixing up physical targets for production and management, find an indication of long-run price behaviour of produced timbers and finally assess the rate of economic return of plantations.
The paper indicates the long-run gap between the demand for and supply of Garjan timber. Some major problems of managing Garjan plantation are pointed out and suggestions affecting the cost factors and yield position are made.
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