BANGLADESH JOURNAL OF FOREST SCIENCE
A Half-yearly Peer Reviewed Journal of Bangladesh Forest Research Institute
A Half-yearly Peer Reviewed Journal of Bangladesh Forest Research Institute
The term allelopathy, literally meaning mutual harm, refers to the positive or negative influences of one plant with or without microbial action upon anotherthroughchemicalmeans other than nutritional. Allelopathy depends on chemical compounds mainly added to the environment from living plants or dead and decaying parts(Tang 1986). Thenumber and diversityofthe compounds involved in allelopathy are growing
rapidly. These chemicals may be produced by various parts of the plant such as roots and leaves (Horseley 1977), pollen (Ortega et al. 1988), seeds or fruits (Friedman et al. 1982), although roots and leaves are the main sources (Horseley 1977). Autotoxicity is apparently a negative feature of allelochemical production avoided by some species through excreting or sequestering of chemicals involved in structures. The
allelochemicals can be classified based on the nature of producers, systematics of donor and receiver, inhibitory and stimulatory activity or
upon the self or alien origin. During the last few years effortshave beenmade to exploitallelopathy for weed management, pest management,
comparison and rational cropping, agroforestry and other.
One hundred and eight species of macrohymenopterans belonging to fifteen families and fifty six genera were recorded from the Silent Valley
National Park. The families Sphecidae, Formicidae, Pompilidae and Apidae contained maximum number of species. The insects were collected from five habitats, viz., tropical evergreen forest, subtropical broad leaved hill forest, montane wet temperate forest, low altitude grasslands and high altitude grasslands. Of the various species recorded in this study, seven genera and eleven species are new reportsfor Kerala and seven species are new reports for India.
Eucalyptus camaldulensis poles were treated with 50 : 50 creosote-light diesel oil mixture. The poles contained an average of 53.85% sapwood which was readily perishable by wood destroying organisms if untreated. The poles were treated by the Bethel Full-Cell process using varying pressure and duration to evaluate the effect on penetration and retention of the preservative mixture. It was found that with the simultaneous increase of both treating pressure and time, no significant increase in pentration was achieved. On the other hand, with the increase of treating pressure only, the retention of pressrvative in the sapwood was increased significantly. A penetration of 3.5 cm with retention of 318. 45 kg/m3 in the treated sapwood could be obtained by using 10.57 kg/cm2 pressure for 3 hours. This amount of penetration is considered adequate to protect the sapwood region of the pole.
Teli garjan (Dipterocarpus turbinatus) is the most important indigenous species included for long term plantation programme in Bangladesh. Site indices models have been derived for the species in the plantations of Bangladesh. The selected models derived in the study could be satisfactorily used for teli garjan plantations having ages 3-60 years and site indices of 25-55 metres based on a base age or rotation of 45 years.
A study was conducted with 15 lesser used/unused medium density
(0.52-0.68) wood species of Bangladesh to determine their hardboard making
characteristics. The species tested were barta (Artocarpus lakoocha), chalta (Dillenia
iiidica), dakroom (Mitragyna rotundifalia), gab (Diospyros peregrine), hargaza (Dillenia
pcntagynn), jhumka bhadi (Engelhardtia spicata), kamdev (Calophyllum polyanthum),
kao (Garcinia cowa), kasturi (Cinnamomum cecidodaphne), kerung (Pongamia pinnata),
moos (Pterospernium acerifolium), pairag (Canarium risiiiiferum), rata (Aphanamixis
polystachya), tali (Palagttiuni polyanthum) and uriam (Mangifera sylvatica). It wasfound
that all the species except barta, kasturi and uriam produced good or even better
quality hardboard than that ofsundri (Heritierafames) a widely used wood species in
Khulna Hardboard Mills
The exact flowering cycles (from seed to seed) ofbamboos are known for few species. Most of the pastreports on bamboo flowering cycles are
based on speculation and estimation (Hasan 1973, Banik 1991). The flowering cycles for many species of bamboo from India, Bangladesh and
Myanmar were reported (Cavendish 1905, Blatter 1930, Bor 1941, Hasan 1973, Bahadur 1980, Naithani 1990, Banik 1991, Alam 1995). This paper
presentsthe estima ted flowering cycles of Bambusa burmanica Gamble, B. cacharensis Majumdar and B. jaintiana Majumdar based on past records and recent flowering (Table 1)
In 1990, a serious root rot disease was observed in different strip plantations of Court Chandpur-Subdalpur railroad, Jessore-Benapole highway and Jessore-Satkhira road of greater Jessore district. These plantations were covered with trees such as Cassia siamea, Acacia
auriculiformis, A. nilotica, Albizia procera, Leucena leucocephala and Dalbergia sissoo. The affected trees died in patches showing wilting symptoms. C. siamea, A. auriculiformis and A. procera were affected most, whereas A. nilotica, L. leucocephala and D. sissoo were least affected. The leaves of the diseased trees became brown, dried up and remained attached to the dead branches. After excavation of roots, whitish mats of mycelia were observed on the branch and anchor roots of the trees. Typical fruit bodies were seen on the collar region, exposed roots and on Clerodendruni viscosum and Glycosmis pentaphylla situated at the vicinity of the infected trees (Figs. 1 and 2). The bark of roots were rotted and, in most cases, the rotting was extended up to the collar region. The fungus responsible for the disease was isolated and identified as Fomes lignosus (Klotzsch) Bres. Heavily infected trees were removed from the sites. Basal area covering one metre radius of each diseased tree was drenched with 2% commercial formalin. The second spray was given 15 days after the first. The sprays, however, could notsave the diseased trees butfurtherspread ofthe disease symptom was checked.
Dendrocalamus hamiltonii and Schizostachyum dullooa are the two important threatened bamboo species of Bangladesh. They flowered gregariously during 1996 to 1998 and 1999 at the bambusetum of Bangladesh Forest Research Institute,Chittagong and RangapaniTeaEstate, Hazarikhil, Chittagong respectively. The flowering cyclesfor D. hamiltonii were estimated as 43 + 5 years and for S. dullooa as 45 + 2, 35 + 2 and 15 + 2 years. Observations were made on flowering nature, death and seed characters of these species. The germination and seedling characters were also recorded. Planta tions of both the species were raised with seedlings by the Forest Department and the NGOs. In future these will be used as ex situ conservation plots.
This paper reports the distribution, nature and impact of damage, life history, number of generations in a year, host records and biocontrol agents of the beehole borer, Zenzera conferta Walker (Cossidae : Lepidoptera) infesting keora (Sonneratia apetala Buch.-Ham.) plantations along the coastal belt of Bangladesh. The pest profusely tunnels in the stem rendering the tree to wind breakage. It probably completes two generations in a year. Besides keora, the pest attacks Sonneratia caseolaris, Avicennia officinalis, A. alba and Tamanx indica. Woodpeckers (Dinopium benghalense and Picoides canicapilltis) and a small black ant were found to feed on the larvae and pupae of the pest.
The community structure and growing stock variations were studied in moist temperate Quercus floribunda forest on four different aspects and altitudesin Garhwal Himalaya during the year 1996. The total density and basal cover values in the tree layer varied from 250 to 340 trees/ha and 18.44 to 38.24 m2/ha respectively. The maximum number ofsaplings (400 saps/ha) of Quercus floribunda were observed on the hill base of SE aspect, whereas, the lowest number ofsaplings (80 saps,/ha) on the hill top of NW aspect. The maximum (1.8131) and minimum (1.4717) diversity values were reported for NE and SE aspects respectively. The highest total growing stock (349.0m3/ha) was observed on SW aspect. On NE aspect a strong positive correlation (r=+0.88) was observed between the growing stock values and diameter classes. Physicochemical properties of soils were found to be promising for the growth of Quercus floribunda forest on northern aspects as compared to southern aspects.
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