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 Sundarbans mangrove forest of Bangladesh is very rich in biodiversity and
provides economic, social and ecological benefits to the country. This important
ecosystem has started loosing its biodiversity because of over-exploitation and
destruction of habitat. Emphasis has been given by the government of Bangladesh
and UNESCO on conservation of biodiversity in the Sundarbans. The paper deals
with the importance of biodiversity, current status of the flora and faunal diversity,
steps already taken and further steps needed for biodiversity conservation in the
Sundarbans forests of Bangladesh.
Key words : Biodiversity, conservation, endangered species, exploitation, extinct
species, Sundarbans
4^°
Agroforestry is not a new concept in Bangladesh. This concept has been practising
in this country for a long time. A case study of financial analysis on agroforestry
research conducted at Ichamati Research Centre under Chittagong district was done.
Tire financial analysis of both the tree crops and agricultural crops has been done
separately and combinedly. The trees were considered as fuelwood with six years
rotation. In both the cases, tire result is found to be negative. The present worth of
benefit is Tk. 12,610 (US$1 = Tk. 40/-) and the present worth of cost is Tk. 44,947. The
net present worth is Tk. 32,337 with a benefit-cost ratio of 0.28. The agroforestry trial
would, however, be profitable if 18 years rotation of the trees with ploe values and
other intangible benefit are considered.
The life cycle of the gall wasp, Andricus quercuscalicis (Burgsdorf) (Cynipidae :
Hymenoptera) involves the alternation between a sexual generation on the male
inflorescences (catkins) of the Turkey oak, Quercus cerris L. in the spring and an
agamic generation on the acorns of the English oak, Quercus robur L. in the autumn.
This study concerns with only the sexual generation of the wasp and its guild of
parasitoids. The generation was followed from the appearance of galls on catkins
until the adult gall wasp emergence in May-June and its parasitoids emergence in late
June.
The density of galls was positively correlated with the density of catkins on the
trees. The distribution of gall was clumped over the catkins. The sex ratio of the wasp
was highly male biased (68% male and 32% female), and the males were protandrous.
The sexes were patchily distributed over the trees. The sexual generation suffered
21.7% mortality through pupal parasitism by four oak-gall generalist parasitoids,
such as Mesopolobus xanthocerus (Thompson), M. tibialis (Westwood), M. fuscipes
(Walker) and M. dubius (Walker) (Pteromalidae : Hymenoptera) and 27.8% through
non-emergence, the cause of which was unknown. The parasitoids emerged from the
sexual galls of A. quercuscalicis were extremely male biased being virtually all males.
Trees of 21 species were grown in wetland rice field under farmers’ management,
including varying degrees of annual root pruning and top pruning to regulate impact on
understory crops. Tree height and girth were measured and pruning intensity was
observed twice annually. Rooting intensity of a few trees annually was observed by
trenching. The fastest-growing trees (mean annual increments in m^/ha at 100 trees/ha
and specified ages in brackets) were Gmelina arborea (10.5 at 6 yrs), Eucalyptus camaldulensis
(3.5 at 9 yrs), Faidherbia albida (1.6 at 9 yrs), Albizia saman (1.2 at 8 yrs), Melia azaderach (0.9
at 9 yrs), Cassia siamea (0.9 at 9 yrs), and Acacia mangium (0.8 at 7 yrs). Growth of most
tree species was slower on poor soil types and where vulnerable to flooding. On such
sites, E. camaldulensis, A. mangium, and Terminalia arjuna were less affected than other
species. Tree management by top and root pruning reduced overall growth by up to 19%
for gbh and 41% for volume, depending on intensity of pruning. Stand volume and mean
annual increment on an area basis in crop fields of average site quality were broadly
equivalent to forest plantations on average or poor sites.
The mangrove of Sundarbans in Bangladesh is intended to be managed on a
sustained yield basis. But a remarkable decline in the growing stock of the merchantable
trees is reported in recent decades. This necessitates exploring avenues for improving
productivity of the forests. There are sizeable areas in the Sundarbans with scanty or
little vegetation due to failure in natural regeneration. Rehabilitation of poorly
stocked and vacant areas by enrichment planting could play a vital role in increasing
the wood production of the forests.
This paper discusses the scope of artificial regeneration in the Sundarbans to
improve the stocking and the yield. Research findings available in this direction have
been reviewed. Excoecaria agallocha and Ceriops decandra appear to be suitable for
planting in less productive but normally inundated areas. Plantations of Nypa
fruticans can be established on vacant canal or riverbanks over the greater parts of the
forests. The raised lands that do not support mangrove vegetation can be planted
with non-mangrove species like Sanianea saman, Albizia procera, Lagerstroemia speciosa
and Acacia nilotica. Studies have been initiated for a remedy to the problem of top
dying of Heritiera fonies, the dominant species of the forest. Research activities from
various aspects are underway to evolve methods to increase tree density and forest
cover.
Physical and chemical properties of some soils from the offshore islands of
Bangladesh have been studied. Results of particle size distribution, pH, ECe, organic
carbon, total nitrogen and cation exchange capacity (CEC) of the soils on profile basis
have been determined. The predominantly loamy texture of the soils indicate that they
are physically suitable for agricultural use.
Daily tidal inundation during the monsoon months and moderate salinity along
with poor drainage conditions are the characteristic features of these soils which may
favour the growth of mangrove species. In fact, in some of the older islands the
mangrove species such as keora (Sonneratia apetala) are growing luxuriantly.
Survival, establishment and early growth of six major and economically important
mangrove plant species, namely sundri (Heritiera fames), gewa (Excoecaria agallocha),
goran (Ceriops decandra), passur (Xylocarpus mekongensis), kankra (Bruguiera sp.) and
baen (Aviccnnia officinalis) were studied in two salinity zones (moderate and strong
saline) of the Sundarbans mangrove forests of Bangladesh at the age of five years after
planting. The objective of the study was to enrich the vacant and poorly regenerated
areas of the Sundarbans for its sustainable production and management.
The percentages of planted seedling’s survival and establishment by fencing at
moderate saline zone were 84.9, 74.3, 63.5, 60.6, 40.6 and 38.9 for gewa, goran, sundri,
kankra, passur and baen respectively. The average height growths of these species were
1.94 m, 1.04 m, 0.90 m, 1.18 m, 1.71 m and 2.90 m respectively. Except gewa and goran
all the seedlings of other four species died due to deer browsing when planted in
unfenced condition.
Evaluation was made on growth response of one year old Eucalyptus camaldulensis
seedlings to various dose-combination of NP fertilizers under a comparatively poor site
condition of Silvicultural Research Station at Keochia. Results indicate that the maximum
average height (262.17 cm) and diameter (2.08 cm) of the seedlings in one year were
attained through application of urea and triple super phosphate (TSP) combinedly at the
rate of 30 and 20 g/pit respectively with a basal dose of muriate of potash (MP) at
20 kg/ha. Application of the above mentioned fertilizer dose promoted above-ground
green biomass production almost 8 times higher than the control. Subsequently, the
biomass distribution to shoot, leaf and twig was modified. The intake of nutritional
elements by the seedlings was found to increase due to application of fertilizer
The growth and biomass production of 17 provenances of Acacia mangium were
studied at the age of 5.5 years at Keochia Silvicultural Research Station, Chittagong.
The provenances showed significant differences in survival, height and diameter
(dbh) growth. In terms of height and dbh, Boite PNG provenance has shown the best
performance among the 17 provenances. But the provenance Iron Range QLD,
produced maximum (15.7 t/ha/yr) above-ground oven-dry biomass followed by
NW of Ingham QLD (11.8 t/ha/yr).
Teak (Tectona grandis Linn, f) is one of the most
well-known versatile timbers in the world. Its
large scale cultivation is much hampered by various
factors. Among them poor germination of
drupes (fruit with seed) is a major constraint. The
causes of poor germination are many such as
emptiness, prolonged and protracted germination,
season and method of seed collection, age of
mother tree and innate problems prevailing in the
seed itself (Dharmalingam 1995). Several informations
exist on method and season of seed collection
of many tree species. But such informations
are scanty in teak. Against this backdrop, a study
was made to find out the influence of collection
methods on germination and seedling attributes
of teak.
Welcome to the Bangladesh Journal of Forest Science (BJFS) – a leading platform for advancing the knowledge and understanding of forest science in Bangladesh and beyond. Established with a commitment to excellence, BJFS serves as a cornerstone for researchers, practitioners, and enthusiasts dedicated to the sustainable management and conservation of forest ecosystems.
