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 paper presents the method of raising seedlings of Calamus viminalis var.
fasciculatus and their performance after planting out. Germination per cent of C. viminalis
was 24.37. Sunlight was pre-requisite for the germination. Optimum time for seedling
pricking from the seed bed to the polybag was 90 days after germination, and in this 100%
survival could be obtained. A survival of 98% was observed in the wildings when they
were transferred from the field to the polybags at an average height of 8.5 cm. One year
old wildings were significantly lower in height in the nursery than that of one year old
polybag-raised seedlings. Survival of planted seedlings at Hinguli, Chittagong in the
field was 77.5% after one year. Average height increment of the seedlings was 25.5 cm
with usually 4-5 leaves one year following planting under a teak plantation.
Hybridization of Acacia auriculiformis and
Acacia mangium occurs naturally because both are
pollen-pistil compatible, found within the same
habitat with overlapping flowering time and share
common pollinators (Zakaria 1991). Natural hybrids
of these two species are reported in Sabah
(Tham 1976) and Papua New Guinea (Turnbull
et al. 1986). The tree form of the hybrid of these two
species is satisfactory because of better stem
straightness, self-pruning stability, better stem
circularity and more disease resistance (FRIM
1992). Species/provenance trials of A auriculiformis
and A. mangium were established at Charkai,
Dinajpur, Bangladesh in 1983,1985 and 1987 at a
spacing of 1.83 m x 1.83 m covering an area of 1 ha.
The seeds were imported from Australia for these
trial plantations. Eight hybrid trees of these two
fast growing tree species were observed in the
plantation raised in 1983. The hybrids found sporadically
distributed in the plantations were identified
by the light colour of their bark. Banik et al.
(1995) also reported some hybrids of these two
species at Harbang forest areas of Chittagong
Forest Division. Some phenological information
and growth performance of these hybrids found
at Charkai are reported in this paper.
The phenological observations of the hybrids
were made very carefully every day for a period of
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.
The life cycle of Melocanna baccifera (Roxb.) Kurz plant ends with flowering, so the
species is a semelparous in nature. In a population flowering is initially sporadic which
gradually becomes gregarious and then again turns into sporadic before mass scale
death of the clumps. The flowering continues in a specific direction like a “wave”, with
a period of 12 to 14 years or more, spreading over the whole forest area. Details of
inflorescence character, flowering nature, anthesis and fruiting behaviour have been
discussed. Unlike most other bamboos, this species produces fleshy green pear-shaped
fruits (seeds). The “seed” viability and germination pattern were studied. The problem
and management system of natural regeneration after the death of flowering clumps
were also discussed.
It was estimated that the species exhibited more than one flowering cycle
(interseeding period) in different localities of Bangladesh-India-Myanmar region. Some
populations have 30-35 years of flowering cycle, and others may have further longer (45,
60,65 years) or shorter (7-10,19-21,25,26,27 years) duration. It appears that there exists
a number of flowering population in the region and they might be isolated from each
other by reproductive time. In the boundary areas, however, populations are likely to
overlap with each other and some of the clumps may flower after shorter, and others
after longer periods or in between. Enormous genetic variabilities arc expected within
this vast natural habitat due to such diversities in flowering cycle that offers opportunities
for selection and improvement of the species.
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