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
Keora (Sonneratia apetala Buch.-Ham.) is one of the most important tree species for large scale plantations in the coastal areas of Bangladesh. The aim of this study was to generate a common volume equation and table for predicting the total and merchantable volume of planted and natural stand of S. apetala in the coastal areas of Bangladesh. A total of 430 sample trees having different girth classes were sampled from the plantation stands of Chattogram, Noakhali, Bhola and Patuakhali. Twenty one (21) models were tested to derive best-fit models for the volume over bark and under bark. The best fit models were selected based on the highest value of R2 (co-efficient of determination), the lowest value of Akaike Information Criterion (AIC) and Root Mean Square Error (RMSE). The selected models were validated by Chi-square test of goodness of fit, Paired t-test, Percent Absolute Deviation (% AD) and 45 degree line test. The best-fit one-variable and two-variable basic models were and respectively. The best-fit models showed the highest efficiency in volume estimation compared to previous developed model in terms of Model Prediction Error (MPE), Model Efficiency (ME) and Root Mean Square Error (RMSE).
The paper reviews information on climate changes, status of forests, biodiversity
and vulnerability of biological resources in Bangladesh particularly in mangrove areas.
Atmospheric concentration of green house gases modifies the global and regional climates
and consequently affects adversely the environment ofBangladesh. There may be increase in
temperature, rainfall and frequency of cyclones, and sea level rise in the coast ofBangladesh.
The country is likely to experience repeated flooding, cyclones, tidal surges, soil erosion,
heavy sedimentation,salinity increase and prolonged drought
The paper reviews information on climate changes, status of forests, biodiversity
and vulnerability of biological resources in Bangladesh particularly in mangrove areas.
The atmospheric concentration of green house gases modifies the global and regional climates
and consequently affects adversely the environment of Bangladesh. There may be an increase in
temperature, rainfall and frequency of cyclones, and sea level rise in the coast ofBangladesh.
The country is likely to experience repeated flooding, cyclones, tidal surges, soil erosion,
heavy sedimentation,salinity increase and prolonged drought.
The forest covers 17% of the total area of Bangladesh but only 7.7% are under
closed tree cover. With regard to biodiversity, the plant kingdom supports about 5,000
angiospermic species including 10% trees, 35% shrubs and woody climbers and 50% herbs.
The mangrovesinclude 70 species of plant. About animals, the mammals comprise 50 species,
birds 275, reptiles 50 and amphibians 8 species compared to 110 species of mammals, 628
birds, 109 reptiles and 22 amphibians in the entire Bangladesh. Considerable number of
plant and animal species is threatened with disappearance due to human pressure, and the
situation will aggravate with changing climate. Extinction or migration ofspecialized plants
and animals will take place with regular flooding, increasing soilsalinity and other ecological
changes. Probable impact of sea level rise in the coastal areas on forests and biodiversity is
unknown. For living organisms, it may be possible to overcome small and gradualsea level
rise but will disappear in case of abrupt change.
Keora (Sonneratia apetala Buch.-Ham.) is a
pioneer species in coastal areas of Bangladesh
(Siddiqi 2001). It alone constitutes 94.4% of the
existing mangrove plantations (Siddiqi and
Shahjalal 1997) because of its high survival and
growth in the newly accreted land. However, the
information on flowering, fruiting and seed
collection are very little. There was no systematic
study in this context. So, for a clear understanding
about the phenology of keora a study over a period
of 12 monthsfrom January to December 1996 was
conducted in the coastal plantation ofKattoli under
Chittagong Coastal Afforestation Division.
A survery was conducted to assess the present status of infestation caused by the beehole borer, Zeuzera conferta Walker(Cossidae: Lepidoptera) in keora (Sonneratia apetala Buch.-Ham.) plantations along the coastal belt of Bangladesh. The survey covered plantations raised in the four Coastal Afforestation Divisions, namely Patuakhali, Bhola, Noakhali and Chittagong of the Forest Directorate. The survey revealed an overall infestation of 20.9% with an average of 15.6,16.6, 26.3 and 25.2% in the four Divisions respectively. A number of plantation attributes, such as age (3-20 years), inundation duration (very low to very high levels with which the keora stand got tidally inundated in a year), canopy closure (open and closed), and stand composition (single species and mixed species), were evaluated for their correlation association with the degree of infestation. The correlations between the degree of infestation and plantation age in Patuakhali (r = -0.28 ) and Bhola (r = -0.31) were non-significant, whereas those in Noakhali (r = -0.71) and Chittagong (r = -0.53) were significant. The infestation trend reached its peak at around the age of seven years and then decreased slowly. Infestation was higher in highly inundated (> 9 months inundation), open canopy and single species stands.
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.
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