Seven different bamboo species have been growing naturally in the forests of Sylhet, Chittagong Hill Tracts, Chittagong and Cox’s Bazar of Bangladesh. Bamboo does not grow naturally in the mangrove and sal (Shorea robusta) forests. The distribution and ecological conditions of species have been described. The overexploitation, fire and other biotic interferences are reducing the area of natural bamboo forests on an average by two per cent annually. Lack of scientific management, especially large scale death after gregarious flowering is also considered to be an important factor for shrinking the bamboo area in the forests. Among the naturally grown forest bamboos the occurrence of Dendrocalamus hamiltonii, Melocalamus compactiflorus and Neohouzeaua dullooa is reducing alarmingly due to the destruction of their habitat. Therefore, these three species have been considered as threatened bamboo species of Bangladesh.

Sissoo (Dalbergia sissoo Roxb.) is a large deciduous tree which is planted throughout Bangladesh for its valuable timber. It grows well on alluvial soil, but it does not grow healthy in the soils of heavy texture (Bakshi 1976). The species can tolerate high soil moisture under well-drained conditions, but it can not withstand water-logging even for a short period (Street 1962). On the other hand, it can tolerate a long dry period. At Homna in Comilla, a road was newly constructed which was water-logged for a long time because of prolonged rainfall. The roadside strip plantations of D. sissoo, Swietenia macrophylla, Albizia procera, Cassia siamea, Acacia auriculiformis and Tertninalia arjuna were raised in June, 1990. The sissoo saplings were growing well with drak green bushy and spreading crowns. Some of them attained a height of about two metres. A wilt symptom first appeared in the last quarter of June, 1991 and it continued to September. By July, about 25% of the 8000 saplings began to wilt. About 5% of them died completely within August. At first the leaves of lower branches became yellowish and continued towards the apex. As a rusult, the entire saplings turned yellow. The leaves lost their turgidity after a few days. Later, these dropped off the branches and finally the saplings died. The vascular tissues in the outer layer of sapwood turned pink. After the death of the saplings the roots and the stem collar stained black.

The effectiveness of the preparation with borax, boric acid and copper sulphate salt (BBC) as a water borne wood preservative was studied in the laboratory soil-block test. Blocks of civit (Swintonia floribunda) and chapalish (Artocarpus chaplasha) wood were dip-treated with the preservative solution and exposed to a common white rot fungus (Polyporous versicolor) and a brown rot fungus (Poria nionticola). The loss in weight of the wood blocks due to the fungal decay was recorded to be in the range 0-1.4%. This showed that the preservative was very effective. The field test of the preservative is being carried out with chapalish and garjan (Dipterocarpus spp.) wood stakes along with untreated ones. All the untreated stakes deteriorated due to fungi or other wood destroying agents within two years, but the treated stakes remained uneffected even after five years of exposure.

Minjiri (Cassia siamea Lam.) is a promising fast growing tree species indigenous to Bangladesh and is included in the plantation programme. An attempt has been made to prepare the biomass tables for the species. The biomass equations were selected to estimate the green weight of the whole tree, weights of the stem, the branches, leaves and twigs, branches and stem; branch, leaves and twigs. The diameter at breast height (D) – biomass and D-height – biomass relationships were determined. It was observed that the logarithmic function to the base “e” gives a good fit model. The conversion factors were also determined to estimate the air-dry and oven-dry weights of the components.

Two provenance trials of Pinus caribaea var. hondurensis were established in randomised complete block design in 1983 and later in 1984 at Keochia Silviculture Research Station, Chittagong, Bangladesh. It was observed that there was no significant difference among the provenances in respect of survival percentage, height and diameter growth and volume yield till December, 1989. All the provenances are doing well in the area. The mean height, diameter at breast height and volume yield per plot of 148.84 ranged from 9.5-10.4 m, 12.5-13.8 cm and 1.242-1.663 respectively for the 1982 trial at the age of 7.5 years. The corresponding data for the 1984 trial at the age of 5.5 years were 4.2-5.4 m, 6.0-7.7 cm and 0.102-0.300 m^ respectively.

The physical and mechanical properties of Bambusa arundinacea, B. longispiculata, B. vulgaris and Dendrocalamus giganteus have been studied at three height levels. The moisture content and shrinkage decrease, whereas specific gravity increases as the height of the culm increases. B. longispiculata exhibits the highest specific gravity among the four species. The diameter shrinkage is found much lower than the shrinkage in wall thickness. The compressive strength, fibre stress at elastic limit and modulus of elasticity increase with the culm height. Among the four species, B. arundinacea shows the highest strength in almost all cases.

The soil moisture stress significantly affected the growth of the four selected eucalypt species. In case of Eucalyptus citriodora the growth improved as the soil moisture content increased up to 53% of field capacity. In case of other species the growth improved up to 67% of field capacity. The root growth was adversely affected with an increase in soil moisture content and therefore there was a decline in the root/shoot ratio. The overall growth was very poor in this highly acid and low fertility level soil.

The growth and distribution of root systems of an annual crop (French dwarf bean) and a young tree species (poplar) in large soil columns at three different soil water supply regimes were studied in a simulated agroforestry under a greenhouse condition at the University of Edinburgh, UK. The root biomass production of bean plants was found unaffected under the limited soil water supply whether grown in a monoculture or in mixed stands in contrast to that of poplar plants. The root system of bean explored only top 36 cm of soil column whereas poplar root system explored beyond the depth of 36 cm . These differential responses of an annual crop and a young tree species may be used as a basis for selecting complementary agroforestry components in a dry area.

The forest soils of Bangladesh have been discussed under the four generalized dendro- ecological regions e. g. (i) Floodplain region, (ii) Plio-Pleistocene Terrace region, (iii) Mio-Pliocene Hill region and (iv) Anthropogenetic landtypes region. The dominant soil forming factors and their attributes on physico-chemical, mineralogical properties and the natural soil fertility in each region have been briefly narrated. In addition, major tree species of the dendro-ecological regions and the opportunity for forest production have been discussed. The limitations for tree growth on different dendro-ecological regions have been mentioned. Emphasis has been given on the role of soil moisture regime, acidity, fertility and soil depth on site specific species selection.

In recent decades, the Chakaria Sundarbans located in Cox’s Bazar district has been subjected to a tremendous human interference. It was once covered with moderately dense mangroves. It is now a denuded area. A major proportion of the forest areas has been converted to shrimp ponds. The remaining areas fall under the normal tidal inundation. The Forest Department sought research backup from the Bangladesh Forest Research Institute (BFRI) to develop techniques for the rehabilitation of the mangroves of Chakaria Sundarbans. Accordingly, a reconnaissance survey was conducted. It showed that the area outside the shrimp farms was suitable for raising mangrove species from silvicultural point of view (Siddiqi et al. 1992). Five species, namely sundri (Heritiera fames’), gewa (Excoecaria agallocha), kankra (Bruguiera sexangula), passur (Xylocarpus mekongensis) and baen (Avicennia officinalis) were chosen for trail in the denuded areas.