The effect ofwax emulsion varying in concentration from 0 to 1.5% at 0.5% increments on the strength and dimensional stability of urea formaldehyde bonded particleboard at three glue levels, 8%, 10% and 12% has been observed. Results show that the addition of wax emulsion is useful to manufacture particleboard at low glue level, viz., 8% and 10%. But it does notshow any appreciable effect on the board made with 12% glue. The properties of particleboards improve with increasing addition of wax emulsion for 8% glue and for 10% glue, the addition of 1% wax has beneficial effect on all the properties under investigation. Beyond this, further improvement is not marked. A combination of 10% glue and 1% wax is found advantageous to manufacture strong particleboard having good dimensional stability.

The growth and yield models/tables for Gmelina arborea Roxb. (gamar) in the plantations of Bangladesh have been prepared based on site indices. Models were derived by the data collected from permanent sample plots and also from temporary sample plots. Step-wise and all probable combinations of the independent variables methods were used to select the best suited models subject to the satisfaction of the statistical and biological requirements. Models were selected to estimate the stand dbh,stand mean height,stand basal area per hectare, total overbark volume yield per hectare and underbark volume yield per hectare upto top-end diameter of 10.0 cm. The yield prediction models derived in the study could satisfactorily be used for gamar plantations within the limitations ofstands of ages 3-12 years and site indices of 7.5 to 20.0 meters based on a base age of 12 years.

Acacia auriculiformis and A.mangium the two fast growing exotic species have been introduced to
Bangladesh for meeting the increasing demand offuelwood and poles. During last decade, thousands of
hectares of plantation have been raised with these two species. In a number of A. auriculiformis
plantations, several outstanding trees have been observed with good growth and vigour. These trees
possess many characteristics of both good growth and vigour. These trees possess many
characteristics ofboth A. auriculiformis andA. mangium. The hybrid trees coppice well and are somewhat
resistant to heartrot disease in addition to its higher growth rate. The per unit area productivity of this
hybrid would be higher than the existing output of either of the parent species. The use of vegetative
propagulesrather than seedlings as a commercialforestregeneration method present an opportunity in
genetic improvement.