Mathematical models for growth and yield prediction of agar (Aquilaria malaccensis lamk) plantations in Bangladesh

Agar (Aquilaria malaccensis Lamk, Family- Thymeleaceae) has drawn unique position due to the production of world’s most expensive essential oil used in fragrances and as medicine. It is one of the most valuable and economically important commercial tree species planted in some potential forest areas of Bangladesh. The growth rate and yield of the species in Bangladesh are not known. Therefore, for scientific management of the forest necessity of the growth and yield models for the species were felt. The present study was made to derive mathematical models for growth and yield of this species in Bangladesh based on site indices. The models were developed through establishment of permanent sample plots (PSPs) and temporary sample plots (TSPs) with area 0.02 ha and shape is circular and rectangular. Diameter at breast height and total height of all trees in the plots were measured for four successive years from PSPs. Step-wise method and all probable combinations of the independent variables method 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 stocking, stand height, stand diameter, stand basal area and stand volume yield per hectare. The yield prediction models derived in the study could satisfactorily be used for Agar tree plantations within stand age of 3.5 to 17.5 years and site indices of 8. To 20.0 meters based on a base age of 12 years.