GROWTH PERFORMANCE OF FIVE AGROFORESTRY TREE SPECIES IN DINAJPUR DISTRICT

Abstract

A study was conducted in Dinajpur Sadar upazila to find out the growth performance of five tree species namely Swietenia macrophylla (mahagoni), Melia azedarach (ghora neem), Albizia richardiana (rajkoroi), Khaya anthotheca (lombu) and Artocarpus heterophyllus (Kanthal) planted in different agroforestry systems. The study was conducted during the period of January 2019 to June 2019. Data were collected from four agroforestry systems namely orchard, cropland, homestead and roadside. There were different age groups of each species. Each age group contained ten trees. Results of all selected tree species showed that the mean height, diameter at breast height and volume were increased with the increase of age up to a certain period. The selected species showed different culmination point for their growth stage. The culmination points of mahagoni, ghora neem, rajkoroi, lombu and kanthal were recorded as 30, 20, 16, 15 and 40 years, respectively. In case of mean annual increment (MAI) of mahagoni in different agroforestry systems, the highest MAI of height was recorded in orchard (3.42±0.23 ft per year), while the highest MAI of diameter was found in cropland (0.73±0.04 inch/year). Consequently, the highest MAI of volume was observed in roadside (1.81±0.13 cft/year) agroforestry system. For ghora neem, the highest MAI of height was recorded in roadside (3.99±0.10 ft/year), but the highest MAI of diameter was found in cropland (0.79±0.03 inch/year) agroforestry system. As a result, the highest MAI of volume was observed in roadside (1.37±0.14 cft/year) and cropland (1.36±0.10 cft/year) agroforestry system. Similar trends of MAI of height, DBH and volume was recorded in rajkoroi and lombu tree species. On the other hand, MAI of kanthal in different agroforestry systems, the highest MAI of height (2.53 ± 0.08 ft/year), diameter (0.91 ± 0.03 inch/year) and volume (1.32 ± 0.09 cft/year) was observed in homestead agroforestry system. Comparing the volume of five studied species, highest growth performance was recorded in lombu followed by rajkoroi, kanthal, ghora neem and lowest was recorded in mahagoni. Findings also showed that in cropland agroforestry system diameter increment was highest than in other systems of all species which might be due to the adaptive mechanism against wind speed in the open cropland. Present findings concluded that growth performance of a species varied in different agroforestry systems and roadside agroforestry system performed better growth for all the species.