Natural Regeneration in Harvested and Unharvested Forest Plantations - Case Study in Chittagong University Forest, Bangladesh

This study was aimed to identify the dominant species establishing during regeneration, their species diversity and whether selection thinning could enhance the regeneration of secondary forest species. Chittagong University Forest was selected for the study and harvested and unharvested sites of forest plantations were demarcated and set 30 quadratic plots (3m × 3m) for each site. Ten per cent selection thinning was done in harvested site although a little anthropogenic disturbance was noticed in both the plantations.  Regenerations were identified into species level and their numbers were counted. Shannon-Weiner diversity index for unharvested plantation was 2.21 and it was 1.45 for harvested plantation. Species evenness index was recorded as 0.81 and 0.74 for unharvested and harvested plantations respectively. Both the plantations did not show a significant difference in diversity of species. According to the Important Value Index (IVI) the dominant species in the harvested site were Acacia auriculiformis followed by Acacia mangium and Albizia lebbeck. In the unharvested site, IVI was the highest for Acacia auriculiformis followed by Aphanamixis polystachya and Lagerstroemia speciosa. In both the sites, Acacia auriculiformis had a significantly (p<0.05) higher number of regeneration in harvested plantations than those of unharvested plantations. Therefore, thinning has a positive impact on natural regeneration and Acacia auriculiformis is the best for natural regeneration in plantations.