Structure and composition of understory treelets and overstory trees in a protected area of Bangladesh

Abstract

Species diversity, composition, and structure of the understory treelet and overstory tree layers were investigated at Lawachara National Park in Bangladesh. Plots were taken following a systematic sampling technique from the whole forest during January to May 2012. In this study, all the overstory trees (diameter at breast height [DBH] ≥ 10 cm) and understory treelets (2 cm ≤ DBH < 10 cm) were investigated and the structure and diversity between them were compared. A total number of 347 individual trees belonging to 69 species and 29 families, and 311 individual treelets belonging to 61 species and 27 families were found in this study. Artocarpus chaplasha and Terminalia catappa were the most important species of tree and treelet respectively. The five most important families both for trees and treelets were Meliaceae, Elaeocarpaceae, Lythraceae, Combretaceae, and Moraceae. The different diversity indices and true diversity value indicate that the overstory tree layer was much more diverse than the understory treelet layer and thus trees may be an appropriate representation of the diversity status of a particular tropical forest type. However, treelet diversity at Lawachara National Park is also considerable and more attention needs to be paid to include treelets in any biodiversity inventory of tropical forest regardless of the size limit of 10 cm DBH.