Vegetation analysis and tree population structure of Sal (Shorea robusta C.F. Gaertn) forests: A case study from the Madhupur and Bhawal National Park in Bangladesh

Sal forests are covering 32% of forest land of Bangladesh and are one of the three major forest resources beside the tropical evergreen and coastal forests. The two National Parks Madhupur and Bhawal comprise most of the Sal forests in Bangladesh. This study examined a comparative analysis of plant species richness, pattern of diversity, forest structure and regeneration of the core areas of these two national parks, which are located in the same agro-ecological zone. In total 129 plant species were identified in the Madhupur National Park where, 43 plant species in the Bhawal National Park. The diversity index and evenness for mature trees, saplings, seedlings, shrubs, climbers and herbs were higher in Madhupur, whereas the concentration of dominance was higher in Bhawal National Park. The dominant species, Sal (Shorea robusta) tended to be more dominant over its natural associates in Bhawal compared to Madhupur National Park. The diameter and height class distributions revealed that the Madhupur National Park had a wider range with a mixture of very young to giant trees, where the Bhawal National Park was lacking giant trees. From the results of the study it can be concluded that the core areas of these two National Parks warrant more protection from human interventions. Protection measures and eco-development activities are needed in order to reduce the anthropogenic pressures on the natural resources of the parks and to meet the livelihood requirements of the local inhabitants