Biological diversity is a key issue to nature conservation. Biodiversity are very essential for food and nutrition, clothing, building and shelter, fuel and energy, medicine and biological control. All over the world forest resources have been destroying and disappearing day by day due to increasing population, industrialization, urbanization and road construction. Especially, the forest destruction rate is very high in least developing countries.The survival percentage of regenerated tree species is gradually decline along with different development stages. Due to rapid population growth, energy deficit, resource shortage, myopic planning, poor management and lack of motivation on the necessity of biodiversity conservation are the main reasons for the loss of wild biodiversity. Biodiversity is heavily disrupted during the past several decades in Bangladesh. Hill forest is the most important sectors of Bangladesh and composed of a number of tropical ever green and semi-evergreen tree species. Due to over exploitation and excessive human interference, the biodiversity is degraded at an alarming rate.This book help to know present species diversity in hilly area.