Anthropogenic disturbances and plant diversity of the Madhupur Sal forests (Shorea robusta C

This study examined the impact of anthropogenic disturbances on species richness, pattern of diversity, forest structure and regeneration of tree species in the Madhupur Sal (Shorea robusta C.F. Gaertn) forests of Bangladesh. The forest sites were classified as low, medium and highly disturbed based on the intensity of historic and current anthropogenic impacts. Plant species richness and biological diversity varied along a disturbance gradient in different forest types. A total of 134 plant species were identified. The highest plant species richness (125 species) was found in the low disturbed forest type, and the lowest species richness (19 species) in the highly disturbed forest type. Plant density (except herbs and saplings) and basal area of mature trees declined with an increase in disturbance intensity. Only a few snags (4.4 ha−1) were found in the low disturbed forest type. The diameter and height distributions revealed that the low disturbed forest type comprised a mixture of very young to giant trees, while the medium and highly disturbed forest types contained only young trees. The relative abundance of the early successional species, S. robusta,increased with the intensity of human disturbances due to its regeneration potential. Highly disturbed forests can no longer be considered natural habitats for natural plant species due to shifting cultivation and agroforestry.