Tree species diversity and population dynamics and regeneration status in the tropical forest of Tripura: confluence of indo-burmese biodiversity hotspot

Tree species diversity, distribution, population dynamics, and regeneration status of tropical forests of Northeastern India are poorly understood. The present study analyzed the structure of a tropical semi-evergreen forest in the Unakoti district of Tripura, NE India. The study was conducted by laying 90 quadrats, each 20 m × 20 m in size. In total, 1696 trees belonging to 42 species from 35 genera and 20 families were sampled from a 3-ha area. The mean density was 565 trees ha⁻¹, and the basal area was 21.84 m² ha⁻¹. The dominant tree species was Tectona grandis, with Importance Value Index (IVI) of 50.34, followed by Schima wallichi (44.04). Shannon–Wiener diversity index (H′) ranges from 2.1 to 2.82 among three sites of the district. High Simpson's index (D) of nearly 1.0 indicates high tree species diversity in these present tropical semi-evergreen forests. Out of 42 species, five species were randomly distributed, and thirty-seven species were contagiously distributed. Tree girth-class-wise, population density in three sites ≥ 90 cm gbh class represents highest (41.22%) followed by 61–90 cm. In the height class interval of three sites, 20–30 m class represents highest, followed by 30-40 m class. Stem density and species richness decreased with increasing girth class of trees. This study emphasizes the anthropogenic influences on community structure, including NTFP collection and deforestation. Valuable species like Azadirachta indica and Tamarindus indica were identified. These findings accentuate the need for conservation efforts and comprehensive vegetation studies to ensure sustainable utilization of forest resources in the face of escalating threats to tropical ecosystems.