Structure, diversity, and regeneration of tropical dry deciduous forest of northern India

Abstract

This study examined the impact of disturbance on the pattern of diversity, forest structure and regeneration of tree species in the Vindhyan dry tropical forest of India. A total of 1500 quadrats distributed over five, 3-ha permanent plots in five sites, differing in degree of disturbance, were used to enumerate and measure the tree species. A total of 65 species with 136,983 individuals were enumerated in the total 15-ha area for stems ⋝ 30 cm height. The number of species and number of stems ranged from 12 to 50 and 8063-65331 per 3-ha area. The number of species and stems for trees ⋝ 10 cm dbh ranged from 3 to 28 species, with a mean value of 16 species ha⁻¹, and from 16 to 477 stems, with a mean value of 256 stems ha⁻¹, respectively. The adult based PCA ordination indicated uniqueness of sites in terms of species composition and habitat characteristics. PCA ordination also showed uniqueness of sites in terms of seedling composition, but the seedling and adult distributions were not spatially associated. The distinct species composition at the different sites and at the two life-cycle stages on the same site is indicative of marked spatio-temporal dynamics of the dry tropical forest. The density-diameter semi-logarithmic curves ranged from a near linear to an overall concave appearance with a limited plateau in the mid-diameter ranges. The α -diversity and its components decreased with increasing disturbance intensity, reflecting enhanced utilization pressure with increasing disturbance. The site-wise and species-wise regression analyses of the number of individuals in different stages of the species revealed that both the level of disturbance and the nature of species strongly affect the regeneration. In conclusion, although the forest is relatively species-poor, the differential species composition on different sites and the temporal dynamics lend a unique level of diversity to the tropical dry deciduous forest.