Elizabeth Nemhoihkim, Enmuanliana, L.K. Thang Ngaihte and B.P. Mishra
Abstract
The study aimed to evaluate the diversity and distribution of tree species along a disturbance gradient in Hmuifang forest of Aizawl district, Mizoram. For detailed investigation 0.5 ha area of 3 forest stands each representing undisturbed stand (>50% canopy cover and <10% Disturbance Index), moderately disturbed stand (20-50% canopy cover and 10-50% Disturbance Index), and highly disturbed forest stand (<20% canopy cover and >50% Disturbance Index) was sampled. Altogether, a total of 115 tree species belonging to 81 genera and 47 families were recorded. Of this, undisturbed stand was represented by 89 species belonging to 66 genera and 41 families, moderately disturbed stand with 63 species belonging to 51 genera and 36 families, and highly disturbed stand with 31 species belonging to 24 genera and 20 families. According to the Importance Value Index, Lindera pulcherrima was the dominant tree species in the undisturbed forest stand, while in the moderately disturbed stand Drypetes indica was dominant, and in the highly disturbed stand, Schima wallichii was abundant. The Shannon Wiener diversity index (Hâ) was computed highest (4.06) in the undisturbed stand, followed by moderately disturbed stand (3.79) and highly disturbed stand (3.05). On the contrary, the Simpsonâs index of dominance (D) was found to be 0.0219, 0.0284 and 0.054 in the undisturbed, moderately disturbed and highly disturbed forest stands respectively. The Pielouâs evenness index (Jâ) was computed as 0.91, 0.898 and 0.888 for the undisturbed, moderately disturbed and highly disturbed forest stands respectively. The highest similarity was recorded between undisturbed and moderately disturbed stands (0.64) followed by moderately disturbed and highly disturbed stand (0.42). The least similarity was recorded between undisturbed and highly disturbed stand (0.37). The study conducted in the three different forest stands reveals that the community composition changes with disturbance showing a strong negative correlation with disturbance.