Structure and composition of tree species in tropical moist deciduous forests of Eastern Ghats of Odisha, India, in response to human-induced disturbances

Abstract

The changes in plant species diversity and community structure in response to human induced disturbances were studied in 12 ha of tropical moist deciduous forest stands of Eastern Ghats of Odisha, India. The forest stands were classified as undisturbed (UD), moderately disturbed (MD) and highly disturbed (HD) categories based on the types and levels of human-induced disturbance. Twenty four transects, each measuring 0.5 ha (5 m × 1000 m) were laid for enumeration of trees with ≥ 30 cm GBH. In total, 5451 trees under 101 species, 78 genera and 37 families were found to occur in the study site. The density of trees and basal area decreased with the increase in the level of disturbance. While the stand density varied in the range of 185.50 in HD stands to 744 stems ha−1 in UD stands, basal area ranged between 12.54 in HD to 36.95 m2 ha−1in UD stands. The number of individuals and number of species per unit area showed a declining trend with increase in girth class. Maximum number of species and density was recorded for trees of low girth class (30–60 cm) in all three stands. Shannon, Simpson, Fisher’s alpha and Margaleff’s indices varied greatly across the three stands experiencing different levels of disturbance. Shannon’s Index varied between 3.20 and 3.42 and Simpson Index ranged from 0.09 to 0.12. The range of variation in Evenness index, Fisher’s alpha index and Margaleff’s index were recorded between 0.75–0.79, 14.45–16.10 and 29.65–34.83, respectively. The diversity of shrub, liana and herb species and regeneration potential of tree species were assessed from two 5 m × 5 m sub-plots located within each transect. Dominance of trees in undisturbed forests, shrubs and lianas in moderately disturbed and herbs in highly disturbed forests were observed. The data generated in the present investigation may prove useful for formulation of appropriate forest management strategies.