We examined the impact of anthropogenic disturbances on plant diversity in a sub-tropical forest of Langol hills, Manipur, Northeast India. Three sites representing various levels of anthropogenic disturbances along an elevational gradient (780-900 m) were earmarked in the forest on the basis of cut stumps analysis. The site I was located at the hill base and was a protected area, site II was located at the mid-hill and was mildly disturbed and site III was located at the top of the hill and was moderately disturbed. The forest vegetation was dominated by Lithocarpus fenestrata Roxb., Schima wallichii (DC) Korthals and Quercus serrata Thunb. A total of 282 species of plants were recorded from across the study sites, representing 210 genera and 82 families. The quantitative characteristics such as density and Importance value index of species varied between the study sites. Species richness in the tree layer was highest in the mildly disturbed forest site II (26 tree species) followed by the protected forest site I (25 tree species) and moderately disturbed forest Site III (18 tree species). In the shrub layer, species richness was highest in Site III (14) followed by Site I (13) and Site II (10) while in the herb layer, the maximum richness was recorded in Site III (21) followed by Site II (18) and Site I (16). The three sites exhibited high community co-efficient values for tree, shrub, and herb layers. The Shannon and Wiener diversity index on the basal cover basis for the tree, shrub, and herb layers varied between 2.37-3.77, 2.68-3.15, and 2.51-2.85 respectively. The distribution pattern of the species in each site followed in the order of contagious > random > regular. The concentration of dominance was low where species diversity was high in all the study sites. Beta diversity was found to decrease with the increase in altitude. Our study indicated that the present forest exhibited high species richness and also suggested that the mildly disturbed forest site favored tree species diversity in the present forest compared to that of protected and moderately disturbed forest sites.