Aboveground Tree Carbon Stocks Along a Disturbance Gradient in Wet Tropical Forests of South Assam, India

Abstract

Human activities have been severely affecting forest structure and functions in humid tropics across the globe. In present study, we estimated aboveground biomass and carbon stocks along a disturbance gradient in wet tropical forests of southern Assam, India, using non-destructive sampling method. A total of 26 forest stands were surveyed and based on a disturbance index grouped into 4 categories, viz. undisturbed (UD), mildly disturbed (MLD), moderately disturbed (MD) and highly disturbed (HD) forests. Mean aboveground carbon (AGC) stocks and basal area decreased with increased disturbance index. Though phytosociological parameters such as species richness, Shannon-Wiener diversity index, tree density, basal area and AGC stocks showed a significant negative correlation with disturbance index, tree density (693 ± 11.6 trees ha−1) and Shannon-Wiener diversity index (1.98 ± 0.07) were highest in mildly disturbed forests. Aboveground carbon stocks were positively correlated with basal area (p < 0.01) and diversity indices (p < 0.01) across disturbance regimes. Tree species such as Cynometra polyandra, Mesua ferrea, Palaquium polyanthum, Mesua floribunda, Artocarpus chama and Stereospermum personatum together contributed 41.3 ± 6.2 % and 42.4 ± 6.7% of the total AGC stocks in undisturbed and mildly disturbed forests, respectively, while Artocarpu schama, Holarrhena pubescens, Mitragyna rotundifolia, Sapium baccatum, Schima wallichii and Toona ciliata contributed 47.2 ± 3.5% in moderately and 55.4 ± 4.0% in highly disturbed forests.