Impact of disturbance on community structure, biomass and carbon stock in montane evergreen forests of Meghalaya, northeast India

Abstract

Forest ecosystems play an important role in regulating global carbon cycle. There are very few studies on biomass and carbon (C) stock from the community managed montane evergreen forests of India. In the present study three traditional forests: Sacred forests (SF), Restricted forests (RF) and Village forests (VF) were studied to analyze the level of disturbance, species diversity, stand characteristics, biomass and C stock. In each forest a belt transect of 20 m wide and 250 m long (0.5 ha) was laid for enumeration of all woody individuals having a diameter at breast height (dbh) of ≥ 5 cm. Species richness, density, basal area and population structure varied between the traditional forest types. The aboveground biomass (AGB) was 273 ± 55.5 in the SF, 195 ± 32.12 in the RF and 75.3 ± 17.1 Mg ha−1 in the VF whereas, the corresponding belowground biomass (BGB) was 59.53 ± 8.4, 44.48 ± 7.5 and 19.9 ± 4.3 Mg ha−1, respectively. Overall, there was a 30% reduction of AGB in RFs and 70% in VFs as compared to the SFs. The mean AGBC stock was 129 ± 26.3, 92.49 ± 15.2 and 39 ± 5.7 Mg C ha−1 in SF, RF and VF. The BGBC ranged from a minimum of 6 to 34 Mg C ha−1 in the study sites. The AGB accumulation was greater in intermediate diameter classes (26 − 45.9 cm) in the RFs and VFs whereas in SFs the diameter class >65cm accounted to about 27-69% of the total AGB. Human disturbance had a strong influence on the species richness and stand characteristics that in turn influence the biomass and C stock in the community forests. It is emphasized that the village forests need to be provided with adequate protection for increasing the C storing potential.