Estimation of carbon stock under different management regimes of tropical forest in the Terai Arc Landscape, Nepal

•Community forests have higher stocks of carbon than government-managed forests.•Aboveground and belowground biomass and soil carbon contribute 99% of total carbon stock.•Estimated carbon stocks differ from earlier studies based on biome-average datasets.•Estimates are consistent with those from similar forest type and site-specific studies.•Evidence of strong association of carbon stocks with forest management regime.

Carbon (C) stocks in the forests of Reducing Emissions from Deforestation and Forest Degradation (REDD+) participating countries have to be estimated and monitored to determine accurate financial incentives and compensation. The research estimated the distribution of C stock across the different pools and management regimes of tropical Sal forest in the Terai Arc Landscape of Nepal. It applied a field measurement-based forest inventory method combined with the best predictive allometric model available, to increase accuracy and precision. Shrub and litter C were estimated by destructive method and Soil Organic Carbon (SOC) up to a depth of 30 cm. Biomass data and samples were collected from 113 plots distributed throughout four different management regimes on 1.1 million ha of forest in the landscape. The estimated average C stock in aboveground biomass, belowground biomass, shrub, litter, SOC and total were 105.58 ± 17.05, 24.92 ± 4.15, 0.23 ± 0.06, 1.49 ± 0.25, 96.53 ± 8.76 and 228.76 ± 19.61 Mg ha−1 respectively. The mass of total C stock varied from 291.55 ± 42.51 Mg ha−1 in protected areas to 237.15 ± 32.54 Mg ha−1 in community forests to 189.16 ± 26.46 Mg ha−1 in government-managed forests and to 126.76 ± 56.36 Mg ha−1 in other forests. These estimates of carbon stocks differed from earlier estimates based on biome-average datasets. They are consistent with those from similar forest type and site-specific earlier studies. Evidence of strong association of C stock with management regime provides valuable information for policy makers to make informed choice of management regime for the landscape.