Comparative Study of Biomass and Soil Organic Carbon Fractions in Buffer and Multiple-use Zones of Ruecheyna Range, JDNP, Bhutan

Forest serves as critical carbon sinks, and their management significantly influences carbon stock capacity. Despite Bhutan’s national commitment to environmental conservation, empirical data on the impact of park management on carbon stock, particularly soil organic carbon fraction, remain unexplored. This study assessed the impact of forest management practices on carbon stock by analyzing the soil organic carbon fractions, such as particulate organic matter (> 53μm) and mineral-associated organic matter (< 53μm), along with biomass stock in Ruecheyna Park Range of Jigme Dorji National Park (JDNP) in Bhutan. The study was conducted using a random sampling design with 30 plots each in the Buffer Zone (BZ) and Multiple Use Zone (MUZ). Aboveground biomass was quantified using species-specific allometric equations, soil organic carbon fraction through physical fractionation, and the loss on ignition method. The data were analyzed using R version 4.3.3 statistical software. Results revealed considerably higher carbon stock in BZ (293±90.05 t ha-1) compared to MUZ (210.65±89.75 t ha-1, p < .001), with biomass carbon accounting for 49.75% in BZ and 44.3% in MUZ of the total stock. Soil organic carbon stock varied significantly with an estimated 147.58 t ha⁻¹ ± 47.94 in BZ and 117.31 t ha⁻¹ ± 45.81 in MUZ. Both POM and MAOM showed greater stability in BZ than MUZ with lower CV. The findings underscore the importance of zone-specific forest management in enhancing stable carbon pools. Moreover, results demonstrate that distinct forest zones exhibit significantly different contributions to stable soil organic carbon fractions, a pattern that would be overlooked when total SOC alone is considered. By explicitly separating SOC fractions across management zones, this study provides a more reliable framework for carbon stock estimation and offers critical insights for zone-specific forest management and long-term carbon sequestration strategies.