Variations in Soil Organic Carbon Stocks under Different Land-Use Categories in Subtropical Ecosystems of Kashmir

Quantification of soil organic carbon (SOC) stocks in different land uses holds vital significance because of its implications regarding carbon sequestration as the largest terrestrial carbon pool. The current study was conducted to quantify and compare SOC stocks in forest land, agricultural land, and barren land-use categories in the subtropical ecosystems of the Himalayan foothills in Kashmir. Results showed the highest SOC value in the forest soil (75 +/- 11.1 Mg C ha(-1)) followed by agricultural soil (58 +/- 7.0 Mg C ha(-1)) and barren land (44 +/- 6.5 Mg C ha(-1)). SOC stocks in different land uses showed broad variations with values as high as 106 +/- 11.3 Mg C ha(-1) (forest soils) and as low as 14.1 +/- 7.1 Mg C ha(-1) (barren land). The forest SOC values responded significantly to species composition with the highest values in Pinus roxburghii Sarg. pure stands as compared with broad leaved forests. Multivariate ordination analyses revealed that the variations in SOC stocks were significantly correlated with vegetation type, altitude, and soil bulk density. The study has identified anthropogenic disturbances as a major factor deteriorating local SOC stocks and recommends immediate soil restoration efforts to enhance the ecological significance of soils as vital regional carbon sinks. Study Implications: The current study was designed to investigate the soil organic carbon (SOC) levels in different land uses of the Kashmir Himalayas, Pakistan. Results revealed forest soils as the major carbon sinks of the region, attributed to diverse species composition having a significant quantity of organic residues, followed by agricultural soils. Barren land-use class exhibited the lowest SOC values due to minimum vegetation cover, erosion, and degradation. Significant correlations of SOC stocks with geographical and edaphic variables were identified by multivariate ordination analysis in the investigated land-use classes. Results validate the significance of forests in enhancing SOC stocks, demanding forest restoration in the area by controlling the forest losses as well as afforestation. This article provides vital information required for better understanding of SOC stocks in different land-use classes in the subtropical ecosystems of the Kashmir region.