Carbon stock dynamics and physico-chemical properties of soils under farm plantations in mid-hills of Himachal Pradesh

Impact of twenty five years old pure and mixed farm plantations of Eucalyptus tereticornis, Populus deltoides, Quercus leucotrichophora and Eucalyptus tereticornis plus Pinus roxburghii and Quercus leucotrichophora mixed with Ulmus villosa was studied on soil carbon density and other physico-chemical properties. The gain or loss of soil carbon stock from plantations was elucidated by comparing the soil properties under plantations with the adjoining area. The study indicated that plantations led to increase in soil organic carbon (SOC) and carbon density. Soil pH under plantations ranged from 5.74–6.41 as compared to 6.20–6.96 in control area. Percent SOC and total soil carbon density was highest in soils under Eucalyptus tereticornis (1.63% and 88.33 Mg ha⁻¹, respectively). Pure plantation of Populus deltoides resulted in maximum increase in actual soil carbon density (69.98%) as compare to area outside the plantations whereas, mixed plantation of Eucalyptus tereticornis plus Pinus roxburghii resulted in minimum increase of 14.19% in actual soil carbon density. Soil carbon density in various plantations followed the trend of Populus deltoides (30.45 Mg ha⁻¹) > Quercus leucotrichophora (22.42 Mg ha⁻¹) > Quercus leucotrichophora plus Ulmus villosa (22.02 Mg ha⁻¹) >Eucalyptus tereticornis (21.66 Mg ha⁻¹) > Eucalyptus tereticornis plus Pinus roxburghii (8.39 Mg ha⁻¹)