Distribution characteristics of soil organic carbon and its physical fractions under the different land uses in Jinyun Mountain
The distribution characteristics of soil organic carbon (SOC) and its physical fractions under the different land uses in Jinyun Mountain were studied in this paper.Subtropical evergreen broad-leaved forest (forest for short),sloping farmland,orchard and abandoned land were selected and soils at the depths of 0-60 cm were sampled in the spring of 2011 to determine the contents of soil organic carbon fractions.Five soil organic carbon fractions,i.e.,coarse particulate organic carbon (cPOC),fine particulate organic carbon (fPOC),intra-microaggregate particulate organic carbon (iPOC),silt and clay within microaggregates (s+c_m),silt and clay (s+c) were separated by physical fractionation technique.The results showed that the contents of SOC,cPOC,fPOC,iPOC,s+c_m and s+c in the whole soil depth from 0 to 60 cm were significantly higher in the forest (9.02,3.14,1.61,0.33,0.42,3.53 g/kg) than those in the orchard (3.27,0.93,0.27,0.10,0.24,1.73 g/kg) and in the sloping farmland (2.58,0.51,0.10,0.12,0.08,1.77 g/kg),which indicated the reclamation of forest would result in the loss of SOC and its fractions.14.90,5.17,2.36,0.42,0.59,6.36 g/kg of SOC and its corresponding fractions in the abandoned land were remarkably higher than those in the sloping farmland,which indicated the abandon from farmland would lead to the effective recovery and sequestration of SOC and its fractions.Among the SOC physical fractions,the ratios of iPOC to SOC were the lowest and accounted for only 3％ in each land use type.The cPOC and fPOC fractions were considered as unprotected carbon pool with higher liability.The ratios of cPOC and fPOC to SOC were highest in the soils of the forest and abandoned land,reached to more than 50％.The ＜53 μm fraction contains organic carbon which is stabilized both as a consequence of its complex chemical composition and by adsorption to silt and clay particles.The ratios of ＜53 μm fraction containing organic carbon to SOC were highest in the soils of the orchard and sloping farmland,65.9 and 71.6％,respectively.The results showed that the liability of soil organic carbon in the soils of forest and abandoned land were higher than those in the orchard and sloping land,that is to say,there is stronger soil fertility in the soils of forest and abandoned land.Furthermore,we suggest that fPOC is a promising fraction for assessing the impact of land use change on SOC in Jinyun Mountain.
国家科技期刊平台
NSTL
万方数据
维普
