Characteristics of Soil Organic Carbon and Labile Organic Carbon under Different Land Use Types at Forest-Drought Valley Ecotone in the Upper Reaches of Minjiang River

This paper investigated characteristics of soil organic carbon and 3 kinds of labile carbon: microbial biomass carbon,water-soluble organic carbon and readily oxidation carbon under six kinds of land use types(including Quercus semicarpifolia secondary forest,Robinia pseudoacacia plantation,shrubbery,shrub,economic forest and farmland) at forest-drought valley ecotone in the upper reaches of Minjiang River.The results showed: Respective content of soil organic carbon and three kinds of labile organic carbon of Quercus semicarpifolia secondary forest was higher or significantly higher than the other five kinds of land use(p0.05);Respective content of soil organic carbon and three kinds of labile organic carbon of farmland was lower or significantly lower than the other five kinds of land use(p0.05).The average soil organic carbon content(13.65 g/kg) under six kinds of land use was lower than that(17 g/kg) in the same area.Under six kinds of land use types,microbial biomass carbon,water-soluble organic carbon and readily oxidation carbon respectively account for 1.36% to 2.35%,0.82% to 1.34% and 7.77% to 10.50% of soil organic carbon.The study showed: Respective soil organic carbon content under six kinds of land use was low,which had the downward trend at ecotone.Moreover,the soil organic carbon was active and easily invert.Thus,reducing artificial interference was important to sustain and increase the soil organic carbon at forest-drought valley ecotone.