中亚热带红壤丘陵区松林生态系统表层土壤活性有机碳空间分异规律

Spatial distribution of topsoil labile organic carbon of Pinus elliottii ecosystem in the central subtropical region

土壤活性有机碳在指示土壤碳库平衡、表征土壤肥力与质量、衡量土壤微生物生长等方面具有重要意义。本文对中亚热带红壤丘陵区松林生态系统93个表层(0～20cm)土壤样品的活性有机碳空间分布特征及其与地形、植被和土壤特性的关系进行了深入分析。结果表明:表层土壤活性有机碳的平均值为1.92g/kg,占土壤有机碳的29.18%,变异系数为46.15%。从不同地貌部位来看,沟道的活性有机碳含量、碳库活度均显著高于坡面。土壤活性有机碳与海拔、乔木地上生物量显著负相关,与灌木地上生物量显著正相关,与土壤有机碳、全氮、全磷、速效氮、有效磷和速效钾呈极显著正相关关系。利用Canoco进行主成分分析表明,第一、二轴可以算是主成分轴,第一轴中主要与土壤有机碳、全氮、速效氮的相关性较强,第二轴中则主要与海拔、pH、全磷、灌木地上生物量相关性较大。土壤碳库活度则与各影响因子的相关性均不显著。

Labile organic carbon is more sensitive to changes in land management or environment conditions than stable carbon,although it is a smaller fraction of soil organic carbon.It also has a disproportionately large effect on nutrient-supplying capacity and the structural stability of soils.Therefore,the spatial distribution and its influencing factors（topography,vegetation and soil properties） have been analyzed in Pinus elliottii ecosystem of central subtropical region.Results indicated that the mean of soil labile organic carbon was 1.92g/kg,accounting for 29.12% of soil organic carbon,and the coefficient of variability was 46.15%.Labile organic carbon and carbon lability in gully areas were significantly higher than that in slope position.The results of correlation analysis showed that labile organic carbon was negatively correlated with elevation and aboveground biomass of arbor layer,positively correlated with aboveground biomass of shrubs,but highly significantly positive with soil organic carbon,total nitrogen,total phosphorus,available nitrogen,available phosphorus and available potassium.Principal component analysis in Canoco showed that the first and second axes were the principal component axes.Soil organic carbon,total nitrogen and available nitrogen were the first principal component axis affecting labile organic carbon,followed by altitude,pH,total phosphorus and above-ground biomass of shrubs.However,carbon lability had no significant correlation with affecting factors.