北方农牧交错带人工林土壤理化性质分布格局

Distribution pattern of soil physical and chemical properties of plantation forest in northern agro-pastoral ecotone

北方农牧交错带是继北方草原之后的中国第二大生态安全屏障,是典型的生态脆弱带。本研究以北方农牧交错带人工林为研究对象,通过野外调查和室内分析,在区域尺度上探讨了人工林土壤理化性质的空间分布格局,并结合气候因子和树种特征,阐述了乔木林和灌木林土壤理化性质差异以及人工林土壤理化性质随气候梯度的变化规律。结果表明:(1)农牧交错带人工林土壤整体呈弱碱性,电导率153.55±3.02μS·cm^(-1)、土壤容重0.53~2.28 g·cm^(-3)、土壤含水量12.54%±0.62%,土壤全碳和全氮含量分别为13.74±0.61 g·kg^(-1)和0.88±0.05 g·kg^(-1)。(2)农牧交错带人工林土壤自西向东酸性增强、容重下降、含水量增加、全碳含量下降、全氮含量增加。(3)在气候梯度上,人工林土壤pH、电导率、容重与降水量显著负相关,而土壤含水量、全碳和全氮含量与年降水量显著正相关;人工林土壤全碳和全氮含量与年均气温和干燥度指数均显著负相关。(4)区域尺度上,乔木林土壤pH显著低于灌木林土壤,灌木林土壤全碳和全氮含量均高于乔木林。

The northern agro-pastoral ecotone is the second largest ecological security barrie,which is a typical ecological fragile zone in northern China.In this study,based on field investigation and indoor analysis,the spatial distribution pattern of soil physicochemical properties in the planted forest in the northern agro-pastoral ecotone was discussed.Combined with climatic factors and tree species identities,the differences of soil physicochemical properties between trees and shrubs and thevariations of soil physicochemical properties in the planted forest with climate gradient were analysed.The results show that:(1)The overall soil of the plantation in the agro-pastoral ecotone was weakly alkaline,the electrical conductivity was 153.55±3.02μS·cm^(-1),the soil bulk density ranged from 0.53 to 2.28 g·cm^(-3),the soil water content was 12.54%±0.62%,and the soil total carbon and nitrogen contents were 13.74±0.61 g·kg^(-1)and 0.88±0.05 g·kg^(-1),respectively.(2)From west to east,soil acidity increased,soil bulk density decreased,soil water content increased,total carbon content decreased,and total nitrogen content increased.(3)On the climate gradient,soil pH,conductivity and bulk density were negatively correlated with precipitation,while soil water content,total carbon and total nitrogen were positively correlated with precipitation.The soil total carbon and total nitrogen contents were negatively correlated with temperature and aridity index.(4)On the regional scale,soil pH of tree soil was significantly lower than that of shrub soil,and soil total carbon and nitrogen contents of shrub soil were higher than those of treesoil.