高寒山地生态修复方式对土壤颗粒碳氮分配的影响

Effects of ecological restoration patterns on soil particulate organic carbon and total nitrogen distribution in alpine mountain

通过探讨草地和林地两种修复方式下不同粒径土壤颗粒有机碳和全氮的分配规律,以期能够为高寒山地生态修复措施对土壤颗粒碳氮的影响提供参考。以空间序列代替时间序列的方法,分别选取不同恢复年限的草地和林地作为研究对象,管理方式分别为仅在生长季封育和常年封育。对生长季野外现场采集的土壤样品在实验室采用离心法对土壤颗粒进行分级,分为砂粒(2000—50μm)、粉粒(50—2μm)和粘粒(<2μm),以此分析不同粒径土壤颗粒中有机碳和全氮的分配规律。结果显示:1)不同修复年限草地和林地土壤颗粒有机碳和全氮的分配主体分别为砂粒和粉粒,草地和林地土壤颗粒有机碳在砂粒中的分配比例分别为57.36%和46.46%,全氮在粉粒中的分配比例分别为44.79%和42.55%。2)两种修复用地三种粒径土壤颗粒碳氮分配比例均与其组分含量呈正相关关系,砂粒的碳氮分配比例主要受地下生物量和土壤总孔隙度影响,粘粒和粉粒碳氮分配比例主要受容重和pH的影响。本研究区植树造林的修复方式对土壤颗粒碳氮的分配影响更为明显。

This study explored the impact of two different ecological restoration approaches on allocations of soil particulate organic carbon and total nitrogen,expecting to provide theoretical references for research on the effects of ecological restoration on the soil carbon and nitrogen pools in alpine mountain regions.By the method of space replacing time,grassland and woodland with different restoration years were selected as research subjects,and the management types were only in the growth season and perennial sealing,respectively.Soil samples collected in the field during the growing season were graded for soil particles by centrifugation in the laboratory,and the soil grain size were classified into sand(50-2000μm),silt(2-50μm),and clay(<2μm)to analyze the distribution of organic carbon and total nitrogen in soil particles.The results showed as follows.Firstly,the main subjects of soil particulate organic carbon(POC)and total nitrogen(TN)in grassland and woodland for different restoration years were sand and silt particles,respectively.Soil organic carbon in sand particle in grassland and woodland accounted for 57.36%and 46.46%,respectively;and total nitrogen(TN)in silt particle in grassland and woodland took up 44.79%,and 42.55%,respectively.Second,the percentages of POC and TN in different soil particles all existed significantly positive correlations with their component contents.The allocation of POC and TN in sand was mainly affected by belowground biomass and soil porosity,while the allocation of POC and TN in clay and silt was mainly affected by bulk density and pH.Those results indicated that influences of the afforestation on allocations of the POC and TN in soil different particles were more obvious.