滇东地区土壤剖面氮同位素垂直分异及空间分异特征

Vertical distribution and spatial differentiation characteristics of nitrogen isotope in soil profile of Eastern Region of Yunnan Province

选取云南石林县不同土壤类型、不同石漠化等级以及不同人为干扰方式影响下的7处典型的土壤剖面为研究对象,研究了剖面中氮同位素垂直分异及空间分异特征.结果表明,土壤中p H值为3.68—6.07,全部土壤剖面呈酸性,总有机碳(TOC)为0.58—29.25 g·kg^(-1),碳氮比(C/N)为1.33—14.70,δ^(15)N介于1.44‰—14.86‰,在随深度的垂直分异中,受剖面中腐殖质层和硝化反硝化反应的影响,土壤中稳定氮同位素呈现一定的规律性变化.在各个剖面之间的空间分异中,两种不同土壤类型下δ^(15)N值的分散程度均存在轻度石漠化剖面>中度石漠化剖面>强度石漠化剖面的规律.同时在受人为影响较小的红壤剖面δ^(15)N值大致呈现强度石漠化剖面>中度石漠化剖面>轻度石漠化剖面的规律.采样区内无论是石灰岩土壤剖面还是红壤剖面δ^(15)N值与土壤理化性质均无显著相关关系.

Seven typical soil profiles under the influence of different soil types,different rocky desertification levels and different human disturbance modes in Shilin County of Yunnan Province were selected as the object of study to investigate the vertical distribution and spatial differentiation of nitrogen isotopes.The results showed that the soil p H was 3.68 to 6.07,the total soil profile was acidic,the total organic carbon（TOC）was 0.58 g·kg-1to 29.25 g·kg-1,the C/N ratio was 1.33 to14.70,andδ15N was 1.44‰to 14.86‰.In the vertical differentiation with depth,the stable nitrogen isotopein the soil showed some regular changes because of the humus layers and nitrificationdenitrification.In the spatial differentiation between the profiles,the degree ofδ15N dispersion in the two different soil types was mild rocky desertification profile〉moderate rocky desertification profile〉intensity rocky desertification profile.At the same time,theδ15N values of the red soil profile,which were less affected by man-made,showed the intensity of rocky desertification profile〉moderate rocky desertification profile〉mild rocky desertification profile.There was no significant correlation betweenδ15N and soil physical and chemical properties in both the limestone soil profile and the red soil profile