大兴安岭主要沼泽湿地土壤碳氮垂直分布特征

Spatial Distribution Characteristics of Soil Organic Carbon and Nitrogen in Main Wetlands in Daxing'anling

为了研究大兴安岭北部两类主要沼泽湿地(柴桦—笃斯越桔和落叶松—杜香)土壤有机碳和全氮的垂直分布特征与积累特征,采用重铬酸钾—外加热法、凯氏定氮仪分别测定了土壤有机碳、全氮质量分数,并用环刀法测定了土壤密度。结果表明:两类湿地剖面有机碳分布均具有明显的储碳层和淀积层;上层的储碳层厚度约为10 cm,有机碳平均质量分数分别为220.09、74.93 g·kg-1,全氮平均质量分数分别为8.36、3.75 g·kg-1;下层的淀积层(10～50 cm)内有机碳和全氮质量分数较低。两类湿地土壤剖面有机碳和全氮质量分数与剖面深度呈指数下降趋势,有机碳、全氮与土壤密度之间相关极显著(P<0.01)。柴桦—笃斯越桔湿地和落叶松—杜香湿地0～50 cm土层,有机碳储量分别为3.66×104、1.19×104t.km-2,全氮储量分别为1.43×103、703 t.km-2。

A survey was conducted to study the profile distribution and accumulation characteristics of organic carbon（C） and total nitrogen（N） in two main wetlands in Daxing＇anling.Potassium dichromate-outside heating method,micro-Kjeldahl method and cutting ring method were used to determine C and N mass fractions and soil density respectively.Results show that there exist distinct deposition horizon and illuvial horizon on the sediment profiles of Betula fruticosa-Vaccinium uliginosum wetland and Larix gmelini-Ledum palustre wetland.In the deposition horizon（0-10cm）,the average mass fractions of C in B.fruticosa-V.uliginosum wetland and L.gmelini-L.palustre wetland were 220.9 and 74.9g·kg^-1,and those of N were 8.4 and 3.8g·kg^-1,respectively,while in illuvial horizon（10-50cm）,they were at lower levels.The mass fractions of C and N decreased exponentially with increasing depth,and had significant correlations with bulk density（P0.01）.At the depth of 0-50cm,the storages of C in B.fruticosa-V.uliginosum wetland and L.gmelini-L.palustre wetland were 3.66×104,1.19×104t·km^-2,and those of N were 1.43×103,730t·km^-2,respectively.