四川栗子坪自然保护区不同海拔土壤氮组分垂直特征及季节动态

[目的]为揭示四川栗子坪国家级自然保护区土壤氮组分(全氮、水解氮、铵态氮、硝态氮)沿海拔梯度的垂直分布差异及其与理化因子响应关系。[方法]于2022年3,6,9,12月测定并分析四川栗子坪海拔1 800,2 100,2 400,2 700 m土壤氮组分及理化因子的垂直变化特征，并采用多变量方差分析及冗余分析法，分析环境因子与氮组分的关系及季节动态。[结果](1)海拔、季节及交互作用对土壤氮组分有显著影响，3,6,9,12月铵态氮含量表现为海拔2 100 m>2 400 m>1 800 m>2 700 m,硝态氮含量表现为海拔2 400 m>2 100 m>2 700 m>1 800 m,沿月份梯度增加，全氮含量呈增加趋势，水解氮、铵态氮、硝态氮含量呈先减后增趋势，12月全氮和硝态氮含量有最大值分别为1.25 g/kg和8.26 mg/kg, 3月水解氮和铵态氮含量有最大值185.14,5.80 mg/kg。全氮、水解氮、铵态氮、硝态氮沿土层变化规律有一致性，呈“V”形；(2)不同季节和海拔理化因子垂直变化特征与氮组分差异较大，土壤全磷、有效磷、速效钾...

Vertical Characteristics and Seasonal Dynamics of Soil Nitrogen Components at Different Elevations in Liziping Nature Reserve, Sichuan

[Objective] To reveal the vertical distribution differences of soil nitrogen components (total nitrogen, hydrolyzed nitrogen, ammonium nitrogen, nitrate nitrogen) in Liziping National Nature Reserve in Sichuan Province and their relationships with physicochemical factors. [Methods] In March, June, September and December 2022, the vertical variation characteristics of soil nitrogen components and physicochemical factors at altitudes of 1 800 m, 2 100 m, 2 400 m and 2 700 m in Liziping, Sichuan Province were determined and analyzed, and the relationship between environmental factors and nitrogen components and their seasonal differences were analyzed by multivariate analysis of variance and redundancy analysis. [Results] (1) Altitude, season and their interaction had significant effects on soil nitrogen composition, and in March, June, September and December the ammonium nitrogen content was 2 100 m＞2 400 m＞1 800 m＞2 700 m above sea level, and the nitrate nitrogen content was 2 400 m＞2 100 m＞2 700 m＞1 800 m above sea level, and the gradient increased over the month, the contents of total nitrogen and nitrate nitrogen showed a trend of increasing first, with the maximum content of total nitrogen and nitrate nitrogen being 1.25 g/kg and 8.26 mg/kg, respectively, in December, and the maximum content of hydrolyzed nitrogen and ammonium nitrogen in March being 185.14 mg/kg and 5.80 mg/kg respectively. The variation of total nitrogen, hydrolyzed nitrogen, ammonium nitrogen and nitrate nitrogen along the soil layer was consistent, and formed a "V" shape. (2) The vertical variation characteristics between physicochemical factors and nitrogen components in different seasons and altitudes were significantly different, and the contents of total phosphorus, available phosphorus and available potassium increased first and then decreased along the depth of soil layer. (3) Seasonal differences in the key factors affecting soil nitrogen composition, organic matter, non-capillary porosity, available potassium, total phosphorus, available phosphorus and capillary porosity in March and December, and organic matter, total potassium and capillary porosity, total phosphorus and available potassium in June and September. [Conclusion] This study provides a specific production practice basis for the response mechanism of soil nutrients to altitude and season and the comprehensive management of ecological conservation in nature reserve.