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

Abstract

[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.

Keywords

• different altitudes
• soil nitrogen components
• seasonal dynamics
• environmental factors
• redundancy analysis
• nature reserve