大围山典型森林土壤有机氮垂直分布特征

Vertical Distribution Characteristics of Typical Forest Soil Organic Nitrogen in Dawei Mountain

为了解亚热带典型森林土壤氮素和有机氮素特征,采集大围山森林公园典型森林土壤剖面(0~100 cm),按每10 cm一层采集土壤样品,研究土壤氮素和有机氮变化规律及其与土壤理化性质的关系.结果表明:1土壤全氮、酸解性有机氮、可溶性有机氮含量均随剖面深度增加而呈下降趋势,受海拔高度影响,高海拔山地花岗岩黄棕壤土壤全氮和有机氮组分含量较高;2土壤有机氮占全氮比平均97.39%±1.17%,酸解性有机氮占全氮比平均64.38%±10.68%,酸解性有机氮各组分均随剖面深度增加而降低;3土壤可溶性有机氮含量范围为9.92~23.45 mg·kg-1,游离氨基酸氮(1.62~12.02 mg·kg-1)占可溶性有机氮比为27.36%±9.95%;4酸解性有机氮、可溶性有机氮与土壤全氮、可溶性总氮、无机氮均达到显著的正相关关系(P<0.05),与土壤容重、有机碳和全磷具有极显著的相关关系(P<0.01).亚热带典型森林土壤中有机氮是土壤全氮的主体,受海拔高度和土壤理化性质的影响,各组分随土壤剖面深度的增加呈下降趋势,有机氮组分与各氮素形态间的转化关系密切,土壤有机氮特征将深刻影响森林生态系统氮的循环过程.

To clarify altitudinal gradient of subtropical forest soil total nitrogen and organic nitrogen,soil samples were collected per 10 cm on soil profile( 0-100 cm) in Dawei Mountain,researched the variation of soil organic nitrogen and correlation with soil physical and chemical properties. The results showed that: 1 Total nitrogen,acid hydrolysable organic nitrogen and soluble organic nitrogen decreased with the increase of depth,content of each component in mountain granite yellow-brown soils was much higher affected by altitude; 2 The average percentage of soil organic nitrogen to total nitrogen was 97. 39% ± 1. 17%,and soil acid hydrolysable organic nitrogen was 64. 38% ± 10. 68%,each component decreased with the increase of soil depth; 3 Soil soluble organic nitrogen content was 9. 92-23. 45 mg·kg- 1,free amino acids( 1. 62-12. 02 mg·kg- 1) accounted for about 27. 36% ± 9. 95% of soluble organic nitrogen; 4 Soil acid hydrolysable organic nitrogen and soluble organic nitrogen were significantly positively correlated with total nitrogen,total soluble nitrogen and inorganic nitrogen( P < 0. 05),were highly significantly correlated with soil bulk density,organic carbon,and total phosphorus( P < 0. 01). Organic nitrogen was the main body of soil nitrogen in typical subtropical forest,each component showed a downward trend increase with soil depth affected by altitude and soil physical and chemical properties. There was a close conversion relationship between soil organic nitrogen and other nitrogen forms,the characteristics of soil organic nitrogen will have profound impact on nitrogen cycling of forest ecological system.