川西高山树线交错带海拔梯度上土壤不同组分氮特征

doi:10.16036/j.issn.1000-2650.2021.04.010

摘要/Abstract

摘要： 【目的】以川西高山树线交错带土壤为研究对象研究在海拔环境梯度下土壤不同组分氮素分布特征及稳定性。【方法】在川西高原高山树线交错带海拔高度3 900、4 080、4 200 m处进行土壤采样,采用物理-化学分级法分析了不同氮组分特征。【结果】高山树线交错带土壤有机氮主要集中在粗粒级组分中（≥0.02 mm）,同一海拔下粒径越大有机氮含量越高,相同粒径下随海拔升高而升高,主要以活性高的颗粒态有机氮形式存在,占比均高于94.08%;土壤矿物结合态氮占比低于土壤总有机氮1.47%,腐殖质（胡敏素）氮含量为主要组分,其次是土壤弱固持有机氮、阳离子固持有机氮和强连接有机氮,稳定性矿物结合态有机氮占总有机氮比例远低于一般土壤。颗粒态有机氮比例随海拔变化显著,矿物结合态氮比例变化不显著。【结论】川西高海拔树线交错带的高寒土壤氮素主要以不稳定颗粒态有机氮形式存在,腐殖化并非主要氮过程。海拔主要通过影响粒级>0.02 mm的土壤有机氮来改变土壤氮库储量及稳定性。矿物结合态有机氮含量极低且各化学分级组分对海拔梯度无显著响应,对氮库稳定性作用微弱。

关键词: 高山树线交错带, 土壤有机氮, 土壤粒级, 化学分级

Abstract: 【Objective】 To study the nitrogen characteristics and stability of different soil components in the western Sichuan Plateau, which provide theoretical support for the alpine soil nitrogen process and its response under the background of global change. 【Method】 Soil samples were collected from the alpine tree line ecotone in the western Sichuan Plateau at an altitude of 3 900, 4 080 and 4 200 m, respectively,and the characteristics of different nitrogen components were analyzed by physical-chemical classification method. 【Result】 The results showed that the soil organic nitrogen was mainly concentrated in the coarse grain fractions (≥0.02 mm) in the alpine treeline ecotone. The larger the particle size at the same altitude, the higher the content of organic nitrogen, and the higher the grain size at the same altitude. The organic nitrogen mainly existed in the particulate form with the proportion of higher than 94.08%. Nitrogen in≤0.02 mm mineral-associated soil organic matter was chemically fractionated, which accounted less than 1.47% of total organic nitrogen in soil, and mainly existed in the form of humus (humin), followed by the nitrogen extracted by Na₂B₄O₇, Na₄P₂O₇ and NaOH solution.The proportion of stable mineral-associated organic nitrogen to total organic nitrogen was much lower than that in general soil.The proportion of particle organic nitrogen changed significantly with altitude, but the proportion of mineral-associated organic nitrogen did not. 【Conclusion】 The organic nitrogen of alpine soil in the high-altitude treeline ecotone in western Sichuan is mainly in the form of unstable particulate organic nitrogen.Humus is not the main nitrogen process. Altitude changed the storage and stability of soil nitrogen pool by affecting soil organic nitrogen with grain size greater than 0.02 mm.The content of mineral-associated organic nitrogen is very low, and the chemical fractional components have no significant response to the altitude gradient, had a weak effect on the stability of the nitrogen pool.

Key words: alpine tree line ecotone, soil organic nitrogen, soil particle size, chemical fractionation

中图分类号:

S153.6

杨济源, 秦纪洪. 川西高山树线交错带海拔梯度上土壤不同组分氮特征[J]. 四川农业大学学报, 2021, 39(4): 496-503.

YANG Jiyuan, QIN Jihong. Nitrogen in Different Soil Fractions in Alpine Treeline Ecotone along Altitudinal Gradient in the West of Sichuan Province[J]. Journal of Sichuan Agricultural University, 2021, 39(4): 496-503.

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