川西亚高山针叶林主要树种对土壤中不同形态氮素的吸收差异  

Differential uptakes of different forms of soil nitrogen among major tree species in subalpine coniferous forests of western Sichuan,China

作　　者：邹婷婷 张子良[1,2] 李娜 袁远爽[1,2] 郑东辉[1,2] 刘庆 尹华军[1,3] 

机构地区：[1]中国科学院成都生物研究所,中国科学院山地生态恢复与生物资源利用重点实验室,生态恢复与生物多样性保育四川省重点实验室,成都610041 [2]中国科学院大学,北京100049 [3]西华师范大学环境科学与工程学院,四川南充637000

出　　处：《植物生态学报》2017年第10期1051-1059,共9页Chinese Journal of Plant Ecology

基　　金：国家重点研发计划项目(2017YFC050-5200);中国科学院前沿科学重点研究项目(QYZDB-SSW-SMC023);国家自然科学基金(31670449);四川省重点研发项目(2017SZ0038);四川省青年科技基金(2016JQ0037)

摘　　要：在陆地生态系统中,植物对土壤有机氮(主要指氨基酸)的获取是一个普遍的生态学现象,然而植物对土壤有机氮的吸收速率及土壤有机氮在植物养分供应中所占比例仍不清楚。为探究土壤无机氮和有机氮对西南高寒森林植物氮源的贡献效应,以川西亚高山针叶林两个主要树种云杉(Picea asperata)和红桦(Betula albo-sinensis)的幼苗为研究对象,采用稳定同位素标记法对K^(15)NO_3、^(15)NH_4Cl和(U-^(13)C_2/^(15)N)甘氨酸3种氮素进行示踪,分析了两个树种对无机氮(NH_4^+-N和NO_3^--N)和有机氮(甘氨酸)的吸收速率及其差异。结果显示:(1)云杉和红桦幼苗在施加同位素标记物2 h后,两种幼苗细根的13C和^(15)N均出现明显的富集现象,表明两种树种幼苗均能吸收甘氨酸。(2)与甘氨酸和NH_4^+-N相比,云杉和红桦幼苗对NO_3^--N有显著的偏好吸收,其吸收速率为NH_4^+-N和甘氨酸吸收速率的5–10倍。(3)两个树种的幼苗对甘氨酸也有较高的吸收速率,其吸收速率高于对NH_4^+-N的吸收速率,表明土壤有机氮(如氨基酸)也是亚高山针叶林植物养分获取的重要氮源。Aims Although acquisition of soil organic nitrogen （N）（mainly amino acids） by plants is a widespread ecological phenomenon in many terrestrial ecosystems, the rate of organic N uptake and their contributions to plant nutrient supply are poorly understood. Our objective was to determine the relative contributions of inorganic N （NOf-N and NH4＋-N） and organic N （amino acids） to plant N uptake in a high-frigid forest ecosystem. Methods The differences in the uptake rate of three different forms of N （NO3--N, NH4＋-N and glycine） were quantified by exposing seedlings of two dominant tree species （Picea asperata and Betula albo-sinensis） in subalpine coniferous forests of western Sichuan, China, to trace quantities of K15NO3,1SNH4C1 and （U-13C2/15N） glycine. Important findings Both 13C and 15N were significantly enriched in fine roots 2 h after tracer application, indica- ting the occurrence of glycine uptake in P asperata and B. albo-sinensis seedlings. The seedlings of two tree spe- cies had a significant preference for NO3--N compared with glycine and NH4＋-N, and the uptake rate of NO3--N was 5 to 10 times greater than that of glycine and NH4＋-N. The roots of seedlings in the two species took up gly- cine more rapidly than NH4＋-N, implying that soil organic N （i.e., amino acids） could be an important N source for the two species in subalpine coniferous forests. The results of this study are of great theoretical significance for un- derstanding N utilization strategies and nutrient regulation processes in plants of the high-frigid forest ecosystems.

关 键 词：有机氮 无机氮 氨基酸 稳定同位素标记 亚高山针叶林 

分 类 号：S718.4[农业科学—林学]