对照（CK，0g N /（m 2·a））、低N（LN，2.5g N /（m 2·a））、中N（MN，5g N /（m 2·a））、高N（HN，7.5g N /（m 2·a））处理。测定凋落叶、根和鲜叶在不同施N水平下C、N、P、K、Ca、Mg的含量。研究目的是为了阐明兴安落叶松叶和根各元素含量及化学计量比的分配格局，揭示叶片凋落前各元素的重吸收率，探讨各元素及其化学计量之间的关联以及对不同水平施N处理的响应。结果表明：①鲜叶、根、凋落叶C、N、P变化范围分别为393.174～518.362、4.405～23.963、0.743～1.671 mg/g，其中鲜叶C、P含量最高，根最低。②LN，MN，HN均显著提高了根的N含量，MN，HN显著提高了鲜叶N含量。植物养分含量在不同器官中存在显著差异。③植物叶片对Ca表现为富集状态，对N、P、K、Mg各元素则体现为重吸收状态。结论显示，鲜叶和根是影响兴安落叶松C、N、P及化学计量比的主导因子。兴安落叶松在N素充足的条件下，施N导致兴安落叶松对N和P奢侈吸收，提高了凋落叶的分解速率并加快了生态系统的养分循环。
关键词：施N;生态化学计量比;养分重吸收率;兴安落叶松
中图分类号：S718.5文献标识码：A文章编号：1006-8023（2019）02-0001-10
Effect of Long-term Nitrogen Deposition on the Stoichiometric Characteristics of Larix gmelinii
CHEN Lu， WANG Qinggui， YAN Guoyong， XING Yajuan
（College of Agricultural Resource and Environment， Heilongjiang University， Harbin 150000）
Abstract：Taking Larix gmelinii from Greater Khingan Mountains as the research object， four nitrogen （N） treatment level plots with unified site conditions were established in Nanwenghe Nature Reserve of Greater Khingan Mountains， included contrast CK （CK， 0g N / （m 2·a））， low nitrogen （LN， 2.5g N / （m 2·a））， middle nitrogen （MN， 5g N / （m 2·a））， high nitrogen （HN， 7.5g N / （m 2·a））. The contents of C、N、P、K、Ca、Mg in leaves， roots and fresh leaves were determined under different N addition gradient. The purpose was to elucidate the aboveground organ leaves and underground organ roots of Larix gmelini . The distribution pattern of each element content and stoichiometry ratio revealed the heavy absorption rate of each element before leaf litter and discussed the relationship between each nutrient element and response to different levels of N application. The results showed that： （1） C、N、P of fresh leaves， roots and littered leaves ranged from 393.174-518.362 mg/g， 4.405-23.963 mg/g， and 0.743-1.671mg/g. The range of C and P content in leaves was the highest， and the lowest in roots. （2） LN， MN， HN significantly increased N content in roots， and MN， HN significantly increased N content in roots. There were significant differences in plant nutrient content in different organs. （3） The plant leaves were eiched to Ca and reabsorbed to the elements. It conclude that the leaf and root were the main factors that affected the chemical measurement ratio and the C， N， P of Larix gmelinii . Under the condition of sufficient nitrogen， nitrogen deposition resulted in the extravagant absorption of N and P by Larix gmelinii ， which could increase the decomposition rate of litter leaves and nutrient cycling in its ecosystem.