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林业科学 ›› 2015, Vol. 51 ›› Issue (1): 22-28.doi: 10.11707/j.1001-7488.20150103

• 论文与研究报告 • 上一篇    下一篇

林龄、叶龄对亚热带杉木人工林碳氮稳定同位素组成的影响

郑璐嘉1,2,3, 黄志群1,2,3, 何宗明4, 王夏怡4, 刘桌明4, 刘瑞强1,2,3, 肖好燕1,2,3   

  1. 1. 湿润亚热带山地生态国家重点实验室培育基地 福州 350007;
    2. 福建师范大学地理研究所 福州 350007;
    3. 湿润亚热带生态地理过程教育部重点实验室 福州 350007;
    4. 福建农林大学林学院 福州 350002
  • 收稿日期:2014-03-20 修回日期:2014-04-27 出版日期:2015-01-25 发布日期:2015-01-23
  • 通讯作者: 黄志群
  • 基金资助:

    "973"计划和重大科学研究计划项目(2014CB954002);国家自然科学基金项目(41371269);教育部新世纪优秀人才支持计划(DB-168).

Influence of Forest and Foliar Ages on The Composition of Stable Carbon and Nitrogen Isotope of Cunninghamia lanceolata in Subtropic China

Zheng Lujia1,2,3, Huang Zhiqun1,2,3, He Zongming4, Wang Xiayi4, Liu Zhuoming4, Liu Ruiqiang1,2,3, Xiao Haoyan1,2,3   

  1. 1. Cultivation Base of State Key Laboratory of Humid Subtropical Mountain Ecology Fuzhou 350007;
    2. Institute of Geography, Fujian Normal University Fuzhou 350007;
    3. MOE Key Laboratory of Humid Subtropical Eco-Geographical Process Fuzhou 350007;
    4. Forestry College, Fujian Agriculture and Forestry University Fuzhou 350002
  • Received:2014-03-20 Revised:2014-04-27 Online:2015-01-25 Published:2015-01-23

摘要:

[目的]研究5个不同林龄(3,8,14,21,46年)、不同叶龄(当年生、1年生、2年生、3年生)杉木人工林叶片的碳、氮稳定同位素组成,并根据它们对氮循环等过程的指示作用来探索不同林龄、叶龄杉木人工林氮循环过程及氮饱和程度的差异,从而为不同生长阶段杉木人工林制定施肥措施提供科学依据.[方法]以福建南平峡阳林场5块相互毗邻的不同林龄杉木人工林为研究对象,在每个林龄的林分内分别设置4个20 m×20 m的试验小区.分别采集不同林龄杉木活叶并根据"主干法"将采集的杉叶分为不同叶龄,然后在每个小区内采集0~10 cm深度土层的土样,用同位素质谱仪测定它们的碳、氮稳定同位素组成(δ13C,δ15N),用碳氮元素分析仪测定叶片氮含量,叶片15N富集指数由叶片δ15N值减去相应的土壤δ15N得到.[结果]叶片δ15N值的变化范围为-2.52‰~2.81‰, 叶片氮含量的变化范围为7.72%~13.5%,二者在不同林龄间均具有极显著差异,并均呈现出幼林和老林较高、处于速生期的林分较低的趋势,且叶片δ15N值与叶片氮含量之间存在显著的相关性,但不同叶龄叶片δ15N值间则不具有显著差异;不同林龄叶片的15N富集指数存在显著差异,呈现出幼林与老林叶片15N富集指数较接近于0的趋势;叶片δ13C的变化范围为-29.93‰~-27.88‰, 不同林龄间差异不显著,但同一林龄不同叶龄叶片的δ13C则有显著差异,且有随着叶龄增大而减小的趋势.[结论]不同林龄叶片δ13C差异不显著但呈现幼年较低的趋势,可能是不同树高导致不同林龄杉木水分利用效率间的差异所致,而同一林龄不同叶龄杉木δ13C间的显著差异则可能是光合作用效率不同造成的.不同林龄在叶片δ15N、叶片氮含量、叶片15N富集指数间的显著差异均指示出处于速生期的林分氮饱和程度显著低于幼林和老林,这说明虽然我国亚热带地区氮沉降现象严重,但氮素仍是限制处于速生期杉木人工林生长的因素.

关键词: 年龄序列, 杉木, 稳定同位素, 氮饱和

Abstract:

[Objective]Aims We measured the composition of foliar carbon and nitrogen stable isotopes (δ13C,δ15N) in Cunninghamia lanceolata plantations at ages of 3, 8, 14, 21 and 46. The aim of this study is to use the isotopic compositions as indicators to explore the degree of nitrogen saturation of C. lanceolata in various forest and foliar ages. [Method]Our experimental site is located at Xiayang forest farm, in Nanping, Fujian, China, where five adjacent C. lanceolata stand at various ages were selected. Four 20 m×20 m plots were established in each stand, the leaves (at different foliar ages) and soil from each plot were collected. The δ13C and δ15N of leaves and soil were measured by using Thermo Scientific MAT253, and the foliar N concentrations were measured with Elemental Analyzer Vario ELIII, and the 15N enrichment factors (EF) were calculated by foliar δ15N minus soil δ15N. [Result]The result showed that foliar δ15N ranged from -2.52‰ to 2.81‰, and the foliar N concentrations ranged from 7.72% to13.5%. There were significant differences in these two parameters among stand ages were, and they all tended to be higher in the 3- and 46-year-old stand compared with those in 8-, 14- and 21-years-old stand. However, no significant difference in foliar δ15N was found among different foliar ages. We also found a significant and positive correlation between foliar δ15N and nitrogen concentration. Meanwhile, the 15N enrichment factors (EF) in leaves were significantly different among foliar ages, and the young and old stand tended to be closer to zero. The foliar δ13C ranged from -29.93‰ to -27.88‰ and there was no significant difference in the δ13C among stand ages. However, there was significant difference in foliar δ13C among foliar ages and it tended to decline with foliar age. [Conclusion]We could attribute the different δ13C among stand and foliar ages to the water use efficiency and the photosynthetic efficiency. The difference of foliar δ15N, foliar N concentrations and 15N enrichment factors in various forest ages indicate that nitrogen might still be a factor that limits the growth of C. lanceolata at pole stage in subtropical region of China, and further studies are needed to verify it, for example, taking the influence of mycorhiza into consideration.

Key words: chronosequence, Cunninghamia lanceolata, nitrogen saturation, stable Isotope

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