植物生态学报 ›› 2015, Vol. 39 ›› Issue (1): 14-22.DOI: 10.17521/cjpe.2015.0002

所属专题: 生态化学计量 青藏高原植物生态学:群落生态学

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高寒森林倒木在不同分解阶段的质量变化

常晨晖, 吴福忠, 杨万勤*(), 谭波, 肖洒, 李俊, 苟小林   

  1. 四川农业大学生态林业研究所林业生态工程四川省重点实验室, 成都 611130
  • 收稿日期:2014-07-07 接受日期:2014-11-06 出版日期:2015-01-10 发布日期:2015-01-22
  • 通讯作者: 杨万勤
  • 作者简介:

    # 共同第一作者

  • 基金资助:
    基金项目 国家自然科学基金(31170423和31270- 498)、国家“十二五”科技支撑计划(2011BAC- 09B05)、四川省杰出青年学术与技术带头人培育项目(2012JQ0008和2012JQ0059)和中国博士后科学基金特别资助(2012T50782)

Changes in log quality at different decay stages in an alpine forest

CHANG Chen-Hui, WU Fu-Zhong, YANG Wan-Qin*(), TAN Bo, XIAO Sa, LI Jun, GOU Xiao-Lin   

  1. Key Laboratory of Ecological Forestry Engineering, Institute of Ecological Forestry, Sichuan Agricultural University, Chengdu 611130, China
  • Received:2014-07-07 Accepted:2014-11-06 Online:2015-01-10 Published:2015-01-22
  • Contact: Wan-Qin YANG
  • About author:

    # Co-first authors

摘要:

倒木是高寒森林生态系统重要的碳(C)库和养分库, 其不同分解阶段的质量变化, 是认识倒木分解过程中C和养分释放的重要基础。以一个分解序列的岷江冷杉(Abies faxoniana)倒木为研究对象, 研究了心材、边材和树皮在5个分解阶段的C:N:P化学计量特征, 以及木质素和纤维素含量动态。结果显示: I至III分解阶段, 随着分解程度加深, 树皮C含量升高, 而心材和边材C含量降低, 从IV分解阶段开始倒木各组分C含量均开始显著降低。除III分解阶段的心材外, 倒木各组分N含量总体表现为随着分解程度加深而增加的趋势, 除边材N含量在V分解阶段时显著升高外, 其余组分均未达到显著性水平。心材和树皮P含量表现为先降后升的变化趋势, 最小值分别出现在III和II分解阶段; 边材P含量表现为随着分解程度加深而增加。在同一分解阶段, 树皮相对于边材和心材均具有最低的C:N:P化学计量比, 易分解比例Fm也表明树皮更易于分解。边材在I和II分解阶段的C:N:P化学计量比最高, 心材在III到V分解阶段C:N:P化学计量比最高。心材C:P、树皮和边材的C:N和C:P临界值与N和P的初始值成反比。纤维素含量随着倒木分解而降低, 不同分解阶段的纤维素含量表现为: 心材>边材>树皮; 但木质素含量随着分解程度加深而增加, 表现为: 树皮>边材>心材; 倒木3个组分纤维素含量下降均快于木质素, 此外, IV和V分解阶段的树皮木质素与纤维素比值显著增高, 且一直处于较高水平。统计分析结果表明: 倒木N含量显著影响不同分解阶段木质素和纤维素分解。由生态化学计量学理论推测: 树皮分解前期易受N限制, 整个分解阶段均易受P限制, 心材和边材在整个分解阶段均易受N和P限制。

关键词: 高寒森林, 分解阶段, 倒木质量, 化学计量比

Abstract: Aims

Log is an important pool of carbon (C) and nutrients in alpine forest ecosystems. Changes in log quality with decay could reveal the process of C and nutrient release during log decomposition. However, little information is available on this. Therefore, this study aims to understand the changes in log quality during log decaying.

Methods

Changes in C, nitrogen (N), phosphorus (P), lignin and cellulose concentrations were investigated in the heartwood, sapwood and bark of fir (Abies faxoniana) logs at five (I-V) decay stages in an alpine forest in western Sichuan, China. The stoichiometry of C:N:P and the ratios of lignin:N, lignin:P, cellulose:N, and cellulose:P were also calculated.

<i>Important findings </i>

C content in bark increased from the stage I to stage III of decay and then significantly decreased, but in the heartwood and sapwood it decreased from the stage I through stage V, especially at stages IV and V. N content increased from the stage I through stage V regardless of the log components. P content in sapwood also showed tended to increase from the stage I through stage V, but P content in heartwood and bark decreased following an increase tendency. In comparison with sapwood and heartwood, bark had the lowest C:N:P stoichiometry at the same decay stages. Percentage of the labile to total C (Fm) also inferred that bark was the most decomposable component. The higher C:N:P stoichiometry in sapwood was observed in logs of the stages I and II, but higher Fm in heartwood was detected from the stage III to stage V. Critical values of C:N in sapwood and bark and C:P in heartwood, sapwood and bark were negatively correlated with the initial N and P concentrations, respectively. Cellulose concentration decreased from the stage I to stage V regardless of log components, and among different components followed the order of heartwood > sapwood > bark at corresponding decay stages. In contrast, lignin concentration increased from the stage I to stage V regardless of log components, and among different components followed the order of bark > sapwood > heartwood at corresponding decay stages. Cellulose degraded faster than lignin regardless of log components, and the ratio of lignin:cellulose increased significantly at the advanced decay stages. Moreover, bark showed a relatively higher lignin:cellulose ratio compared with sapwood and heartwood. In addition, statistical analysis suggested that the degradation of lignin and cellulose in logs would be affected by N concentration. Bark decay was limited by N at early decay stages but by P at all decay stages, and the decay of heartwood and sapwood was limited by both N and P based on ecological stoichiometry theory.

Key words: high-frigid forest, decay stage, log quality, stoichiometry