生物多样性 ›› 2014, Vol. 22 ›› Issue (4): 449-457.DOI: 10.3724/SP.J.1003.2014.14101

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密度制约对宝天曼落叶阔叶林锐齿栎死亡前后分布格局的影响

王婷1, 任思远1, 袁志良2, 祝燕3, 潘娜1, 李鹿鑫1, 叶永忠2,,A;*()   

  1. 1.河南农业大学林学院, 郑州 450002
    2 .河南农业大学生命科学学院, 郑州 450002
    3.中国科学院植物研究所植被与环境变化国家重点实验室, 北京 100093
  • 收稿日期:2014-05-26 接受日期:2014-07-16 出版日期:2014-07-20 发布日期:2014-07-24
  • 通讯作者: 叶永忠
  • 基金资助:
    国家自然科学基金(31270493)和植被与环境变化国家重点实验室2012年开放课题(LVEC-2012kf06)

Effects of density dependence on the spatial patterns of Quercus aliena var. acuteserrata trees in deciduous broad-leaved forest in the Baotianman Nature Reserve, central China

Ting Wang1, Siyuan Ren1, Zhiliang Yuan2, Yan Zhu3, Na Pan1, Luxin Li1, Yongzhong Ye2,*()   

  1. 1. Forestry College, Henan Agricultural University, Zhengzhou 450002
    2. College of Life Sciences, Henan Agricultural University, Zhengzhou 450002
    3. State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Science, Beijing 100093
  • Received:2014-05-26 Accepted:2014-07-16 Online:2014-07-20 Published:2014-07-24
  • Contact: Ye Yongzhong

摘要:

为了在温带和亚热带的过渡带中验证森林树木死亡是否受密度制约的影响, 我们在宝天曼国家级自然保护区选择1个100 m×100 m的暖温带落叶阔叶林样地, 用双变量函数g(r)(the pair-correlation function)研究了锐齿栎(Quercus aliena var. acuteserrata)死亡前(活树和枯木统称为死亡前树木)和死亡后(活树为死亡后树木)的分布格局。把样地中的锐齿栎分为幼树(1 cm ≤ DBH<10 cm)、小树(10 cm ≤ DBH<20 cm)和成年树(DBH≥20 cm)3个不同的生长阶段来研究密度制约对空间分布格局的影响机制。结果表明: (1)死亡前锐齿栎在r>5 m尺度呈聚集分布, 死亡后幼树(1 cm≤DBH<10 cm)和成年树(DBH≥20 cm)在1-25 m尺度呈现随机分布, 死亡后小树(10 cm≤DBH< 20 cm)在r<1.5 m和2.5-4.5 m的尺度为随机分布, 在r>5 m的尺度呈聚集分布; (2)采用随机标签零模型和案例-对照设计的方法, 排除生境异质性影响后, 将幼树和小树的分布格局作为案例, 将成年树的分布格局作为对照, 并代表生境异质性的作用, 通过小径级树木与成年树分布格局的对比发现, 密度制约效应对死亡前后的锐齿栎分布格局均具有影响; (3)幼树和小树在成年树周围的分布死亡前为显著聚集分布格局, 死亡后剩余树木的聚集强度下降; 随着与成年树之间距离的增加, 死亡后的幼树(仅包括现存的活树)逐渐向随机分布格局演替。本研究初步表明锐齿栎空间格局受生境异质性的影响并呈现出显著的聚集效应, 排除生境异质性影响后, 锐齿栎死亡前后的空间格局受到密度制约的影响, 这一结果为Janzen-Connell假说提供了支持。

关键词: 落叶阔叶林, Quercus aliena var. acuteserrata, 密度制约, 分布格局, Janzen-Connell假说, 宝天曼国家级自然保护区

Abstract

To determine the contribution of density dependence to tree mortality in the transitional region between temperate and subtropical zone, a deciduous broad-leaf forest plot (100 m×100 m) in the Baotianman National Nature Reserve was selected and a pair-correlation function g(r) (the pair-correlation function) was employed to examine the spatial pattern of a single species. Individuals of the dominant species Quercus aliena var. acuteserrata were divided into three growth stages: saplings (1 cm ≤ DBH < 10 cm), juveniles (10 cm ≤ DBH < 20 cm), and adult trees (DBH ≥ 20 cm). Each stage was then divided into pre-mortality (including all living and dead trees) and post-mortality (only living trees) status to examine the contribution of density dependence to the spatial patterns of Q. aliena var. acuteserrata. The results showed that: (1) Pre-mortality Q. aliena var. acuteserrata trees showed an aggregated distribution pattern at r > 5 m scale. Post-mortality Q. aliena var. acuteserrata saplings and adult trees had a random distribution pattern at a 1-25 cm scale. Post-mortality juveniles had a random distribution pattern at r < 1.5 m and 2.5-4.5 m scales and an aggregated distribution pattern at r > 5 m scale. (2) The spatial pattern of adult trees was regarded as a control pattern accounting for environmental heterogeneity. The spatial pattern of pre- and post-mortality saplings and juveniles showed density-dependent distribution responses by random labeling null model with a case-control design; (3) Pre-mortality saplings and juveniles showed a clumped distribution around adult trees, whereas the post-mortality saplings and juveniles displayed a weak clustering with mortality caused by density dependence. With increasing distance to adult trees, post-mortality saplings and juveniles showed a gradually increasing random distribution. Our findings indicate that habitat heterogeneity contributes to the spatial distribution of Q. aliena var. acuteserrata with an aggregation effect. After the effect of habitat heterogeneity was removed, spatial distribution of Q. aliena var. acuteserrata trees with different pre-mortality and post-mortality status were all affected by density dependence effect in the Baotianman National Nature Reserve. These conclusions provide support for the Janzen-Connell hypotheses.

Key words: deciduous broad-leaf forest, Quercus aliena var. acuteserrata, density dependence, distribution pattern, Janzen-Connell hypotheses, Baotianman National Nature Reserve