Biodiv Sci ›› 2014, Vol. 22 ›› Issue (4): 449-457.DOI: 10.3724/SP.J.1003.2014.14101

• Orginal Article • Previous Articles     Next Articles

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

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