生物多样性 ›› 2016, Vol. 24 ›› Issue (10): 1093-1104.DOI: 10.17520/biods.2015341

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不同取样强度下古田山木本植物幼苗组成 及其分布格局比较

郭印1,2, 王云泉1,2, 陈磊2,*(), 米湘成2, 任海保2, 陈声文3, 陈建华1,*()   

  1. 1 浙江师范大学化学与生命科学学院, 浙江金华 321004
    2 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
    3 古田山国家级自然保护区管理局, 浙江开化 324300;
  • 收稿日期:2015-12-03 接受日期:2016-10-19 出版日期:2016-10-20 发布日期:2016-11-10
  • 通讯作者: 陈磊,陈建华
  • 基金资助:
    国家自然科学基金面上项目(31270495)

Comparing tree seedling composition and distribution patterns under different sampling intensities in the 24 ha Gutianshan forest dynamics plot

Yin Guo1,2, Yunquan Wang1,2, Lei Chen2,*(), Xiangcheng Mi2, Haibao Ren2, Shengwen Chen3, Jianhua Chen1,*()   

  1. 1 College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua, Zhejiang 321004
    2 State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093
    3 Gutianshan National Nature Reserve Administrative Bureau, Kaihua, Zhejiang 324300
  • Received:2015-12-03 Accepted:2016-10-19 Online:2016-10-20 Published:2016-11-10
  • Contact: Chen Lei,Chen Jianhua

摘要:

幼苗阶段是森林群落更新的瓶颈, 研究木本植物幼苗组成和分布格局对正确认识森林群落构建以及多样性维持机制具有十分重要的意义。以往基于幼苗阶段的研究取样强度较小, 主要涉及常见种, 缺乏对稀有种的有效监测。我们对古田山24 ha森林样地幼苗监测网络进行了扩建, 在已有507个1 m × 1 m幼苗监测样方的基础上, 增设了285个5 m × 5 m幼苗样方, 对样方内所有高度≥ 10 cm且胸径< 1 cm的木本植物幼苗按大样地监测标准进行了定位、挂牌、鉴定和测量。本研究利用2012年5 m × 5 m幼苗监测样方的首次调查数据, 比较了24 ha大样地中不同取样强度下幼苗和非幼苗(胸径≥ 1 cm的木本植物)个体在物种组成、多样性分布格局以及生境偏好等方面的差异。结果表明: (1) 285个5 m × 5 m幼苗监测样方共计有木本植物幼苗138种20,581株, Shannon-Wiener多样性指数以及经多度校正的物种丰富度指数均显著高于1 m × 1 m幼苗监测样方以及24 ha大样地的非幼苗个体, 该结果与基于Rarefaction方法计算的物种数期望值结果一致; 与1 m × 1 m幼苗监测样方结果相比, 5 m × 5 m幼苗监测样方内物种数-取样面积曲线趋于饱和。(2) 5 m × 5 m幼苗监测样方幼苗与24 ha大样地非幼苗个体物种多度呈异速增长关系, 表明植物在幼苗阶段受到负密度制约效应的影响, 死亡率相对较高。(3)取样强度和胸径阈值的选取对群落稀有种的界定有重要影响, 朱砂根(Ardisia crenata)、山鸡椒(Litsea cubeba)、美丽胡枝子(Lespedeza thunbergii subsp. formosa)等物种在24 ha样地水平被认为是稀有种, 但是在5 m × 5 m幼苗样方却属于常见种。(4)指示种分析结果表明, 基于不同取样强度的幼苗生境指示种与基于大样地非幼苗个体的分析结果存在较大差异。在5 m × 5 m幼苗样方中, 13个物种与单一生境类型显著相关, 其中仅有3个物种与1 m × 1 m幼苗样方指示种相同, 与24 ha大样地非幼苗相比, 仅有2个共有指示种。总之, 不同取样强度可显著影响幼苗物种多样性格局的分析结果, 通过样方扩建对林下幼苗进行系统监测, 可进一步加深对群落生物多样性维持机制的认识。

关键词: 古田山, 木本植物幼苗, 取样强度, 稀有种, 物种多样性维持机制

Abstract:

As the seedling stage is the bottleneck in forest tree regeneration, knowledge of the composition and structure of seedlings is crucial to understanding the mechanisms of community assemblage and diversity maintenance. However, based on the limited sampling intensity common in previous studies, seedling census datasets are representative of common species, but are ineffective for monitoring rare species. In this study, we established a new seedling monitoring network in the 24 ha Gutianshan (GTS) forest dynamics plot (FDP) consisting of 285 seedling plots (5 m × 5 m) in 2012. In the seedling pots, all woody plants (DBH < 1 cm and height ≥ 10 cm) were tagged, mapped and measured every two years. We used the first census data to investigate seedling composition, species diversity patterns, seedling, and non-seedling species habitat association. Our results showed that: (1) There were 138 species, consisting of a total of 20,581 individuals in 285 seedling plots of 5 m × 5 m. The Shannon-Wiener diversity index and Rarefied species richness were higher than those of the 1 m × 1 m seedling plots and 24 ha FDP census (DBH ≥ 1 cm). Similar results were found when using rarefaction approach. Compared with 1 m × 1 m seedling plots, the number of species showed a significant increase and the species-area curve became more asymptotic. (2) The relationship between seedling abundance and tree species exhibited negative allometry, suggesting that the mortality rate of plants in the seedling stage was relatively high compared with the rate found in the non-seedling stage due to the negative density dependence. (3) Sampling intensity and selection of DBH cutoffs influence the definition of rare species. Some rare species defined by trees with DBH ≥ 1 cm were not actually rare when individuals with DBH < 1 cm were considered (i.e. Ardisia crenata, Litsea cubeba, Lespedeza thunbergii subsp. formosa). (4) The indicator species of the 5 m × 5 m seedling plots were different from those found in the 24 ha FDP and the 1 m × 1 m seedling census. 13 species was significantly correlated with single habitat type in these 5 m × 5 m seedling plots, which shared only three species that identified as indicator species for 1 m × 1 m seedling plots and two species for non-seedling plots. In conclusion, sampling intensity influenced patterns of tree seedling composition and community diversity, and increasing sampling intensity can provide deeper insights into the processes of diversity maintenance.

Key words: Gutianshan (GTS), tree seedling, sampling intensity, rare species, mechanisms of maintenance of species diversity