生物多样性 ›› 2014, Vol. 22 ›› Issue (2): 141-156.DOI: 10.3724/SP.J.1003.2014.13195

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弄岗北热带喀斯特季节性雨林15 ha监测样地的树种组成与空间分布

王斌, 黄俞淞, 李先琨*(), 向悟生, 丁涛, 黄甫昭, 陆树华, 韩文衡, 文淑均, 何兰军   

  1. 广西壮族自治区、中国科学院广西植物研究所, 广西桂林 541006
  • 收稿日期:2013-08-30 接受日期:2013-10-25 出版日期:2014-03-20 发布日期:2014-04-03
  • 通讯作者: 李先琨
  • 基金资助:
    国家自然科学基金(31270469, 31300359);国家科技支撑计划课题(2011BAC09B02)

Species composition and spatial distribution of a 15 ha northern tropical karst seasonal rain forest dynamics study plot in Nonggang, Guangxi, southern China

Bin Wang, Yusong Huang, Xiankun Li*(), Wusheng Xiang, Tao Ding, Fuzhao Huang, Shuhua Lu, Wenheng Han, Shujun Wen, Lanjun He   

  1. Guangxi Institute of Botany, Chinese Academy of Sciences, Guilin, Guangxi 541006
  • Received:2013-08-30 Accepted:2013-10-25 Online:2014-03-20 Published:2014-04-03
  • Contact: Li Xiankun

摘要:

北热带喀斯特季节性雨林(northern tropical karst seasonal rain forest)是在我国热带北缘喀斯特地区分布的典型森林植被类型之一。由于富钙偏碱的地球化学背景及多样性的生境类型, 同时受季风气候影响, 该森林呈现群落结构多样、树种组成丰富、特有成分突出等特点。基于大型固定监测样地对该森林树种组成与空间分布进行的研究, 是探明该区域生物多样性形成与维持机制的基础。我们于2011年底建立了广西弄岗北热带喀斯特季节性雨林15 ha监测样地, 依照CTFS (Center for Tropical Forest Science)全球森林生物多样性监测规范, 定位并调查了样地内每一棵胸径≥1 cm的木本植物。结果表明: (1)样地内有监测树种223种, 隶属于56科157属; 独立个体总数为68,010株(含分枝为95,471株), 平均胸径为4.84 cm; (2)树种科、属的区系均以热带成分为主, 大戟科、马鞭草科、梧桐科等为优势科; (3)个体数最多的11个树种的个体数之和占到总个体数的51.64%, 前58个树种的占90.19%; 稀有种有75种, 占总树种数的33.63%; (4)群落结构稳定且更新良好, 主要优势种的径级结构均呈倒“J”形, 无明显断层; (5)树种分布在空间上表现出明显差异, 黄梨木(Boniodendron minus)等强耐旱型树种分布于山顶周围; 蚬木(Excentrodendron tonkinense)等树种分布于山坡中部; 对叶榕(Ficus hispida)等喜湿耐荫型树种分布于山谷周围; (6)胸径>20 cm的个体较多分布在山坡中下部, 极少分布在山顶周围; 胸径10–20 cm的个体较均匀分布于整个样地; 分枝和萌枝较多分布在山顶周围; (7)种–面积散点图在2–7 ha的取样面积下分化形成两条曲线, 表明了树种数量组成在空间上具有强烈异质性。研究初步认为: 强烈生境异质性及独特地质背景可能是影响该喀斯特森林物种组成及空间分布的重要因素。

关键词: 喀斯特季节性雨林, 区系分析, 种–多度格局, 种–面积曲线, 径级结构, 空间分布

Abstract:

Northern tropical karst seasonal rain forest, located on the northern margin of the tropical limestone karst region of China, is unique in the world and represents one of the world’s most remarkable types of karst forest. The limestone karst forests in this region display various characteristics, such as a variety of community structures, high species richness, and abundant endemic biological species, owing to the special limestone soils with abundant Ca and relatively high pH, the variety of heterogeneous habitats, and the impacts of the monsoon climate. An approach to the analysis of species composition and spatial distribution based on the investigation of a permanent plot is fundamentally important for revealing mechanisms of biodiversity maintenance in this area. The 15 ha Nonggang Northern Tropical Karst Seasonal Rain Forest Dynamics Plot (22.43°N, 106.95°E) was established in 2011. The plot is located in the Nonggang (or Longgang) National Nature Reserve in Guangxi, southern China, adjacent to northeastern Vietnam. Based on the standard field protocol of the Center for Tropical Forest Science (CTFS), all free-standing individuals in this plot with DBH (diameter at breast height)≥1 cm were tagged, mapped and identified to species. The results of the study were as follows: (1) A total of 95,471 individuals, including trees with multiple trunks, belonging to 223 species, 157 genera and 56 families were recorded in the plot. (2) Community composition, both at the family and the generic level, was dominated by tropical floristic elements. The most dominant families were Euphorbiaceae, Verbenaceae, and Moraceae. (3) The 11 species with the greatest numbers of individuals represented 51.64% of the total individuals, and the 58 species with the greatest numbers of individuals represented 90.19% of the total individuals in the plot. Seventy-five species were considered to be rare species because they were represented by no more than one tree per hectare, accounting for 33.63% of the total species. (4) The DBH size-class structure of all species in the plot exhibited a reverse J-shaped pattern, indicating good regeneration across the community. (5) Species composition exhibited strong spatial variation in the plot. The strongly drought-resistant Boniodendron minus and Memecylon scutellatum were the dominant species on the mountain peaks. Excentrodendron tonkinense and Cleistanthus sumatranus were the dominant species on the middle slopes. The strongly shade-tolerant Erythrina stricta and Ficus hispida were the dominant species on the valley bottoms. (6) The trees with DBH>20 cm showed a higher density in the valley bottoms, whereas the trees with DBH between 10 and 20 cm were distributed evenly over the entire plot. The individual trees showing ramifications and the tree sprouts showed a higher density on the mountain peaks. (7) The species–area relationship scatter diagram consisted of two curves for sampling areas ranging between 2 and 7 ha, indicating strong spatial heterogeneity of species composition in the plot. The study suggested that the strong habitat heterogeneity and the special geological background of the area may be important for regulating the species composition and spatial distribution of trees in this karst seasonal rain forest.

Key words: karst seasonal rain forest, floristic characteristics, species–abundance pattern, species–area relationship, size class structure, spatial distribution