广西流星天坑植物群落结构与多样性
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国家自然科学基金 (31260113)


Plant Community Structure and Species Diversity in Liuxing Tiankeng of Guangxi
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    摘要:

    以广西乐业流星天坑为研究对象,在流星天坑腰部与底部设置样地,采用样方法调查冠层树种及林下植物群落;并用数量生态学的方法分析了天坑植物群落的组成、结构与物种多样性,探讨其生境关联。结果表明:(1)在天坑调查的样地中,胸径大于10 cm的冠层树种个体60株,隶属于13科、17属、18种,个体密度约为188株/hm2。林下植物种群共记录到94株个体,隶属于28科、38属、43种,个体密度为23 500株/hm2。群落物种多样性较丰富,ShannonWiener多样性指数和均匀度指数均较高;冠层树种的科属多样性很高,体现出群落组成的古老和隔离性质。(2)樟科是流星天坑植物群落的优势科,在群落冠层包含4个种14株个体,在林下包含3个种,7株个体,其中2种与群落冠层共有;群落的林下层含物种数较多的科包括大戟科(4种)、菊科(3种)、凤尾蕨科(3种)、鳞毛蕨科(3种),但天坑植物群落中种群水平的优势现象不明显。(3)林下植物包含了各种生长型,以灌木数量最多,禾草类植物数量最少,乔木的幼苗也较少,体现出天坑的生境提供了较丰富的资源生态位,同时也表明乔木的幼苗更新不良。(4)流星天坑大树数量比例高,在样地中记录到的60株个体中,最小胸径为17.0 cm, 最大胸径104.0 cm,胸径> 30 cm的大树共34株,占全部立木比例56.6%,体现出天坑森林群落的原始性并且未受到干扰破坏。(5)双向指示种分析表明,广西乐业天坑林下植物对生境的响应更为敏感,但无论冠层还是林下层其现状分布并不能完全把坑腰和坑底两种生境分离。该研究结果为深入开展天坑这种特殊生境下植物种群以及群落的发生、演替和生态适应性的研究提供了基础数据及理论依据。

    Abstract:

    A field survey was carried out in the Liuxing Tiankeng of Leye, Guangxi, to collect plant community data. Sampling plots were set up using quadrat method at the middle and the bottom of Liuxing Tiankeng for the census of canopy trees and understory plant community. Species composition, community structure, and diversity were analyzed using quantitative ecology methods and the specieshabitat association was explored. The results are as follows, (1) 60 canopy trees with a diameter at breast height (DBH) = 10 cm were found from the sampling plot, which belonged to 13 families, 17 genera, and 18 species, and the stem density was ≈188 plant/hm2. In the understory layer, 94 plant individuals of 43 species from 28 families and 38 genera were recorded, and the stem density was 23 500 plant/hm2. The species diversity in the community was rich, and ShannonWiener diversity index and evenness index was relative high. The family and genericlevel diversity of canopy trees was very high, reflecting the ancient and isolated nature in the community composition. (2) The dominant family was Lauraceae in Liuxing Tiankeng, which consisted of 4 species and 14 individuals in the canopy layer; while in the understory, it comprised 3 species and 7 individuals, of which 2 species were shared by the canopy layer. Families dominant in the understory layer with rich species were Euphorbiaceae (4 species), Compositae (3 species), Pteridaceae (3 species), and Dryopteridaceae (3 species). However, the specieslevel dominance was not obvious in the Tiankeng plant community. (3) The plant community in the understory layer encompassed various growth forms, with the majority of shrubs, the least of graminoids, and the less abundant tree seedlings, reflecting that the habitat in Liuxing Tiankeng provided abundant resource niches, and that the trees could not regenerate well with seedlings and saplings. (4) A high percentage of large trees existed in Liuxing Tiankeng. Of the 60 trees recorded, tree DBH ranged from 17.0 cm to 104.0 cm, with 34 trees having > 30 cm DBH, accounting for 56.6% of all the trees. These findings showed that Tiankeng forest community was primitive and free from human disturbance. (5) Twoway indicator species analysis (TWINSPAN) showed that plant community in the understory layer was more sensitive in response to habitat heterogeneity. However, none of the existing distribution in the canopy and understory layer could entirely separate the habitats at the middle and the bottom of Liuxing Tiankeng. These results will provide the baseline data and theoretical basis for further research on the occurrence, succession, and ecological adaptation of the plant communities in the karst Tiankengs with such special habitats.

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苏宇乔,薛跃规,范蓓蓓,等.广西流星天坑植物群落结构与多样性[J].西北植物学报,2016,36(11):2300-2306

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  • 在线发布日期: 2016-12-12
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