生物多样性 ›› 2022, Vol. 30 ›› Issue (4): 21340.  DOI: 10.17520/biods.2021340

• 研究报告: 植物多样性 • 上一篇    下一篇

喀斯特常绿落叶阔叶林死亡个体空间分布格局及生境关联

鲁梦珍1,2,3, 曾馥平1,2,3, 宋同清1,2, 彭晚霞1,2, 张浩1,2, 苏樑1,2, 刘坤平1,2, 谭卫宁4, 杜虎1,2,*()   

  1. 1.中国科学院亚热带农业生态研究所亚热带农业生态过程重点实验室, 长沙 410125
    2.中国科学院环江喀斯特生态系统观测研究站/广西喀斯特生态过程与服务重点实验室, 广西环江 547100
    3.中国科学院大学, 北京 100049
    4.广西木论国家级自然保护区管理中心, 广西环江 547100
  • 收稿日期:2021-08-29 接受日期:2022-01-06 出版日期:2022-04-20 发布日期:2022-04-20
  • 通讯作者: 杜虎
  • 作者简介:*E-mail: hudu@isa.ac.cn
  • 基金资助:
    国家自然科学基金(42071073);国家自然科学基金(31971487);广西重点研发计划(桂科AB17129009);中国科学院青年创新促进会项目(2021366);河池市特聘专家项目

Spatial distribution pattern and habitat-association of snags in karst evergreen deciduous broad-leaved mixed forests

Mengzhen Lu1,2,3, Fuping Zeng1,2,3, Tongqing Song1,2, Wanxia Peng1,2, Hao Zhang1,2, Liang Su1,2, Kunping Liu1,2, Weining Tan4, Hu Du1,2,*()   

  1. 1 Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125
    2 Guangxi Key Laboratory of Karst Ecological Processes and Services/Huanjiang Observation and Research Station of Karst Ecosystem, Huanjiang, Guangxi 547100
    3 University of Chinese Academy of Sciences, Beijing 100049
    4 Management Center for Guangxi Mulun National Nature Reserve, Huanjiang, Guangxi 547100
  • Received:2021-08-29 Accepted:2022-01-06 Online:2022-04-20 Published:2022-04-20
  • Contact: Hu Du

摘要:

树木死亡在森林动态中发挥着重要作用, 环境因子是影响树木死亡的重要因素。为了阐明喀斯特常绿落叶阔叶林死亡个体空间分布格局及其与环境的相关性, 本研究以木论25 ha森林动态监测样地的两次木本植物调查数据为基础, 分析了死亡个体的物种组成、径级结构、分布格局及其与生境的关联。结果表明, 样地内共有死亡个体17,306株, 隶属57科130属194种; 其中, 死亡率排名前三的科和属分别为八角枫科、蔷薇科、大风子科以及山麻杆属(Alchornea)、火棘属(Pyracantha)、八角枫属(Alangium); 在物种水平上, 山麻杆(Alchornea trewioides)、毛桐(Mallotus barbatus)、野桐(Mallotus japonicus)等死亡率较高。样地内死亡个体的平均胸径为3.83 cm, 最大47.11 cm; 径级分布呈倒“J”型。从分布格局来看, 样地内大部分死亡个体在0-50 m的尺度上呈聚集分布, 部分大径级树木死亡个体趋向于随机分布。生境关联分析发现, 个体死亡率与山顶、陡坡、缓坡、洼地呈正关联的物种数分别为41种、13种、41种和38种, 呈负关联的物种数分别为38种、67种、33种和10种, 与各生境无关联的物种数分别为4种、3种、9种和35种; 多度排名前20的物种其个体死亡率均与4种生境类型呈现出正关联或者负关联; 不同径级个体死亡率都与山顶生境呈正关联, 与缓坡生境呈负关联, 其中5 cm ≤ DBH < 10 cm和10 cm ≤ DBH < 15 cm个体死亡率均与洼地生境呈正关联; DBH ≥ 15 cm个体死亡率与陡坡生境呈正关联, 与洼地生境呈负关联。在喀斯特亚热带常绿落叶阔叶林中, 死亡个体空间分布格局总体表现为聚集分布, 树木死亡受生境作用的影响较大。

关键词: 树木死亡, 径级结构, 空间点格局分析, 生境关联, 喀斯特生态系统

Abstract

Aims: Tree mortality is a natural demographic process that plays a key role in determining forest dynamics and succession. Elucidating spatial patterns and driving factors of tree mortality would help researchers to better predict forest dynamics. In this respect, studies of the relationships between dead individuals and their habitats can aid the analysis of spatial distribution patterns. Previous studies on tree mortality have focused mainly on the causes and processes of tree death, temporal and spatial variabilities, impacting on ecosystems, and the abundance patterns and death dynamics of snags. Therefore, this study aims to determine the distribution patterns of dead individuals at different scales and the relationship between snags and habitats in a karst forest.

Methods: Using the data collected from two surveys of a 25 ha forest dynamic plot in the Mulun National Nature Reserve in Guangxi, China, we analyzed the species composition, size class structure and spatial patterns of snags, and its association with habitats. First, the univariate pair correlation was employed to analyze the distribution pattern of dead individuals of different species. Then, the Torus-translation method was utilized to analyze tree mortality and habitat-type associations.

Results: A total of 17,306 snag individuals, belonging to 57 families, 130 genera, and 194 species were found in the plot. The three families with the highest numbers of dead trees were Alangiaceae, Rosaceae, and Flacourtiaceae, with Alchornea, Pyracantha, and Alangium being the top three genera and Alchornea trewioides, Mallotus barbatus, and Mallotus japonicus the top three species with the highest mortality rates. The average diameter at breast height (DBH) of the snags was 3.83 cm, with the maximum DBH being 47.11 cm. The snags had an inverse J-type tree size structure. Within the scale of 0-50 m, the snags were mostly aggregated in the plot, but some large-sized trees were randomly distributed. The numbers of species whose mortality were positively associated with a hilltop, steep slope, gentle slope, and depression were 41, 13, 41, and 38, respectively, whereas the numbers of species with a negative association with the same habitat types were 38, 67, 33, and 10, respectively. Those of species with no association with hilltop, steep slope, gentle slope, and depression were 4, 3, 9, and 35, respectively. Among the 20 most dominant trees in the area, all were found to have either a positive or negative association with the four habitat types, with the mortality of each size class being positively correlated with hilltops but negatively correlated with gentle slopes.

Conclusion: Our study revealed that the distribution of snags in the surveyed plot was aggregated in a karst evergreen and deciduous broad-leaved forest in the Mulun National Nature Reserve,. This indicates that tree mortality was nonrandom and more highly impacted by the habitat type and topography.

Key words: tree mortality, DBH class structure, point pattern analysis, habitat association, karst ecosystem