植物生态学报 ›› 2019, Vol. 43 ›› Issue (9): 834-842.doi: 10.17521/cjpe.2018.0153

• 研究论文 • 上一篇    

黄土高原腹地人工林下草本层群落构建机制

施晶晶1,2,赵鸣飞1,2,王宇航1,2,薛峰1,2,康慕谊3,1,江源1,2,3,*()   

  1. 1北京师范大学地理科学学部自然资源学院, 北京 100875
    2北京师范大学地理科学学部中药资源保护与利用北京市重点实验室, 北京 100875
    3北京师范大学地表过程与资源生态国家重点实验室, 北京 100875
  • 收稿日期:2018-07-03 接受日期:2018-10-18 出版日期:2019-09-20 发布日期:2020-01-03
  • 通讯作者: 江源 E-mail:jiangy@bnu.edu.cn
  • 基金资助:
    国家科技基础性工作专项(2011FY110300);国家自然科学基金(41630750);国家自然科学基金(41271059)

Community assembly of herbaceous layer of the planted forests in the central Loess Plateau, China

SHI Jing-Jing1,2,ZHAO Ming-Fei1,2,WANG Yu-Hang1,2,XUE Feng1,2,KANG Mu-Yi3,1,JIANG Yuan1,2,3,*()   

  1. 1College of Resources Science & Technology, Faculty of Geographical Science, Beijing Normal University, Beijing 100875, China
    2Beijing Key Laboratory of Chinese Medicine Resource for Protection and Utilization, Faculty of Geographical Science, Beijing Normal University, Beijing 100875, China
    3State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, Beijing 100875, China
  • Received:2018-07-03 Accepted:2018-10-18 Online:2019-09-20 Published:2020-01-03
  • Contact: JIANG Yuan E-mail:jiangy@bnu.edu.cn
  • Supported by:
    Supported by the National Basic Work of Science and Technology of China(2011FY110300);the National Natural Science Foundation of China(41630750);the National Natural Science Foundation of China(41271059)

摘要:

群落构建机制是生态学研究的核心论题。生态位理论和中性理论是阐明群落构建的两种主要理论, 但这两种理论分别强调的环境过滤和扩散限制对群落构建的影响尚存争议。该研究以黄土高原人工林下草本层群落为研究对象, 将群落物种组成数据与地理空间、气候、地形以及生物因子相结合, 运用随机森林模型(RF)和基于距离矩阵的多元回归方法(MRM), 探究了各个因子的重要性, 并通过邻体主坐标矩阵(PCNM)和基于距离的冗余分析(db-RDA)分别筛选显著的空间结构和环境因子, 最后结合筛选出的PCNM特征值和环境变量进行变差分解。研究结果显示: 1)林下草本层群落组成相似性随地理距离和生境差异的增加而减小。2)地理距离与生境差异共同解释了群落组成相似性变化的47.8%。其中, 空间因子和环境因子的独立解释率分别为14.1%和9.8%, 两者的联合解释率为23.9%。3)地理距离和年降水量是引起研究区内物种组成变化的关键因子, 且地理距离的重要性大于年降水量。在黄土高原腹地, 扩散限制与环境过滤共同主导了人工林下草本层群落的构建过程。

关键词: 群落构建, 生态位理论, 中性理论, 环境过滤, 扩散限制, β多样性, 林下草本层群落

Abstract:
Aims Many competing theories seek to identify the mechanisms behind the community assembly. Niche theory and neutral theory are among the two most competing mechanisms. Exploring factors controlling the patterns of β-diversity is an approach to reveal the underlying mechanisms of community assembly. In this paper, we aim to reveal the β-diversity pattern of understory in planted forests of the central Loess Plateau and to evaluate the relative influences of deterministic (environmental filtering) and stochastic (dispersal limitation) processes on the community assembly.
Methods We sampled in total 107 sites of planted forests spatially spreading over the central Loess Plateau. In each site, three plots (10 m × 10 m) were randomly designed each at a distance of about 50 m. The floristic composition, community structure, and environmental conditions were investigated in each plot. We calculated the dissimilarity (βsim) of species composition, geographic distance and environmental divergence for each of the 5 671 site pairs. We used random forest (RF) to quantify the influence of the selected factors on species composition, and distance-based multivariate regression method (MRM) to fit the relationship between dissimilarity, geographic distance and environmental divergence. To quantify how and in what extent the environmental filtering and the dispersal limitation influence the species composition among sites, we performed the principle coordinates of neighbor matrices (PCNM) and distance-based RDA (db-RDA) to select the pronounced independent variables. We then partitioned the variance into three parts, namely, 1) independent contributions of geographic distance; 2) independent contributions of environmental divergence; and 3) the joint contribution of both.
Important findings The community similarity declined with increasing geographical distance and environmental divergence. Geographical distance and environmental divergence together explained 47.8% of variance in the dissimilarity in species composition. The spatial variables accounted for 14.1%, while the environmental variables accounted for another 9.8% of the variance in dissimilarity of species composition. Annual precipitation and basal area of trees are the two most important environmental factors influencing the pattern of dissimilarity of species composition. These results implied that both environmental filtering and the dispersal limitation play important roles in shaping the community assembly of the herbaceous layers of planted forests in the central Loess Plateau.

Key words: community assembly, niche theory, neutral theory, environmental filtering, dispersal limitation, β diversity, understory community