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林业科学 ›› 2016, Vol. 52 ›› Issue (8): 1-9.doi: 10.11707/j.1001-7488.20160801

• 论文与研究报告 • 上一篇    下一篇

鄂西南亚热带常绿落叶阔叶混交林的自然恢复动态及其影响因素

冯广, 艾训儒, 姚兰, 刘峻城, 黄永涛, 林勇   

  1. 湖北民族学院林学园艺学院 恩施 445000
  • 收稿日期:2015-04-02 修回日期:2016-06-08 出版日期:2016-08-25 发布日期:2016-09-19
  • 通讯作者: 艾训儒
  • 基金资助:
    湖北省林学重点(特色)学科及楚天学者计划项目(2013XKJS_10517);湖北省教育厅重点项目(D20122901);湖北民族学院研究生学位论文培优基金(PY201507)。

Dynamics of Natural Restoration of Subtropical Evergreen-Deciduous Broadleaved Mixed Forests in Southwest Hubei Province and Influencing Factors

Feng Guang, Ai Xunru, Yao Lan, Liu Juncheng, Huang Yongtao, Lin Yong   

  1. School of Forestry and Horticulture, Hubei University for Nationalities Enshi 445000
  • Received:2015-04-02 Revised:2016-06-08 Online:2016-08-25 Published:2016-09-19

摘要: [目的]比较环境与空间因素在群落恢复与构建中的作用,分析亚热带常绿落叶阔叶混交林自然恢复过程中的群落结构和物种多样性变化规律,为进一步深入了解此类森林的自然恢复机制奠定基础。[方法]在湖北木林子国家级自然保护区的老龄林、35年天然次生林(1980年采伐)和20年天然次生林(1995年采伐)中各随机选取10块森林动态固定样地(20 m×20 m),对不同恢复阶段森林群落木本植物多度、胸高断面积、物种丰富度、稀疏物种丰富度(以100个树木个体为基数)进行比较,采用冗余分析(RDA)对30块样地进行排序。将空间(PCNM)和环境变量(土壤与地形)一同作为解释变量对不同恢复群落物种组成进行方差分解,以环境和恢复时间作为解释变量对30块样地的木本植物多度、胸高断面积、物种丰富度和稀疏物种丰富度数据进行多元回归分析。[结果]群落在恢复过程中,木本植物多度(F=8.64,P<0.01)、物种丰富度(F=10.24,P<0.001)和稀疏物种丰富度(F=9.615,P<0.01)均显著减少,胸高断面积(F=14.2,P<0.001)显著增加,土壤环境则无显著变化(P>0.05);土壤密度、土壤pH、坡向、坡度、海拔和坡位对研究区物种组成的解释能力显著(P<0.05);方差分解显示,恢复20年次生林、恢复35年次生林和老龄林分别有31.4%,36.8%和54.1%的物种组成变异受环境影响,空间因素(PCNM变量)仅对恢复35年次生林(16.8%)和老龄林(23.2%)的物种组成变异具有显著影响(P<0.05),而对恢复20年次生林无显著影响(P>0.05);同步自回归结果显示,恢复时间、凋落物厚度、坡度、海拔、坡向机土壤pH对群落结构与多样性具有显著影响(P<0.05)。[结论]亚热带常绿落叶阔叶混交林在自然恢复过程中,群落结构、物种多样性以及环境因素均会发生明显变化,环境、空间及恢复时间是决定群落组成的关键因素。种源空间扩散、优先效应等随机过程对次生林的群落构建具有决定性作用,而环境选择等确定性过程对老龄林的群落构建起主导作用。随着恢复进程的推进,次生林与老龄林的物种组成差异会逐渐减少。

关键词: 亚热带常绿落叶阔叶混交林, 自然恢复, 次生演替, 环境选择, 确定性过程与随机过程, 木林子国家级自然保护区

Abstract: [Objective] Evergreen-deciduous broadleaved mixed forest is one of the main vegetation types in northern parts or high elevations of subtropical regions of China. It is characterized as transitional features from evergreen to deciduous broad-leaved forests. Due to long term and repeated anthropogenic disturbances, these forests were subjected to different extents of degradation. Until now, very few studies have been carried out on mechanisms of restoration of the degraded forests. In this study, by comparing the roles of environmental and spatial factors in restoration and rehabilitation of communities, patterns of variation in community structure and species diversity during the natural restoration in subtropical regions can therefore be analyzed, laying a foundation for deepening our understanding of the mechanisms of natural restoration of this type of forest.[Method] 10 sample plots (20 m×20 m in size) were selected at random and configured as fixed plots for monitoring forest dynamics, respectively in old-growth forest, 35-year-old secondary forest (harvested in 1980) and 20-year-old secondary forest (harvested in 1995) in the Mulinzi National Nature Reserve in Enshi of Hubei Province. For forest communities at different stages of restoration, abundance of woody plants, basal area at breast height, species richness, and richness of rare species (100 individual trees as baseline) were compared. One-way ANOVA and Turkey-HSD were conducted to assess the differences in stem density, basal area, species richness, and rare species richness among the three succession stages. The redundancy analysis (RDA) and non-metric multidimensional scaling (NMS) ordinations were used to differentiate the plots. The environmental and spatial factors (PCNM variables) were treated as explanatory variables to partition the variations at each succession stage. The relative effects of environmental factors and restoration period after disturbance on the four community characteristics were analyzed by performing multivariable regression analysis.[Result] During the process of community restoration, the abundance of woody plants, species richness and rare species richness had a significant decrease, while basal area had a significant increase. Species composition were significantly different among different restoration forests (Adonis, P<0.05). However, all the soil factors did not show any significant differences. Environmental factors showed a greater influence than the spatial configurations. Environmental factors explained 31.4%, 36.8%, 54.1% of species composition variations of 20-year-old, 35-year-old secondary forest and old-growth forest, respectively. Spatial configuration explained 16.8% and 23.2% composition variations for the 35-year-old secondary and old growth forests respectively, while no significant influence on the 20-year-old secondary forest were found. The spatial auto-regression showed that soil pH, litter thickness, elevation, slope gradient, slope orientation and the restoration time played an important role in the restoration of community structure and species diversity.[Conclusion] The community structure, species diversity and environmental features of the subtropical evergreen-deciduous broadleaved mixed forest varied significantly during the secondary succession process after anthropogenic disturbances. Environment, space, and time were the key factors determining community composition and dynamics. The stochastic process (such as dispersal process or prior effect) exerted the greatest influence on community assembly at the early stages of forest restoration, meanwhile, the deterministic process represented by environmental filtering played a dominant role in community assembly of old-growth forest. The differences in species composition between secondary and old-growth forests declined gradually with the progress of secondary succession.

Key words: the subtropical evergreen-deciduous broadleaved mixed forest, natural recovery, secondary succession, environmental filtering, deterministic versus stochastic process, Mulinzi national nature reserve

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