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林业科学 ›› 2020, Vol. 56 ›› Issue (2): 24-31.doi: 10.11707/j.1001-7488.20200203

• 论文与研究报告 • 上一篇    下一篇

秦岭3种天然林细根分布特征及其与土壤理化性质的关系

祝乐1,许晨阳1,2,耿增超1,2,*,刘莉丽3,侯琳3,王志康1,王强1,陈树兰1,李倩倩1   

  1. 1. 西北农林科技大学资源环境学院 农业部西北植物营养与农业环境重点实验室 杨凌 712100
    2. 农业部农业环境重点实验室 北京 100081
    3. 西北农林科技大学林学院 杨凌 712100
  • 收稿日期:2018-04-08 出版日期:2020-02-25 发布日期:2020-03-17
  • 通讯作者: 耿增超
  • 基金资助:
    国家林业公益性行业科研专项(201304307);农业部农业环境重点实验室开放基金(K4030217149)

Characterization of Fine Roots Distribution in Three Natural Forests of Qinling Mountains and Their Relations with Soil Physical and Chemical Properties

Le Zhu1,Chenyang Xu1,2,Zengchao Geng1,2,*,Lili Liu3,Lin Hou3,Zhikang Wang1,Qiang Wang1,Shulan Chen1,Qianqian Li1   

  1. 1. Key Laboratory of Plant Nutrition and Agri-Environment in Northwest China, Ministry of Agriculture College of Natural Resources and Environment, Northwest A&F University Yangling 712100
    2. Key Laboratory for Agricultural Environment, Ministry of Agriculture Beijing 100081
    3. College of Forestry, Northwest A&F University Yangling 712100
  • Received:2018-04-08 Online:2020-02-25 Published:2020-03-17
  • Contact: Zengchao Geng

摘要:

目的: 研究秦岭3种天然林细根分布特征及其与土壤理化性质的关系,为秦岭地区生态治理和森林恢复提供科学依据。方法: 采用土柱法对秦岭辛家山林区云杉林、红桦林及云杉+红桦混交林3种天然林进行根系取样,分析细根生物量密度、细根根长密度、细根体积、细根比根长与土壤有机质含量、孔隙度、密度、硝态氮含量、铵态氮含量和湿度的关系。结果: 随土壤深度增加,3种天然林土壤的有机质含量、孔隙度、硝态氮含量、铵态氮含量和湿度均降低,但密度升高;随土壤深度增加,3种天然林各细根指标均降低,其中细根生物量主要集中在腐殖质层,各林分在腐殖质层的占比均大于69%;腐殖质层具有最高的细根根长密度、细根体积和细根比根长,分别是淀积层的3.76~4.85、2.63~3.80和1.26~1.67倍,分别是母质层的11.13~14.98、6.32~16.01和1.76~3.28倍;3种天然林中,混交林各土层的细根根长密度最高(平均值为0.45 cm·cm-3),云杉林各土层的细根根长密度、细根体积和细根比根长最低(平均值分别为0.26 cm·cm-3、0.88 mm-3·cm-3和0.60 cm·g-1);相关性分析表明,3种天然林分各细根指标与土壤的有机质含量、孔隙度、密度、硝态氮含量、铵态氮含量和湿度均呈极显著或显著相关,其中细根生物量密度、细根根长密度、细根体积与土壤有机质含量的正相关性最高(r值分别为0.813、0.795和0.784),与土壤密度的负相关性最高(r值分别为-0.715、-0.658和-0.683);主成分分析表明,影响细根分布的第一主成分因子包括土壤有机质含量、硝态氮含量、密度、孔隙度、湿度和铵态氮含量;通径分析表明,土壤有机质含量对细根生物量密度的直接正效应最高,土壤湿度的间接效应最高且主要是通过有机质含量的间接效应来实现。结论: 秦岭3种天然林的细根指标均随土壤深度增加而减少,土壤腐殖质层为细根集中分布层;3种天然林分中,混交林的细根发达程度最高,云杉林最低;根系分布受多种土壤因子影响,影响程度表现为有机质>硝态氮>密度>孔隙度>湿度>铵态氮;土壤有机质含量直接影响细根生物量密度;土壤湿度主要通过土壤有机质的间接作用影响细根生物量密度。在对秦岭地区进行生态治理和森林恢复工作过程中,应综合考虑细根生物学特性,合理配置不同树种,注意森林土壤有机质的积累,从而起到维护森林生产力,增强森林生态系统功能的作用。

关键词: 天然林, 细根, 分布特征, 土壤性质

Abstract:

Objective: To further understand the role of fine roots in forest soil, the distribution of fine roots in three natural forests of Qinling Mountains and their relationships with soil physical and chemical properties were characterized in order to provide a scientific baseis for ecological management and forest restoration in Qinling Mountains. Method: Soil columns were sampled from three natural forests of Qinling Mountains, namely Picea asperata forest, Betula albo-sinensis forest and mixed forest of P. asperata and B. albo-sinensis. The relations between root parameters (fine root biomass, fine root length density, fine root volume and fine specific root length) and soil properties (soil organic matter, soil porosity, soil density, soil nitrate nitrogen, soil ammonium nitrogen and soil moisture) were studied. Result: Soil physical and chemical properties of the three natural forests showed vertical stratification along the soil profile. The organic matter content, porosity, nitrate content, ammonium content and moisture all decreased with increasing soil depth. Soil density increased with the increase of soil depth. The fine root indexes of the three natural forests decreased with the increase of soil depth. Fine root biomass mainly concentrated in humus layer, auouating for more than 69% in the humus layer for all the three natural forests, which also had the highest fine root length density, fine root volume and fine specific root length, where was 3.76-4.85, 2.63-3.80, 1.26-1.67 times as high as that in illuvial layer, and 11.13-14.98, 6.32-16.01, 1.76-3.28 times as high as that in parent material layer. Among the three forest stands, the fine root length densities in layers of mixed forest were the highest (its mean value was 0.45 cm·cm-3); the fine root length density, fine root volume, and specific fine root length in layers of the P. asperata forest were the lowest (the mean value were 0.26 cm·cm-3, 0.88 mm-3·cm-3, 0.60 cm·g-1respectively). The result of correlation analyses showed that there were extremely significant or significant correlations between root parameters and soil properties (soil organic matter, soil porosity, soil density, soil nitrate, soil ammonium and soil moisture) of the three natural forests. Among them, positive correlations between fine root biomass, fine root length density, fine root volume and soil organic matter were the highest (the r value were 0.813, 0.795 and 0.784 respectively); and negative correlations with soil density were the highest (the r value were -0.715, -0.658 and-0.683 respectively). The principal component analysis showed that soil organic matter, soil nitrate, soil density, soil porosity, soil moisture, and soil ammonium contents were the first principal components affecting the distribution of fine roots in natural forests. The path analysis showed that soil organic matter had the greatest direct effect on fine root biomass density; soil moisture had the greatest indirect effect on fine root biomass density, mainly through the effect of soil organic matter. Conclusion: The root parameters of the three natural forests in Qinling Mountains decreased with the soil depth. The fine roots were well-developed and concentrated in the humus layer of forest soil. Among the three forest stands, the fine roots of mixed forest were the most-developed, and the fine roots of P. asperata forest were the least-developed. The root distribution was affected by soil factors, and the extent of influence of those factors were ranked in the order of organic matter > nitrate content > density > porosity > moisture > ammonium content. Soil organic matter directly affected fine root biomass density, while soil moisture indirectly affected fine root biomass density through the influence of soil organic matter. Therefore, in the process of ecological management and forest restoration in Qinling Mountains, biological characteristics of fine roots should be taken into account, with appropriate deployment of different tree species, and sufficient attention to the accumulation of organic matter in forest soil to maintain forest productivity and enhance the function of forest ecosystem.

Key words: natural forest, fine root, distribution characteristics, soil property

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