• 论文与研究报告 •

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

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

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.