摘要
【目的】研究不同密度配置下的毛白杨人工林在造林4年后根系的空间分布特征,旨在探究不同密度配置是否对毛白杨根系分布存在影响,为毛白杨合理配置提供理论依据。【方法】选取2种造林密度(2 m×3 m和3 m×4 m)的5年生毛白杨人工林为研究对象,采用根钻法,在水平方向30、60、90、120、150 cm处,垂直方向20、40、60、80 cm处依次取样,每株共取得20个根系样品,共选取18株标准木,获得360个样品。对细根生物量、根长密度、根重密度等的空间分布特征进行研究。【结果】1)造林初期密度对树木的树高存在显著影响,胸径影响不显著。2)不同造林密度会对毛白杨人工林细根空间分布特征产生显著影响。株行距为2 m×3 m的细根生物量、细根根重密度均显著高于3 m×4 m密度配置;而比根长、根长密度、根表面积密度则以3 m×4 m密度配置下更优。3)水平方向上,2 m×3 m密度条件下,距树干水平距离0~30 cm处细根生物量显著高于其他水平距离,且0~30 cm细根生物量显著高于3 m×4 m。2 m×3 m密度下比根长、比表面积均随水平距离增加而增加,以120~150 cm处最大,而3 m×4 m密度下比根长各水平距离间均无显著差异。4)垂直方向上,两种密度下生物量、根重密度均呈现随着垂直深度的增加而逐渐减小的趋势,且均以0~20 cm深度处最大。5)3 m×4 m密度下根长密度表层显著高于其余深度土层,而2 m×3 m密度下60~80 cm根长密度分配比例(27.30%)接近0~20 cm处(27.25%),表层及深层均有较大细根分配比例。2 m×3 m较高密度40~80 cm根长密度占整株的53.64%,高于3 m×4 m较低密度40~80 cm的45.62%。【结论】不同密度配置显著影响毛白杨细根的空间分布,2 m×3 m较高密度配置会导致毛白杨根长密度分配比例下沉,即密度带来的竞争关系导致植物细根的向下伸长,吸收更深层次的土壤资源。
【Objective】This paper has characterized the spatial distribution characteristics of the root system of Populus tomentosa plantation with different densities after 4 years of afforestation,aiming to explore whether different densities have an effect on the root distribution,in order to provide a theoretical basis for the rational planting of Populus tomentosa.【Methods】Five-year-old Populus tomentosa plantations with two planting densities(2 m×3 m and 3 m×4 m)were selected as the research objects.The root drill method was used for the harvesting of samples.The samples were taken at the layer of 30 cm,60 cm,90 cm,120 cm and 150 cm in the horizontal direction,as well as 20 cm,40 cm,60 cm and 80 cm in the vertical direction.In total,20 root samples were obtained from each plant.A total of 18 standard trees were selected,and 360 samples were obtained.The spatial distribution characteristics of fine root biomass,root length density and root weight density were studied.【Results】1)Planting density had a significant effect on tree height,but not on DBH.2)The spatial distribution characteristics of the fine roots of Populus tomentosa plantation were significantly affected by different planting densities.The biomass and density of fine roots with a planting density of 2 m×3 m were significantly higher than those with a 3 m×4 m density.The specific root length,root length density and root surface area density were better under a 3 m×4 m density.3)In the horizontal direction,with a planting density of 2 m×3 m,the fine root biomass at the horizontal distance of 0-30 cm from the trunk was significantly higher than other horizontal distances,which was also significantly higher than that with a density of 3 m×4 m.Under the density of 2 m×3 m,the specific root length and specific surface area increased with the increase of the horizontal distance,which was the largest at 120-150 cm,while the specific root length at the density of 3 m×4 m had no significant difference between the horizontal distances.4)In the vertical direction,the biomass and root weight density decreased with the increase of vertical depth under the two densities,which reached the maximum values at 0-20cm depth.5)Under the density of 3 m×4 m,the root length density in the surface layer was significantly higher than that in the other layers,while the distribution ratio of the root length density at the 60-80 cm layer(27.30%)was close to that at the 0-20 cm layer(27.25%)under the density of 2×3m.The distribution ratio of fine roots in the surface layer and deep layer was larger.The root length density of the 40-80 cm layer under the density of 2 m×3m accounted for 53.64%of the whole plant,which was higher than that of 45.62%of the 40-80 cm layer under the 3 m×4 m density.【Conclusion】Different densities significantly affect the spatial distribution of the fine roots of Populus tomentosa.A high density of 2m×3 m would lead to a decrease in the distribution ratio of root length density in the deep soil layer,that is,the competition caused by density would lead to a downward elongation of fine roots,which helps the absorption of deeper soil resources.
作者
鲜李虹
刘勇
常笑超
王凯
宋协海
王洋
XIAN Lihong;LIU Yong;CHANG Xiaochao;WANG Kai;SONG Xiehai;WANG Yang(College of Forestry,Beijing Forestry University,Beijing 100083,China;Key Laboratory for Silviculture and Conservation of Ministry of Education,Beijing Forestry University,Beijing 100083,China;Beijing Da′an Forest Farm Management Office,Beijing 100083,China)
出处
《中南林业科技大学学报》
CAS
CSCD
北大核心
2022年第8期48-58,共11页
Journal of Central South University of Forestry & Technology
基金
国家重点研发计划项目“白杨工业资源材高效培育技术研究”(2016YFD0600403)。
关键词
毛白杨
造林密度
细根空间分布
细根生物量
比根长
Populus tomentosa
planting densities
spatial distribution of fine roots
fine root biomass
specific root length
作者简介
第一作者:鲜李虹(xianlh11@163.com),硕士研究生;通信作者:刘勇(lyong@bjfu.edu.cn),教授,博士,博士生导师。
