为了解燕山北部山地4个乔木造林树种的根系空间分布特征的差异,对立地条件相近的7a生油松、樟子松、蒙古栎及华北落叶松的根系空间结构特征(水平分布、垂直分布、不同径级根系分布)进行了研究。结果表明,樟子松、油松的根系水平分布范围及所占土体体积高于其他2个树种,且根长密度及根面积密度较低;华北落叶松根系与其他树种相比分布的土层更浅,所占土体体积较小,但根长密度及根面积密度明显高于其他3个树种,华北落叶松根系在土壤中的分布更为密集;各树种根系的水平分布范围都远超地上的冠幅,樟子松与蒙古栎的根幅与冠幅比较大,分别达到了3.82和3.09;各树种根系的生物量、根系长度和根系的表面积都随与主干的距离以及深度的增加而下降,但比根长则相反。由于采用的是裸根苗造林,蒙古栎的根幅、生物量、比根长及比根面积等参数明显低于其它3个树种,蒙古栎建议采用直播造林或容器苗造林。从根系在土壤中的分布特征来看,油松、樟子松更能适应瘠薄、干旱的土壤,而华北落叶松的根系分布较浅,且更为集中,易受到土壤干旱胁迫的影响。

In order to understand the spatial distribution of tree roots in the northern mountain region of Hebei Province,this study chose four tree species which grow well for seven years and have similar growth conditions:Pinus tabuliformis,Pinus sylvestris var.mongolica,Quercus mongolica, Larix principis-rupprechtii as the research object.Our objective was to study the spatial structure characteristics of four tree species roots (horizontal distribution,vertical distribution,root distribution of different diameter classes).The results show that the horizontal distribution and volume of roots of Pinus sylvestris var.mongolica and Pinus tabuliformis are higher than those of the other two species,and the density of root length and root area are lower.Compared with other tree species,the root system of Larix principis-rupprechtii has a shallower soil layer and a smaller soil volume,but the root length density and root area density are higher than those of the other three species,and the root system of Larix principis-rupprechtii is more concentrated in soil.The horizontal distribution range of root system of each tree species is much larger than that of the aboveground,and the root width and crown width of Pinus sylvestris var.mongolica and Quercus mongolica are larger,reaching 3.82 and 3.09 respectively.What’s more,the biomass,root length and surface area of root system decreased with the increase of the distance from the trunk and the depth of root,but the opposite is true for specific root length.Because of the bare root seedling afforestation technology,the root width,biomass,specific root length and specific root area of Quercus mongolica are lower than those of other three tree species,so direct seeding afforestation or container seedling afforestation is recommended for Quercus mongolica. According to the distribution characteristics of root system in soil, Pinus tabuliformis and Pinus sylvestris var.mongolica are more adaptable to poor and arid soil,but the root distribution of Larix principis-rupprechtii is shallower and more concentrated,which should be influenced by soil drought stress.