天坛公园油松、侧柏大树根系分布特征

【目的】树木的根系分布是影响灌溉效果的重要因素,为了实现园林树木的科学灌溉,对两种常见园林树木的根系分布特征开展研究。【方法】采用根钻法对天坛公园60年生油松、侧柏大树根系进行定点逐层取样,利用Win-RHIZO Pro根系分析系统分析各径级根系(直径1mm、1~2mm、2~5mm)的根长、根表面积、根重和根体积等指标,研究油松、侧柏根系空间分布特征。【结果】结果表明,油松和侧柏各径级根系的总根长和总根表面积均以直径1mm根系最多,直径2mm的吸收根为总根量的主体。在垂直分布上,两树种均在0~60cm深度范围内有大量吸收根存在,其中,10~40cm土层是油松根系集中分布区,0~40cm土层是侧柏根系集中分布区。油松吸收根根长密度和根重密度随土层深度增加表现出先增加后减小的趋势,峰值出现在20~30cm土层处;侧柏吸收根根长密度和根重密度随土层深度增加表现出逐渐下降的趋势,峰值出现在0~10cm土层处。【结论】公园绿地中油松、侧柏的根系分布在垂直方向上与野外林地根系分布更为接近,而与同为城市绿化树的行道树根系分布差异较大;而水平方向上分布较均匀,这可能是由于公园休闲场所的密植特征造成的。

The root distribution characteristics of big trees of Pinus tabulaeformis and Platycladus orientalis in the Temple of Heaven Park

Objective]The root distribution is an important factor that affects the effect of irrigation.In order to realize the scientific irrigation of landscape trees,this paper investigated root system distribution of two commonly used garden trees to provide theoretical basis for reasonable irrigation.Methods]In this study,sixty-year-old Pinus tabulaeformis and Platycladus orientalis were used as study objects in the Temple of Heaven Park.The root drilling method was used to sample the roots in different soil layers of sampling points.Win-RHIZO Pro root analysis system was utilized to analyze root length,root surface area,root weight,and root volume of each diameter class (diameter＜1 mm,1-2 mm,2-5 mm).Then the root spatial distribution characteristics of P.tabulaeformis and P.orientalis were summerzied.Result]The results showed that the roots of diameter＜ 1 mm had the most largest total surface area length among three classes of root diameter for both P.tabulaeformisand P.orientalis,and the absorbing roots of diameter＜2 mm were the main part of root.For the vertical direction,both tree species had a large amount of absorbing roots in the soil layer of 0 to 60 cm.The soil layers of 10-40 cm and 0-40 cm were the root concentrated distribution layers for p.tabulaeformis and P.orientalis respectively.The densities of absorbing root length and root weight of P.tabulaeformis first increased and then decreased with the increase of soil depth,and the peak appeared in the 20-30 cm soil layer.The densities of absorbing root length and root weight of P.orientalis showed a declining trend with the increase of soil depth,and the peak appeared in the 0-10 cm soil layer.Conclusion]This study showed that the vertical distributions of roots of P.tabulaeformis and P.orientalis in the park were more close to those of natural forests rather than street trees,although street trees and trees in the park were both urban greening trees.The horizontal distributions of roots were relatively uniform,which may result from the dense planting of trees in the park.