藏东南巨柏根系结构特征分析

Root Structure and Specific Characteristics of Cupressus gigantea in Southeast Tibet

本文选择巨柏的主要天然分布区,按照不同的地类,采用挖掘和典型取样调查的方法,按照地径(D_0≤5cm、5cm<D_0≤10cm、10cm<D_0≤30cm、30cm<D_0≤50cm、50cm<D_0≤100cm),根系直径(d>10cm、5cm<d≤10cm、3cm<d≤5cm、1cm<d≤3cm、d<1cm),分5个等级开展巨柏的根系结构研究。结果表明:巨柏根系的侧根数量随地径的增大,巨柏细根(d<1cm)发达,数量占总根量的95%以上,主要分布在距离树干1~1.5m的直径范围,不同地类巨柏细根数量差异显著。不同地类巨柏根系垂直分布有较大差别,河岸阶地、坡麓地的巨柏根系分布较浅,其平均深度为37.31cm;裸露岩石及水线岸边主根沿石缝无规律延伸。根系延伸范围与根系的直径成对数关系,水平分布范围是垂直分布范围的31.1倍,根幅与冠幅比为7.76,根长与株高的比为0.04。河岸阶地与坡麓地是巨柏迁地保护的理想地类,研究结果对巨柏的迁地保护具有一定的意义。

The main natural distribution area of Cupressus gigantea was selected for this study. By digging roots and typical sample survey in terms of ground diameter( D_0≤5cm、5cm<D_0≤10cm、10cm<D_0≤30cm、30cm<D_0≤50cm、50cm<D_0≤100cm) and the root diameter( d>10cm、5cm<d ≤10cm、3cm<d≤5cm、1cm<d≤3m、d< 1cm),Cupressus gigantea root structure were studied in five grades. The results showed: Cupressus gigantea had more developed fine roots which accounted for more than 95% of the total roots,the fine roots were mainly distributed in the diameter range of 1 ~ 1. 5m from the trunk. The fine root numbers presented significant difference in different site types. The vertical distribution varied notably in different site types. Roots were shallow in river bank and terrace,with average depth of 37. 31 cm. The taproot grew along with rock cracks in bare rock and waterline and shoreline in no pattern. The logarithmic relationship between the root extension range and diameter was found,the horizontal distribution of root system was 31. 1 times of the vertical distribution,the root width and crown width ratio was 7. 76,and the root depth and height ratio was 0. 04. The terraces and slope were found as perfect lands for Cupressus gigantea. The results provide a theoretical basis for ex-situ conservation of Cupressus gigantea.