华北土石山区公路边坡常见植物根系地下分布特征

以京承高速公路（三期）边坡常见植物为研究对象，通过全挖法，调查研究华北土石山区公路边坡常见植物根系地下分布特征。结果表明：1）木本植物根系的总根长和总干质量远远大于草本植物；2）在不同土层，随着地下深度的加深，木本植物的根长和根干质量所占比例逐渐降低，而草本植物沙打旺和紫花苜蓿的则逐渐升高，草本植物高羊茅的根系集中分布在垂直坡面的地下10cm范围内；3）植物总根长的比较结果为胡枝子〉刺槐〉紫穗槐，高羊茅〉沙打旺〉紫花苜蓿；木本植物刺槐和紫穗槐以粗根的根长比例最大，胡枝子细根的根长比例最大，草本植物紫花苜蓿和沙打旺粗根的根长比例最大，高羊茅细根的根长比例最大；4）随着地下深度的加深，刺槐、紫穗槐、紫花苜蓿和沙打旺的主根与边坡夹角逐渐变小，最终贴着岩面顺势向下生长，遇到岩面后会改变其生长方向或扎入岩缝生长；5）高羊茅须根与边坡的夹角约为10°，基本为沿着坡面向下生长，胡枝子无明显主根，地下分布深度较浅，以茎干为中心向坡面四周延伸。

Characteristics of root system distribution of common plants on freeway slopes in earthy-rocky mountain area of North China

A study was conducted on the distribution characteristics of common plants on Jingcheng freeway （The third period） , by using the methods of digging out whole root system. Results showed that ： 1） the total root length and biomass of woody-plants were larger than that of herbaceous-plants. 2） The ratio of root length to biomass of woody-plants reduced gradually with the soil depth, vice verse in herbaceous-plants. Roots of Festuca arundinacea distributed within the scope of 10 cm topsoil. 3） Total length of these plants was Lespedeza bicolor Turcz. 〉 Robinia pseudoacacia L. 〉 Amorpha fruticosa L. and Festuca arundinacea 〉 Astragalus adsurgens Pall. 〉 Medicago sativa L.. For woody-plants, Robinia pseudoacacia L. and Amorpha fruticosa L. had the largest proportion of thick roots and Lespedeza bicolor Turcz. had the largest proportion of thin roots. For herbaceous-plants, Astragalus adsurgens Pall. and Medicago sativa L. had the largest proportion of thick roots, and Festuca arundlnacea had the largest proportion of thin roots. 4） The angle of slope and taproots of Robinia pseudoacacia L. , Amorpha fruticosa L. , Medicago sativa L. and Astragalus adsurgens Pall. became smaller gradually as soil depth, and grew down along rock surface finally, or change growth direction when the taproots meeting hard stone, or enter intocrack. 5） The fibres-roots of Festuca arundinacea grew down along sticked stone, and the angle with slope was about 10 degree. Lespedeza bicolor Turcz. had no obvious taproots, therefore, its roots distributed shallow and grew along slope taken trunk as center.