江苏太湖地区草坪根系形态对初期降雨径流的影响

Effect of lawn root morphology on initial rainfall runoff in the Taihu Region of Jiangsu Province

选取马蹄金(Dichondra erpens Forst)、麦冬(Ophiopogon japonicus var.nana)、红花酢浆草(Oxalis corymbosa)、白三叶(Trifolium repens)4种不同根系形态特征的草坪,通过在相近覆盖度上设置径流小区,分析不同草坪对初期降雨径流的影响,解析不同根系形态与水土流失的关系。结果表明:(1)4种草坪的根呈伞型分布,其中马蹄金根系主要由根径≤1 mm的细根组成,麦冬根径≤1 mm的根长密度占60%以上,白三叶占48%以上,而红花酢浆草的根系主要由根径>1 mm的粗根组成。(2)马蹄金水土保持效能最好,其次是麦冬,再次是白三叶,红花酢浆草最差。(3)相关分析显示:草坪的水土保持效能主要受根径≤1mm的根长密度影响,水土流失量与其呈显著负相关,细根型草坪对初期降雨径流的拦截效能高。

Four types of lawn with different root morphological characteristics were chosen in the present research, which are Dichondra erpens Forst, Ophiopogon japonicus var. nana,Oxalis corymbosa and Trifolium repens.The runoff plots were set up in the area with similar lawn coverage in order to analyze the impact of these four lawns on the initial rainfall runoff and the relationship between the types of lawn and the loss of soil and water. The results showed that：（1）the roots of the four types of lawn spread in umbellate form. Specifically,the roots of Dichondra erpens Forst mainly consist of fine roots（ diameter≤1 mm）,the root length density of the fine roots of Ophiopogon japonicus var. nana accounts for more than 60% and that of Trifolium repens accounts for more than 48%, while the roots of Oxalis corymbosa mainly consist of coarse roots（diameter 〉 1 mm）.（2）Dichondra erpens Forst showed the best soil and water conservation efficiency,followed by Ophiopogon japonicus var. nana, then Trifolium repens and last Oxalis corymbosa.（3） The correlation analysis showed that the efficiency of soil and water conservation is mainly influenced by the root length density of fine roots,while soil and water loss amount has negative correlation with the root length density of fine roots. Lawn with fine roots are better to intercept the surface runoff.