泥石流源区新银合欢细根质量动态与垂直分布特征

Dynamics and vertical distribution patterns of fine root weights of different aged Leucaena leucocephala stand in debris flow source area

以中国科学院东川泥石流观测站人工林中3、5、9、14和20年生新银合欢为研究对象,采用分层挖掘法对距树干1.0 m处细根质量动态与细根质量密度分布进行研究。结果表明：新银合欢细根质量在相同范围剖面中并非随树龄的增加而单一增大,而是先减小后增大;不同树龄细根质量密度最大值都出现在0~20 cm土层,呈现出明显的表聚特征,但随树龄的增加,根系集中化特征减弱,表现为向深层化扩张、均匀化方向发展;细根质量密度与土层深度相关性关系明显,垂直分布特征遵循指数函数分布,其中根径D≤2 mm细根在细根分布特征中起主导作用,而2 mm〈D≤5 mm细根对细根分布特性影响不大。研究结果可为生物措施防治泥石流提供重要依据。

In this study,Dynamics and vertical distribution patterns of fine root weights of different aged Leucaena leucocephala were investigated by mean of dig method from up to down at the distance 1.0m from the stem,in Dongchuan Debris Flow Observation and Research Station,Chinese Academy of Sciences.The results indicated that the weights of fine roots of tree were not solely increasing with the increasing tree age,but decreased at first and then increased in the similarly ranged profile.The maximum weight densities of fine roots for different aged tree were completely located at 0-20cm soil layer,also the root appeared an obvious accumulation trait in the topsoil layer.However,its centralized feature weakened as the time went by,showing a deep-seated and uniform grow trend. In addition,there were apparent correlations between soil depths and fine root weight densities,which decreased at an exponent function with increases of soil depths.Compared with the less important particles（2mmD≤5mm）,the fine roots（D≤2mm） determined the entire trends of the dynamics and vertical distributions of fine root weights,which will be the important basis of debris flow control with biological measures.