对湘北地区四川桤木人工林根系生物量的测定，研究了四川桤木人工林不同径级根系生物量分布情况，分析了不同径级根系的根长、比根长、根长密度的空间分布特征。结果表明：①四川桤木人工林大根、中根、小根、细根生物量分别占林分根系生物量总和的55%、22%、14%、9%。约66%的根系生物量集中在0~30cm土层，从而证明桤木为浅根性树种。②四川桤木人工林各径级根系根长变化趋势是细根>小根>大根>中根。比根长的变化是：细根>小根>中根>大根。③四川桤木人工林各径级根系的根长密度分布规律各不相同。

According to the messurement of the root biomass of Si Chuan Qi Mu plantation in Xiang Bei distract, Research the distribution of different drive-lever root biomass,Analised the characteristic of each space of boot drive-lever's root length,than the root length ,root length density.The result shows that :1.The big root , middle root, small root,fine root biomass of Si Chuan Qi Mu plantation accounted for stand root sum total fifty five persent ,twenty two persent,nine persent. About sixty six persent root biomass focus in 0~30cm soil, This prove that Qi Mu was the shallow root trees.2.Every drive-lever root length trend in Si Chuan Qi Mu plantation is fine root than small root than big root than middle root .Than root length 's change is :fine root than small root than middle root than big root .3.Every drive-lever root biomass's root length density distribution in Si Chuan Qi Mu plantation is different.