中文摘要：

采用完整土块法,以千年桐（Aleurites montana）人工林为研究对象,测定了1~5级细根的形态、生物量和组织碳（C）、氮（N）含量,分析了不同径级和序级与细根形态指标的差异性,对序级与细根生物量、碳氮含量及它们之间的关系进行探讨。结果表明：直径≤1 mm的细根根尖数、根系累计长度、根系累计表面积分别占据总量的99.66%,88.42%,69.82%;随着根序从1级根到5级根升高,千年桐细根直径由0.86 mm增加到1.35 mm,组织密度由0.11 g/cm3上升到0.47 g/cm3,根表面积密度由0.46 m2/m3降低到0.085 m2/m3,比根长由32.04 m/g减少到16.41 m/g;千年桐细根直径、比根长、根表面积密度、根组织密度及生物量与序级之间回归分析发现它们与序级之间具有二次函数、指数函数、线性函数、三次函数及高斯峰值函数关系;1~5级细根生物量对总生物量的贡献分别为：18.7%,30.9%,27.1%,16.6%,6.7%;N含量随着根序升高由16.73 mg/g下降到11.83 mg/g,C含量则由454.97 mg/g上升到494.43 mg/g;千年桐细根C/N比的变异受根组织N含量的影响程度达到93%,而受C含量的影响程度仅为50%。上述结果证明,千年桐细根的结构特征、生物量和碳氮含量之间存在密切联系,为了解千年桐根系结构与功能提供重要依据。

英文摘要：

Taking Aleurites montana plantation as the object,measured root morphology,biomass,carbon and nitrogen concentration of the first five orders roots. Analyzed differences between different diameter,root orders and morphological parameter,relationships of fine root biomass,C and N concentration with fine root orders by means of regression were discussed. The results showed that the root tips,accumulative root length and surface area of root d≤1mm accounted for the majority of total roots,accounting for the total respectively as 99. 66%,88. 42%,69. 82%; Along with the fine root ascending from the first to fifth order,root diameter increased from 0. 86 mm to1. 35 mm,tissue density rose from 0. 11 g / cm3 to 0. 47 g / cm3,root surface area density decreased from 0. 46 m2/m3 to 0. 085 m2/ m3,specific root length reduced from 32. 04 m/g to 16. 41 m/g; Fine root diameter,specific root length,surface area density,tissue density,biomass with root order can be represented by quadratic,exponential,linear,cubic or Gaussian peak functions; From the first to fifth fine root order contribution to the total biomass respectively as 18. 7%,30. 9%,27. 1%,16. 6%,6. 7%; Fine root tissue N concentration reduced from 16. 73 mg / g to 11. 83 mg / g,C concentration increased from 454. 97 mg / g to 494. 43 mg / g with ascending fine root order; Moreover,C / N ratio in roots was mainly affected by tissue N rather than tissue C concentrations,the former affected reached 93%,the later only reached 50%; These results suggested that there are systematic differences in fine root morphology and structure,biomass,and tissue carbon and nitrogen contents among different root orders,this provides an important basis for understanding fine root architecture and function of Aleurites montana.