Abstract:In order to understand the variation patterns of nutrient elements for the first-order roots of woody plants in subtropical evergreen broad-leaved forests, the carbon and nitrogen concentrations of the first-order roots of 89 tree species in Wanmu Forest Nature Reserve, Jian'ou, Fujian Province, were determined based on root order method. The results showed that the mean C, N concentrations in the first-order roots of 89 tree species were 433.9 and 13.7 mg/g, and C:N ratio was 36.7, which variation coefficients were 6.4%, 39.2% and 39.9%, respectively. There were significant differences in C concentration of the first-order roots among different leaf habits (such as evergreen and deciduous trees) and growth forms (including tree, semi-tree or shrub and shrub). However, there was no significant difference in N concentration and C:N ratio. The differences in C, N concentrations and C:N ratio of the first-order roots among six main families (Lauraceae, Fagaceae, Aquifoliaceae, Symplocaceae, Pentaphylacaceae and Elaeocarpaceae) were significant. The N concentration of first-order roots increased with the phylogeny level from low to high. Therefore, it was indicated that the interspecific variation of the first-order roots in C concentration was lower than N concentration in the subtropical evergreen broad-leaved forest, the N concentration of the first-order roots was influenced by phylogeny, however, the concentration of C was affected by leaf habits and growth forms, showing a certain convergence effect.