[Seasonal dynamics of carbon and nitrogen concentrations in Phellodendron amurense fine roots].

Taking a 23 years old Phellodendron amurense plantation as test object, the first five order roots of P. amurense were sampled to study the seasonal dynamics of their total carbon (TC), total nitrogen (TN), total non-structural carbohydrates (TNC), and soluble N concentrations, with the correlations among these parameters analyzed. In the first five order roots, the TNC occupied 49% of TC, and the soluble N accounted for 26% of TN. Within the growth season, the rate of TNC to TC increased from 42% in the first order roots to 52% in the fifth order roots, and the rate of soluble N to TN decreased from 28% to 21% correspondingly. All the first five order roots had the lowest concentration of TC but the highest concentration of TN in spring, and the lowest concentrations of TNC and soluble N in summer. The increase of the TC concentration in the roots decreased the concentrations of TNC and soluble N, whereas the increase of the TN concentration decreased the TNC concentration significantly and increased the concentration of soluble N. From the first to the fifth order roots, the TC and TN had an increasing correlation with TNC but a decreasing correlation with soluble N, suggesting the close correlations of TNC and soluble N with TC and TN in P. amurense fine roots.