Abstract: The contents and resorption efficiencies of N, P, K, Mg, Cu, Zn, Fe and Mn in the leaves of Xanthoceras sorbifolia Bunge were measured by atomic absorption spectroscopy. N, P, and K declined throughout the growing season. This was probably a consequence of “dilution effect” and resorption of nutrients. Mg presented a single peak curve, which was probably resulted from physiological functions. Fe and Mn presented “V”-shaped trends, Cu “W” and Zn “N”. These phenomena may be related to nutrient absorption characteristics of the trees and phenological periods. Overall, the order of contents was N>P>K>Mg>Fe>Zn>Mn>Cu. But the order differed with time. Positive correlations occurred significantly between macroelements. By contrast, there was no significant correlation between microelements except Fe and Zn. A negative correlation occurred significantly between Fe and N. It was probably caused by antagonistic actions. The C/N ratio increased significantly. However, the N/P ratio decreased insignificantly. Nutrient resorption efficiency was in the order of Mg>N>K>P, with significant difference. Microelements can not be absorbed because of their poor mobility. The nutrient resorption efficiency of N, P, K, Mg reflects the higher ability of nutrient conservation and use efficiency.

Key words: bioenergy, Xanthoceras sorbifolia Bunge, nutrient elements, Dynamics variation, resorption