LEAF NUTRIENT DYNAMICS AND RESORPTION EFFICIENCY OF QUERCUS LIAOTUNGENSIS IN THE DONGLING MOUNTAIN REGION
东灵山地区辽东栎叶养分的季节动态与回收效率

Six elements, N, P, K, Mg, Ca and Fe, were analyzed in leaves of Quercus liaotungensis to evaluate the nutrient resorption efficiency of this species in the Dongling mountain region. The concentrations and storage of all six elements varied greatly in the life history of the leaves. N, P and K contents decreased abruptly at the early stage of leaf expansion, and then gradually thereafter. Their storage peaked in the last ten days of July. The concentration and storage of Ca increased continuously over the growing season, while Mg showed no obvious pattern. Nutrient resorptions were observed in N, P, K and Mg, and the resorption efficiencies of N and P were 67% and 87%, respectively. Ca and Fe accumulated in the leaves of this species. Comparison of leaf nutrient dynamics in some Quercus species indicates that N concentration in mature leaves of deciduous species is slightly, but not significantly higher than that of evergreen species, and that N resorption efficiencies have a significant, positive association with N concentration in mature leaves. The concentrations of N and P were found to be significantly related in both mature and shed leaves of the Quercus species.