Changes in Nitrogen and Phosphorus and Their Retranslocation in Leaves of Evergreen and Deciduous Broadleaved Trees

The leaves of evergreen broadleaved tree species Ilex rotunda, Machilus thunbergii, Pittosporum tobira and deciduous broadleaved tree species Celtis sinensis, Ginkgo biloba, Cornus florida were collected from the time of full leaf expansion to the end of growing season. The N and P concentrations in new and old leaves of evergreen broadleaved species dropped rapidly from May to July, and then changed slightly, and the changes of N and P concentrations in old leaves were small. The N and P concentrations in leaves of deciduous broadleaved species gradually decreased with time. P retranslocation efficiency for most tree species was greater than their N retranslocation efficiency. N and P retranslocation efficiencies in the evergreen species were higher than that in the deciduous species.