Protecting biodiversity must be emphasized in tree breeding. The breeders used to pay more attention togenetic gain in traditional tree breeding. Otherwise long term breeding aims at maintaining genetic variationof forest population. Abundent biodiversity in natural forest land is the basic for long term breeding. Theproperty and developing tendency of forest population will be studied mainly. So, the direction and object fortraditional tree breeding research as well as the teaching courses for genetics and breeding of tree must beadjusted and supplemented.