There arc eight species and four varieties of oak in northeast China. This paper reports and describes the distribution and phylocoenogenesis of the Korean pine-broadleaved mixed forest and the mongolian oak formation. The close relationship between the flora of Ussuli—Amur region and Japan is discussed. Analyses of heat and energy balance, and biomass of mongolian oak forests arc provided. Many measurements indicate that, in a nonclosed stand, the wood production of a stand is positively correlated with leaf area index (LAI).