Abstract: At present there exist two ecologically different types of sub-alpine dark conifer forests in China and Japan,which are mainly composed of Picea, Abies etc.Most of Abies and Picea species belong to typical cold-temperate type.The summer temperature at the lower limit of these trees in different latitudes can be derived by the regression equation:Y=0.12X+10.01 The warm-temperate type of dark conifet forest is composed of only few species such as Abies beshanzuensis.There also developed the equivalents of these two types of dark conifer forests during the late glacial period(30000-22000 B.P.).Their southern boundaries in east low-lying plains are defined as 37°N and 30°N,respectively.The summer temperature in the early glacial period dropped 9.4-9.8℃ in east plains and 7.0℃ in west plateaus.That testified the existence of"cold-trough" in the glacial period in east China.The cold-wet climate in the early glacial period reflects a unique climate regime during the transitional period from interglacial to full glacial. The flourish of dark conifer forests is a vegetation response to the climate.