贵州梵净山水青冈林在地理分布上的意义

 In this paper, the distribution of three species of beech forests, regarding their position on differently facing slopas and at different elevations, as well as their pollen distribution, on Fanching Shan situated in  Kweichow  Province  in  South-eastern China is discussed.      It is the fact that (1) Being affected by the air currents of the Pacific Monsoon, and by its own topographic variation, the difference between the north and south slopes in its eastern and western flanks reflected on the plant communities by the humidity-warmth relationships (fig. 2, 3; tab. 2, 3, 4). (2) The patterns of the hori- zontal distribution of three species in China show that Fagus engleriana has a northern-most range, F. longipetiolata the southern-most range, while F. lucida is intermediate between them (fig. 5). (3) From the palynological analysis of the soil layers, the waxing and waning of the different tendencies of Fagus spp. on different slopes are rather prominent.      The discussion is made mainly as follows.  The relationship between the state of growth and humidity-warmth conditions is shown (fig. 6).  In accordance with the conditions of the vertical, horizonal and palynological distribution of beeches, we have tried to present a figure (fig. 7) which shows the waxing and waning tendencies of three species of Fagus historically, with respect to different slopes.  The southern slope of western flank (Ws) is now in a state moderate growth of Fagus longipetio- lata; in the past, there had been a period which saw this beech enjoying a gradual increase, but later on it began to wane till it reaches the present state.  The Wn slope had seen a gradual increase of Fagus lucida in the historical time (at the same time there was an accompanying slow increase of F. longipetiolata), till a certain period when the total number of beech pollen grains decreases gradually in the analysis; this is followed again by a slight increase, the last increase is apparently due to the fact that in spite of the decrease of F. lucida, there was a great increase in F. longi- petiolata.  The two effects combine to make the line of curve to lower rather than to rise.  The Es slope has in its historical past a period when beeches were favoured with a steady increase, and this tendency is apparently still in progress today, although it is approaching its culmination.  The En slope had seen Fagus engleriana in a slowly receding tendency, and sees it now almost in the process of being eli- minated, to be replaced by F. lucida.  Through the explanation given above, we have thereby an understanding about the relationship between the climatic changes in the historical time and the waxing and waning of the different beeches in both time andspace.