On the acid soils of the Chilterns plateau a graduated series of 4 soil types is recognized. The differentiation is based on acidity, exchangeable Ca, basicity, soil texture, and the kind and distribution of organic matter both on the surface of the soil and in the upper soil layers. Corresponding with these 4 soil types there are 4 seres, each consisting of grassland, woodland of Fraxinus excelsior-Quercus robur or oak and beechwood (Fagus silvatica). Vegetationally the woodlands of the seres are distinguished by the floristic composition, the biological spectra, the kind of shrub layer and the height attained by mature beech (age approx. 140). In the descending series of soil fertility beech attains the mean heights of 107, 82, 70 and 60 feet. In the sere the change from ash-oak dominance to beech dominance is accompanied by a change in the relation between the percentages in the biological spectra of the scapose hemicryptophytes and caespitose hemicrypto-phytes, the former decreasing and the latter increasing in importance. A change in the soil also takes place eventually "mull" gives way to "mor." This is supported by data of acidity and the distribution of the organic matter in the soil under beech and under adjoining ash and oak of the same sere. It is held that pure beechwood cannot be regarded as the climatic climax on these acid soils.