SPECIES-AREA RELATIONSHIPS IN AN AREA OF INTERMEDIATE SIZE.

Species-area relationships in plots of varying size in Purwell Meadow, Hertfordshire (total area 24.6 ha), are examined, and compared with previously published data for other areas. It is shown that the species-area relationship in both small and large areas in the British Isles is usually one of a continuous exponential increase in the number of species as the size of the area in which they occur is increased. However, in areas of intermediate size, such as Purwell Meadow, there may be a gradual change in species-area relationships, during which the rate of increase in the number of species is a logarithmic one. [ABSTRACT FROM AUTHOR]