Estimation of the age of a fairy circle (Lycopodium complanatum L. var. chamaecyparissus (A. Br.) Döll)

During a period of years I have measured the dimensions of the above mentioned fairy circle in the heath land of Doornspijk (Gelderland), where it is mainly accompanied by Calluna vulgaris (L.) Hull. As it does not deviate very much from the ideal shape of a circle, I can give, for the purpose of this paper, only the diameters, being in 1947: 6.0 m, in 1951: 7.0 m, in 1955: 8.1 m and in 1964: 11.25 m, all in mean value. The circle is closed, the vegetation at the margin is very rich, showing many hundreds of spikes, inside it is extremely poor. The dynamic behaviour, with the diameter as a function of time, presents an exponential curve with surprising exactness, such that an extrapolation towards the year of coming into being seems to be possible, under the assumption that the process of development was statistically homogeneous.