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We analysed crown dynamics at the stand level in three plots of an even-aged sessile oak stand (one unthinned reference plot and two plots of different thinning intensities) of a long-term experiment in Rhineland Palatinate, Germany. Crown projections and stem locations were recorded in 1977, 1994 and 2004. Spatial structures of stems and crowns were analysed using the index of Clark and Evans and Ripley's K-function. In the unthinned plot, despite crowns being highly asymmetric, it was shown that crowns did not expand in a way that makes their distribution more regular. In this dense plot with slender trees, the stability constraint was probably more important than the search for light. In the thinned plots, spatial distributions of both stems and crowns were found to be regular, in general with more regular distributions for crowns than for stems. The more regular spatial distributions of crowns were attributed to …