Some long-term observations on cyclical and seral processes in Dutch heathlands

Abstract

Changes over a period of 10–30 years in the vegetation of some Dutch heathlands were studied, using aerial photographs and information derived from observations and permanent plots. The sites studied are situated in (formerly) Calluna vulgaris-dominated heathlands, known to be infested in the past by the heather beetle Lochmaea suturalis, Thoms., followed by a Calluna die-off. No interference by management practices had interrupted the natural changes in the vegetation following the infestation. Evidence for both seral and cyclical changes is presented. It is concluded that abiotic factors, i.e. physiographically controlled minor differences in the soil type, determine whether a cyclical or seral change will occur.