Changes in a lichen-rich dry sand grassland vegetation with special reference to lichen synusiae and Campylopus introflexus
Biermann, Rüdiger; Daniels, Fred J. A.
This paper documents and describes the chronological changes in a lichen-rich dry sand grassland vegetation in the Netherlands. It is based on the results of a permanent plot study during 1981-1994. All 3-4 years the dominant lichen synusia and grass species were recorded in each square meter of a 26 x 36 m2 plot. The dominance distribution was mapped and dominance transitions were recorded for all square meters. This method quickly provides solid information on vegetation structure and changes, and allows an interpretation in terms of synusial succession. In 1981 the plot was dominated by the Cladonia glauca synusia Trapeliopsis granulosa-type, Cladonia-Cladina synusia and Cladina portentosa synusia, which were positively associated with dominance pattern of respectively Corynephorus canescens, C. canescens and Festuca ovinay, and F. ovina. A strong decrease of the Cladina portentosa synusia could be recorded after a period of dry summers and dry and cold winters (1982-1986) and a strong decrease of the Cladonia-Cladina synusia after a strong increase of the game stock (1989-1990). The Cladonia glauca synusia Trapeliopsis granulosa-type continuously decreased, the neophytic moss Campylopus introflexus continuously increased, finally changing the entire plot into a monotonous, dense moss carpet with an open canopy of Corynephorus canescens. The causes of changes are discussed.