DOMINANCE PATTERN CHANGES OF A LICHEN-RICH CORYNEPHORUS GRASSLAND IN THE INLAND OF THE NETHERLANDS

Abstract

This paper documents the pattern changes of a Corynephorion-grassland during the period 1981-2004. All 2-3 years the dominant moss- and lichen microcommunity (mc) types and the dominant grass species were recorded in all 936 square meter subplots of a 26 m x 36 m plot. The study site is situated in the National Park “De Hoge Veluwe”, the Netherlands. The area is roamed mainly by deer and wild sheep. Climate is oceanic. Main purpose of the study is long-term monitoring of vegetation dynamics in relation to grazing and climate. In 1981 the densely vegetated plot was mainly dominated by the Cladonia glauca – Trapeliopsis granulosa mc type (5), the Cladonia glauca mc type with reindeer lichens (6) and the Cladonia portentosa mc type (8) and the grasses Corynephorus canescens (C) and Festuca filiformis (F). The subplot dominance of Corynephorus canescens appeared positively correlated with that of mc type 5, whereas the subplot dominance of Festuca filiformis was correlated with those of mc types 6 and 8. The Campylopus introflexus mc type (4) was dominant in one subplot only. During 1981-1984 the subplot dominance frequency of mc types 6 and 8 increased, while that of mc type 5 decreased. These changes are in line with known progressive succession features of the Spergulo-Corynephoretum. During 1984-1994 almost all mc types from 1981 disappeared and in 1994 the plot was almost completely dominated by the Campylopus introflexus mc type (4) and Corynephorus canescens. In the beginning of this period (1985, 1986, 1987) some winter months were very cold and dry (continental). Thereafter the oceanic Festuca filiformis and Cladonia portentosa (mc type 8) died off. Moreover game density in the National Park increased. The resulting open places with sand and litter were easily occupied by the highly invasive neophytic moss Campylopus introflexus (mc type 4). From 1994 onwards we observe again a development towards the situation of 1981.The dominance frequency of the Campylopus introflexus mc type (4) continuously decreased with the oldest moss carpets being overgrown by lichens of the mc types 5, 6 and 8. Subplot dominance frequency of Festuca filiformis is increasing; however Corynephorus canescens is still the dominant grass species nowadays. The “recovery” of the stand might be due to the rather stable environmental conditions during the last ten years. We postulate that the vegetation structure in terms of square meter subplot dominance of microcommunities and grasses in Corynephorion vegetation is regulated by the magnitude of climatic stress and grazing pressure, and by the presence of Campylopus introflexus.