Droge stroomdalgraslanden langs Maas en Niers

The grasslands characteristic of dry sandy soils found along rivers in the nature reserves Zelderse Driesen and Rivierduintjes bij Mook have been investigated by means of the Braun-Blanquet method. Whereas a community with high species diversity is still found in the Zelderse Driesen, the plant cover of the Rivierduintjes bij Mook has lost all the stenotope species characteristic for the lower syntaxonomic units, due to intensive recreation and the absence of summer grazing. Such a community containing only character species from higher phytosociological units as well as accompanying species has been called a basic community (Basalgesellschaft; KOPECKÝ & HEJNÝ, 1974). As the word ‘basic’ suggests an original and fundamental situation, while the term ‘basic community’ is mostly used for a syntaxon which is floristically incomplete because of a disturbance, we suggest to replace the term ‘basic community’ by the term ‘trunk community’ (Rumpfgesellschaft). In order to restore the original species diversity in the reserve an increase of the grazing pressure and a decrease of recreation activities are advised.