On the lateglacial and postglacial vegetation of South Limburg (Netherlands)

The present study deals with the late-glacial and post-glacial development of the vegetation in the loess region of South Limburg (Netherlands). In the lateglacial time the continental element in the vegetation (Artemisia) is very pronounced, probably due to the particular soil conditions in South Limburg. The zonation of FIRBAS (1949) has been applied to the South Limburg diagrams. Zone I: Tundra, a temporary amelioration of the climate (Bölling time) can be observed. Zone II: Closed pine forests present (Alleröd time). Zone III: In the lower part of the zone Pinus dominant, afterwards Belula. Zone IV: Decrease of the percentages of the herbs; Pinus dominant in the vegetation; first appearance of Corylus. Zone V: Pinus and Corylus dominant; in the lower part of the zone Ulmus and Quercus present, in the upper part also Alnus and Tilia. The development of the vegetation in the following periods of the Holocene has been interpreted with the aid of dates from the field of plant sociology. Along a valley the vegetation of the bogs itself (usually Alnion glutinosae or Alnion incanae), the vegetation on the colluvial soils (Ulmion) and the vegetation along the slopes and on the plateaus (Carpinion) were distinguished. The changes in the vegetation of these vegetation units have been followed (Fig. 3, 4 and 5). The course of the curves in the pollen diagrams has been explained by taking into account the natural succession, human influence, soil conditions, and size of the investigated bogs. Zone VI and zone VII: In the Alno-Ulmion Tilia cordata dominant. In zone VII first appearance of Fagus outside the valleys. Zone VIII: Strong influence of man in the valleys by which Tilia and Alnus decrease and Quercus and Corylus increase. Outside the valleys less influence of man resulting in a proceeding increase of Fagus. Zone IX: Regeneration of the forests in the valleys (exc. Tilia and Ulmus): Alnus increases, Corylus decreases. Outside the valleys Fagus dominant. Between the Fagus belt and the Alno-Ulmion belt probably a Querceto-Carpinetum present. Zone X: Large-scale clearance of the forests. Outside the valleys Fagus and Carpinus decrease and Corylus and Quercus increase. In the valleys transformation of the Alno-Ulmion into grassland. In the upper part of the zone increase of Pinus due to planting.