In the low-lying parts of The Netherlands peat-cutting in the past resulted in many large and small lakes. The larger ones were often reclaimed and turned into arable land. In smaller ones a process of secondary succession led to the establishment of reed and sedge fens. Due to changes in the management many of the still existing fens have been left over to natural developments over the last decades. Here succession rapidly led to woodland communities. These woodlands are initially often dominated by Salix species, soon followed by Alnus glutinosa and Betula pubescens. In species composition these young woodlands are closely related to the Carici elongatae-Alnetum glutinosae. There are, however, considerable differences in species composition. This woodland type as found in the western parts of The Netherlands was also recognized in relev6s from Belgium, western Germany and Norfolk in the UK. As it also differs in ecological conditions from the brooks and rivulets accompanying forms of the Alnion glutinosae elsewhere in western Europe, it is here proposed to treat these communities as a separate community-type within the Alnion glutinosae.