THE RIPARIAN COMMUNITY OF NORTH-WEST EUROPEAN LOWLAND STREAMS

1. Riparian plant communities along lowland streams have been affected by man for the past 15000 years. During this period climatological ch anges have also taken place. The present situation in north-west Europ e is a result of these influences so that the choice of reference situ ations is necessarily arbitrary.2. Dominant abiotic factors that influ ence riparian vegetation are local hydrology and soil composition, and the pH, lime content and nutrient concentration of the feeding ground water. 3. Riparian plant communities are described as phytosociologica l units. Depending on abiotic characteristics, sequences from spring t o lower course and from the stream bank to the boundaries of the strea m valley are reported. The Pruno-Fraximetum association is, and has be en for thousands of years, one of the main riparian vegetation types o f (lowland) streams. 4. In many European countries, restoration projec ts are being performed or planned. One of the restoration measures is the planting of trees or shrubs along streams as buffer strips. A phyt osociological approach, based on knowledge of the local hydrology and nutrient/ion availability, is better by far than the general practice of standard plantation. Such an approach requires research in advance, which increases the initial costs of projects, but can be expected to provide far better results in the long term, and ultimately save mone y.