Nature development and vegetation succession in the foreland of the river Waal (The Netherlands)

Nature conservation in the Netherlands changed from strict conservation and protection into nature development by restoring natural processes. By means of permanent plots and repeated vegetation mapping, we investigated the long term changes in vegetation composition in a river foreland under nature development, especially its effect on dry sandy to loamy grasslands of the Medicagini-Avenetum (Sedo-Cerastion), Bromo-Eryngietum (Artemisietea) and ‘fluviatile species’. The Medicagini-Avenetum pubescentis strongly declined in the Netherlands and became rather rare and strongly threatened. Restoration of this highly valued community has a high priority in nature development projects along the Dutch rivers. After 14 years of nature management the surface area of the nitrophylous tall forb communities of the GalioUrticetea strongly increased, while the Bromo-Eryngietum decreased. The Sedo-Cerastion ruderalized. On the levee nature development appeared to have no negative or positive effect on the total cover of Medicagini-Avenetum and the fluviatile species. However some fluviatile species decreased while others strongly increased. On former arable land and pastures these species increased due to in-blowing sand. Here Cirsium arvense and Rumex obtusifolius are replaced by Calamagrostis epigejos, which itself is later replaced by the strongly increasing Rubus caesius. Vegetation changes appear to be very dynamic showing both regressive and progressive succession. After 14 years of nature development, still no real improvement of the dry species rich Sedo-Cerastion grasslands occurred. This is most probably due to insufficient grazing intensity.