Long-term effects of drainage on species richness of a fen meadow at different spatial scales

Changes in species richness on a local scale are illustrated with an example of vegetation changes over 26 years in a species-rich fen meadow (Calthion palustris), which had been impacted by a deep drainage channel. The changes were monitored in the meadow as a whole and in 19 permanent plots situated in sites with various intensities of drainage. The similarity with an undisturbed local reference type of the hay meadow community was calculated for all. plots and every year. After 26 years, the overall loss of species in the meadow as a whole (including all ditches) was less than 12%, white the overal loss in species in the permanent plots was 45%. Several species that declined in the permanent plots had survived in the ditches, while others, in particular sedges had migrated to tow-tying areas. This example illustrates the need to survey changes in species richness on multiple scales. (c) 2005 Elsevier GmbH. All. rights reserved.