In recent decades considerable changes in agricultural practices (especially increased fertilisation, early and increased cutting) have led to the decline of many characteristic grassland species. Formerly widespread species have become rare, and many grassland species are considered to be nowadays threatened and are on Red Lists. The continuous loss of species-rich grassland habitats remains unabated and affects even species that are still relatively widespread and abundant. The associated fragmentation and reduced gene flow will therefore impact the genetic diversity of local populations also of these species. The present study concerns a formerly common grassland species that has experienced a sharp decline in large parts of the study area (Saar-Lor-Lux) within the last decades. Alopecurus rendlei, is an annual grass occurring in fragmented and sometimes very small populations on periodically humid to wet grassland sites with moderate nutrient supply. The aims of the study were to analyse genetic ...