Constraints in the restoration of mountain meadows invaded by the legume Lupinus polyphyllus

Abstract

Semi‐natural grasslands invaded by the legume Lupinus polyphyllus need the introduction of target species in order to promote highly endangered native target plant communities. However, which techniques are best suited to achieve both invader control and the introduction of target species at the same time? Few studies have investigated restoration techniques that support native plant communities in mountain meadows and control the invader simultaneously. We employed the restoration techniques seed bank activation and green hay transfer in combination with manual removal of the invasive L. polyphyllus on three types of grassland (Nardus grassland, mesic and wet mountain hay meadows) in the low mountain ranges of the Rhön UNESCO Biosphere Reserve in central Germany. Vegetation reacted differently to specific measures depending on the type of grassland. L. polyphyllus cover could be effectively reduced by L. polyphyllus removal in Nardus grassland and mesic hay meadow sites, but not in wet meadows. In Nardus grassland, the cover of target species was lowered by the application of green hay. The target species cover of wet mountain hay meadows declined in response to seed bank activation. When restoring mountain meadows, restoration practitioners should thus first consider the specific vegetation types. As our study indicates that target mountain meadow species may react negatively to restoration measures in the short term, the long‐term effects of the application of green hay should be studied.