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.

Long-term success of floodplain meadow restoration on species-poor grassland

“…A range of rare and endangered plant species of floodplain meadows, many of which are listed in the Red Lists of Germany and Hesse, were successfully established on the restoration sites. However, our results confirm that the ecological restoration of grassland is challenging, even if the sward is disturbed prior to diaspore introduction (Kiehl et al, 2010;Harvolk-Schöning et al, 2020;Hansen et al, 2022). Thirteen to sixteen years after restoration, the vegetation composition of the restored plots was similar to the unrestored reference grassland plots, with only slight changes towards the composition of the donor sites.…”

“…Generally, the restoration of species-rich grassland using freshly cut plant material is more challenging on species-poor grassland sites compared to arable fields or raw soils (Kiehl et al, 2010;Hansen et al, 2022;Valkó et al, 2022). Soil preparation is commonly regarded as an important prerequisite for successful target species introduction.…”

Transfer seeds, hay, or soil blocks? The importance of the completeness of biological inputs to address dispersal and establishment limitations during the restoration of plant assemblages in floodplain grasslands

“…The vegetation litter introduced by hay transfer is known to potentially have contrasting effects. On the one hand, as a physical barrier to light penetration, it can inhibit seed germination or cause young seedling death (Donath et al 2007; Albert et al 2019; Hansen et al 2022). While this can be favorable to the restoration process by lowering the ruderal species cover (Albert et al 2019), it can also be detrimental to the installation of target species contained in sown seed mixtures or hay itself (Valkó et al 2022).…”

Reversing expansion of Calamagrostis epigejos in Carpathian mountain grasslands by mowing and application of hemiparasitic Rhinanthus alectorolophus

“…However, its effects need further study because the response of various types of mountain grasslands to the transfer of green or dry hay may be highly variable. Hay transfer on Nardus grasslands may even result in a short‐term decrease in the presence of target species because low‐growing species may struggle to grow through the layer of transferred material (Hansen et al., 2022). Grazing may also be introduced as a measure facilitating propagule transport (Valkó et al., 2016).…”