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

Abstract

QuestionsThe expansion of Calamagrostis epigejos poses a significant threat to the biodiversity of mountain grasslands. We asked whether grasslands dominated by C. epigejos can be restored through mowing and the application of hemiparasitic Rhinanthus alectorolophus.LocationCarpathian Violion caninae alliance mountain grassland close to Vrchslatina, Veporské vrchy Mts, Slovakia.MethodsWe conducted a before–after control–impact experiment in a grassland entirely dominated by C. epigejos: six blocks, each with four treatment combinations: (i) mowing once in summer, (ii) mowing in summer and autumn, (iii) mowing in summer and seed sowing of R. alectorolophus, (iv) mowing in summer and autumn along with seed sowing of R. alectorolophus. We monitored the above‐ground biomass of C. epigejos, R. alectorolophus, the combined above‐ground biomass of other species, and the vegetation composition annually from 2014 to 2017. Linear mixed‐effect models and redundancy analysis (RDA) were employed to analyze the effects of the treatments on C. epigejos and community parameters.ResultsSowing established R. alectorolophus at the plots mown twice in the first year, but its density strongly declined in subsequent years. R. alectorolophus and mowing twice significantly reduced C. epigejos biomass and herb layer cover. They also increased community evenness and the ratio between other species and C. epigejos biomass with a more pronounced effect on the plots where R. alectorolophus was applied. Mowing twice led to increased species richness, evenness, the number of target grassland species and their proportion in the community. R. alectorolophus had an additional positive impact on community evenness and the proportion of target species. RDA identified R. alectorolophus as the main driver of the directional community change triggered by the experimental treatments.ConclusionMowing twice per season proves to be an efficient restoration management strategy for mountain grasslands dominated by C. epigejos. Sowing R. alectorolophus, however, may be employed as an additional measure to accelerate the decline of C. epigejos at the outset of the restoration process and enhance community structure and composition.