Extensive Bekämpfung des Adlerfarns fördert die floristische Vielfalt

Abstract

Low-Intensive control of bracken promotes floristic diversity. In Switzerland, the native bracken (Pteridium aquilinum) is threatening local species diversity. In the present study, we investigated the impact of low-intensity bracken control treatments on the floristic diversity of a protected Mesobromion-Type grassland near Chur (Grisons, Switzerland). In 2008, we started a long-term bracken control experiment where bracken was removed once a year by uprooting and mowing, respectively. In 2015, i.e. 8 years after the start of the experiment, bracken was significantly less vital on the treatment plots as compared to the adjacent control plots. Uprooting in early June proved to damage bracken significantly more effectively than mowing. On the treatment plots, the number of vascular plant species per m² was significantly greater than on the control plots, and also plant species composition differed significantly between treated and untreated plots. In conclusion, even low-intensity treatments such as uprooting or mowing once a year in early June does both effectively harm bracken and foster species richness in the herb layer. Uprooting is particularly recommended if other vascular plant species should be preserved.