Traditional haymaking is essential to sustain and restore species-rich subalpine grasslands

Abstract

The high plant diversity in subalpine grasslands is threatened by the abandonment of land use, such as traditional haymaking. In addition, changing environmental conditions might lead to vegetation shifts even when traditional land use is maintained, as observed in mountain grasslands in Switzerland during the last decades. Maintaining and restoring the typical diversity of such grasslands might therefore require modified management methods. We conducted a six-year experiment to assess the responses of plant species richness, mean ecological indicator values, and vegetation composition to five management treatments: traditional haymaking, traditional haymaking complemented by scraping (i.e. manual raking) in autumn, traditional haymaking complemented by scraping in spring, only scraping in spring, and abandonment. We hypothesized that haymaking complemented by scraping in either season would remove additional biomass, reduce inter-specific competition, and increase species richness by creating open patches that can promote species establishment. We found positive effects of haymaking complemented by scraping and negative effects of abandonment on plant species richness. In addition, combining haymaking and scraping tended to positively affect habitat quality, indicated by changes in mean indicator values, while abandonment showed the opposite effect. Interestingly, traditional haymaking combined with scraping in autumn promoted the development of the vegetation towards the composition similar to the originally present vegetation type. Our findings show that traditional land use is essential to maintain species-rich subalpine grasslands. Further, they imply that traditional land use can be modified to compensate for the negative developments caused by environmental changes and help restore the typical vegetation.