Can re-establishment of cattle grazing restore bryophyte diversity in abandoned mesic semi-natural grasslands?

Abstract

Changes of agricultural practices have led to decline of semi-natural habitats sustained by traditional animal husbandry in many European regions. The abandonment of semi-natural pastures leads to increase of vascular plant biomass and subsequent decline of weak competitors such as bryophytes. Re-establishing traditional animal husbandry may potentially restore biodiversity but the success of such measures remains insufficiently known. In this study, we asked if re-establishing cattle grazing on previously abandoned grasslands will restore their bryophyte communities. The effect of cattle grazing on bryophyte communities of mesic semi-natural grasslands was studied in south-western Finland in a comparison of (i) continuously grazed pastures, (ii) previously abandoned pastures where grazing was re-established during 1990s, and (iii) abandoned pastures, where grazing had ceased during late 1960s to early 1980s. The average cover, species richness, species density and species diversity of bryophytes were significantly higher in the continuously grazed than in the abandoned grasslands. Ordination analyses revealed clear differences also in community structure between the management classes. Re-established grasslands were ecologically heterogeneous and situated in between the continuously grazed and abandoned grasslands in all characteristics, indicating variable effect of the restoration measure. Seventeen bryophyte species were recognized as significant indicators of the three grassland classes, four of which could be used as indicators of valuable grassland habitats. Although there was variation in the consequences of re-introduction of grazing, the results give evidence of positive effect of grazing on regaining bryophyte diversity of abandoned grasslands.