Low-intensity management promotes bryophyte diversity in grasslands

Bryophytes constitute an important and permanent component of the grassland flora and diversity in Europe. As most bryophyte species are sensitive to habitat change, their diversity is likely to decline following land-use intensification. Most previous studies on bryophyte diversity focused on specific habitats of high bryophyte diversity, such as bogs, montane grasslands, or calcareous dry grasslands. In contrast, mesic grasslands are rarely studied, although they are the most common grassland habitat in Europe. They are secondary vegetation, maintained by agricultural use and thus, are influenced by different forms of land use. We studied bryophyte species richness in three regions in Germany, in 707 plots of 16 m(2) representing different land-use types and environmental conditions. Our study is one of the few to inspect the relationships between bryophyte richness and land use across contrasting regions and using a high number of replicates. Among the managed grasslands, pastures harboured 2.5 times more bryophyte species than meadows and mown pastures. Similarly, bryophyte cover was about twice as high in fallows and pastures than in meadows and mown pastures. Among the pastures, bryophyte species richness was about three times higher in sheep grazed plots than in the ones grazed by cattle or horses. In general, bryophyte species richness and cover was more than 50% lower in fertilized than in unfertilized plots. Moreover, the amount of suitable substrates was linked to bryophyte diversity. Species richness of bryophytes growing on stones increased with stone cover, and the one of bryophytes growing on bark and deadwood increased with larger values of woody plant species and deadwood cover. Our findings highlight the importance of low-intensity land use and high structural heterogeneity for bryophyte conservation. They also caution against an intensification of traditionally managed pastures. In the light of our results, we recommend to maintain low-intensity sheep grazing on sites with low productivity, such as slopes on shallow soils.Halbnatürliche, extensiv bewirtschaftete Grünländer sind Biodiversitätshotspots Mitteleuropas (WILSON et al. 2012). Moose sind ein wichtiger Bestandteil dieser Biodiversität. Aufgrund der spezifischen Ansprüche und der Empfindlichkeit vieler Moosarten gegenüber Umweltveränderungen ist ein Rückgang der Moosdiversität durch intensive Landnutzungsformen zu erwarten. Während sich Untersuchungen zur Moosdiversität bislang hauptsächlich auf Offenlandhabitate mit hoher Moosdiversität beschränkten (z. B. Trockenrasen, Moore; LÖBEL et al. 2006, PEINTINGER & BERGAMINI 2006), fand mesophiles oder intensiv genutztes Grünland, also der Großteil der mitteleuropäischen Kulturlandschaft, bislang kaum Beachtung. Neben der Landnutzung spielen verschiedene Umweltparameter eine wichtige Rolle zur Erklärung von Diversitätsmustern bei Moosen (z. B. pH-Wert des Bodens, Vegetationsdeckung; LÖBEL et al. 2006) und sollten deshalb in Analysen einbezogen werden. Im Rahmen dieser Studie untersuchten wir deshalb die Diversität von Moosen in unterschiedlichen Grünlandtypen mit unterschiedlichen Nutzungsregimen. Wir untersuchten zudem welche Umweltparameter neben den Landnutzungseffekten die Muster der Moosdiversität erklären. Um generelle Trends von regionalen zu unterscheiden, führten wir unsere Untersuchungen in drei verschiedenen Regionen durch