Review: Effects of mowing and grazing on plant diversity and vegetation composition in Central European semi-natural wet grasslands

Extensive land-use is crucial to conserve semi-natural wet grasslands, which are hotspots of Central European biodiversity and a habitat for numerous rare species. Yet, as extensive land-use became economically unviable, insufficient or inappropriate management increasingly threatens these habitats, resulting in habitat degradation. Ongoing species losses, also in managed wet grasslands, suggest that current regimes might need optimization. Efficient conservation of remaining wet grasslands requires management concepts that are both cost-effective and sustainable, and simultaneously ensure high biodiversity. While annual mowing is widely used and generally considered suitable, grazing is viewed more critically and remains less commonly implemented. However, grazing is gaining attention as a cost- effective alternative that additionally ensures biomass utilization. For both mowing and grazing, uncer- tainties remain concerning optimal intensity, timing, techniques or livestock type, particularly in inter- action with site-conditions. We reviewed 60 peer-reviewed studies conducted in 16 European countries to assess the effects of mowing and grazing on species diversity and vegetation composition in wet to moist, oligo- to eu- trophic grasslands. We compared these findings to selected conservation-oriented (German-language, mostly non-peer-reviewed) management recommendations. Finally, we evaluated critical factors for successful conservation and identified research gaps. Mowing had increasingly positive effects with up to two annual cuts, especially in meso- to eutrophic grasslands. Negative effects were often linked to suboptimal timing, affecting species dis- proportionately. Spatial and temporal diversification of mowing was beneficial to balance necessary nutrient depletion with protection of sensitive species. Grazing, was frequently achieving conservation goals, too. Yet, grazing was described as less pre- dictable and more complex due to multiple interacting factors. Continuous monitoring and flexible on- demand management was essential for successful grazing. Across both regimes, high soil moisture, increasing risks for soil compaction by machinery or tram- pling, and fine-scale heterogeneity in productivity and disturbance sensitivity posed challenges. Mosaic mowing or adaptive grazing through herd management or fencing effectively minimized these risks and maximized biodiversity outcomes. In sum, both mowing or grazing can effectively maintain species-rich wet grasslands, but grazing only if funding and logistics allow continuous adaptations to site-conditions. Indeed, a combination of both regimes holds the highest conservation potential, because their flexible, complementary use sup- ports a wider range of species and mitigates regime-specific limitations such as biomass utilization in mowing or uneven vegetation structures under grazing.