Grazing vs. mowing: A meta-analysis of biodiversity benefits for grassland management

• Grazing had more positive effect on conservation values in most grasslands.
• Annual mowing had a more positive effect in some situations.
• Despite numerous relevant studies found, most were of low quality.

To maintain the high biodiversity of semi-natural grasslands, management by grazing or mowing is needed. Given the limited resources and few remaining areas, the best management method should be used. However, only a few studies comparing the effects of mowing and grazing on grassland biodiversity exists. Therefore, the goal of the present review was to extract as much data as possible from the literature and evaluate them using a meta-analysis approach. We searched scientific and grey literature for studies comparing the effects of grazing and annual mowing on outcomes relevant for biodiversity conservation. We identified 35 relevant studies on grazing and annual mowing that provided data suitable for the meta-analysis. We found that grazing generally had a more positive effect on the conservation value of semi-natural grasslands compared to mowing, but effect sizes were generally small to moderate for most contrasts. Furthermore, effects varied across some grassland characteristics e.g. for different grassland types, with grazing and mowing having a similar effect or mowing having a more positive effect in certain cases. Our results suggest, that in most cases grazing should be the preferred management method when managing for grassland conservation.