Cutting height shapes biomass yield but not herbage properties in semi-natural grasslands

The declining demand for biomass delivered from semi-natural grasslands, driven by rapid socio-economic change, is a major threat for grassland abandonment accelerating biodiversity loss. Developing management strategies that intentionally reduce biomass removal, such as increasing cutting height, may help overcome utilisation challenges in regions with limited demand for hay. This study represents the first phase of a long-term field project established in semi-natural grasslands. We tested the effect of three cutting heights (5, 15, and 25 cm) on biomass yields and herbage properties in mesic grassland. We further assessed the effects of functional groups (grasses versus forbs) and individual plant species on these parameters to disentangle cutting height effects from site-specific variation in plant species composition. Biomass declined by ~ 50% when cutting height increased from 5 to 25 cm. The proportion of grass biomass positively influenced fibre content and negatively influenced lipid concentrations, although these effects were attenuated at the highest cutting height. Despite reduced biomass, herbage nutritive value remained stable across cutting heights. We conclude that management strategies incorporating higher cutting heights can substantially reduce harvested biomass yield while maintaining herbage quality providing a practical tool to facilitate biomass utilisation and contribute to the prevention of semi-natural grassland abandonment.