Beyond upland exclosures: what is the effect of low-intensity grazing on carbon storage?

Land management is a key control of terrestrial carbon (C) storage and can be used to mitigate rising CO₂ emissions. The UK uplands hold approximately one-third of national terrestrial C in their soils. The dominant land-use is extensive livestock grazing management. However, our understanding of the impact of grazing on upland C storage is limited to studies comparing the presence versus the absence of herbivores. Utilising a grazing density manipulation we show no sheep and low-intensity sheep grazing provide similar benefits, in that they enhance plant and soil C accumulation. In contrast, under high-intensity sheep grazing there is a net loss in predicted soil C accumulation. We propose that low-intensity sheep grazing is optimal to sustain the diversity of key upland species, compared to high-intensity grazing and no sheep. We provide evidence that low-intensity sheep grazing can be used to minimise trade-offs between multiple upland land-use objectives, namely species conservation.