Marginal agricultural land, which in the UK refers particularly to upland grazings, will see changes in management driven by markets, subsidies, grants and environmental change with implications for biodiversity.

Using a large-scale, long-term grazing experiment in the UK uplands we assessed the impact of intensification (tripling sheep numbers), abandonment (removal of sheep) and grazer diversification (partial replacement of sheep by cattle) on vegetation composition in a heterogenous area of grassland.

Species benefiting from increased grazing included Anthoxanthum odoratum, Nardus stricta, and Trichophorum cespitosum. Species that benefitted from the removal of grazing included Narthecium ossifragum, Pteridium aquilinum, and Vaccinium myrtillus.

Responses differed between vegetation communities; the more productive acid grassland communities showed little change when grazing was removed, whilst the less productive mire communities contained species, capable of increasing after grazing removal.

Increased grazing and, to a lesser extent, the introduction of cattle increased species diversity.

Synthesis and applications. Vegetation change in relatively infertile grasslands is slow and features shuffling dominance amongst species in the initial vegetation. Initial structural changes affect other trophic levels in this experiment; the slow change in composition will affect the system over longer timescales. Management decisions in the uplands encompass complex trade-offs between production, biodiversity and a range of ecosystem services. Predicting the consequences of decisions is difficult given the slow dynamics of unproductive habitats.09-May-2019