Effects of sheep stocking on the plant community and agricultural characteristics of upland Anthoxanthum odoratum–Geranium sylvaticum meadow in northern England

In the UK, upland hay meadows ( Anthoxanthum odoratum–Geranium sylvaticum grassland) with high plant biodiversity are rare and confined to submontane areas of northern England. We report results from a 5‐year experiment to test suggestions that recent biodiversity declines were attributable to increased sheep‐stocking density and a longer spring stocking period, thus delaying the shut up date for the growth of the hay crop. Longer stocking periods and higher stocking densities decreased the forage mass at 8 July, but they increased herbage N content and digestibility, reduced plant species diversity and reduced populations and seed production of Rhinanthus minor . Compared with unstocked swards, the similarity of the vegetation to Anthoxanthum odoratum–Geranium sylvaticum grassland was reduced by 16·9% when stocking with sheep continued until 27 May each year, and by 8·3% when sward heights were maintained at 3 cm compared with 5 cm. Increased mean sward height and height of R. minor were positively correlated with accumulated temperatures. Results support suggestions that recent reductions in the nature value of these grasslands might be a consequence of high stocking densities persisting until later in the spring, carried out during a 1‐year period with warmer temperatures.