The effects of grazing management on the vegetation of mesotrophic (meadow) grassland in Northern England.
Abstract
Haymeadows in the Yorkshire Dales and the North Pennines in N. England are normally grazed with cattle and sheep outside the 2-3 month summer period, when a hay or silage crop is grown. Experimental exclosures were used from Aug. 1987 to June 1991 to prevent this grazing for various periods in the year in a Site of Special Scientific Interest meadow (Geranium sylvaticum-Anthoxanthum odoratum meadow, Bromus hordeaceus subcommunity) at Ravenstonedale, Cumbria. Vegetation change was investigated using biomass samples taken in June of each year. Experimental treatments were: no grazing at any time of the year; no grazing from the time of the hay cut until 1 Jan; no grazing from 1 Jan. to the time of the hay cut; control plots in which the normal grazing regime was followed each year. All other management factors were kept constant. All plots showed vegetation changes related to treatment and to time. The main trend was the treatment effect, with the greatest reduction in species richness occurring in the ungrazed plots. Changes in the species composition of the plots were associated with species' strategies in the established and regenerative phase. A. odoratum and Cynosurus cristatus increased their standing crop when autumn-grazed and decreased when spring-grazed. Autumn grazing and ungrazed treatments allowed an increase in the standing crop of Poa trivialis and Lolium perenne. Spring grazing favoured Sanguisorba officinalis, Geranium sylvaticum and Cirsium heterophyllum. Dactylis glomerata, B. hordeaceus, Festuca rubra and Holcus lanatus increased when not grazed, while grazing in spring and autumn was essential to maintain Trifolium repens in the sward. Management designed to manipulate plant species composition in old meadowland is discussed.