The influence of sward management on foliage arthropod communities in a ley grassland

Published source details Purvis G. & Curry J.P. (1981) The influence of sward management on foliage arthropod communities in a ley grassland. Journal of Applied Ecology, 18, 711-725.
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This study is summarised as evidence for the following.

	Action	Category
	Use grazing instead of cutting for pasture or grassland management Action Link
	Reduce grazing intensity on grassland (including seasonal removal of livestock) Action Link

Use grazing instead of cutting for pasture or grassland management

A replicated trial in perennial ryegrass Lolium perenne and white clover Trifolium repens pasture in 1976-1977 in County Kildare, Ireland (Purvis & Curry 1981) found that effects of grazing vs. cutting varied between invertebrate groups and sampling dates. Fewer spiders (Araneae) occurred in continuous, lightly grazed (2-105 spiders) or intermittent, heavily grazed (2-121 spiders) plots than in cut plots (10-429 spiders/suction sample) for seven of eleven months. Wasps (Hymenoptera) showed mixed effects with fewer in continuous, lightly grazed than cut plots for three months, but the opposite for one month and no difference for seven months. In total, fewer small invertebrates occurred in grazed (13,120-17,750 invertebrates) than in cut (17,800-21,050 invertebrates/suction sample) plots during peak abundance in July-August 1977, but numbers were similar after cutting took place in September. The treatments included continuous grazing with 10-30 sheep/ha, intermittent grazing with 60-100 sheep/ha for 1-2 week periods, grass cut twice a year for silage, and two treatments combining cutting and grazing. Each treatment was tested in two 0.2 ha plots. Plant-dwelling invertebrates were sampled using a D-vac suction net in ten areas/plot (each measuring 0.09 m²). Most natural enemy and pest groups were not differentiated.
Reduce grazing intensity on grassland (including seasonal removal of livestock)

A study of a perennial rye grass Lolium perenne and white clover Trifolium repens ley grassland in Ireland (Purvis & Curry 1981) found that management-induced changes in grass height had immediate effects on arthropod abundance. Arthropod abundance was greatest (up to 10,351/m²) in taller/denser silage grass and lowest (as few as 394/m²) in short grass subject to periodic heavy sheep-grazing. The abundance of most groups, particularly larger insects, increased in areas left for silage, whilst numbers of mites (Acari), springtails (Collembola) and many other taxa decreased most under heavy grazing and after cutting. The cropping systems had no overall influence on the range of dominant taxa. The five treatments were intermittent grazing, silage cut only, silage cut followed by grazing, grazing and silage, and continuous grazing. Inorganic fertilizers were applied as appropriate. Plant-dwelling arthropods were sampled at random (ten samples of 0.1 m²) in each plot using a 'D-Vac' suction net monthly from May to September 1976 and in March 1977.