Effects of timing of grazing on arthropod communities in semi-natural grasslands
Published source details Lenoir L. & Lennartsson T. (2010) Effects of timing of grazing on arthropod communities in semi-natural grasslands. Journal of Insect Science, 10, 1-24.
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This study is summarised as evidence for the following.
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Delay mowing or first grazing date on pasture or grassland Action Link |  | |
Delay mowing or first grazing date on pasture or grassland Action Link |  |
Delay mowing or first grazing date on pasture or grassland
A replicated study in 1997-2005 at two pastureland sites at Pustnäs and Harpsund in southern Sweden (Lenoir & Lennartsson 2010) found that delaying the start of grazing had mixed effects on different groups of insects and spiders. Ground beetles (Carabidae) were found in higher numbers in late-grazed plots (2.0-5.4 beetles/trap) compared to continuously grazed plots (1.4-3.6 beetles/trap) at Pustnäs, while at Harpsund ground beetles were more abundant in continuously grazed pasture early in the season, but became more abundant in the late-grazed plot after grazing commenced. Spiders (Araneae) were more abundant in late-grazed plots at Pustnäs, but only until grazing started. At Harpsund, spider abundance was not affected by grazing, although some spider groups did show a response. Ant (Formicidae) numbers and diversity were higher in continuously grazed plots at Pustnäs until the start of grazing in late-grazing plots. At Harpsund there was no overall difference between treatments, although numbers of some individual species differed. The experiment used an enclosed 1 ha plot in a 2 ha pasture at Pustnäs and a 4 ha plot in a 12 ha pasture at Harpsund. The pastures were grazed from May to September with 1.2-1.8 cows/ha. Enclosed areas were ungrazed until late July.
Delay mowing or first grazing date on pasture or grassland
A replicated study of spider (Araneae) and insect communities in two semi-natural grasslands in Sweden (Lenoir & Lennartsson 2010) found that the effect of delayed grazing depended on taxa. Small spiders, some ground beetles (Carabidae) and ants (Formicidae) were more abundant in conventional, continuous grazing (May-September) than in traditional late grazing (mid-July-September) while larger spiders and some ground beetles were more abundant in late grazing. Overall, abundance of ground beetles was higher in continuous grazing in the early summer but higher in late grazing in the late summer. Pitfall traps were used within and outside one grazing exclosure (1-4 ha) at each site, 7-10 times from May-August 2002-2005. Ant abundance was also measured by annually mapping nest density.
