Simple modifications of mowing regime promote butterflies in extensively managed meadows: Evidence from field-scale experiments

Published source details Bruppacher L., Pellet J., Arlettaz R. & Humbert J.Y. (2016) Simple modifications of mowing regime promote butterflies in extensively managed meadows: Evidence from field-scale experiments. Biological Conservation, 196, 196-202.
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This study is summarised as evidence for the following.

	Action	Category
	Delay cutting or first grazing date on grasslands to create variation in sward height Action Link
	Use rotational mowing Action Link

Delay cutting or first grazing date on grasslands to create variation in sward height

A replicated, randomized, paired, controlled study in 2010–2013 in 23 meadows in the Swiss Plateau, Switzerland (Bruppacher et al. 2016) found that delaying the first cutting date on extensively managed meadows increased the abundance, but not species richness, of butterflies and burnet moths. Before 15 June, the abundance of butterflies and burnet moths in delayed cut meadows (1.7–2.3 individuals/100 m) was higher than in standard agri-environment scheme (AES) meadows (1.1–1.3 individuals/100 m). After 15 June, delayed cut meadows retained higher butterfly abundance (12.6 individuals/100 m) than standard meadows (2.3 individuals/100 m). After 15 July, delayed cut meadows had lower abundance (9.3 individuals/100 m) than standard meadows (17.9 individuals/100 m), but there was no difference by the end of the summer (delayed: 12.0; standard: 14.6 individuals/100 m). There was no significant difference in the species richness of delayed (10 species) and standard (8 species) meadows. In 2010, at 11 sites (>5 km apart), two meadows (0.3–1.7 ha) which had been in AES since at least 2004 were randomly allocated to two treatments: standard Swiss AES management (no cutting before 15 June) or delayed cutting (no cutting before 15 July). An additional standard meadow was included at a 12th site. On average, standard meadows were cut twice/year, while delayed cutting meadows were cut 1.5 times/year. From late April–August 2013, butterflies were surveyed along a transect (65–215 m) through the middle of each meadow. Three surveys were conducted before 15 June, one from 15 June–15 July, and two after 15 July.

(Summarised by: Andrew Bladon)
Use rotational mowing

A replicated, randomized, paired, controlled study in 2010–2013 in 24 meadows in the Swiss Plateau, Switzerland (Bruppacher et al. 2016) found that leaving some areas uncut when mowing extensively managed meadows increased the abundance, but not species richness, of butterflies and burnet moths. Before first mowing, the abundance of butterflies and burnet moths in meadows with uncut refuges from previous years (1.0–2.9 individuals/100 m) was higher than in standard agri-environment scheme (AES) meadows without refuges (1.1–1.3 individuals/100 m). After 15 June, there was no difference in butterfly abundance between meadows with refuges (1.8–19.9 individuals/100 m) and standard meadows (2.3–17.9 individuals/100 m). The overall species richness of meadows with refuges (10 species) was similar to standard meadows (8 species). However, species richness of specialist butterflies was higher in meadows with refuges (1.7 species) than in standard meadows (1.1 species). In 2010, at 12 sites (>5 km apart), two meadows (0.3–1.7 ha) which had been in AES since at least 2004 were randomly allocated to two treatments: standard Swiss AES management (no cutting before 15 June) or refuge cutting (no cutting before 15 June and leaving 10–20% of the meadow uncut). The location of the uncut area had to vary between cuts. Meadows were cut on average twice/year. From late April–August 2013, butterflies were surveyed along a transect (65–215 m) through the middle of each meadow. Three surveys were conducted before 15 June, one between 15 June and 15 July, and two after 15 July.

(Summarised by: Andrew Bladon)