Pollinator insects benefit from rotational fallows

Published source details Kuussaari M., Hyvonen T. & Härmä O. (2011) Pollinator insects benefit from rotational fallows. Agriculture, Ecosystems & Environment, 143, 28-36.
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This study is summarised as evidence for the following.

	Action	Category
	Provide or retain set‐aside areas in farmland Action Link
	Create uncultivated margins around intensive arable or pasture fields Action Link

Provide or retain set‐aside areas in farmland

A replicated, randomized, controlled study in 2003–2004 in an arable field in Jokioinen, Finland (Kuussaari et al. 2011) found that second-year set-aside plots sown with less competitive grasses had a higher abundance and species richness of butterflies and day-flying moths than first-year set-aside or second-year set-aside sown with competitive grasses. On set-aside plots sown the previous year with less competitive grasses, both the abundance (30 individuals/1,000 m) and species richness (4.2 species/plot) of butterflies and day-flying moths were higher than in plots sown with competitive grasses (5 individuals/1,000 m; 0.7 species/plot) or plots sown that spring with competitive (2 individuals/1,000 m; 0.5 species/plot) or less competitive grasses (3 individuals/1,000 m; 0.7 species/plot). However, there was no significant difference from plots where competitive (9 individuals/1,000 m; 2.0 species/plot) or less competitive (21 individuals/1,000 m; 2.9 species/plot) grasses had been sown under the crop in the previous year, or from stubble fields (17 individuals/1,000 m; 4.2 species/plot). No butterflies or moths were recorded in cereal plots. In 2003, a 16.5-ha field was divided into four blocks, each containing eight 0.3-ha plots. Plots were assigned to eight treatments: grass mix sown in 2003 and left to develop in 2004, spring barley sown in 2003 followed by grass mix sown in 2004, spring barley sown in 2003 with undersown grass mix which developed in 2004, spring barley sown in 2003 and left as stubble in 2004, and spring barley sown in both years. Two grass mixes, containing more and less competitive species, were used. In June–July 2004, butterflies and day-flying moths were recorded four times, two weeks apart, on one 250-m zig-zag transect through each plot.

(Summarised by: Andrew Bladon)
Create uncultivated margins around intensive arable or pasture fields

A replicated, site comparison study in 2003–2004 in an arable field in Jokioinen, Finland (Kuussaari et al. 2011) reported that permanent, uncultivated field margins had a higher abundance and species richness of butterflies and day-flying moths than sown fallow plots or spring cereals. Results were not tested for statistical significance. In permanent, uncultivated margins the abundance (120 individuals/1,000 m) and species richness (9.4 species/plot) of butterflies and day-flying moths were higher than in temporary, in-field, sown fallow plots that were one-year-old (abundance: 2–3 individuals/1,000 m; richness: 0.5–0.7 species/plot) or two-years-old (abundance: 5–30 individuals/1,000 m; richness: 0.7–4.2 species/plot), or left as stubble (abundance: 17 individuals/1,000 m; richness: 4.2 species/plot). No butterflies or moths were recorded in spring cereal fields. Six species showed a significant preference for permanent margins over temporary fallow plots (Essex skipper Thymelicus lineola, ringlet Aphantopus hyperantus, Lewes wave Scopula immorata, shaded broad-bar Scotopteryx chenopodiata, silver-ground carpet Xanthorhoe montanata, black-veined moth Siona lineata). In 2003, ten permanently uncultivated, 250-m long, 2.5-m wide field margins next to a 16.5-ha field were selected. The field was divided into four blocks, each containing eight 0.3-ha plots. Six plots/block were sown with grasses in either 2003 or 2004 and left fallow (see paper for details), one plot/block was sown with spring barley in 2003 and left as stubble in 2004, and one plot/block was sown with spring barley in both years. In June–July 2004, butterflies and day-flying moths were recorded four times, two weeks apart, on one 250-m transect through each margin or plot.

(Summarised by: Andrew Bladon)