Early succession of butterfly and plant communities on set-aside fields

Published source details Steffan-Dewenter I. & Tscharntke T. (1997) Early succession of butterfly and plant communities on set-aside fields. Oecologia, 109, 294-302.
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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
	Maintain species-rich, semi-natural grassland Action Link
	Provide or retain set-aside areas in farmland Action Link

Provide or retain set‐aside areas in farmland

A replicated, site comparison study in 1992 in agricultural land in Baden-Württemberg, Germany (Steffan-Dewenter & Tscharntke 1997) found that naturally regenerated set-aside had a higher species richness of butterflies than either set-aside sown with lacy phacelia Phacelia tanacetifolia or cereal crops, and that butterfly species composition changed with set-aside age. Butterfly species richness was higher in naturally regenerated set-aside (11–13 species) than in sown set-aside (7 species) or cereal crops (4 species), but lower than in old meadows (20 species). Species richness did not differ with set-aside age (11–13 species), but species composition did. Butterfly species found in older set-aside tended to be less migratory, spend longer as caterpillars (1-year-old: 61 days; 4-years-old: 105 days), and have fewer generations/year (1-year-old: 2.5 generations/year; 4-years-old: 1.9 generations/year). In 1992, four fields in each of seven management types were studied: former cereal fields left to naturally develop as set-aside for each of 1, 2, 3 and 4 years, 1-year-old set-aside sown with lacy phacelia, old meadows (>30 years old), and cereal fields (rye Secale cereale or wheat Triticum aestivum). Set-aside fields and old meadows were mown once/year in July. From May–October 1992, butterflies were counted along transects nine times/field.

(Summarised by: Andrew Bladon, edited from Farmland synopsis)
Maintain species-rich, semi-natural grassland

A replicated, site comparison study in 1992 in agricultural land in Baden-Württemberg, Germany (Steffan-Dewenter & Tscharntke 1997) found that old meadows had a higher species richness of adult butterflies and caterpillars than either recently established set-aside. Adult butterfly species richness was higher in old meadows (20 species) than in naturally regenerated set-aside (11–13 species), sown set-aside (7 species) or cereal crops (4 species). Caterpillar species richness was also higher in old meadows (16 species) than in naturally regenerated set-aside (3–7 species). Butterfly species found in meadows tended to be less migratory, spend longer as caterpillars (meadow: 121 days; set-aside: 44–105 days), and have fewer generations/year (meadow: 1.8 generations/year; set-aside: 1.9–2.7 generations/year) than species in recently established set-aside. In 1992, four fields in each of seven management types were studied: old meadows (>30 years old), former cereal fields left to naturally develop as set-aside for each of 1, 2, 3 and 4 years, 1-year-old set-aside sown with lacy phacelia Phacelia tanacetifolia, and cereal fields (rye Secale cereale or wheat Triticum aestivum). Meadows and set-aside fields were mown once/year in July. From May–October 1992, adult butterflies were counted along transects nine times/field. In September 1992, moth and butterfly caterpillars were sampled twice by sweep-netting.

(Summarised by: Andrew Bladon, edited from Farmland synopsis)
Provide or retain set-aside areas in farmland

A site comparison study of set-aside in southern Germany (Steffan-Dewenter & Tscharntke 1997) found that numbers of plant and butterfly species were higher in naturally regenerated set-aside than cereal or set-aside sown with Phacelia tanacetifolia, but that number of plant species decreased and butterfly species composition changed with set-aside age (1-4 year-old). Numbers of plant species were higher in four naturally regenerated set-aside fields (20-30 species) than in a cereal field (1) or 1-year-old set-aside sown with P. tanacetifolia (3). The number of species decreased significantly with age of naturally regenerated set-aside fields from one (30 plant species) to three-years-old (20 species). Cover of annual herbs declined rapidly in the 3rd to 4th year of set-aside. The number of butterfly species was higher in naturally regenerated set-aside (11-13 species) than cereal (4) or sown set-aside (7). Butterfly species richness did not differ with set-aside age (11-13 species), but species composition changed greatly. Butterfly body size tended to decrease with set-aside age (from 24 mm to 23 mm) and mean life-span of caterpillars increased (from 61 days to 105 days). Plant species and cover were sampled in 49 m² plots in September 1992 and flowering plant abundance was estimated nine times from May-October. Adult butterflies were counted along transects, nine times per field (May-October 1992) and caterpillars were sampled twice in September 1992 by sweep-netting.