Succession of bee communities on fallows

Published source details Steffan-Dewenter I. & Tscharntke T. (2001) Succession of bee communities on fallows. Ecography, 24, 83-93.
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This study is summarised as evidence for the following.

	Action	Category
	Provide set-aside areas in farmland Action Link
	Plant dedicated floral resources on farmland Action Link
	Provide or retain set-aside areas in farmland Action Link
	Plant nectar flower mixture/wildflower strips Action Link

Provide set-aside areas in farmland

A second replicated trial in the same region (Steffan-Dewenter & Tscharntke 2001) examined the abundance and species richness of foraging bees, both solitary and social, on annually mown set-aside fields of different ages and management. The number of bee species increased with the age of set-aside fields, from 15 species on 1-year-old fields to 25 species on 5-year-old fields. Two-year-old set-aside fields had the most bee species - 29 on average, compared to 32 species for old meadows, including an average of around five oligolectic species (specialising on pollen from a small group of plant species). One-year-old set-aside fields sown with phaceliahad an average of 13 bee species, mainly common, generalised species of bumblebee Bombus and Lasioglossum.
Plant dedicated floral resources on farmland

In a replicated study of foraging bee communities on set-aside fields of different ages and management (four replicates of each) in Germany, Steffan-Dewenter & Tscharntke (2001) found that 1-year-old set-aside fields sown with phacelia had a similar abundance but fewer species of bee (13 species/field on average) than 1- to 5-year-old naturally regenerated set-aside fields (15-29 species/field). Bees found on phacelia were mainly common species of bumblebee and the solitary bee genus Lasioglossum, whereas several endangered and specialised bees were found foraging on naturally regenerated set-aside.
Provide or retain set-aside areas in farmland

A replicated site comparison study near Karlsruhe, south Germany (Steffan-Dewenter & Tscharntke 2001) examined the abundance and species richness of foraging bees, both solitary and social, on annually mown set-aside fields of different ages and management. The number of bee species increased with the age of set-aside fields, from 15 species on 1-year-old fields to 25 species on 5-year-old fields. Two-year-old set-aside fields had the most bee species – 29 on average, compared to 32 species for old meadows, including an average of around five oligolectic species (specializing on pollen from a small group of plant species). One-year-old set-aside fields sown with phacelia had an average of 13 bee species, mainly common, generalized species of bumblebee Bombus and Lasioglossum.
Plant nectar flower mixture/wildflower strips

A replicated study in 1993 in Germany (Steffan-Dewenter & Tscharntke 2001) found that one-year-old set-aside fields sown with phacelia Phacelia tanacetifolia had similar numbers of bees (Apidae), but fewer bee species (13 species/field on average), than one- to five-year-old naturally regenerated set-aside fields (15-29 species/field). Bees found on phacelia were mainly common species of bumblebee Bombus spp. and the solitary bee genus Lasioglossum spp., whereas several endangered and specialized bees were found foraging on naturally regenerated set-aside. The percentage cover of flowers did not differ between ages of set-aside, but was higher (more than 25% cover of flowers) in phacelia-sown set-aside fields and old meadows than on naturally regenerated set-aside (around 10%). The following field types were studied: one- to five-year-old naturally regenerated set-aside fields, one-year-old phacelia-sown set-aside fields, >30-year-old orchard meadows. There were four replicates of each field type, with a total of 28 sites. Fields were set-aside after harvest in autumn and mown in July. Orchard meadows were mown once or twice in June-August. Between May and August percent flower cover was estimated on five occasions. Bee species and the flowering plant species visited by the bees were surveyed six times between April and August on 30 minute transects in each field.