Pollinator insects benefit from rotational fallows

• Published in: Agriculture, ecosystems & environment ecosystems & environment, 2011-09, Vol.143 (1), p.28-36
• Main Authors: Kuussaari, Mikko, Hyvönen, Terho, Härmä, Oskari
• Format: Article
• Language: English
• Subjects: agricultural land; Agrostis; Bumblebee; Butterfly; Day-active moth; Ecosystems; fallow; Farmland biodiversity; Festuca; field experimentation; Flowering; Grasses; Honey bee; Insects; pollinating insects; Rotational; seed mixtures; Seeds; Set-aside experiment; sowing; species diversity; Stubble; Summer
• ISSN: 0167-8809; 1873-2305
• DOI: 10.1016/j.agee.2011.03.006

► Less competitive grasses and extended fallow duration promote pollinators. ► First year stubble as good as two-year sown fallow for pollinator richness. ► Bumblebees increased faster than Lepidoptera in experimental fallows. The importance of rotational fallows for pollinating insects in intensively cultivated farmland was studied in a three-year field experiment. The focus was on the establishment method (undersowing or seed mixture sown post-tillage), seed mixture (competitive Festuca pratensis– Phleum pratense– Trifolium pratense or less competitive Agrostis capillaris– Festuca ovina mixture) and duration (1 or 2 years) of the fallow. The seed mixture and duration affected the pollinators more than the method of establishment. Pollinator species richness was higher in fallows sown with less competitive than with competitive grasses and it increased in the second year. Stubble fields reached as high pollinator species richness already during the first year as fallows with less competitive grasses did in the second year. Pollinator abundance was highest in those treatments in which species richness of flowering plants was highest. The results suggest that the benefits of rotational fallows for pollinators increase when they are established as stubble or using seeds of less competitive grasses and when the field is fallowed for (at least) two summers.