1 Section for Crop Sciences, Department of Plant and Environmental Sciences, Faculty of Science, Københavns Universitet2 Department of Agriculture & Ecology, Crop Science, Department of Agriculture & Ecology, Faculty of Life Sciences, Københavns Universitet3 Department of Agriculture & Ecology, Crop Science, Department of Agriculture & Ecology, Faculty of Life Sciences, Københavns Universitet4 Section for Crop Sciences, Department of Plant and Environmental Sciences, Faculty of Science, Københavns Universitet
The effects of farming system on plant density and flowering of dicotyledonous herbs of high value for bees were investigated in 14 organic and 14 conventional winter wheat fields and adjacent road verges. The organic and conventional winter wheat fields/road verges were paired based on the percentage of semi-natural habitats in the surrounding landscape at 1-km scale. Mean density of high value bee plants per Raunkiaer circle was significantly higher in organic winter wheat fields and their adjacent road verges than in their conventionally farmed counterparts. The effect of organic farming was even more pronounced on the flowering stage of high value bee plants, with 10-fold higher mean density of flowering plants in organic fields than in conventional fields and 1.9-fold higher in road verges bordering organic fields than in those bordering conventional fields. In summary, organic farming had a strong positive effect in both road verges and wheat fields on the density of high value bee plants. This was due to the absence of herbicides and to practices inherent to organic farming systems, such as the use of clover (a high value bee plant) as a green manure and fodder crop.
Agriculture, Ecosystems and Environment, 2013, Vol 173, p. 66-71