During the last decades, raised inputs, changed cultivation measures and changes in the farm layout have been implemented in order to raise crop yields. The result has been an intensification of farming with negative consequences for farmland biodiversity. In this study, the impact of different levels of agricultural intensity on plant species richness in winter wheat (Triticum aestivum L.) production has been examined.
The presence of vascular plant species in 160 fields was examined at 32 farms in Uppsala County in the plain districts of south central Sweden. The sampling was performed between the 19th of June and the 13th of July 2007, during the flowering period of the winter wheat.
The relationship between species richness and eight different variables measuring aspects of intensity was examined: yield, crop cover, nitrogen application, herbicide use, soil cultivation, proportion arable land, field size and perimeter-area ratio. Crop management intensity was quantified using farmers' questionnaires. Landscape data was collected by using the block database from Uppsala County Administrative Board and analysed with GIS. Further, the variation in species richness within the farms and between the farms was examined using additive partitioning.
Increased proportion crop cover decreased species richness of plants in arable fields significantly. This was found on both organic and conventional farming systems. Crop cover reflects intensive agricultural practices with high levels of inputs in combination with the appropriate timing of the cultivation measures, which results in a dense and competitive crop stand. Species richness was generally higher on organic than conventional farms. Variables measuring landscape structure seemed to be of minor importance for weed species diversity in arable fields.
Approximately 70 % of the total diversity within the region could be attributed to differences between farms. Local field diversity, between ...
