Effects of organic and conventional crop management on vineyard biodiversity

Although organic farming is rapidly expanding in the vineyards of southern Europe, conventional crop management, using treatments that require a number of chemical inputs to guarantee yields is still the most common approach to crop management. To gauge the effects of these management systems on biodiversity, communities of vascular plants, butterflies, moths and birds were studied in vineyards in the Priorat Appellation of Origin (Catalonia, NE Spain). Measurements inside plots (all four taxonomic groups) and in grass strips between crop lines (only butterflies and vascular plants) were taken in organically and non-organically treated vineyards. Crop treatment was found to have an important effect, stronger on the most sessile organisms. Organic farms hosted consistently richer communities of both vascular plants and butterflies, a trend that was also observed - albeit less significantly - in moths. The weaker response in this group was probably due to insufficient sampling. Birds, the most vagile of the surveyed taxa, showed no significant response to treatments. Grass strips acted in all cases as reservoirs of biodiversity and hosted richer assemblages. The current trend of placing vineyards on slopes without terracing should ensure the existence of uncultivated strips within the vineyards to enhance the biodiversity of these agroecosystems. As well, parameters such as altitude and urban surface area are important drivers of biodiversity in this region. Our results suggest that organic farming may contribute to halting the widespread decrease that is occurring in communities of butterflies and other insects in this region.