Impact of soybean cropping on arable biodiversity in Argentina.

POGGIO, SANTIAGO L; DE LA FUENTE, ELBA B; GHERSA, CLAUDIO M

Miami

Congreso; Pan-American Weed Resistance Conference; 2010

Bayer Crop Sciences

Agro-ecosystems retain an important share of the existing biodiversity, although its decline has been a major consequence of habitat loss and land conversion from complex to simplified landscapes under increasing agricultural intensification. We present here an across scale assessment of the impact of soybean cropping expansion on the arable biodiversity occurring in agricultural mosaics of the Rolling Pampa in Argentina. Pampean landscapes have been increasingly simplified with the adoption of no-tillage cultivation and HTGM-soybean in 1996, which have promoted fencerow removal and woodlot clearance to enlarge fields, and the plowing of pastures and road verges to grow soybeans. Weed richness of soybean crops declined more importantly at landscape than at field scale between 1998 and 2009. Whilst soybean richness declined from 71 to 17 at landscape scale, mean weed species number within fields decreased from 19 to 6. Fencerows had noticeably higher richness than soybean fields at local and landscape scales, which were positively related to farmland complexity, supporting the role of spatial heterogeneity in maintaining plant diversity in agro-ecosystems. Importantly, fencerow vegetation would be also providing food and shelter for many animal populations that perform key ecosystem function in agricultural landscapes, such birds, rodents and arthropods regulating the size of weed and pest populations within fields. In the face of ongoing landscape homogenization under agricultural intensification, maintaining dense networks of fencerows and road verges may become critical for conserving farmland biodiversity in modern Pampa landscapes.