Monocultural sowing in mesocosms decreases the species richness of weeds and invertebrates and critically reduces the fitness of the endangered European hamster.

Oecologia. 2018 Feb;186(2):589-599. doi: 10.1007/s00442-017-4025-y. Epub 2017 Dec 5. Tissier ML1, Kletty F2, Handrich Y2, Habold C2. Author information 1 Université de Strasbourg, CNRS, IPHC, UMR 7178, 67000, Strasbourg, France. mathilde.tissier@hotmail.com. 2 Université de Strasbourg, CNRS, IPHC, UMR 7178, 67000, Strasbourg, France. Abstract Intensive cereal monoculture is currently the main cause of biodiversity decline in Europe. However, it is difficult to disentangle the effects of intensive monoculture (e.g. pesticide use, mechanical ploughing and reduced protective cover), let alone evaluate how far the reduction of crop diversity affects biodiversity. It remains unclear to which extent the consequent decrease in food resources affects farmland biodiversity, and particularly vertebrate species. We therefore designed this study in mesocosms to investigate the effects of monoculture crops (organic wheat or corn seeds) and mixed crops (a combination of organic wheat, corn, sunflower and alfalfa seeds) on (1) the species richness of weeds and invertebrates and (2) the reproductive success of the European hamster (Cricetus cricetus), a critically endangered umbrella species of European farmlands. We found a negative impact of organic monoculture crops on plant and invertebrate species richness, with values respectively 38% and 28% lower than those obtained for mixed organic crops. The reproductive success of hamsters was reduced by 82% in monoculture mesocosms. These results highlight that monoculture per se can be detrimental for farmland biodiversity (i.e. from plants to vertebrates), even before taking into account the use of pesticide and mechanization. We believe that future research should further consider how food reduction in agroecosystems affects farmland wildlife, including vertebrates. Moreover, we argue that conservation actions must focus on restoring plant diversity on farmland to reverse the observed trend in farmland wildlife decline. KEYWORDS: Agriculture; Biodiversity; Conservation; Nutritional deficiencies; Reproduction PMID: 29209843 DOI: 10.1007/s00442-017-4025-y