Monocultural sowing in mesocosms decreases the species richness of weeds and invertebrates and critically reduces the fitness of the endangered European hamster
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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.
KeywordsBiodiversity Nutritional deficiencies Reproduction Agriculture Conservation
We are grateful to Pierre Ulrich for his help and work at the Fort Joffre and to Cédric DeVigne for his advice on invertebrate trapping. Many thanks to Michel Hoff for helping with plant species identification. The experimental protocol followed EU Directive 2010/63/EU guidelines for animal experiments and the care and use of laboratory animals, and was approved by the Ethical Committee (CREMEAS) under agreement number 00624-01. This work was supported by the LIFE + Biodiversity Grant N° LIFE12 BIO/FR/000979 and the Ministère de l’Ecologie, du Developpement Durable et de l’Energie. The funders did not participate in the study design, data collection and analysis, the decision to publish, or the preparation of the manuscript. Many thanks to the anonymous reviewers and the editor who helped improving this manuscript and to Joanna Lignot for copyediting.
Author contribution statement
MLT and CH designed the study. MLT and FK collected the data and FK performed invertebrate and plant species identification. MLT carried out statistical analyses and wrote the manuscript. YH, FK and CH contributed significantly to manuscript revisions and gave final approval for publication.
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