Évaluation de l’impact de la culture de colza sur la biodiversité aviaire en France : enjeux, méthodes, premiers résultats

Abstract

Indices based on common birds are suitable to represent biodiversity, and are now commonly used. Farmland birds' indices in France and Europe show worrying trends. A diagnosis of the impact of oilseed crops raises methodological issues. Ecological studies usually establish statistical links between common birds and agriculture described by great types of farming systems. The specific case of landscapes with cereals cropping systems requires more precise descriptions. We carried out a study using national databases to assess the impact of land use at the scale of small agricultural regions. The importance of oilseed rape area was not a major determinant of birds' indices, and the statistical models explained little of the observed variability. This suggests the diagnosis should take other factors into account, like management of the cropping systems and the landscape configuration. This exploratory study based on statistical correlations is complementary to analytical and accurate field studies more suitable to highlight causality effects.