Organic fields sustain weed metacommunity dynamics in farmland landscapes

Laura Henckel (1) , Lucas Borger (1) , Helmut Meiss , Sabrina Gaba (2) , Vincent Bretagnolle (1)

1 CEBC - Centre d'Études Biologiques de Chizé - UMR 7372
2 Agroécologie [Dijon]

Agro-ecosystems constitute essential habitat for many organisms. Agricultural intensification, however, has caused a strong decline of farmland biodiversity. Organic farming (OF) is often presented as amore biodiversity-friendly practice, but the generality of the beneficial effects of OF is debated as the effects appear often species- and context-dependent, and current research has highlighted theneedtoquantify therelativeeffectsof local- and landscape-scalemanagement on farmland biodiversity. Yet very few studies have investigated the landscapelevel effects of OF; that is to say, how the biodiversity of a field is affected by the presence or density of organically farmed fields in the surrounding landscape. We addressed this issue using the metacommunity framework, with weed species richness in winter wheat within an intensively farmed landscape in France asmodel system.Controlling for the effects of local and landscape structure, we showed that OF leads to higher local weed diversity and that the presence of OF in the landscape is associated with higher localweed biodiversity also for conventionally farmed fields, and may reach a similar biodiversity level to organic fields in field margins. Based on these results,we derive indications for improving the sustainable management of farming systems.

Mots clés: weeds; agroecology; organic farming; agricultural intensification; landscape heterogeneity; spatial scale

Domaines: Sciences de l'environnement

Laura Henckel, Lucas Borger, Helmut Meiss, Sabrina Gaba, Vincent Bretagnolle. Organic fields sustain weed metacommunity dynamics in farmland landscapes. Proceedings of the Royal Society B: Biological Sciences, 2015, 282 (1808), pp.20150002. ⟨10.1098/rspb.2015.0002⟩. ⟨hal-01199764⟩