Organic farming and seminatural habitats for multifunctional agriculture: a case study in hedgerow landscapes of Brittany

Finding more sustainable ways to produce food is a major challenge for
humanity in the face of biodiversity extinction and climate change.
Consequently, research on the ability of agroecosystems to provide
multiple functions is growing. In this regard, the relative importance of
organic farming and landscape-scale measures for improving
multifunctionality has recently been debated. We investigated the
effects of the farming system (conventional vs organic) at the field
scale, the total length of hedgerows in the landscape, and their
interaction with the multifunctionality of 40 winter cereal fields in
Brittany (France). Our multifunctionality assessment integrated 21
indicators of biodiversity conservation, nutrient cycling, soil structure,
pest and disease regulation, food production, and socio-economic
performance. Many indicators of biodiversity conservation, pest
and disease regulation, and socio-economic performance were higher in
organic than in conventional systems. However, indicators of nutrient
cycling and soil structure did not improve and food production was much
lower in organic systems. Total hedgerow length in the landscape had less
influence than organic farming on indicators, although we observed
positive interactions. Granivorous carabid abundance and semi-net margin
were highest in organic fields located in well-preserved hedgerow
landscapes. Our study suggests that field-scale organic farming
is necessary to promote biodiversity conservation and associated
ecological functioning in crop fields, whereas landscape-scale
preservation of semi-natural habitats alone is likely insufficient.
Preservation of hedgerows in the landscape brings additional ecological
and socio-economic benefits for organic systems without compromising
agricultural production. More broadly, our results call for more ambitious
research into the myriad possible combinations of farming practices and
agri-environmental measures at both field and landscape scales, to improve
both belowground and aboveground functioning.