Disentangling direct and indirect drivers of farmland biodiversity a landscape scale

To stop the ongoing decline of farmland biodiversity there are increasing claims for a paradigm shift in agriculture, namely from conserving and restoring farmland biodiversity at field scale (alpha-diversity) to doing it at landscape scale (gamma-diversity). However, knowledge on factors driving farmland gamma-diversity is currently limited. Here, we quantified farmland gamma-diversity in 123 landscapes and analysed direct and indirect effects of abiotic and land-use factors shaping it using structural equation models. The direction and strength of effects of factors shaping gamma-diversity were only partially consistent with what is known about factors shaping alpha-diversity, and indirect effects were often stronger than direct effects or even opposite. Thus, relationships between factors shaping alpha-diversity cannot simply be up-scaled to gamma-diversity, and also indirect effects should no longer be neglected. Finally, we show that local mitigation measures benefit farmland gamma-diversity at landscape scale and are therefore a useful tool for designing biodiversity-friendly landscapes.

Automated summary

The study found that factors shaping farmland gamma-diversity differ from those shaping alpha-diversity, with indirect effects often stronger than direct effects. Therefore, relationships between factors shaping alpha-diversity cannot be simply up-scaled to gamma-diversity, and indirect effects should not be neglected. Local mitigation measures can benefit farmland gamma-diversity at landscape scale.