In a recent study published in Journal of Applied Ecology we used surveys of crop and farmland bird diversity on farms across Sweden’s main agricultural areas and illustrate the importance of structural crop diversity for farmland bird diversity. We also underline the absence of a distinction between different crop species in current EU Common Agricultural Policy Greening, while simultaneously setting levels on crop diversification too low resulting in little to no change in landscape-scale crop diversity on Swedish farmland.
Crop diversification has been introduced as an environmental strategy in the ‘Greening’ of the EU Common Agricultural Policy (CAP) for 2015–2020. The primary target of crop diversification is soil and ecosystem resilience, but claims for potential benefits for farmland biodiversity are also common. However, understanding of relationships between the number (compositional heterogeneity) and spatial arrangement (configurational heterogeneity) of crop fields and biodiversity is generally poor, making such claims relatively unfounded.
From a pre-implementation assessment, we found that >97% of the assessed farms would not be required to change their management under the CAP crop diversification measure (minimum of three crops for farms with 30+ ha), suggesting that this measure has generated little change on Swedish farms.
Our research shows that an increased number of crops at the farm level may actually promote biodiversity, in this case farmland birds, but only if the various crops differ regarding their structure and management. The effects are especially prominent in agricultural plains where crop diversity adds valuable variety.
Unfortunately CAP Greening fails to take advantage of this distinction between different types of crops and is therefore likely to have modest benefits for biodiversity, at least in the Swedish agricultural landscape.
We recommend that future efforts to manage farmland biodiversity should include ways of increasing the structural diversity of crops at the scale of farms and landscapes.
Associate Professor Sönke Eggers Dr Jonas Josefsson Department of Ecology, Swedish University of Agricultural Sciences, Box 7044, SE-75007 Uppsala, Sweden BirdLife Sweden, Stenhus Gård, Lilla Brunnby 106, SE-38662 Mörbylånga, Sweden.
The study: Josefsson, J., Å. Berg, M. Hiron, T. Pärt, and S. Eggers. 2016. Sensitivity of the farmland bird community to crop diversification in Sweden: does the CAP fit? Journal of Applied Ecology. doi: 10.1111/1365-2664.12779
Sönke Eggers and Jonas Josefsson are researchers at the Department of Ecology, Swedish University of Agricultural Sciences. Sönke Eggers is also a board member of BirdLife Sweden.