Biodiversity-food trade-offs when agricultural land is spared from production

Abstract: Biodiversity conservation in agricultural landscapes, the world’s predominant land use, could involve sparing, or setting aside, agricultural land from production, implying biodiversity–food trade-offs. Employing bird species and agricultural data in two panel data sets, we evaluate the extent of set-aside’s trade-offs in England between 1992 and 2007. Mixed biodiversity outcomes are reflected in a marginal effect, of a 100 ha increase in set-aside, associated with a 1%–2% increase in species abundance and richness, no impact on Shannon-Wiener diversity, and a 0.03 standard deviation fall in phylogenetic diversity. Lower phylogenetic diversity indicates that populations of less genetically distinct bird species appear when set-aside increases. These effects are discontinuous for abundance and richness, and larger in the long run than in the short run for richness and phylogenetic diversity. Set-aside led, on average, to a 7%–9% fall in cereal land. In turn, this led to an up to 2% decline in cereal output. A yield increase of 5%–10% is likely due to the setting aside of mostly marginal land. Biodiversity–food trade-offs in agricultural landscapes could be minimized with a carefully targeted set-aside policy, based on clearly defined biodiversity goals, and in settings where there is still scope for intensification.

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