Optimising nature conservation outcomes for a given region-wide level of food production

The land sharing-sparing framework aims to quantify the trade-off between food production and biodiversity conservation, but it has been criticised for offering, for reasons of simplicity, an unrealistically limited set of different land uses.
Here, we develop the framework to evaluate a much larger suite of land-use strategies in which the areas and yields of three land-use compartments, natural habitat, high-yield farmland, and lower-yield farmland, are varied simultaneously. For two regions of England, we use functions that relate the local population density of breeding bird species to farm yield to simulate species-specific region-wide population sizes under each strategy.
We find that geometric mean population size, averaged across all species, is maximised when farmland yields are higher than the current average yield, and when spared land combines both natural habitat and low-yield farmland. This conclusion is relatively insensitive to the maximum yield considered feasibl...