Biogeographic patterns of species richness across the UK will constrain the impacts of land-sparing versus sharing on regional biodiversity
A land-sparing scenario suggests a polarisation of land-use where the most productive and potentially productive lands are intensified to increase yield and this spare the less productive land from farming such that areas relax back into later successional habitat types. However the grain at which such polarisation of land-use is implemented seems to be negotiable and coudl potentially be realised across a farm as well as at a much larger landscale scale. Irrespective of grain, the land-sparing scenarion assumes a positive association between late-successional vegetation and maximum species richness over a range of groups. We tested this assumption by modelling species richness of bryophytes, breeding birds and butterflies at the 10 x 10km square scale in terms of the cover of woodland, total habitat diversity and cover of intensive land-use. We also quantified the relative importance of climatic gradients within the same analyses. The results show group-specific patterns. Limited between-group covariance is likely to result in regionally specific outcomes of land-sparing on biodiversity. We also discuss the impact of appropriate scaling on such analyses and the problems that can arise when within-square diversity combines alpha and beta diversity.