Coincidence of High Nature Value farmlands with bird and butterfly diversity

The amount of High Nature Value farmland (HNVf) is a commonly used environmental indicator for assessing the performance of the Common Agricultural Policy, to support sustainable agriculture and monitor changes in agricultural land use in Europe. HNVf comprises agricultural areas of semi-natural state, low-intensity farming and fine-scale landscape mosaics of different habitat types. For a successful implementation, the identification of HNVf should correctly reflect the variation in biodiversity values between different agricultural landscapes. We examined how well the Finnish HNVf indicator and the sub-indicators constituting it – recalculated for the purposes of this study for five study regions – reflect the variation in bird and butterfly species richness and diversity patterns at different spatial scales. We found that butterfly diversity index was positively associated with the HNVf indicator at the finest scale of 0.5 km × 0.5 km squares. Among the HNVf sub-indicators, extensive cultivation of grasslands was most strongly related to the farmland bird diversity and the density of edge to the butterfly diversity. Thus, the HNVf concept reflects well the distribution of butterflies in the Finnish agricultural landscapes but insufficiently the diversity patterns of farmland birds. Importantly, semi-natural vegetation and long-term pastures – the backbone of the concept – presently occur in small and highly fragmented patches in agricultural landscapes in Finland. The Pan-European concept of HNVf has restricted application to farmland birds of this boreal country and the national HNVf concept may need to be revised.