High nature value farmlands to identify crucial agroecosystems for multi-taxa conservation

Agricultural expansion is among the main drivers of biodiversity loss worldwide, yet agroecosystems can host an important share of biodiversity, which in turn provides multiple ecosystem services. Pinpointing agroecosystems that sustain high biodiversity levels is thus fundamental for safeguarding both biodiversity and human well-being. In Europe, the High Nature Value Farmlands (HNVF) concept was introduced to assess and enhance farmland biodiversity conservation under EU policies. While several approaches exist for identifying HNVF, the species-based approach seems the most reliable for identifying biodiversity-rich agroecosystems. We relied on Species Distribution Models to map bird species richness across Italy and assess the environmental factors affecting it. Then, we identified HNVF based on 1) richness of species of EU conservation interest and 2) richness of Italian Farmland Bird Index species. We also assessed if bird-based HNVF can be good surrogates for the diversity of wild bees, amphibians, and reptiles. The richness of both conservation-interest and farmland birds was enhanced by herbaceous crops, landscape heterogeneity, and length of rivers, while it was negatively affected by woody crops. HNVF identified by the two approaches were located in different regions. HNVF based on the richness of conservation-interest birds also hosted a higher richness of wild bees, while HNVF based on farmland birds hosted a higher richness of reptiles. Our study identified key environmental and landscape factors shaping bird species richness in agroecosystems, providing valuable insights for landscape-level conservation actions under EU agricultural policies. Species-based HNVF can complement vegetation- or landscape-based approaches for the identification of biodiversity-rich agroecosystems, providing a comprehensive framework to assess, promote, and maintain farmland biodiversity, favouring multiple taxa.