{Quantifying effects of spatial heterogeneity of farmlands on bird species richness by means of similarity index pairwise}

Many studies have shown how intensification of farming is the main cause of loss biodiversity in these environments. During the last decades, agroecosystems in Europe have changed drastically,mainly due to mechanization of agriculture. In this work, species richness in bird communities was examined on a gradient of spatial heterogeneity of farmlands, in order to quantify its effects. Four categories of farmland spatial heterogeneitywere defined, based on landscape and landuse parameters.Teimpact of features increasing the spatial heterogeneitywas quantified comparing the similarity indexes between birdcommunities in several farmlands of Central Italy.Te effects of environmental variables on bird richness were analyzed using GLM. Te results highlighted that landscape features surrogates of high nature values (HNVs) of farmlands can increase more than 50% the bird species richness. Te features more related to bird richness were hedgerows, scattered shrubs, uncultivated patches, and powerlines. Te results confirmthat the approach based on HNV for evaluating the farmlands is also suitable in order to study birds' diversity. However, some species are more sensitive to heterogeneity, while other species occupy mainly homogeneous farmlands. As a consequence, different conservationmethodsmust be considered for each farmland bird species.