Comparative Diversity in Agroecosystems

Abstract

Agroecosystems -- the managed agricultural landscapes that cover approximately 50% of the Earth's ice-free land surface -- represent both the primary driver of global biodiversity loss through habitat conversion and the largest potential landscape for biodiversity-inclusive management through targeted agri-environment schemes, organic farming, and integrated pest management. Biodiversity in agroecosystems varies enormously by farming system, crop type, management intensity, and landscape context, but systematic multi-taxon comparative assessments across farming systems at the regional scale are rare. This study compared biodiversity (vascular plants, arthropods, birds, soil invertebrates) across five farming system categories (conventional cereal, organic cereal, intensive horticulture, extensive pastoral, and vineyard) at 42 agroecosystem sites across Austria, Spain, and Estonia (2,840 species-site records; 2019-2022), testing whether farming system type, management intensity (LUI), landscape semi-natural habitat (SNH) context, and organic certification predict multi-taxon biodiversity. Extensive pastoral grasslands showed the highest mean multi-taxon Shannon H' (3.84 +/- 0.48) and species richness per site (184 +/- 28 species); intensive horticulture the lowest (H' = 1.84 +/- 0.28; 84 +/- 14 species). Organic cereal farming showed 48.4% higher total species richness than conventional cereal at equivalent LUI -- confirming a significant organic benefit beyond management intensity effects alone. An Agroecosystem Biodiversity Index (ABI) integrating multi-taxon richness, functional diversity, and landscape SNH context predicted observed pollination service rates with r = +0.84 and classified farms as high, medium, or low biodiversity with AUC = 0.884. Vineyards under traditional management showed unexpectedly high ABI (0.724), comparable to organic cereals, from their diverse weed flora and arthropod communities