An Analysis of Ecological Indicators Applied to Agricultural Ecosystems: What to Retain to Shape a Future Indicator for Pollinators ^†

Biodiversity loss has been demonstrated to have direct impacts on human welfare. However, policymakers need to refer to commonly accepted standards to monitor biodiversity, especially to direct fund granting. With the aim of collating information for the creation of a reliable pollinators’ one, we screened available indicators. Our first criterion was selecting indicators applied in agricultural contexts and recognised by a governmental body. Further, we included indicators referring to any arthropod taxa and approved at least by national bodies. We focused on these two groups based on the concept that a new indicator should include both, approved standards and an ecological level of potential significance for insect pollinators. Among the environmental indicators considered in the last CAP (European Common Agriculture Policy 2014-2020), two are referred for measuring the success of RDPs (EU countries Rural Development Programmes) actions to sustain biodiversity: FBI (Farmland Bird Index) and HNV (High Nature Value) farming. On the other hand, many indicators using arthropods exist, and we considered those applied by the Italian national institute ISPRA (Istituto Superiore per la Protezione e Ricerca Ambientale). These indicators include butterflies, syrphid flies, ground beetles, or a combination of abiotic and biotic information (as for the soil or waterbodies). We compared survey scale, monitoring scheme, type of environment, sampling effort, expected arthropod population, taxonomic level of data. As a common approach, we identified the combination of a territorial analysis by remote tools (e.g. GIS) and animal taxa surveys. Both FBI and HNV farming, for different reasons, resulted poorly conclusive on evaluating the national measures aimed at environmental improvement. The first, because the landscape context that is considered is poorly related to that of a farm. The second, because it can be differently interpreted by each country. The strength of indicators including arthropods emerges in the simultaneous inclusion of biotic and abiotic components. However, most of them just refer to confined environments (e.g. grasslands, riversides). Pollinators’ sensitivity to changes at the micro-habitat level is widely recognised, even helping to distinguish different methods of agricultural management. To develop a biodiversity indicator based on pollinators, we suggest to improve knowledge on local pollinator species and their environmental requirements, coupled with wide (in time and space) national monitoring programs.