Agriculture and Biodiversity: Systematic Overview Identifies Important Avenues for Future Research

The intensification of agriculture has greatly changed Europe’s agroecosystems, with major implications for biodiversity. An overview study by Agroscope and the Swiss Ornithological Institute identifies the most important areas for future research with a view to minimising the uncertainties of currently available knowledge.

The intensification of agriculture in Europe in recent decades has drastically changed lowland agroecosystems. Homogenisation of the landscape, loss of semi-natural habitats, increased use of external inputs (synthetic fertilisers and plant-protection products) and climate change are the main drivers of species decline and loss.

Researchers from Agroscope and the Swiss Ornithological Institute summarised data from 1208 studies that assess the impact of common farming practices such as fertilisation, grazing, organic farming and pesticide use on biodiversity indicator species groups, including plants, birds, bees and annelids. The aim was to identify thematic knowledge groups and research gaps and to give an overview of the methods used by scientists. Described as a ‘systematic map’, the study is a standardised tool for identifying scientific evidence on a specific sub-topic and allows avenues for future quantitative studies to be highlighted.

Evidence on the implications of field management for biodiversity

Individual field-management practices, e.g. fertilisation, tillage, grazing and mowing, are well documented, as are suites of practices from organic farming. Flora, carabids, spiders, bees, birds and earthworms are the most-studied biodiversity groups at species-group level. Whereas flora, carabids and spiders are indicators used to assess the impacts of a wide range of practices, annelids tend to be associated with agronomic interventions affecting soil structure (e.g. tillage, fertilisation, crop rotation and crop-residue management). Bees and syrphids, for their part, are indicators for flower strips; butterflies and orthopterans, for the grazing and mowing of grasslands, and birds for the adoption of agri-environmental schemes at landscape scale.

Opportunities for future research should focus on less-common practices, less-studied species groups and regions

The study also showed that less-common practices such as intercropping, undersowing and agroforestry have not yet been sufficiently researched. Nor is much known about the effects of harvesting methods, biological pest control and the use of insecticides. This is particularly notable in the case of intermediate cropping, as winter cover crops are widely used in Europe and offer numerous benefits, including effective weed control and increased soil fertility.

Certain species groups such as amphibians and reptiles, snails, centipedes and millipedes are also underrepresented in the biodiversity studies analysed. Moreover, studies are also unevenly geographically distributed: research in Latvia, Croatia, Slovenia, Moldova, Ukraine and the Balkan countries remains patchy or poorly documented compared to research in Western Europe.

Database of methods and indicators

The authors of the study have developed a database based on reliable methods and indicators for assessing biodiversity. It shows which indicator species groups react to which practices, and supports stakeholders wishing to set up biodiversity monitoring. The database is freely accessible and can serve as a basis for more detailed studies.