For several decades the agricultural use of Central Europe’s cultivated countryside has been more intensive than ever before, with devastating consequences for many species of animals and plants. Even species like the hare that were once plentiful have vanished in many places. In a nutshell: species diversity in cultivated and agricultural land is in great danger. So what is the quickest but most comprehensive way to record changes in biodiversity? Which are the easy-to-measure, universal indicators that demonstrate species diversity even for a large area like temperate Europe?

Three years of fieldwork and identification

In the context of the EU’s “Greenveins” project, researchers in seven European countries from France to Estonia studied 25 areas each of 16 square kilometres in agricultural regions to determine their species and structural diversity. They determined the plants, birds and selected groups of arthropods such as spiders, wild bees or ground beetles occurring in them. Based on their studies, they attempted to form connections between species groups or landscape elements in order to detect indicators of this kind. The field observations lasted three years, and the results of the study were published in the scientific journal “Journal of Applied Ecology” in October this year. (1)

Unproductive plus unfertilised equals high species diversity

“It is really rather simple,” says Dr. Regula Billeter, Assistant Professor at the ETH Zurich Professorship for Plant Ecology, who co-directed the study. “All the landscapes in temperate Europe react in a similar way.” The more “unproductive” areas the study regions contained – i.e. hedges, fallow land, flower-rich field margins and extensively used meadows, the more species occurred in the corresponding areas. That’s why the countryside’s “furniture” is a good indicator of species diversity.

The researchers also showed that the level of fertilising is another important indicator of species diversity. The more fertiliser is applied, the fewer species of plants and birds occur in these regions. Birds suffer indirectly from fertilising, because it brings the diversity of seed-bearing herbs to vanishing point; insects put on less weight because of the fertiliser. That’s why birds find less food for themselves and their brood in fertilised areas.

But not all the organisms studied fit into the scheme. The diversity of beetles hardly seems to decrease as a result of fertilising. Another reason why individual species groups cannot be used as global indicators of species diversity.

Klettgau is a bug’s paradise

In a European comparison, the Swiss cultivated landscapes chosen for this study turned out not so badly. For example the study area in Klettgau in the canton of Schaffhausen had the largest number of different heteropterans (bugs), while that in the Reusstal valley was conspicuous through its diversity of plants. Billeter says this is attributable to the fact that many species-rich wetlands in the agricultural countryside in the Reusstal were protected and preserved. She explains the diversity of heteropterans in the Klettgau by the systematic encouragement of flowering fallow fields.

According to the ETH Zurich researcher, the discoveries emerging from the study are intuitively clear, and might appear obvious. However, the study is unique with regard to the geographic coverage – the studies were carried out simultaneously in seven countries -, the size and diversity of the study regions and the numerous indicators used.

Influence on EU agricultural policy

Billeter is “very pleased” that such unequivocal results emerge from this comprehensive study. She says the results are an important scientific backdrop for EU agricultural policy because the EU determines the agricultural policy for the whole of Europe, not for individual regions, i.e. it uses the same yardstick to measure all agricultural landscapes with widely differing “endowments”. In the researcher’s view, that’s why developing universally valid indicators of species diversity is also important.

Regula Billeter has derived recommendations for agricultural policy and land management from the study. She says the best plan is to maintain the existing extensive elements in the countryside. She also recommends the expansion of close-to-nature regions or elements such as hedges wherever possible. According to the researcher, “These recommendations are not entirely novel, but the study is an impressive demonstration of the correctness and importance, and it certainly does no harm to recall them again.” She finds confirmation of this opinion in the demand for the full text of the publication: the paper has already been requested by many different interested individuals and institutions.