Ecological structures in open landscapes – small elements, big impact

Why structures are important
Hedges, copses, ponds, and enhanced forest edges are small but crucial elements in our landscape. They provide habitat, food, and refuge for plants, insects, reptiles, amphibians, birds, and small mammals. However, such structures have become rare in the intensively farmed agricultural landscape of the Swiss Plateau. This has had a noticeable impact on biodiversity.

The study in the Swiss Plateau
A recent analysis from the cantons of Bern and Solothurn shows that the more ecological structures there are in a landscape, the greater the biodiversity. The study examined key and target species in the groups of vascular plants, breeding birds, and butterflies, for which agriculture bears a special responsibility (UZL species).

The study shows that all three species groups benefit from ecological structures in open land. In the case of vascular plants, the number of UZL species increases with the proportion of area with ecological structures per square kilometer. Even with an area share of 10%, there is still no sign of saturation in this positive correlation (see Figure 2). Breeding birds use copses and forest edges as breeding sites and singing perches. Their species richness increases significantly up to a structural share of around 5% (see Figure 2).

Combination with biodiversity promotion areas brings the greatest benefit
Butterflies respond particularly strongly when ecological structures are combined with extensively managed biodiversity promotion areas (BFF2). The positive effect of ecological structures on the number of UZL butterfly species increases with the proportion of BFF2 in open land (see Figure 3). Extensively managed habitats enlarge and connect habitats, thereby enhancing the effect of the structures. The study shows that ecological structures are valuable on their own, but their effect is further enhanced by high-quality biodiversity promotion areas.

Potential not yet fully exploited in the Swiss Plateau
The study shows surprisingly clearly that the proportion of ecological structures in open land is positively correlated with the diversity of UZL species. The correlation could be even clearer if small-scale structures such as herbaceous vegetation strips, ditches, stone piles, and brush piles were also included in the analysis. The combination with extensively farmed land is particularly effective. However, the potential is hardly being exploited in the Swiss Plateau today: many areas are structurally poor, even though small structures take up little space and would be relatively easy to implement. The potential has not yet been fully exploited on existing biodiversity promotion areas either. In order for farmers to take such measures, more attractive subsidies and appropriate compensation are needed.