Landscapes sampling area
Habitats sampling area

Broad-based long-term surveys

BDM focuses on surveying common and widespread species. Inspired by already established surveying programs, BDM chose a systematic sampling grid consisting of three distinct nationwide networks.

Species diversity in landscapes

How many species populate a landscape depends on numerous factors, since species ranges are defined not only by biogeographical distribution patterns and physical features such as geology, relief and climate, but also by land uses. The more different habitat types like grassland, forest or arable land add up to form a landscape and the closer to nature they are being managed, the more species will find a suitable site to colonize.

The BDM sampling network for species diversity in landscapes consists of roughly 450 sampling areas covering 1 square kilometer each. It serves to survey vascular plants, butterflies and breeding birds (by the Swiss Ornithological Institute), with 20% of the total surface being sampled each year. In the Jura and Southern Switzerland, the sampling network has been densified to obtain reliable data for these regions.

Species diversity in habitats

The BDM sampling network for species diversity in habitats encompasses roughly 1,450 sampling areas covering 10 square meters each. Differentiated habitats include forests, grassland, settlements, arable land, alpine pastures and mountains. Surveys target vascular plants, mosses and mollusks.

The BDM sampling network for aquatic insects holds approximately 500 sections, each 5 to 100 meters long and located in minor watercourses. Surveys cover the larvae of mayflies, stoneflies and caddisflies (so-called EPT species group).

Diversity of species communities

“Diversity of species communities” describes the development of species compositions in various habitats and within Switzerland’s individual regions. It is based on presence and absence data of individual species gathered in the two BDM sampling networks established for species diversity in landscapes and species diversity in habitats.

A wide variety of diverse species communities is a good thing, as homogenization of any kind will invariably result in a loss of biodiversity. Biotic communities grow to be more and more alike if land uses become increasingly similar or intensive, or if the same species are introduced nationwide, whether on purpose or by accident.

Each of the three circles is home to three species. Sharing two species, the circle in the middle is more similar to the circle on the left than to the one on the right, since the latter holds just one species occurring in both.

For current BDM results please go to the FOEN website

Environmental indicators

BDM data are also used for one of the Federal Council’s legislature indicators (in German, French or Italian only).

Legislature indicator

Landscapes sampling network
Habitats sampling network
Watercourses sampling network