Landscapes monitoring network

At the landscape level, biodiversity is monitored by fieldworkers walking a track (transect) predefined on a map for each 1-km2 sampling area, recording each species they find.


  • Impression of BDM field work: A field worker kneels by the roadside and records a plant species on her smartphone.

    Vascular plants

    All species growing within 2.5 metres to the left and right of the path along a predetermined route (transect) are identified and recorded. The strip in question is wide enough to cover not only the edge of the path, but also the predominant land use (e.g. field, meadow, forest). Due to the location at the edge of the path, small-scale habitats such as embankments, copses and ruderal areas, which are important for the biodiversity of a landscape, are also recorded. The route is completed twice in an assessment year (exception: only one assessment is made in mountain areas).
  • A field worker catches a butterfly on an alpine pasture with a net.


    The transect followed for this taxon is also followed for vascular plants. Field workers identify all butterflies that fly past at a maximum distance of five metres. The app is used to log each observation with GPS coordinates. Depending on the altitude level, four to seven assessments are carried out per year. Each year, around 3,000 kilometres of transects are covered for BDM surveys on butterflies, and around 900 kilometres for vascular plants. Since the start of BDM, employees have covered over 70,000 kilometres for these two taxa!
  • A field worker looks through his binoculars in search of breeding birds in the mountain forest.

    Breeding birds

    The assessments of breeding birds are coordinated with the ornithological programme “Monitoring Common Breeding Birds”. Employees walk a transect measuring roughly five kilometres in length, along which they search a sampling area of one square kilometre as comprehensively as possible for the presence of breeding birds. Three morning excursions take place in the valleys and two morning excursions take place at higher altitudes in predetermined time slots.

Sampling area

Auf der Landschaftszeichnung ist eine Fläche von einem Quadratkilometer farbig markiert. Darin eingezeichnet ist der Verlauf der Transektroute.

Sampling area of one square kilometer for monitoring biodiversity in landscapes, with a marked transect (red line) for plant and butterfly assessments. The birds are monitored over the entire area as part of the monitoring of common breeding birds by the Swiss Ornithological Institute in Sempach.

Landscapes sampling network

Reliefkarte der Schweiz mit Seen und Flüssen. Das regelmässige Stichprobennetz mit den Kilometerquadraten ist eingezeichnet, wobei auffällt, dass die Aufnahmequadrate im Jura und an der Alpensüdflanke enger beieinander liegen aufgrund der Stichprobenverdichtung.

The BDM sampling network for species diversity in landscapes consists of roughly 500 sampling areas covering 1 square kilometer each. It serves to monitor 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.

Surveying step by step

This photo series follows BDM employees during a species survey of a sampling area. For a larger view, please click on the images.

  • The botanist stands by the roadside and searches for the existing vascular plants.
    Each sampling site extends over one square kilometer. Following a precisely set trail within an area (a so-called “transect”), field biologists will look for vascular plant species by the sides of roads and paths.
  • A field worker kneels by the roadside and records a plant species on her smartphone.
    Each transect is 2.5 kilometers long. Any species found on or along a transect is entered into the BDM smartphone app.
  • The botanist looks at a grass flower through the magnifying glass.
    Sometimes the field worker has to look closely to precisely identify a species.
  • A field worker stands on a gravel path and tries to catch a butterfly with the net.
    Butterflies are sampled along transects as well. Whenever it is not possible to identify a specimen in flight, it will be netted.
  • Close-up of two plastic tubes with one butterfly each
    Inside a plastic tube and well protected from harm, the butterfly can be observed in detail. The field worker notes the species found in the BDM app. Once identified, each little critter is promptly released.
  • A field worker looks through his binoculars in search of breeding birds in the mountain forest.
    Whenever possible, breeding birds are monitored covering all of a sampling area. For this purpose, the Swiss Ornithological Institute’s mostly volunteer fieldworkers will visit each area three times a year (only twice in the mountains).

Methodology guides

The methodology for the field and laboratory work is described in detail to ensure a standardised procedure. The corresponding methodology documents are publicly accessible.

Monitoring networks at a glance

Find a descriptive overview of the BDM monitoring networks online.

Watercourse monitoring network

Field workers survey aquatic invertebrates over a section of 5 to 100 metres in length, depending on the width of the watercourse. The animals are collected for identification in specialised laboratories.

Terrestrial habitats monitoring network

Field workers monitor the selected species groups over a circular area of 10 square metres. They collect the vascular plants directly on-site. They take samples of moss types and snails for analysis in specialised laboratories.

Breeding Birds

Surveys of breeding birds are carried out by the Swiss Ornithological Institute Sempach in coordination with the “Monitoring Common Breeding Birds" programme.