Reliable data on our vital resource

Biological diversity is a vital resource. That is why it is essential for Switzerland to know how the country’s biodiversity is doing and developing. Furthermore, Switzerland has committed itself to long-term biodiversity monitoring by signing the Convention on Biological Diversity (CBD). To this end, the Federal Office for the Environment FOEN has launched Biodiversity Monitoring Switzerland (BDM).

Procedure

‟Impression

Monitoring the aquatic fauna means getting wet: Equipped with fishing boots, field workers wade through the water of smaller rivers and streams along a precisely defined section. The sediment is stirred up at several points and collected with a standard dip net, after which all of the aquatic invertebrates are separated out and identified at family level. This can be used to calculate various water quality indices.

This methodology is in line with the widely used modular step-by-step concept for macrozoobenthos – see box opposite. The larvae of the three insect orders mayflies, stoneflies and caddisflies are collected and identified down to species level in the laboratory by specialists. In addition, information on ecomorphology and water quality is also recorded at a measuring point, which provides further information for analysis.

Measuring point

‟The

The measuring point in a watercourse is shown in blue. The length of the section may vary depending on the situation.

Monitoring network

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The monitoring network for surveying the diversity of aquatic insects comprises around 500 sections of around 5 to 100 metres in length in smaller watercourses. 

Step by step

This photo series follows a BDM employee as she takes samples from a stream in the watercourse monitoring network. Click on the pictures for a larger view.

  • The photo shows a mountain stream.
    1
    One of roughly 500 BDM stonefly, caddisfly and mayfly sampling sites by a small Swiss watercourse.
  • The biologist measures the width of a mountain stream with a measuring tape.
    2
    The BDM fieldworker records the watercourse section’s position, length and width.
  • The biologist stands in fishing boots in the torrential water of the mountain stream and takes a sample from the bottom of the water with a special landing net.
    4
    In a spot defined by the monitoring method, she places a net in the watercourse, stirring up the stream bed with her boot. As a result, insect larvae are washed into the net.
  • The field worker wipes over stones with her left hand while holding the landing net in her right hand to catch the organisms that have been released.
    5
    Large rocks in the stream make it possible to collect critters by hand.
  • The biologist sits on the ground, with two plastic bowls and various small containers spread out in front of her, into which she packs the catch with the help of tweezers.
    6
    Back on land, she eliminates pebbles and bycatch, carefully picking the tiny invertebrates.
  • The water in the plastic bowl is carefully poured over a corner into a sieve, leaving the gravel behind.
    7
    Eventually, the fieldworker sieves through the remaining material in order to catch any remaining larvae.
  • A close-up of the plastic trays and the small boxes filled with catches.
    8
    Full sample containers ready for transport.
  • One of the species specialists identifies the larvae of the river insects in a Petri dish under the binoculars.
    9
    Later, specialists sort and analyse the aquatic invertebrates in the laboratory.

Preparation

‟Preparing
  • Determining the annual sample
  • Assembling field teams and determining workloads
  • Adapting methodology guides for the field surveys, if necessary
  • Adjusting the list of species authorised for the survey, if necessary

Instructions

  • Launch events for the field teams for each species group: Notification of new developments, discussion of methodologically sensitive points
  • Special instructions during the field season, especially with regard to weather conditions (safety aspects)
  • Targeted educational events (e.g. identification of difficult species groups, further training, official verification)

Field work

Impression of the BDM field work on vascular plants: A field worker kneels at the edge of the path, holding a plant in one hand and a smartphone for data entry in the other.
  • Field surveys according to regular methodology. Some of the sampling areas are surveyed twice for quality control by secondary groups.
  • Vascular plants, butterflies, breeding birds: Observation and species identification on-site. Noting of species observations in the BDM app.
  • Moss types, snails, aquatic invertebrates: Collecting of samples without further identification. For aquatic invertebrates, pre-sorting of samples on-site.
    Dispatch of samples for further processing and identification

Laboratory work

Impression of BDM laboratory work: An employee determines the larva of a water insect under the binoculars.
Snails
  • Washing and sieving of soil samples
  • Sorting of snail shells
  • Identification of snail shells at species level
Moss types
  • Identification of moss samples at species level
Aquatic invertebrates
  • Identification of aquatic invertebrates down to family level. Sharing of sample material for species identification
  • Identification at species level for mayfly, stonefly and caddisfly larvae

Quality controls

  • Plausibility checks on species identification, queries to field staff
  • Calculation of routine key figures as indicators of data quality
  • Evaluation of the consequences of methodological errors or deviations
  • Decisions on the validity or invalidity of raw data

Data administration

  • Import/entry of field data and laboratory protocols into a central database
  • Checking the completeness of recordings and data records
  • Incorporating decisions from quality control
  • Documentation of all corrections to the raw data in a database log

Releasing and using data

  • The revised data is declared valid and made available for data analyses
  • Data analyses on current topics
  • Calculation of further biodiversity indicators for the federal government and the cantons, e.g. legislative indicators, environmental indicators, contribution to the “Cercle Indicateurs”
  • Data analysis by third parties, on request (e.g. universities)
  • Data and species records are forwarded to the respective national data and information centre

Support in the field: recording app

BDM field work is digital: A field worker holds a smartphone in her hand, the start screen of the BDM app is recognisable.

Nowadays, it makes sense to record species in the field using a smartphone app. However, BDM has been recording data digitally for 20 years. In the beginning, it used Palm Pilot devices; today, field workers use standard Android smartphones. A crucial advantage from the outset: standardised data formats, species names and categories for all field workers, plus rapid data import. Vascular plant surveys in rural areas alone generate around 50,000 species observations every year across Switzerland! The app used was customised for the BDM and has been continuously developed since its first routine use in 2012. The app can be made available on request.

Procedure

‟Impression

In order to monitor vascular plants, mosses and gastropods in habitats, fieldworkers first localize each 10 square meter sampling site by means of a GPS device and a magnetic locator. Once the magnet buried at the center is found, the sampling site is delimitated using a piece of string of 1.8 meters of length.

Using the BDM smartphone app, plant species are recorded directly on the spot. While this usually eliminates the necessity of transferring field notes to a computer, some plants need to be collected for subsequent identification. Mosses and gastropods are always passed on to experts for identification.

Sampling area

‟The

The circular sampling area for terrestrial habitats is 10 square metres and is highlighted in orange above for clarity.

Monitoring network

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The monitoring network for biodiversity in habitats comprises around 1450 measuring points, each 10 square metres in size. A distinction is drawn between forest, meadows and pastures, settlements, fields, alpine pastures and mountain areas as habitats. Vascular plants, moss types and snails are monitored.

Step by step

The photo series follows a BDM employee on a visit to a sampling area. Click on the pictures for a larger view.

  • The field worker uses a yellow magnetic locator to find the centre of the sampling area.
    1
    The BDM field worker locates the sampling area using GPS and a magnetic locator. A magnet is buried at each area’s center to make sure it can be found again with utmost precision every 5 years.
  • The picture shows how the field worker measures the radius of the sampling area using a string attached to a wooden stick.
    2
    With a piece of string attached to the center post helping to keep the predefined radius, the BDM fieldworker identifies all vascular plants growing in a circular area of 10 square meters.
  • The botanist enters the species found into the smartphone.
    3
    She records all plant species she has identified in the dedicated BDM smartphone app.
  • Botanist looking through the orange Bussole, a surveying device that allows the exact direction of the compass to be determined.
    4
    Using a surveying compass, the fieldworker selects 8 spots at the edge of the sampling area for soil samples.
  • The field worker has taken a soil sample. The excess soil material is removed from the sampler with a trowel.
    5
    A standardized soil sampler cuts a square 125-cm2 sample of litter and topsoil down to a depth of 5 centimeters.
  • The soil sample is packed in a white carrier bag.
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    Soil samples are bagged and later sifted through in the lab to find any gastropods shells contained.
  • Kneeling on the ground, the botanist looks through the magnifying glass in search of mosses.
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    Finally, the sampling area is assessed for mosses.

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An important addition to the number of species

The data from the BDM monitorings can be used to determine the average number of species in habitats and landscapes. But is this information sufficient to describe biodiversity in Switzerland in great detail? No, it's not! Relatively long species lists may be compiled for a particular habitat type or a particular region, but these may differ only slightly between the individual sampling areas. This indicates that such species communities are not particularly diverse. This fact is taken into account by the “Diversity of Species Communities” indicator, which compares the species lists of the sampling areas. Particularly high diversity is only achieved when as many species as possible occur per plot and the overlap of species lists between the sampling areas is low.

Example of a simple calculation

The number of species is counted separately for each area. The indicator value is calculated from the mean value of these species numbers. To calculate the diversity of species communities, however, the species lists (presence-absence data) of two sampling sites are compared with each other. The proportion of different species is calculated using a diversity index commonly used in ecology, known as the Simpson Index.

  • In the diagram on the left, two circles each represent an area. One has four flowers, the other three. One light blue flower can be found in both circles.
  • In the right-hand diagram, the two circles are superimposed, the light blue flower is in the intersection.
    In the diagram on the right, the two circles are superimposed; the light blue flower is located at the intersection.

The same procedure is used for all possible combinations of two sampling sites. The average of all calculated index values gives the indicator value. An indicator value of 1 means maximum diversity of the species communities. On a purely hypothetical level, this would occur if no species occurred in two compared sites. An indicator value close to 0 means that the species communities are very uniform. Although the calculation is simple in principle, on a computational level it is complex due to the various comparisons involved.

So what happens if the species composition changes over time? Two scenarios are set out below.

  • In this scenario, a rare species becomes more common. In the example, the violet species has recently appeared on the right-hand site. Compared to the initial state, the mean species diversity has increased from 3.5 to 4.0 species. At the same time, the species communities are becoming more diverse, with the Simpson Index rising from 0.67 to 0.75.

  • In this case, a common species is becoming more frequent. The orange species migrates into the right-hand site and continues to occur in the left-hand site as it did in the initial state. In this scenario, the mean species diversity also increases from 3.5 to 4.0 species. However, this makes the species communities more similar and the Simpson Index falls from 0.67 to 0.5.

Procedure

  • 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.

    Butterflies

    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.
    1
    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.
    2
    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.
    3
    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.
    4
    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
    5
    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.
    6
    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).

Hotspot Special Edition

Cover of the Hotspot special issue on 20 years of biodiversity monitoring in Switzerland.

The Hotspot special edition on 20 years of BDM shows who works behind the data and highlights current developments in biodiversity.

Download PDF

National Database

BDM data and the species records are forwarded to the respective national data and information centre and integrated into its databases. Data on vascular plants are sent to InfoFlora, data on moss types to Swissbryophytes and data on butterflies, snails and aquatic invertebrates to info fauna.
InfoSpecies