The figure below illustrates mean plant species numbers per square kilometer found in Switzerland’s different biogeographical regions, with the Swiss mean situated at 242 species. Sampling areas harboring the most species—on average 260—are located in the Jura and the Northern Alps, while the lowest average number of species was found in sampling areas in the Central Alps.
Mean vascular plant species numbers in 1-km2 sampling areas in Switzerland’s biogeographical regions. Swiss mean: 242
Comments
• Due to the comparatively high share of species-poor sampling areas at high altitudes, the Central Alps present the lowest species average among Switzerland's regions. However, regions at lower altitudes in the Central Alps include extremely species-rich areas as well. For example, BDM field workers found more than 300 plant species per square kilometer in several lowland sampling areas in the cantons of Wallis and Graubünden, with as many as 350 species in one particular area on the southern slope of the Rhone river valley.
• Species found in more than 50% of high-altitude sampling areas are all alpine grassland species such as Alpine Bluegrass (Poa alpina), Dandelion (Taraxacum officinale agg.), Scheuchzer’s Bellflower (Campanula scheuchzeri) and Dwarf Eyebright (Euphrasia minima). Seen from a nationwide point of view, individual rock species are far less widespread, possibly because they often prefer lime-rich or silicate-rich subsoil, which naturally limits them to the Lime Alps and Silicate Alps respectively. Grassland species, on the other hand, are less dependent on a particular kind of substrate. However, methodological factors very likely contributed to this result, too, since using the transect route method causes some rock areas to be bypassed completely.
• Recording over 1,700 species on its transects, BDM covered 65% of all vascular plant species occurring in Switzerland.
For frequency and development data on individual species as well as additional information please refer to the Z8 indicator “Population Size of Common Species”.
• For complete data and complementary information please refer to the complete datasheet.
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