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Every hundred meters a point: The Swiss government’s land-use and land-cover statistics record information about land use and land cover in Switzerland on 4.1 million data points using aerial images from swisstopo. As part of the Project “Monitoring the Effectiveness of Habitat Conservation in Switzerland” WSL’s Remote Sensing Group is using this valuable data source to monitor the state and development of habitats of national importance – bogs and fens, dry meadows and pastures, amphibian breeding sites and alluvial areas. When dry meadows, for example, become overgrown with shrubs and woodland, they lose their value.
The researchers working with Christian Ginzler first tested how well land-cover statistics document the around 6000 habitats of national importance. With fens, dry meadows and pastures, which cover large areas, two thirds of the objects are at least covered with enough points to be able to give reliable reports about their condition. With most of the usually very small raised bogs, however, over 35 per cent of the objects receive no point at all. This data-set is therefore of limited use for monitoring their condition.
Comparing the land-cover statistics from 1979/85 and 2004/09 shows that many fens, as well as dry meadows and pastures of national importance, are becoming increasingly overgrown. Management interventions such as the closure of irrigation channels have, however, helped in some cases to reverse the trend. Moreover, not protected fens became more overgrown than those that are protected, and more bushes grew in meadows near dry meadows and pastures than in protected ones. In conclusion, with the data from the land-use and land-cover statistics, such trends can be detected and appropriate maintenance measures implemented in time. (Beate Kittl, Diagonal 2/17)