Florenwandel in der Sächsischen Schweiz: Geographisches Informationssystem erlaubt Vergleich mit historischen Daten

Abstract

Walz, U.; Müller, F.: Changes of the flora of Saxon Switzerland – GIS allows comparison with historical data. – Hercynia N.F. 42 (2009): 197–215.In the area of Saxon Switzerland (Germany), a historical plant mapping project was carried out by Hans Förster between the 1920s and the 1960s, the data of which are still available today. Within the scope of this mapping project, the occurrence of plant species was recorded for a grid with a cell size of 1*1 km. These data were digitised and imported into a geographic information system. The comparison of these data with the results of a current mapping of the flora of Saxon Switzerland allows for detailed conclusions on spatial changes of the floral distribution. Especially affected by decrease are species of mountain meadows and mat grass swards, species of periodically wet grasslands, species of mesophile to thermophile edges, species of wet meadows, species of lowland hay meadows on lightly to moderately fertilised soils, species of calcareous fens, species of semi-natural dry grasslands, species of thermophile forests and species of transitional mires. The influence of land use changes on the flora is analysed using the example of grassland species. Plants of dry, nutrient-poor grasslands exhibit comparably slight changes in their spatial distribution. This finding is consistent with an observed increase of grassland in relatively dry conditions with sizes of about 300 ha and an increase of grassland sites with a high solar flux with sizes of about 50 ha. Species of wet or periodically wet, nutrient-poor grasslands have clearly decreased. Reasons for this circumstance are the transformation of grassland into forests and especially the drainage and intense agricultural use of these habitats.