Boros Emil

We carried out a comparative mapping of the wetlands of the 18–20th centuries on four sampling sites. The investigated sites were on the western, southeastern and eastern part of the Great Hungarian Plain. Each of these sites had a different hydrological history, history of land usage and represented different land coverage and hydrological situation at the time. Two types of material was used in the investigation: archive maps, namely the First Military Map (made in 1782–1785, 1: 28 800 scale), and Third Military Map (made in 1869–1884, 1: 25 000 scale), and aerial photos taken in 2005 and 2006. The mapping of the wetlands was carried out with manual digitising on the screen based on georeferred maps, photographs and field experiences.We used ESRI ArcMap 9.2 GIS software for this process. We found that the surface area of wetlands had been declining up to 10–40%, depending on the hydrological and land usage situation on the different investigated areas. In addition, intensive fragmentation was occuring, especially between the 19–20th centuries. This significant wetland drainage caused the well-known landscape changes in Hungary during the last two centuries. Biodiversity was negatively influenced by these changes. However, the current wetland ecosystem is still an important refuge of the protected and endemic species of the Pannonian fauna. The GIS database of current wetlands, small pools and pans was used in the investigation of microcrustacean populations. This GIS database can also be useful for nature conservation and environmental management efforts, because climate change may also trigger more wetland degradation in the Carpathian Basin during the next few decades.