Middle Age paleoecological and paleoclimatological reconstruction in the Carpathian Basin

Three programs of medieval environmental history research of fourteen sites was undertaken between 1998 and 2008 as part of the "Evolution of the Hungarian mires, peats and marshes", "Environment history of Hungary," and "Geoarcheological investigations of Hungary" projects. This present study was to demonstrate the facilities of paleoecological and paleoclimatological investigations (pollen, macrofossil, sediment works) completed on the core sequence of the Nadas Lake at Nagybarkany (Hungary). The Nadas Lake at Nagybarkany is a small peat-bog in the eastern Cserhat Mountains. The formation of the lake can be traced back to the late Glacial. The sediments deposited in the lakebed provide a record of climatic and hydrologic changes. A higher water level could be demonstrated from the late Glacial to the mid-Holocene, when the reed-beds covered a small area only. This was followed by a hiatus spanning about 5000 years, caused by the deepening of the lakebed during the Imperial Age, around 20-50 AD. The water level decreased and the water quality was more eutrophic. A reed-bed evolved around the lake. Paludification started with a bulrush floating mat phase at the close of the Middle Age, ca. 1300 AD. The initiation of the Sphagnum-bog underwent similar phases as in the other Hungarian peat-bogs. Although some anthropogenic disturbances can be reconstructed in the development of the peatland, some climatic effects and authogenic processes might be separated by paleoecological analyses.