Holocene history of environment and human impact on two islands in the Ostholstein lakeland area, Northern Germany

Abstract

Holocene sediment cores from contemporary terrestrialised kettle holes on two islands in the Ostholstein lakeland area, Northern Germany, were investigated by palaeoenvironmental methods. Records from such isolated locations, such as these island mires, are an important source of information on small-scale vegetation changes. Pollen, non-pollen palynomorphs and macrofossils were used to reveal anthropogenic impact as well as lake level fluctuations. Changes in the peat decomposition and the ratio of organic to minerogenic content in the sediment facilitated correlation with past ground water table levels and accordingly with former lake levels. The palynological surveys indicate that human impact on the islands expanded in prehistoric times during phases of low lake levels or periods of stable hydrological conditions. The first distinct low level is recorded between ca. 8210 and 7740 cal. yr b.p. Another major low level period was detected for the time span from approximately 5290 to 4600 cal. yr b.p. After a subsequent period with a wetter climate, indicated by rising and fluctuating lake levels culminating at ca. 2420 to 2180 cal. yr b.p., a third lowering occurred until about 660 cal. yr b.p. This period was interrupted by minor fluctuations in lake levels from ca. 1770 to 1630 cal. yr b.p. and from ca. 1370 to 1010 cal. yr b.p.