Journal of Paleolimnology

, Volume 30, Issue 3, pp 297–306

Natural environmental changes and human impact reflected in sediments of a high alpine lake in Switzerland

  • C. Ohlendorf
  • M. Sturm
  • S. Hausmann
Article

DOI: 10.1023/A:1026032829150

Cite this article as:
Ohlendorf, C., Sturm, M. & Hausmann, S. Journal of Paleolimnology (2003) 30: 297. doi:10.1023/A:1026032829150

Abstract

From the high alpine Sägistalsee (1935 m a.s.l.), 13.50 m of continuously laminated sediments comprising the last 9050 years, were analyzed. Even though Sägistalsee is a high elevation site, human-induced environmental changes start as early as 4300 cal. BP and leave a clearly detectable signal in the mineralogy of the sediments, which is much stronger than the signal from natural environmental changes that occurred before this time. Variations in the physical and mineralogical sediment properties of this clastic sequence reflect erosional changes in the catchment, where almost pure limestone contrasts with carbonaceous, quartz-bearing marl, and shist. The calcite/quartz (Cc/Qz) ratio was found to be most indicative of these changes, which occurred around AD 1850 and at 650, 2000, 3700, and 6400 cal. BP. The first four are interpreted as erosion events, which are related to human-induced changes in the vegetation cover and land use. We associate them to the recent development of tourism and grazing, the medieval intensification of pasturing, Roman forest clearance, and Bronze Age forest clearance, respectively. The Cc/Qz-ratio increases significantly within less than 100 years during these events, reflecting the erosion of unweathered or poorly weathered soils. The time intervals in between are characterized by a gradually decreasing Cc/Qz-ratio and reflect the stabilization or formation of new soils. Only the change at 6400 cal. BP, which represents the initial gradual stabilization of the catchment, is related to the immigration of Picea abies.

ErosionWeatheringSedimentologyMineralogyGrain SizeHuman impact

Copyright information

© Kluwer Academic Publishers 2003

Authors and Affiliations

  • C. Ohlendorf
    • 1
    • 2
  • M. Sturm
    • 1
  • S. Hausmann
    • 3
  1. 1.Swiss Federal Institute of Environmental Science and Technology (EAWAG), Überlandstrasse 133DübendorfSwitzerland and
  2. 2.Geomorphology and Polar Research (GEOPOLAR), Institute of Geography, FB 8University of Bremen, Celsiusstrasse FVG-MBremenGermany
  3. 3.Institute of Plant SciencesUniversity of Bern, Altenbergrain 21BernSwitzerland