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

Ohlendorf, Christian; Sturm, Michael; Hausmann, Sonja (2003). Natural environmental changes and human impact reflected in sediments of a high alpine lake in Switzerland. Journal of Paleolimnology, 30(3), pp. 297-306. Kluwer Academic 10.1023/A:1026032829150

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From the high alpine Sagistalsee (1935 m a.s.l.), 13.50 m of continuously laminated sediments comprising the last 9050 years, were analyzed. Even though Sagistalsee 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.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Department of Biology > Institute of Plant Sciences (IPS) > Palaeoecology
08 Faculty of Science > Department of Biology > Institute of Plant Sciences (IPS)

Subjects:

500 Science > 580 Plants (Botany)

ISSN:

0921-2728

Publisher:

Kluwer Academic

Language:

English

Submitter:

Peter Alfred von Ballmoos-Haas

Date Deposited:

26 Nov 2019 09:38

Last Modified:

26 Nov 2019 09:38

Publisher DOI:

10.1023/A:1026032829150

Uncontrolled Keywords:

erosion; weathering; sedimentology; mineralogy; grain size; human impact; climate

BORIS DOI:

10.7892/boris.135409

URI:

https://boris.unibe.ch/id/eprint/135409

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