Impact of Holocene climate changes on alpine and treeline vegetation at Sanetsch Pass, Bernese Alps, Switzerland

Berthel, Nadine; Schwörer, Christoph; Tinner, Willy (2012). Impact of Holocene climate changes on alpine and treeline vegetation at Sanetsch Pass, Bernese Alps, Switzerland. Review of palaeobotany and palynology, 174, pp. 91-100. Amsterdam: Elsevier 10.1016/j.revpalbo.2011.12.007

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In order to infer reactions of treeline and alpine vegetation to climatic change, past vegetation changes are reconstructed on the basis of pollen, macrofossil and charcoal analysis. The sampled sediment cores originate from the small pond Emines, located at the Sanetsch Pass (connecting the Valais and Bern, Switzerland) at an altitude of 2288 m a.s.l. Today's treeline is at ca. 2200 m a.s.l. in the area, though due to special pass (saddle) conditions it is locally depressed to ca. 2060 m a.s.l. Our results reveal that the area around Emines was covered by treeless alpine vegetation during most of the past 12,000 years. Single individuals of Betula, Larix decidua and possibly Pinus cembra occurred during the Holocene. Major centennial to millennial-scale responses of treeline vegetation to climatic changes are evident. However, alpine vegetation composition remained rather stable between 11,500 and 6000 cal. BP, showing that Holocene climatic changes of +/− 1 °C hardly influenced the local vegetation at Emines. The rapid warming of 3–4 °C at the Late Glacial/Holocene transition (11,600 cal. BP) caused significant altitudinal displacements of alpine species that were additionally affected by the rapid upward movement of trees and shrubs. Since the beginning of the Neolithic, vegetation changes at Sanetsch Pass resulted from a combination of climate change and human impact. Anthropogenic fire increase and land-use change combined with a natural change from subcontinental to more oceanic climate during the second half of the Holocene led to the disappearance of P. cembra in the study area, but favoured the occurrence of Picea abies and Alnus viridis. The mid- to late-Holocene decline of Abies alba was primarily a consequence of human impact, since this mesic species should have benefitted from a shift to more oceanic conditions. Future alpine vegetation changes will be a function of the amplitude and rapidity of global warming as well as human land use. Our results imply that alpine vegetation at our treeline pass site was never replaced by forests since the last ice-age. This may change in the future if anticipated climate change will induce upslope migration of trees. The results of this study emphasise the necessity of climate change mitigation in order to prevent biodiversity losses as a consequence of unprecedented community and species displacement in response to climatic change.

Item Type:	Journal Article (Original Article)
Division/Institute:	10 Strategic Research Centers > Oeschger Centre for Climate Change Research (OCCR) 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)
Graduate School:	Graduate School of Climate Sciences
UniBE Contributor:	Schwörer, Christoph, Tinner, Willy
Subjects:	500 Science > 580 Plants (Botany)
ISSN:	0034-6667
Publisher:	Elsevier
Language:	English
Submitter:	Peter Alfred von Ballmoos-Haas
Date Deposited:	04 Oct 2013 14:41
Last Modified:	05 Dec 2022 14:12
Publisher DOI:	10.1016/j.revpalbo.2011.12.007
Web of Science ID:	000303185600008
URI:	https://boris.unibe.ch/id/eprint/16892 (FactScience: 224598)