Early-Holocene afforestation processes in the lower subalpine belt of the Central Swiss Alps as inferred from macrofossil and pollen records

Gobet, Erika; Tinner, Willy; Bigler, Christian; Hochuli, Peter A.; Ammann, Brigitta (2005). Early-Holocene afforestation processes in the lower subalpine belt of the Central Swiss Alps as inferred from macrofossil and pollen records. Holocene, 15(5), pp. 672-686. Sage 10.1191/0959683605hl843rp

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To reconstruct the vegetation history of the Upper Engadine, continuous sediment cores covering the past 11 800 years from Lej da Champfer and Lej da San Murezzan (Upper Engadine Valley, c. 1800 m a.s.l., southeastern Switzerland) have been analysed for pollen and plant macrofossils. The chronologies of the cores are based on 16 and 22 radiocarbon dates, respectively. The palaeobotanical records of both lakes are in agreement for the Holocene, but remarkable differences exist between the sites during the period 11 100 to 10 500 cal. BP, when Lej da Champfer was affected by re-sedimentation processes. Macrofossil data suggest that Holocene afforestation began at around 11400 cal. BP. A climatic deterioration, the Preboreal Oscillation, stopped and subsequently delayed the establishment of trees until c. 11000 cal. BP, when first Betula, then Pinus sylvestrislmugo, then Larix 300 years later, and finally Pinus cembra expanded within the lake catchment. Treeline was at c. 1500 m during the Younger Dryas (12 542- 11 550 cal. BP) in the Central Alps. Our results, along with other macrofossil studies from the Alps, suggest a nearly simultaneous afforestation (e.g., by Pinus sylvestris in the lower subalpine belt) between 1500 and 2340 m a.s.l. at around 11 400 to 11 300 cal. BP. We suggest that forest-limit species (e.g., Pinus cembra, Larix decidua) could expand faster at today's treeline (c. 2350 m a.s.l.), than 550 m lower. Earlier expansions at higher altitudes probably resulted from reduced competition with low-altitude trees (e.g. Pinus sylvestris) and herbaceous species. Comparison with other proxies such as oxygen isotopes, residual A14C, glacier fluctuations, and alpine climatic cooling phases suggests climatic sensitivity of vegetation during the early Holocene.

Item Type:

Journal Article (Original Article)

Division/Institute:

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

UniBE Contributor:

Gobet, Erika; Tinner, Willy and Ammann, Brigitta

Subjects:

500 Science > 580 Plants (Botany)

ISSN:

0959-6836

Publisher:

Sage

Language:

English

Submitter:

Peter Alfred von Ballmoos-Haas

Date Deposited:

02 Dec 2015 11:07

Last Modified:

20 May 2016 13:02

Publisher DOI:

10.1191/0959683605hl843rp

Uncontrolled Keywords:

Palynology; vegetation history; timberline; succession; afforestation; Preboreal Oscillation; numerical methods; early Holocene: Swiss Alps

BORIS DOI:

10.7892/boris.73227

URI:

https://boris.unibe.ch/id/eprint/73227

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