Uppermost Limit, Extent, and Fluctuations of the Timberline and Treeline Ecocline in the Swiss Central Alps during the past 11,500 Years

Pollen and macrofossils were analyzed at two sites above today's treeline (or tree limit) in the Swiss Central Alps (Gouillé Loéré, 2503 m a.s.l., and Lengi Egga, 2557 m a.s.l.) to test two contrasting hypotheses about the natural formation of timberline (the upper limit of closed forest) in the Alps. Our results revealed that Pinus cembra--Larix decidua forests near timberline were rather closed between 9000 and 2500 B.C. (9600-4000 ¹⁴C yr BP), when timberline fluctuations occurred within a belt 100-150 m above today's tree limit. The treeline ecocline above timberline was characterized by the mixed occurrence of tree, shrub, dwarf-shrub, and herbaceous species, but it did not encompass more than 100-150 altitudinal meters. The uppermost limit reached by timberline and treeline during the Holocene was ca. 2420 and 2530 m, respectively, i.e., about 120 to 180 m higher than today. Between 3500 and 2500 B.C. (4700-4000 ¹⁴C yr BP) timberline progressively sank by about 300 m, while treeline was lowered only ca. 100 m. This change led to an enlargement of the treeline-ecocline belt (by ca. 300 m) after 2500 B.C. (4000 ¹⁴C yr BP). Above the treeline ecocline, natural meadows dominated by dwarf shrubs (e.g., Salix herbacea) and herbaceous species (e.g., Helianthemum, Taraxacum, Potentialla, Leontodon t., Cerastium alpinum t., Cirsium spinosissimum, Silene exscapa t., and Saxifraga stellaris) have been present since at least 11,000 cal yr ago. In these meadows tree and tall shrub species (>0.5 m) never played a major role. These results support the conventional hypothesis of a narrow ecocline with rather sharp upper timberline and treeline boundaries and imply that today's treeless alpine communities in the Alps are close to a natural stage. Pollen (percentages and influx), stomata, and charcoal data may be useful for determining whether or not a site was treeless. Nevertheless, a reliable and detailed record of past local vegetation near and above timberline is best achieved through the inclusion of macrofossil analysis.

An annotated bibliography of CERC coastal ecology research /

Includes indexes.

Gorgas Memorial Institute of Tropical and Preventive Medicine. Hearing, Ninety-third Congress, second session. March 13, 1974.

Mode of access: Internet.

DOE/EPA/NSF/ONR joint program on bioremediation : interagency announcement of opportunity : Environmental Protection Agency, Department of Energy, National Science Foundation, Office of Naval Research jointly announce the availability of 1996 grants for research.

Mode of access: Internet.

The United States Environmental Protection Agency announces the availability of 1996 grants for research on endocrine disruptors, role of interindividual variation in human susceptibility to cancer, risk-based decisions for contaminated sediments.

Mode of access: Internet.

Second International Colloquium on Mars : abstracts for a colloquium held at the California Institute of Technology, Pasedena, California, January 15-18, 1979.

Item 830-H-10 (microfiche)

The higher life in art : a series of lectures on the Barbizon school of France, inaugurating the Scammon course at the Art Institute of Chicago /

Includes index.

Beach fauna study of the CERC Field Research Facility, Duck, North Carolina /

Issued April 1977.

An annotated bibliography of CERC coastal ecology research /

Includes indexes.

Summaries of the UDAEC basic research programs in metallurgy, solid state physics and ceramics.

"January 1964 (DTIE Issuance Date)."

Summaries of the UDAEC basic research programs in metallurgy, solid state physics and ceramics : (fiscal year 1964)

"January 1965 (DTIE Issuance Date)."

Summaries of the USAEC basic research program in chemistry : (off site).

Includes indexes.