Influence of human impact and bedrock differences on the vegetational history of the Insubrian Southern Alps

Vegetation history for the study region is reconstructed on the basis of pollen, charcoal and AMS14C investigations of lake sediments from Lago del Segrino (calcareous bedrock) and Lago di Muzzano (siliceous bedrock). Late-glacial forests were characterised byBetula andPinus sylvestris. At the beginning of the Holocene they were replaced by temperate continental forest and shrub communities. A special type of temperate lowland forest, withAbies alba as the most important tree, was present in the period 8300 to 4500 B.P. Subsequently,Fagus, Quercus andAlnus glutinosa were the main forest components andA. alba ceased to be of importance.Castanea sativa andJuglans regia were probably introduced after forest clearance by fire during the first century A.D. On soils derived from siliceous bedrock,C. sativa was already dominant at ca. A.D. 200 (A.D. dates are in calendar years). In limestone areas, however,C. sativa failed to achieve a dominant role. After the introduction ofC. sativa, the main trees were initially oak (Quercus spp.) and later the walnut (Juglans regia). Ostrya carpinifolia became the dominant tree around Lago del Segrino only in the last 100–200 years though it had spread into the area at ca. 5000 cal. B.C. This recent expansion ofOstrya is confirmed at other sites and appears to be controlled by human disturbances involving especially clearance. It is argued that these forests should not be regarded as climax communities. It is suggested that under undisturbed succession they would develop into mixed deciduous forests consisting ofFraxinus excelsior, Tilia, Ulmus, Quercus and Acer.

Excavation at Bakr Awa 2010 and 2011

The site of Bakr Awa is situated in north-eastern Iraq, in the Plain of Shahrizor. Excavations were undertaken in 1960/61by the Iraqi Department of Antiquities and 2010/11 by the University of Heidelberg/Germany. Occupation layers from the beginning of the Early Bronze Age tothe Ottoman period were uncoveredin the lower city and on the citadel. Archaeological evidence from the secondmillennium B.C. shows the most intensive settlement activities and apparent prosperity at Bakr Awa. Several forms of pottery, small finds and architecture reflect dynamic processes of cultural and political transformation at this site located in an area of transition between northern and southern Mesopotamia and western Iran.

Archaeological Research at Sirkeli Höyük: Preliminary Results of the Latest Excavations (2012 & 2013) and their Implications

Sirkeli Höyük is an ancient settlement located 40 km east of Adana on the left bank of the Ceyhan River in Plain Cilicia. The main mound covers an area of approximately 300×400 m and rises to a height of ca. 30 m above the level of the surrounding plain. Due to its strategic location overlooking a road that crosses the Misis mountains, Sirkeli Höyük always played an important role within Plain Cilicia. J. Garstang’s (1936-1937), B. Hrouda’s (1992-1996) and H. Ehringhaus’ (1997) excavations have shown that the site was occupied from the 4th to late 1st millennium B.C. Since 2006, a new Swiss-Turkish team is investigating Sirkeli Höyük again. Due to modern excavation techniques and an interdisciplinary approach, the architectural and material remains that have been uncovered by the new excavations have yielded much new information. Apart from a more precise pottery sequence, the new project has discovered an extensive lower town surrounded by an elaborate double city wall. The paper will summarize the results that have been gathered since 2006, with particular focus on the campaigns 2012-2013, and aims to show how they may contribute to the understanding of the cultural developments in this region.

Middle to Late Holocene vegetation history of the Upper Engadine (Swiss Alps): the role of man and fire

o reconstruct the vegetation and fire history of the Upper Engadine, two continuous sediment cores from Lej da Champfèr and Lej da San Murezzan (Upper Engadine Valley, southeastern Switzerland) were analysed for pollen, plant macrofossils, charcoal and kerogen. The chronologies of the cores are based on 38 radiocarbon dates. Pollen and macrofossil data suggest a rapid afforestation with Betula, Pinus sylvestris, Pinus cembra, and Larix decidua after the retreat of the glaciers from the lake catchments 11,000 cal years ago. This vegetation type persisted until ca. 7300 cal b.p. (5350 b.c.) when Picea replaced Pinus cembra. Pollen indicative of human impact suggests that in this high-mountain region of the central Alps strong anthropogenic activities began during the Early Bronze Age (3900 cal b.p., 1950 b.c.). Local human settlements led to vegetational changes, promoting the expansion of Larix decidua and Alnus viridis. In the case of Larix, continuing land use and especially grazing after fire led to the formation of Larix meadows. The expansion of Alnus viridis was directly induced by fire, as evidenced by time-series analysis. Subsequently, the process of forest conversion into open landscapes continued for millennia and reached its maximum at the end of the Middle Ages at around 500 cal b.p. (a.d. 1450).

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.