The question of the origin of Alpine farming and pastoral activities associated with seasonal vertical transhumance and dairy production in the Silvretta Alps (Eastern Switzerland) has recently... Show moreThe question of the origin of Alpine farming and pastoral activities associated with seasonal vertical transhumance and dairy production in the Silvretta Alps (Eastern Switzerland) has recently benefitted from renewed interest. There, pastoral practises began during the Late Neolithic (2300 BC), but alpine dairy farming was directly evidenced so far only since the Late Bronze Age/Early Iron Age (1300–500 BC). The vegetation development, timberline shifts at 2280 m a.s.l. and environmental conditions of the subalpine Urschai Valley (Canton of Grisons, Switzerland) were reconstructed for the small (8 m2) Plan da Mattun fen based on palynological and geochemical analyses for the last six millennia. The X-ray fluorescence (XRF) analyses are among the first ones performed on a European peatland in such altitudes. A high Rb/Sr ratio in the fen peat sediments revealed an increase in catchment erosion during the time when the forests of the Upper Urschai Valley were steadily diminished probably by fire and livestock impact (2300–1700 BC). These landscape openings were paralleled by increasing micro-charcoal influx values, suggesting that prehistoric people actively set fire on purpose. Simultaneously, palynological evidence for pastoralism was revealed, such as pollen from typical herbs indicating livestock trampling, and abundant spores from coprophilous fungi. Since then, vertical transhumance and pastoral activities remained responsible for the open subalpine landscape above 2000 m a.s.l., most probably also in the context of milk and dairy production since 1300 BC, which is characteristic for the European Alps until today. Show less
Oppenheimer, C.; Wacker, L.; Xu, J.; Galván, J.D.; Stoffel, M.; Guillet, S.; ... ; Büntgen, U. 2017
Ranking among the largest volcanic eruptions of the Common Era (CE), the ‘Millennium Eruption’ of Changbaishan produced a widely-dispersed tephra layer (known as the B-Tm ash), which represents... Show moreRanking among the largest volcanic eruptions of the Common Era (CE), the ‘Millennium Eruption’ of Changbaishan produced a widely-dispersed tephra layer (known as the B-Tm ash), which represents an important tie point for palaeoenvironmental studies in East Asia. Hitherto, there has been no consensus on its age, with estimates spanning at least the tenth century CE. Here, we identify the cosmogenic radiocarbon signal of 775 CE in a subfossil larch engulfed and killed by pyroclastic currents emplaced during the initial rhyolitic phase of the explosive eruption. Combined with glaciochemical evidence from Greenland, this enables us to date the eruption to late 946 CE. This secure date rules out the possibility that the Millennium Eruption contributed to the collapse of the Bohai Kingdom (Manchuria/Korea) in 926 CE, as has previously been hypothesised. Further, despite the magnitude of the eruption, we do not see a consequent cooling signal in tree-ring-based reconstructions of Northern Hemisphere summer temperatures. A tightly-constrained date for the Millennium Eruption improves the prospect for further investigations of historical sources that may shed light on the eruption's impacts, and enhances the value of the B-Tm ash as a chronostratigraphic marker. Show less
Agro-pastoral activities in the past act as environmental legacy and have shaped the current cultural landscape in the European Alps. This study reports about prehistoric fire incidents and their... Show moreAgro-pastoral activities in the past act as environmental legacy and have shaped the current cultural landscape in the European Alps. This study reports about prehistoric fire incidents and their impact on the flora and vegetation near the village of Ardez in the Lower Engadine Valley (Switzerland) since the Late Neolithic Period. Pollen, charcoal particles and non-pollen palynomorphs preserved in the Saglias and Cutüra peat bog stratigraphies were quantified and the results compared with the regional archaeological evidence. Anthropogenic deforestation using fire started around 4850 cal. BP at Saglias and aimed at establishing first cultivated crop fields (e.g. cereals) and small pastoral areas as implied by the positive correlation coefficients between charcoal particles and cultural and pastoral pollen indicators, as well as spores of coprophilous fungi. Pressure on the natural environment by humans and livestock continued until 3650 cal. BP and was followed by reforestation processes until 3400 cal. BP because of climatic deterioration. Thereafter, a new, continuous cultivation/pastoral phase was recorded for the Middle to Late Bronze Age (3400–2800 cal. BP). After rather minor human impact during the Iron Age and Roman Period, intensive agriculture was recorded for the Medieval Period. The area around Ardez was used for crop cultivation from about 1000 cal. BP until the start of the ‘Little Ice Age’ (600 cal. BP). Despite a land-use reorganisation, the following gradual decrease in agricultural activities led to the extant mixture of a cultivated, grazed and forested landscape in the Lower Engadine. In addition, this study demonstrates the excellent value of the fungus Gelasinospora as a highly local marker of past and today’s fire incidents, as well as of the use of micro-charcoals from pollen slides and macro-charcoals (>150 µm) from pollen sample residues for the reconstruction of short- and long-term fire histories. Show less
