Palaeoecological evidence for Mesolithic to Medieval climatic change and anthropogenic impact on the Alpine flora and vegetation of the Silvretta Massif (Switzerland/Austria)

In a high altitude region such as the Silvretta Alps (Switzerland/Austria), past and extant settlement activities are known to have had large influences on the alpine flora and vegetation. The Silvretta Massif harbors more than 230 archaeological sites above 2000 m a.s.l. on a total area of 550 km², from the Mesolithic period to Modern Times, but received little attention in these matters up to recently. The Fimba Valley within the Silvretta area – with 47 known archaeological sites (6 prehistoric, 21 from the Medieval and/or Modern Times, 20 undated) located over an area of 62 km² – provides evidence of a broad range of former human presence, as well as peat records allowing the reconstruction of Holocene climatic change and anthropogenic impact on past vegetation. Here, we present a high resolution, multi-proxy study (including pollen, cryptogam spores, and non-pollen palynomorphs) on a 177-cm-long radiocarbon dated peat core from the Las Gondas Bog in the Fimba Valley (2363 m a.s.l.). Palynological evidence adds and confirms previous dendrochronological results, revealing extensive high Pinus cembra (Arolla pine) stands around the bog at 10,400 cal bp and between ca. 8600–6700 cal. bp, more than 300 altitudinal meters above today's timberline, and belonging therefore to the highest population known for Central Europe. In addition, our palaeoecological results correlate well with the archaeologically known human impact during the Neolithic, Iron Age and Medieval periods. The exploitation of alpine landscape resources (cultivation of cereals in the valleys) and livestock grazing (in the subalpine and alpine areas) has therefore a long tradition going back at least for 6200 years in the Silvretta region.