Palaeobotanical investigations at the mammoth site of Niederweningen (Kanton Zürich), Switzerland

Palaeobotanical investigations at the Niederweningen 2003 mammoth site concentrated on the middle peat layer, in which the remains of mammoth and other vertebrates have been found. This peat developed during an interstadial characterised by the presence of Picea. The slopes around the site were occupied by open forest tundra composed of species such as Picea abies, Larix, and probably Betula pendula/pubescens. The herb vegetation was similar to that of modern subalpine grasslands. Pinus cembra and Pinus mugo were present at higher elevations on the surrounding hills during the time of peat growth. The mire development started with overgrowth processes. During the interstadial the succession developed towards a wetland complex with different mire associations, where among other species Betula nana was abundant. The middle peat layer is intercalated with lake sediments, which were deposited during stadial climatic conditions without any noteworthy growth of trees. The pollen spectrum, as well as radiocarbon and luminescence dating, place the peat into the Middle Würmian (Marine Isotope Stage 3). The peat with the mammoth findings is hence significantly younger than the peat layers previously investigated in cores from two nearby drilling sites.