Late quaternary vegetation and hydrological change at Ljubljansko barje (Slovenia)

Abstract

This paper investigates changes in the vegetation and hydrology at Ljubljansko barje (Slovenia) using a multi-proxy approach (pollen, diatoms, geochemical and stable isotope analysis). During the Lateglacial Ljubljansko barje was a deep, oligotrophic lake surrounded by open woodland comprised predominantly of Pinus and Betula which in the early Holocene, when the lake became shallower and mesotrophic ( Fragilaria pinnata, δ 15N ~ 3.3‰, δ 13C ~ − 33.7‰, C/N ~ 7.9), was replaced by broadleaved tree taxa ( Tilia, Ulmus, Quercus, Corylus) and Picea. This was followed by the spread of Fagus and after ~ 9200 cal yr BP Abies and planktonic and oligotrophic diatom taxa ( Aulacoseira italica, Gomphonema angustum) as well as an increased allochthonous influx (silt, SiO 2, Al 2O 3). Between ca. 6750 and 6000 cal yr BP the diatom data suggest shallower and oligotrophic conditions, whereas the stable isotope record (increased δ 13C and decreased δ 15N) indicates terrestrial input. Changes in forest composition (increase of Quercus, Alnus, Corylus) and the spread of herb taxa were probably advanced by human impact on the environment. The beginning of organic sedimentation, dated to 6000 cal yr BP, was followed by an increase of Fagus and Abies and by eutrophication and peat growth at ~ 5200 cal yr BP.