Lydie Dudová

Formation, succession and landscape history of Central-European summit raised bogs: A multiproxy study from the Hrubý Jeseník Mountains

Central-European raised bogs, developed on mountain summits, are specific ecosystems of high conservation importance, but their history remains largely unknown. Pollen, macrofossils, testate amoebae and peat characteristics were analysed in a peat sequence of the Vozka bog (Hrubý Jeseník Mountains, Eastern Sudetes, Czech Republic). Past water chemistry and water-table depths were reconstructed by transfer functions calibrated from recent testate amoeba data and long-term environmental averages. Peat initiation started in the middle Holocene (approximately 4200 bc) by the process of paludification, resembling the development of Atlantic blanket bogs. Around 100 bc the vegetation changed from Eriophorum vaginatum-poor fen to the ombrotrophic-bog vegetation similar to the recent situation. A hiatus in peat sequence was revealed between ad 1320 and 1954. It can be explained either by human activities, or by an extreme drought causing decomposition of previously accumulated peat. Local bog development was largely independent of landscape development inferred from pollen records. In the middle Holocene, mixed spruce-elm-hazel woodland was recorded close to the treeline. During 2400–800 bc a gradual transition to mixed spruce-fir woodlands with admixture of beech took place, and from approximately 800 bc spruce and fir became dominant. The major human impact started approximately ad 1230 and was connected with settlement and mining in the foothills.

Holocene vegetation history of the Jeseníky Mts: Deepening elevational contrast in pollen assemblages since late prehistory

We tested how did the vegetation of a Central European mountain region with a fragmented alpine zone develop during the Holocene and when did human land use start to alter summit grasslands. For the last 6,000 years, the main gradient correlated with altitude, which is a complex factor corresponding to temperature and geomorphology (flat summits vs alluvia of mountain rivulets). This elevational differentiation became more pronounced after 2,250cal BP. i.e. since the Iron Age. Human impact might facilitate beech expansion at high elevations, with Picea-dominated forests being restricted to alluvia and around mid-elevation basin peatlands prior to establishment of modern Picea plantations.