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Changes in habitat conditions in a Late Glacial fluviogenic lake in response to climatic fluctuations (Warta River valley, central Poland)

Forysiak Jacek, Okupny Daniel, Obremska Milena, Antczak-Orlewska Olga, Płóciennik Mateusz, Pawłowski Dominik, Baradyn Daria, Kotrys Bartosz, Luoto Tomi P., Nevalainen Liisa, Borówka Ryszard K.

Geological Quarterly

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2023

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Vol. 67, No. 1

art. no. 1

EN

The Warta River valley was greatly influenced by the ice sheet of the Last Glacial Maximum (LGM). A small peatland located in the Warta drainage system is here used as a palaeoarchive of climatic and habitat changes during the Late Glacial (Weichselian). The Ługi sediment profile was investigated using multi-proxy (pollen, Chironomidae, Cladocera and geochemistry) analyses that recorded changes in a fluviogenic sedimentary depression. After the Poznań Phase (LGM), Ługi functioned as an oxbow lake that was cut off from the active river channel as a result of fluvial erosion. Since that time, the Warta River has flowed only along the section now occupied by the Jeziorsko Reservoir. Sedimentation of lacustrine deposits started at the beginning of the Late Glacial. Summer temperature reconstructions indicate cool Oldest and Younger Dryas, but no clear cooling in the Older Dryas. During the Younger Dryas the palaeolake was completely occupied by a peatland (fen), which periodically dried out during the Holocene. Investigation of this site has tracked the reaction of the habitat to climatic, hydrological and geomorphological changes throughout the Late Weichselian.

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Postglacial evolution of a small lake in the South Baltic coastal zone based on geochemical, pollen and subfossil Cladocera analysis

Niska M., Gadziszewska J., Jonczak J., Florek W., Kruczkowska B.

Oceanological and Hydrobiological Studies

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2018

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Vol. 47, No. 4

384--397

EN

The paper presents sedimentary records acquired as part of the research on the coastal cliff located between 221.3 and 221.4 km of the Slovincian (Słowinskie) Coast near Debina. Palynological and subfossil Cladocera analysis of sediments combined with geochemical data proves the existence of varying environmental conditions that occurred depending on the climate fluctuation. The Debina reservoir was formed in the Late Glacial period. Mud and gyttja were deposited in an initially cold proglacial lake. Species of Cladocera identified in this period indicate a deeper oligotrophic reservoir. The end of the Late Glacial cooling inhibited the development of fauna in the reservoir. Climate change at the beginning of the Holocene improved the habitat conditions in the Debina paleolake, which is reflected in the growth of zooplankton biodiversity and enrichment of the aquatic pollen content. We distinguished three phases that illustrate the evolution of the studied aquatic-mire ecosystem. In the following periods, the trophic level in the reservoir increased and significant water-level fluctuations led to periodic transformations of reservoirs into peat bogs. Gradually, the water-level lowering and the intensification of eolian processes led to terrestrialization of the paleolake.

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Late Pleistocene and Holocene environmental evolution of the Wkra River Valley near Bielawy Gołuskie (central Poland) recorded in palaeo-oxbow lake deposits

Niska M., Jonczak J., Gadziszewska J.

Geological Quarterly

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2017

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Vol. 61, No. 2

305--318

EN

This study aimed to reconstruct environmental changes in the Wkra River Valley near Bielawy Gołuskie (central Poland) based on geochemical, palynological and subfossil Cladocera analysis of deposits filling a palaeo-oxbow lake. Two sediment boreholes collected from the palaeochannel bend (BG-1) and neck (BG-2) include full sequences of organic deposits lying on clastic deposits. The lower part of the BG-1 borehole contains gyttja that accumulated during the Younger Dryas and the Preboreal, which is covered by reed peat of Preboreal and Boreal age. On top of this is alder peat that accumulated during the Atlantic. The ages of the gyttja and peat were confirmed by both radiocarbon dating and palynological analysis. The peats are characterized by a significant content of organic matter, which is relatively stable over time. This indicates a low intensity of mechanical denudation in the catchment, which is supported by low concentrations of aluminum and potassium. Calcium values greatly exceed these elements, suggesting that the lake was mainly fed by groundwater. Variation in trophic conditions over time is indicated by a vertical variability in the content of nitrogen, as well as by the Cladocera population. The strong decomposition of peat in the top layer of the mire, and increased concentrations of phosphorus and heavy metals, testify to increasing human activity during the most recent time periods.

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Multi-proxy reconstruction of mire development in the Poręby Wojsławskie Ecosystem (Sandomierz Basin, Southeastern Poland)

Chodorowski J., Plak A., Pidek I. A., Dobrowolski R.

Geochronometria

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2013

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Vol. 40, no. 3

177--186

EN

Multi-proxy analysis (sedimentological, palaeobotanical, geochemical data and results of radiocarbon dating) of the biogenic sediments from a small mire ecosystem in the Sandomierz Basin (SE Poland) is presented. The ecosystem contains a full hydroseral sequence from minerotrophic to ombrotrophic wetland. It is one of the few sites in this region which is so thoroughly investigated in terms of the palaeoenvironmental record. Changes in the water supply of the mire area, and conse-quently the changes in the plant and sediment succession, were well correlated with the regional tendencies in precipitation and temperature during the Late Glacial/Holocene transition and in the Holocene. Human impact is very well recorded in pollen diagram from the Subboreal period.