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Many aquatic primary producers can use bicarbonates as a carbon source for photosynthesis. Charophytes of the two genera: Chara and Nitellopsis are quite efficient in this process. Some species of these macroalgae produce carbonate encrustations, mainly calcium carbonate, constituting up to 86% of the summer maximum dry weight of the standing crop. In this study, we analyzed the fate of inorganic carbon accumulated this way in Chara spp. and Nitellopsis obtusa from six Polish lakes located in two regions (warmer W Poland and cooler NE Poland). Our study distinguished two groups of charophyte species that differed in the way of CaCO3 release from their summer standing crops. On average, the corticate Chara rudis and C. tomentosa belonging to the first group were less efficient in depositing CaCO3 from summer to autumn than the less corticate C. contraria and ecorticate N. obtusa of the second group. The latter two species were more efficient in inorganic carbon burial in sediments. On the contrary, dissolution of encrustation was more typical of the first species group and was facilitated by decreasing the pH and saturation index of calcite in lake water. The final output of CaCO3 loss mainly resulted from combined species‐specific features, lake water properties and overwintering patterns. Our study revealed that inorganic carbon cycling through charophytes involves burial and dissolution and is more complex than previously thought. [ABSTRACT FROM AUTHOR]

Based on archival cartographic sources, teledetection materials, and research results in the scope of history and environmental sciences, changes occurring in the catchment of Lake Rotcze and its close vicinity over the last two hundred years were analysed. The area of the catchment is dominated by moderately fertile minerogenic soils on which forest assemblages developed (poor hornbeamoak forest Tilio-Carpinetum and thermophilous oak forest Potentillo albae-Quercetum). The first trace of anthropopressure was a clearing at the southern shore of the lake, for agricultural use, established not later than at the turn of the 17th and 18th century. The forests were almost completely cleared in the first quarter of the 20th century, and transformed into cultivated land of the village of Grabniak. A large fragment of the catchment is occupied by peatlands, constituting the final stage of lake-peatland succession developed in the former bay of fossil Lake Uściwierskie of which Lake Rotcze constitutes the remains. During the 20th century, the peatlands were intensively drained. This resulted in their overdrying, and growing over with bushes and marshy forests. In the 20th century, Grabniak was an agricultural village. Over the last 25 years, it has turned into a recreation resort. The relatively short agricultural and settlement activity in the lake catchment, in comparison with other parts of Poland, makes the lake appropriate for palaeolimnological reconstruction in terms of looking for reference conditions (sensu WFD).

During the Holocene, multiple thermal changes commonly occurred in the northern hemisphere. They are well-recorded in lakes with minimum human impact from the Arctic Circle area. The development of these lakes reflects ecological and climatic changes occurring from the formation of the lakes until present-day times. All environmental fluctuations affect biodiversity and are reflected in the number and composition of species. The goals of this study were to detect the ecological changes in a small Finnish lake using pollen, Cladocera and geochemical analyses. The research area is located within the northern zone of boreal coniferous forest and is the most sparsely populated region of Finland. The lake is located in Kuusamo uplands, E Finland, near the polar circle and over 20 km from the Russian border. Indicators of cold water were found only during the initial stage, after the 8.2 ka event and then the temperature was higher. Trophy was high at the beginning of the lake development and then a significant increase in trophy was found after 2600 BP. The impact of human activity is hardly traceable in Arctic Circle Finland throughout the Holocene Thermal Maximum. During the late-Holocene (after 4200 yr cal. BP), this impact is still weak and, even as late as the 20th century, only a few traces of human activity are recorded. General conclusion is that long-term climatic shift has been the most important factor driving changes in the limnology of Lake Talvilampi. [ABSTRACT FROM AUTHOR]

Wetlands are very vulnerable ecosystems and sensitive to changes in the ground water table. For the last few thousand years, hydrological balance has also been influenced by human activity. To improve their cropping features, drainage activity and fertilizing were applied. The drainage process led to an abrupt change of environment, the replacement of plant communities and the entire ecosystem. The problem of carbon sequestration is very important nowadays. A higher accumulation rate is related to higher carbon accumulation, but the intensity of carbon sequestration depends on the type of mire, habitat, and climatic zone. The main aim of this article was an examination of the changes in poor-fen ecosystem during the last 200 years in relation to natural and anthropogenic factors, using paleoecological methods (pollen and macrofossils). The second aim was a detailed investigation of the sedimentary record to aid our understanding of carbon sequestration in the poor fen of temperate zone. This case study shows that fens in temperate zones, in comparison with boreal ones, show higher carbon accumulation rates which have been especially intensive over the last few decades. To reconstruct vegetation changes, detailed palynological and macrofossil analyses were done. A 200-year history of the mire revealed that it was influenced by human activity to much degree. However, despite the nearby settlement and building of the drainage ditch, the precious species and plant communities still occur. [ABSTRACT FROM AUTHOR]

Lake overgrowing is a natural phenomenon, however, the controlling factors of this process are not completely understood. Geological drillings are an important source to help clarify the issue. In the paper, geological cross-sections through biogenic sediments that fill the lake basins in the Uściwierskie Lowering and Brzeziczno Lake were presented and discussed. In the Lake Brzeziczno basin, lake sediments fill-in most of the basin volume and are often interlayered with moss remains. Fine-detrituous gyttja is overlain with coarse-detrituous gyttja, covered by peat sediments, mainly sedge-moss peat. A floating mat is encroaching on the lakes. In lake basins of Uściwierskie Lowering, calcareous-detrituous gyttja dominates the lakes sediments, filling-in most of the volume of the basins. On the western shores of lake basins, sedge-moss peat covers lake sediments but eastern shores remain deprived of sediments due to long-term lake level fluctuation and wind activity. Lake overgrowing models are discussed. We suggest that dynamic models, which include lake level fluctuations, better explain lake overgrowing then the classic, static hydroseral model. [ABSTRACT FROM AUTHOR]

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