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In Central Europe, Late Quaternary landscapes experienced multiple phases of geomorphologic activity. In this study, we used a combined geomorphological, pedological, sedimentological and palynological approach to characterize landscape development after the Last Glacial Maximum (LGM) near Lake Wygonin in Northern Poland. The pedostratigraphical findings from soil pits and drillings were extrapolated using ground-penetrating radar (GPR) and electric resistivity tomography (ERT). During the Pomeranian phase, glacial and fluvioglacial processes dominated the landscape near Lake Wygonin. At the end of the glacial period, periglacial processes became relevant and caused the formation of ventifacts and coversands containing coated sand grains. At approximately 15,290–14,800 cal yr BP, a small pond formed in a kettle hole (profile BWI 2). The lacustrine sediments lack eolian sand components and therefore indicate the decline of eolian processes during that time. The increase of Juniperus and rock-rose ( Helianthemum ) in the pollen diagram is a prominent marker of the Younger Dryas. At the end of the Younger Dryas, a partial reshaping of the landscape is indicated by abundant charcoal fragments in disturbed lake sediments. No geomorphologic activity since the beginning of the Holocene is documented in the terrestrial and wetland archives. The anthropogenic impact is reflected in the pollen diagram by the occurrence of rye pollen grains ( Secale cereale ) and translocated soil sediments dated to 1560–1410 cal yr BP, proving agricultural use of the immediate vicinity. With the onset of land use, gully incision and the accumulation of colluvial fans reshaped the landscape locally. Since 540–460 cal yr BP, further gully incision in the steep forest tracks has been associated with the intensification of forestry. Outside of the gully catchments, the weakly podzolized Rubic Brunic Arenosols show no features of Holocene soil erosion.

High-resolution biological proxies (pollen, macrofossils, Cladocera and diatoms), geochemical data (μ-XRF element scans, TOC, C/N ratios, δ 18 O carb and δ 13 C org values) and a robust chronology based on varve counting, AMS 14 C dating and tephrochronology were applied to reconstruct lake system responses to rapid climatic and environmental changes of the Trzechowskie palaeolake (TRZ; Northern Poland) during the late Allerod – Younger Dryas (YD) transition. Palaeoecological and geochemical data at 5–15 years temporal resolution allowed tracing the dynamics of short-term shifts of the ecosystem triggered by abrupt climate change. The robust age control together with the high-resolution sampling allowed the detection of leads and lags between different proxies to the climate shift at the Allerod-Younger Dryas transition. Our results indicate (1) a water level decrease and an increase in wind activities during the late Allerod and the Allerod-YD transition, which caused intensified erosion in the catchment, (2) a two-decades delayed vegetation response in comparison to the lake depositional system. Comparison with the Lake Meerfelder Maar record revealed slightly different vegetation responses of the Trzechowskie palaeolake at the YD onset.

In this work we present the complicated situation of a faunistically and floristically valuable ecosystem of the Rakutowskie Lake wetlands complex, which is part of the Special Protection Area for Birds of &ldquo, Błota Rakutowskie&rdquo, (PLB40001) and &ldquo, Błota Kł&oacute, cieńskie&rdquo, Habitats Directive Sites (PLH040031) included in the Natura 2000 network. Numerous ornithological observations have drawn our attention to the problem of rapidly progressing overgrowth of the lake and significant fluctuations in its water surface area. These fluctuations, especially in the spring period, significantly limit safe reproduction possibilities of very rare species of water&ndash, marsh birds. A multidirectional and comprehensive spectrum of research works allowed us to determine the genesis of the ecosystem and show that the shallow lake is undergoing the final stage in its evolution. The economic aspect of human activity (changes in land use and land development works) has contributed to serious degradation of the ecosystem. Climate changes observed in recent years (increased air temperature and, consequently, higher evaporation) additionally deepen and accelerate this process. The research made it possible to determine how the ecosystem functions today, but it is also an attempt to determine our predictions about its future.

The Wda River valley in northern Poland is a polygenetic valley located in a former subglacial meltwater channel that after ice sheet retreat hosted separate and then interconnected lake basins, subsequently replaced by a river. In one part of the river system an abandoned Lateglacial valley is found. This dry valley is a unique feature in the area located within the limit of the Scandinavian Ice Sheet during the Last Glaciation in the Central European Lowland. We investigated lacustrine and fluvial sediments and landforms in the valley and applied palynological analysis combined with radiocarbon dating to reconstruct the valley evolution from the early period of river inception in the Lateglacial through the formation of lakes during the Pleistocene/Holocene transition up to the establishment of a modern river system in the early Holocene. Three coeval processes were identified: (1) formation of lake basins in the subglacial channel connected by a river, (2) erosion of the river bed between the lakes, and (3) sediment deposition at the mouths of the channels in the lake basins first generating delta fans and eventually filling the lakes entirely. The valley formation was associated with diachronous melting of dead ice blocks buried in the subglacial channel controlled by the capacity of the hydrological system to evacuate the meltwater. Most of the lake basins in the study area were formed during the Bolling–Allerod period, but one section of the subglacial channel not affected by thermokarst processes survived protected by dead ice blocks throughout the entire Lateglacial. Accelerated dead-ice decay at the beginning of the Holocene triggered widespread lowering of the base level, which caused lake disappearance and the formation of the modern river system. The processes reconstructed in the central section of the Wda River indicate a highly dynamic and diachronous river valley development during the Lateglacial and early Holocene whereby the valley formation was interwoven with the formation of lake basins within the valley triggered by melting of dead ice blocks in the substratum.