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Detailed studies on fossil remains of plants or animals in glacial lake sediments are rare. As a result, environmental conditions right at the moment of deglaciation of the large N-Hemisphere ice-sheets remain largely unknown. Here we study three deglacial phases of the Fennoscandian Ice Sheet as a unique, repeated element in a long sediment record preserved at Sokli in northern Finland. We summarize extensive multi-proxy data (diatoms, phytoliths, chironomids, pollen, spores, non-pollen palynomorphs, macrofossils, lithology, loss-on-ignition, C/N) obtained on glacial lake sediments dated to the early Holocene (ca. 10 kyr BP), early MIS 3 (ca. 50 kyr BP) and early MIS 5a (ca. 80 kyr BP). In contrast to the common view of an unproductive ice-marginal environment, our study reconstructs rich ecosystems both in the glacial lake and along the shores with forest on recently deglaciated land. Higher than present-day summer temperatures are reconstructed based on a large variety of aquatic taxa. Rich biota developed due to the insolation-induced postglacial warming and high nutrient levels, the latter resulting from erosion of fresh bedrock and sediment, leaching of surface soils, decay of plant material under shallow water conditions, and sudden decreases in lake volume. Aquatic communities responded quickly to deglaciation and warm summers and reflect boreal conditions, in contrast to the terrestrial ecosystem which responded with some delay probably due to time required for slow soil formation processes. Birch forest is reconstructed upon deglaciation of the large LGM ice-sheet and shrub tundra following the probably faster melting smaller MIS 4 and MIS 5b ice-sheets. Our study shows that glacial lake sediments can provide valuable palaeo-environmental data, that aquatic biota and terrestrial vegetation rapidly accommodated to new environmental conditions during deglaciation, and that glacial lake ecosystems, and the carbon stored in their sediments, should be included in earth system modeling.

This paper presents the results of multi-disciplinary research carried out on the deposits of a residual channel (“Peerdemeers”) of the Kale/Durme River in the Moervaart depression, NW Belgium. The combination of physical, botanical, zoological and chemical analyses allowed a detailed reconstruction of the channel ecosystem and the vegetation in the surrounding landscape during the Younger Dryas and Early Holocene. A chronology for the record was provided by radiocarbon dating. Vegetation patterns were influenced by major climate changes that occurred during this period. During the early Younger Dryas, the river channel was active and vegetation was open with scattered birch copses, shrubs, grasses and herbs. The channel was cut-off in the late Younger Dryas, while some heath developed in the area. The Friesland Phase is characterised by a lithological change and increase in water level in the residual channel. Dwarf birch disappeared and boreal forests developed. The area however, remained relatively open compared to other coversand areas in NW Europe. The Rammelbeek Phase is considered as a drier, more continental climate phase in which forest expansion was temporarily interrupted and grasslands became more abundant. Also at the “Peerdemeers” site an increase in grasses is recorded. During the entire period (ca. 1,000 years) there is no hard evidence for human activity. The absence of archaeological evidence is in sharp contrast with the preceding (Allerod) and succeeding periods (Boreal). This suggests that environmental conditions during the YD and PB were probably too unfavourable for hunter-gatherers to remain in the Moervaart area.

This paper presents the results of multi-disciplinary research carried out on the deposits of Moervaart depression, NW Belgium, one of the largest palaeolakes (∼25 km2) that existed during the Lateglacial interstadial in NW Europe. The multi-proxy study, including physical (organic matter and calcium carbonate, magnetic susceptibility, micromorphological), botanical (pollen, macrofossils, diatoms), zoological (ostracods, molluscs, chironomids) and chemical analyses (stable carbon and oxygen isotopes) has resulted in a detailed reconstruction of the Lateglacial landscape as well of the local conditions that prevailed in the lake itself. A chronology of the record was provided by radiocarbon dating and comparison with radiocarbon dates of the nearby Rieme site. These yielded a good match with the regional biostratigraphy. During the Lateglacial, vegetation and geomorphology of the landscape in general changed from a tundra landscape to a boreal forest. The vegetation development, however, was interrupted by a number of cold reversals. Three centennial-scale cold oscillations are present in the record: 1) the so-called Older Dryas corresponding to GI-1d in the Greenland ice-cores, 2) a short and pronounced cold event during the early Allerød, which could be correlated to GI-1c2 and 3) a cooling event during the late Allerød probably corresponding to the Intra Allerød Cold Period (IACP) or GI-1b. The latter most likely was responsible for the disappearance of the Moervaart palaeolake.

The results of multi-disciplinary research carried out on the deposits of the Moerbeke “Driehoek” site, located along the northern bank of the extensive Moervaart palaeolake (NW Belgium), are presented. The multi-proxy study, including sedimentological (organic matter, calcium carbonate and grain-size) and botanical (pollen, macrofossils, NPP) analyses, provided evidence of repeated aeolian deflation during the Allerod. Our results demonstrate, in combination with evidence from other soil archives within the Moervaart area, that the Allerod period in NW Europe was sedimentologically much less stable than hitherto assumed, especially during the GI-1c2 event and middle Allerod. Some of the Allerod deflation events were caused by centennial abrupt climatic oscillations, such as the short but pronounced cold GI-1c2 event, while others were likely the result of intense forest fires or a combination of both. These observations call for a revision of the existing Lateglacial litho- and chronostratigraphic schemes for the sand-belt of northern Europe.

High-resolution Early Holocene palynological records from the middle Meuse River valley were missing until recently. In order to investigate environmental and inferred climate changes during the Preboreal, sediments from a former residual channel of the Meuse River near Haelen were studied. Detailed multi-proxy analyses, including microfossils, macroremains and loss-on-ignition measurements, were carried out at a high temporal resolution. An accurate chronology of the >1000-year-long record was provided by accelerator mass spectrometry (AMS)14C wiggle-match dating.The channel was abandoned during the late Younger Dryas, when accumulation started with gyttja. This period was characterised by an open landscape with herbaceous vegetation and dwarf shrubs. Patches of birch were present on the floodplains around depressions and (oxbow) lakes. Some pines survived the cold in sheltered locations. In the residual channel the water was flowing temporarily and aquatic plant communities developed with predominantly submerged taxa and algae. The shores were fringed by willows and sedges and were probably used as a watering place by large herbivores.Following the Late-glacial/Holocene climate warming, dated in the Haelen record around 11,520 cal BP, birch woodlands expanded on the river floodplains and slopes of terraces during the Friesland Phase. Open vegetation with herbs and juniper remained present on the nearby terraces. An increase in the water level of the oxbow lake and seepage of groundwater occurred. Along the shores herbaceous vegetation was present. Around 11,420 cal BP, birch expansion was interrupted by the dry continental Rammelbeek Phase. On the river floodplain and terrace slopes, open grassland vegetation developed and on the terraces, grasslands and open grounds were abundant. In the residual channel the water became stagnant and floating-leaved vegetation developed. At the start of the Late Preboreal, around 11,270 cal BP, a sudden shift to a more humid climate took place and birch forests expanded again on the river floodplains and terrace slopes. Poplar became more abundant in these forests, and birch and poplar swamp forests were present near the site. Pine expanded atc. 11,160 cal BP on the higher sandy and gravelly terraces. During the Late Preboreal a reed swamp developed on the shores of the residual channel.At the onset of the Boreal, around 10,710 cal BP, woodlands, initially with hazel, but later also with oak, elm and lime, started to develop, while pine forest remained present on the higher terraces. Hazel shrubs were growing on the terrace slopes. Birch and poplar forests occurred on moist parts of the floodplains. Around the residual channel they formed a zone behind the reed swamps surrounding the oxbow lake. Vegetation with water lilies was present in open water.The Haelen record shows, despite a lack of archaeological evidence, indications for the presence of Mesolithic people in the area during the Preboreal. These include the occurrence of (natural or man-made) fires, in combination with the presence of trampled areas and disturbed grounds and possibly consumption of Nymphaeaceae seeds and tubers.

The warming at the Younger Dryas–Holocene transition (∼11,600 cal. BP) triggered the rearrangement of vegetation across Europe. To better understand that response, we analysed both an extended fossil pollen data set and robust present-day site parameters from NE Germany in a data model comparison approach. This approach allowed to quantify past plant abundances in sub-regional landscape patterns, as defined by soil types and relief. Betula was the first tree taxon to expand from scattered stands that already existed during the Younger Dryas. The major tree taxa Betula and Pinus fully established after 200–400 years as largely separated stands of Pinus on well drained sandy and Betula on fertile morainic soils. Corylus started to spread after 11,200 cal. BP, yet the final expansion was delayed until ∼10,800 cal. BP. Corylus established on gleyic soils, from which it largely expelled Betula . Throughout the first two millennia of the Holocene, open grasslands existed on fine grained soils, where seasonal dryness prevented the establishment of deciduous trees.

Based on radiocarbon and optically stimulated luminescence (OSL) results obtained in the last 5 yr, this paper discusses the absolute chronology of the formation of one of the largest sand dunes within NW Belgium, the Great Ridge of Maldegem-Stekene. Multiproxy analysis of 6 sedimentary sequences points to a complex formation history covering the entire Late Glacial. Dry phases, characterized by eolian deflation and sedimentation, alternated with wet phases in which numerous mostly shallow dune slacks were filled with freshwater. The latter reached their highest water level during the first half of the Allerød, attracting both animals (e.g. European elk) and humans (Federmesser hunter-gatherers). Near the end of the Allerød, all dune slacks finally disappeared as they were filled in with windblown sand ("coversand"), likely forcing prehistoric hunter-gatherers to leave the area.

A 2 m thick laminated lacustrine deposit of silt and clay recovered from the high-latitudinal site at Sokli (northern Finland) provides a unique mid-Weichselian fossil record for Fennoscandia. High-resolution botanical and zoological analyses of the lacustrine deposit allow detailed reconstruction of the regional vegetational development and of the history of the lake and the wetland ecosystem within the Sokli basin during the early part of the Weichselian Middle Pleniglacial (= equivalent to Marine Isotope Stage (MIS) 3). The inferred terrestrial vegetation represented by the Sokli MIS 3 sequence (so-called Tulppio Interstadial) was probably low-arctic tundra, treeless but with shrub elements including juniper, willow, dwarf birch, ericoids, lycopods and a rich herb flora with a variety of arctic–alpine taxa and heliophilous, pioneer elements. The presence of herbs such as Rubus chamaemorus, Epilobium palustre, Potentilla palustris and Sphagnum, Drepanocladus and other mosses suggests that the lake was fringed by wet meadows and peatlands or peaty telmatic communities. The distributional ranges of pine and tree birch were probably only a few hundred kilometres south or southeast of Sokli. This is concordant with evidence for the presence of boreal tree taxa during the MIS 3 in the Baltic countries and further east in Europe, but contradicts with the commonly inferred treeless tundra or grass-dominated steppe conditions in central Europe.

The vegetation of the northern Upper Rhine Graben (southwestern Germany) is reconstructed for the end of the Lateglacial and the Holocene by means of palynological analyses in combination with AMS 14c dating. Analogous to adjacent lowland areas, the Younger Dryas climatic deterioration did not result in a complete deforestation of the area and open pine woodlands with locally birch stands and shrubs persisted. A subdivision of the Younger Dryas period, into a humid first phase, followed by a dry second phase was also reflected in our records. For the Holocene, the pollen diagrams show two regionally different vegetation developments, related to substrate and variations in annual precipitation: in the south the ‘classical’ succession of pine then hazel is followed by other deciduous trees, whereas in the northern part, pine kept its dominance far into the Subboreal.

15 abrupt warming transitions perturbed glacial climate in Greenland during Marine Isotope Stage 3 (MIS 3, 60-27 ka BP). One hypothesis states that the 8-16 °C warming between Greenland Stadials (GS) and Interstadials (GI) was caused by enhanced heat transport to the North Atlantic region after a resumption of the Atlantic Meridional Overturning Circulation (AMOC) from a weak or shutdown stadial mode. This hypothesis also predicts warming over Europe, a prediction poorly constrained by data due to the paucity of well-dated quantitative temperature records. We therefore use a new evidence from biotic proxies and a climate model simulation to study the characteristics of a GS-GI transition in continental Europe and the link to enhanced AMOC strength. We compare reconstructed climatic and vegetation changes between a stadial and subsequent interstadial - correlated to GS15 and GI14 (∼55 ka BP) - with a simulated AMOC resumption using a three-dimensional earth system model setup with early-MIS 3 boundary conditions. Over western Europe (12°W-15°E), we simulate twice the annual precipitation, a 17 °C warmer coldest month, a 8 °C warmer warmest month, 1300 °C-day more growing degree days with baseline 5 °C (GDD5) and potential vegetation allowing tree cover after the transition. However, the combined effect of frequent killing frosts

Quantitative palaeotemperature estimates for the earlier part of Oxygen Isotope Stage (OIS-) 3 are inferred from subfossil chironomid remains. The high-latitudinal study site of Sokli, northeast Finland, provides for a unique lacustrine deposit covering the earlier part of OIS-3, and the chironomid remains found in the sediments show that a shallow lake with a diverse fauna was present at the study site throughout the record. Using a Norwegian calibration data set as a modern analogue, mean July air temperatures are reconstructed. The chironomid-inferred July air temperatures are surprisingly high, reaching values similar to the current temperature at the study site. Other proxies that were applied to the sediments included the analysis of botanical and zoological macro-remains, and our results concur with temperature estimates derived from climate indicator taxa. Summer temperatures for interstadial conditions, reconstructed with climate models, are as high as our proxy-based palaeotemperatures. © 2007 Springer Science+Business Media B.V.

Scandinavia is generally considered to have been covered extensively with ice throughout marine isotope stages (MIS) 4–2 between 75 and 10 ka. Here we present evidence for ice-free, warm conditions in the central area of the Scandinavian glaciations during MIS 3. Our multiproxy data obtained from a lacustrine sequence in northern Fin-land reveal not only significant response in the northeastern sector of the Scandinavian Ice Sheet to warming during the early part of MIS 3, but also indicate rapid climate warming to present-day temperatures in this ice-free period. New climate-model simulations for interstadial conditions in MIS 3 confirm the high mean July temperatures northeast of the Scandinavian Ice Sheet in response to the high insolation values and the presence of the ice sheet during MIS 3.