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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.

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.

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.

Botanical microfossils, macroremains and oribatid mites of a Weichselian interstadial deposit in the central Netherlands point to a temporary, sub-arctic wetland in a treeless landscape. Radiocarbon dates and OSL dates show an age between ca. 54.6 and 46.6 ka cal BP. The vegetation succession, starting as a peat-forming wetland that developed into a lake, might well be linked with a Dansgaard-Oeschger climatic cycle. We suggest that during the rapid warming at the start of a D-O cycle, relatively low areas in the landscape became wetlands where peat was formed. During the more gradual temperature decline that followed, evaporation diminished; the wetlands became inundated and lake sediments were formed. During subsequent sub-arctic conditions the interstadial deposits were covered with wind-blown sand. Apart from changes in effective precipitation also the climate-related presence and absence of permafrost conditions may have played a role in the formation of the observed sedimentological sequence from sand to peat, through lacustrine sediment, with coversand on top. The Wageningen sequence may correspond with D-O event 12, 13 or 14. Some hitherto not recorded microfossils were described and illustrated.

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.

In order to compare environmental and inferred climatic change during the Preboreal in The Netherlands, five terrestrial records were analysed. Detailed multi-proxy analyses including microfossils (e.g., pollen, spores, algae, and fungal spores), macroremains (e.g., seeds, fruits, wood, mosses, etc.), and loss on ignition measurements were carried out with high temporal resolution. To link the five Preboreal records, accurate chronologies were produced by AMS C-14 wiggle-match dating. The Dutch records show that following the Lateglacial/Holocene climate warming, birch woodlands expanded between 11,530 and 11,500 cal BP during the Friesland Phase of the Preboreal. After the Friesland Phase, two distinct climatic shifts could be inferred: (1) around 11,430-11,350 cal BP the expansion of birch forests was interrupted by a dry continental phase with open grassland vegetation, the Rammelbeek Phase. This phase was coeval with the coldest part of the Preboreal oscillation (PBO) as observed in the delta O-18 record of the Greenland ice-core records and has been attributed to a large meltwater flux that resulted in a temporary decrease of the thermohaline circulation in the North Atlantic. (2) At the start of the Late Preboreal, between 11,270 and 11,210 cal BP, a Sudden shift to a more humid climate occurred and birch forests expanded again. A simultaneous increase in the cosmogenic nuclides C-14 and Be-10 suggests that these changes in climate and vegetation were forced by a sudden decline in solar activity. Expansion of pine occurred during the later part of the Late Preboreal. At the onset of the Boreal, between 10,770 and 10,700 cal BP, dense woodlands with hazel, oak, elm and pine started to develop in The Netherlands. (C) 2007 Elsevier Ltd. All rights reserved.

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Detailed botanical (microfossil and macroremain), zoological and geochemical analyses (major and trace elements including C, Al, S, Ca, Fe, P, As, Zn, U, Ba and Rare Earth Elements) of organic deposits provide new insights into Early Holocene environmental change in the Kreekrak area (southwestern Netherlands). The age assessment of the record is based on high resolution AMS 14 C wiggle-match dating (WMD). For the first time an AMS 14 C WMD based chronology covering the Late Glacial/Holocene transition and early Preboreal is introduced for a site in The Netherlands. The Kreekrak botanical record reflects the end of the Younger Dryas to early Boreal and can be well correlated with pollen records from other sites in The Netherlands and Belgium. The palaeo-topography showed that the Kreekrak deposits formed in an abandoned channel of the River Schelde. Around ca. 11,490 cal BP, at the end of the Late Glacial/Holocene transition, infilling of the lake started with predominantly organic deposits in slowly running water. As a result of the warmer climate the area became forested with birch and poplar during the Friesland Phase (ca. 11,490-11,365 cal BP). Biological productivity of the lake and its surroundings increased. Aquatic vegetation developed in the lake, while shrubs of willow, reed swamps and grasslands fringed the shores. Precipitation increased, which caused a rise in the lake water table and an increase in the supply of oxic surface (= river) water into the Kreekrak lake. During this period, the Kreekrak lake was fed by inflowing river water, run-off, precipitation and seepage of Fe-rich groundwater. Around ca. 11,435 cal BP the water became stagnant probably as result of a total cut-off of the river channel. Inflow of river water ceased, while the supply of reduced Fe-rich groundwater became dominant. During the Rammelbeek Phase (ca. 11,365–11,250 cal BP), the climate was more continental and the abundance of grasslands and open herbaceous vegetation increased. Biological productivity remained high. In the lake, the supply of Fe-rich groundwater continued, the water level slightly decreased but aquatic vegetation remained present. At the end of the Rammelbeek Phase a sudden reduction in the supply of Fe-rich reduced groundwater caused a lowering of the groundwater level in the area, resulting in the development of a hiatus. Due to this hiatus, the Late Preboreal (11,250–10,710 cal BP) is absent from the record. During the early Boreal (10,710–10,000 cal BP) the landscape became densely forested and accumulation of peat in the former lake resumed due to a slowly rising groundwater level. The Boreal was a relatively stable period with low sedimentation rates. The combination of palaeobotanical and geochemical analyses in the Kreekrak record shows a close interrelation between landscape development and geochemistry. It appears that the environmental development of this area during the Late Glacial/Holocene transition and Early Holocene was largely influenced (directly or indirectly) by major climatic changes that occurred during this period, which determined local phenomena such as the composition and density of the vegetation, occurrence of seepage and river activity. Further research of this type has the potential to develop the application of major- and trace element geochemistry in palaeoenvironmental reconstructions.

The Early Holocene landscape near Zutphen (The Netherlands) is reconstructed by means of microfossil, macroremain and bone analyses. In this area early Mesolithic sites were found on a river dune along a former river channel. AMS14C dating provided a detailed chronology for the sites and river channel deposits. Between ca. 9800–9600 B.P. open herbaceous vegetation was present on the river dunes. The residual channels were fringed by reed swamps and willow shrubs, with birch and poplar woodlands inland. During this period there are indications of natural or man-made burning of the reed swamp vegetation along the residual channel. Also trampling zones along the lake edge were more abundant. However, no archaeological sites were discovered in the vicinity. From ca. 9600 B.P. on, the area became more densely forested; willow, birch and poplar replaced the reed swamps along the residual channels, while pine colonised the river dunes. Archaeological finds show that early Mesolithic people inhabited the area between ca. 9400 and 9200 B.P. and between ca. 8900–8700 B.P. During the earlier period, records of Urtica, Plantago and coprophilous fungi may point to trampling and/or eutrophication as a result of the presence of large herbivores and people along the channel shores. After ca. 8700 B.P. people probably left the area when open water was no longer available in the vicinity.

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The Lateglacial and Early Holocene vegetation history of the northern Wetterau and Amöneburger Basin, two intra-montane basins in Hessen, central-west Germany, is reconstructed by means of pollen and macrofossil analyses. Regional pollen assemblage zones are defined for the Lateglacial and Early Holocene. After calibration of the radiocarbon dates and establishment of age/depth relationships, the ages of the pollen zone boundaries are calculated. The regional vegetation changes correlate closely with the major fluctuations in the delta18O curve of the Greenland ice cores spanning the same time period. During the early Lateglacial, the open herbaceous vegetation with dwarf shrubs in the northern Wetterau was replaced by woodlands. Initially these woodlands consisted of birch, but after the immigration of pine, mixed forests of pine and birch developed. Soon after its immigration pine became dominant and pine woodlands largely replaced the birch forests. Only on the locally wetter substrates of the river floodplain did Betula stands persist. Gradually the importance of herbaceous communities declined and the pine woodlands lost their open character. During the Lateglacial two regressive phases in the vegetation succession are reflected in the data which are equated with the Older- and Younger Dryas biozones. At the beginning of the Younger Dryas, the forest-limit was lowered and the importance of herbaceous communities increased. Later, pine woodlands thinned and Ericales became part of the vegetation, indicating the development of more acid, nutrient-poor soils. A subdivision of the Younger Dryas biozone into a wetter, colder first part and a drier, warmer second part is suggested. At the beginning of the Early Holocene, pine woodlands became more closed and soils more stabilised. The transition between the Younger Dryas and Preboreal biozones is indicated by a lithological change to organic (-rich) deposits. Betula stands persisted on the locally wetter substrates of the fluvial plains. At the end of the early Preboreal, there was an extension of Betula stands on the river floodplains. This is interpreted as a phase in which climate was temporarily wetter, perhaps a reflection of a short-term climatic oscillation, the so-called Preboreal oscillation. During the Preboreal biozone, ferns became more important in the local vegetation of the mires, and later during the Boreal they formed the undergrowth of swamp forests. During the Boreal biozone, a major expansion of hazel took place in both areas. On the hills and slopes of the northern Wetterau and the Amöneburger Basin, open pine forests and hazel scrub developed with grasses and Pteridium in the field layer. In the river valleys, pine forests were replaced by deciduous mixed forests with oak, elm and later also with lime.

Late Pleistocene climatically induced environmental changes are reconstructed by applying a multidisciplinary approach on floodplain sediments of small- to medium-sized catchments in central Germany. Radiocarbon dating, pollen analysis and the presence of an accurately dated tephra layer allow the establishment of a reliable chronology. The beginning of the Younger Dryas is marked by a change in fluvial activity that lasts for several hundred years. During this period gravels and sands were deposited by a braided river system. Fluvial systems at this time were predominantly controlled by the climatic conditions of the surrounding uplands, where the climatic deterioration led to a lowering of the forest limit and enhanced periglacial slope processes. An open pine forest prevailed in the basin areas and no evidence of slope wash and solifluction was found. The second part of the Younger Dryas is characterised by a meandering fluvial system and the deposition of overbank fines. The rapid transition from Younger Dryas to Preboreal coincides with an increase in organic deposition.

Cryoturbated organic beds and channel fills, intercalated with sandy and gravelly fluvial units, have been studied in an opencast brown-coal mine near Nochten (Niederlausitz), eastern Germany. The fluvial-aeolian sequence covers parts of the Early, Pleni- and Late-glacial. The detailed chronology is based on 11 radiocarbon and 12 OSL dates, covering the period between ca. 100 kyr and 11 kyr BP. Basal peat deposits are correlated with an Early Weichselian interstadial. During this period boreal forests were present and minimum mean summer temperatures were > 13°C. Early Pleniglacial deposits are absent. The Middle and Late Pleniglacial environments were treeless and different types of tundra vegetation can be recognised. Minimum mean summer temperatures varied between 10 and 15°C. Vegetation and climate is reconstructed in detail for the periods around 34-38 kyr BP and 24-25 kyr BP. Around 34-38 ka, a mixture between a low shrub tundra and a cottongrass tussock-subshrub tundra was present. The botanical and sedimentological data suggest that from the Middle to the Late Pleniglacial, the climate became more continental, aridity and wind strength increased, and the role of a protecting winter snow cover decreased. A sedge-grass-moss tundra dominated around 24 and 25 kyr BP. Copyright © 2001 John Wiley & Sons, Ltd.

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Comparison of palynological data from lake deposits and soils from locations along a transect approaching the remains of a Palaeolithic settlement in the Younger Dryas stadial shows four cycles in the vegetation from (open) pine forest to open ground vegetation and back to (open) pine forest. This outcome is discussed in terms of the impact of man on the vegetation in the later part of the Weichselian Lateglacial.

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