In search of the Bølling-Oscillation: a new high resolution pollen record from the locus classicus Lake Bølling, Denmark

Krüger, Sascha; Damrath, Martin

doi:10.1007/s00334-019-00736-3

Cited by 25 publications

(21 citation statements)

References 76 publications

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“…Presumably Juniperus sp. and For Hippophaë sp., a second, albeit weakly pronounced maximum can be observed which can be compared to other sites in Schleswig-Holstein (Usinger 1985; as well as Denmark (Krüger & Damrath 2019;Mortensen et al 2011) and suggests, that sea buckthorn was prevalent among the shrub vegetation. The characteristics of the assemblage zone are mainly in line with those of the Hippophaë-Betula nana-PAZ as well as partly with the Helianthemum-Betula nana-PAZ as defined by Usinger (1985).…”

Section: Nahmentioning

confidence: 59%

“…The separation from the Pleniglacial is linked to a significant increase in Artemisia values as well as characteristic species as Hippophaë, Helianthemum, Selaginella selaginoides and an increase in overall AP (arboreal pollen) percentages (De Klerk 2008b;Hoek 1997;Iversen 1954;Menke 1968;Van der Hammen 1951;Van Geel 1989). Following the results of Krüger and Damrath (2019) Meiendorf as biostratigraphic expression equals the term Bølling (Iversen 1942) in classical Danish research context. Therefore, and to further avoid confusion of terms, we refrain from using the term Bölling/Bølling as designation for the first phase of the later following Allerød period (Usinger 1981c;1985).…”

Section: Biostratigraphical Terminology and Zonation Of The Lateglacialmentioning

confidence: 99%

“…As supplement to the macrofossil data Betula pollen were measured in order to differentiate between a Betula nana-type and a B. pubescens-type (Beug 2004). Therefore, a fixed threshold of 21.5 μm was applied following Birks (1968), Karlsdóttir et al (2007), Kolstrup (1982), Krüger and Damrath (2019), Mortensen et al (2011) andUsinger (1975;1978a;1981b;. Pollen of termophilous taxa such as Alnus, Quercus, Ulmus, Tilia, Carpinus, Corylus, Fagus, Hedera and Ilex aquifolium are regarded as rebedded if appearing in a Lateglacial context.…”

Section: Pollen Analysismentioning

confidence: 99%

“…Due to extreme drought, temporally undefined wildfires occurred here, which subsequently led to the formation of the Usselo and Finow horizons at terrestrial sites (Crombé 2016;Hoek 1997;Kaiser 2003;Kaiser et al 2009;Tolksdorf et al 2014;Van der Hammen and Van Geel 2008). In limnic archives of Jutland and Schleswig-Holstein at the transition from the Allerød period to the Dryas 3 period often hiatuses can be observed (Krüger & Damrath 2019;Iversen 1942;Usinger 1981a;Usinger and Wolf 1982). Here, these hiatuses are mainly the result of the mentioned droughts that in turn are responsible for lake level fluctuations and extensive redeposition processes (Kasse 1997;Usinger 1981a).…”

Section: A Significant Increase In Pollen Concentration Is Mainly Duementioning

confidence: 99%

“…Another challenge is the ambiguity in biostratigraphical terminology on a geographically large scale that are only gradually being overcome (De Klerk 2004a;Donner 1995;Hoek 1997;2009;Krüger & Damrath 2019;Litt et al 2007;Mangerud et al 1974;Menke 1968;Usinger 1985). The comprehensive research results from Schleswig-Holstein could just marginally contribute to the discussion of terminology, as radiocarbon dates were rarely used to ensure a reliable chronological frame.…”

Section: Introductionmentioning

confidence: 99%

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Sequence completed – palynological investigations on Lateglacial/Early Holocene environmental changes recorded in sequentially laminated lacustrine sediments of the Nahe palaeolake in Schleswig-Holstein, Germany.

Krüger¹,

Mortensen²,

Dörfler³

2020

Preprint

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The exploration of Lateglacial vegetation history in Schleswig-Holstein is elaborate and comprehensive. Despite being one of the most studied areas, regarding to the Lateglacial, no biostratigraphy covering the complete Lateglacial and Early Holocene periods without hiatus have so far been recovered. In this paper we present a biostratigraphy of the Nahe palaeolake, therewith intending to deal with this desideratum.The special strength of the presented sequence is expressed in the fact that these are the only palynologically investigated sequentially annual laminated limnic sediments of the Lateglacial in Schleswig-Holstein. These laminated sediments, as well as radiocarbon dating of botanical macrofossils and three geochemically confirmed cryptotephra layers (Laacher See Tephra, Vedde Ash and Saksunarvatn Ash), provide excellent chronological control and allow for a Europe-wide correlation. Particularly important is a complete discussion of the vegetation history and the spatial proximity to Late Palaeolithic sites, which renders it possible to evaluate potential humanenvironment-interaction long before classical palynological human indicators occur. (2017) and radiocarbon ages of bones and antler suggest a temporal classification into the Dryas 3 period and partly into the early Preboreal period. Faunal remains have been investigated by WildFor that time, a ford situation can be reconstructed at the south-eastern end of the lake in the form of a shallow water area above a sand ridge, situated at the foot of the morain. The composition of the finds, antler technology as well as the topographical situation reflect a comparable situation as reconstructed for the Ahrensburg tunnel valley, located only 18 km to the south (Rust 1943; Rust and Gripp 1937). Materials and Methods Field methods and samplingThe coring took place in October 2017. A modified Livingston piston corer (Mingram et al. 2007)the so called Usinger-corerwas used to extract the sediment cores. Two overlapping sediment sequences with a diameter of 80 mm and a length of 16 m have been reached by drilling. Each 1-msegment was cut longitudinally, stored in PVC-liners and processed at the Institute for Pre-and Protohistoric Archaeology in Kiel, Germany. In order to connect the core sequences a series of distinct layers and stratigraphic marker horizons have been defined in the parallel cores. In this way, a composite core was constructed, representing a continuous record avoiding gaps (Dörfler et al. 2012).The interdisciplinary approach of the study required that the results of different methods could be correlated across depths. Therefore, a grid of 5 mm step size was created spanning the lower 5 m of the sequence. Each sample has been labelled according to consecutive numbers (953 potential samples in total, 11.10 m -15.89 m below the surface). A preliminary examination with 16 pollen samples determined the focus sequence for the analyses. The scope of the analyses is set on the sequence between sample 330 (12.745-12.750 m, ~10,030 cal yr BP) and 90...

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Section: Nahmentioning

confidence: 59%

Section: Biostratigraphical Terminology and Zonation Of The Lateglacialmentioning

confidence: 99%

Section: Pollen Analysismentioning

confidence: 99%

Section: A Significant Increase In Pollen Concentration Is Mainly Duementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Sequence completed – palynological investigations on Lateglacial/Early Holocene environmental changes recorded in sequentially laminated lacustrine sediments of the Nahe palaeolake in Schleswig-Holstein, Germany.

Krüger¹,

Mortensen²,

Dörfler³

2020

Preprint

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First automatic size measurements for the separation of dwarf birch and tree birch pollen in MIS 6 to MIS 1 records from Northern Germany

Theuerkauf,

Nehring,

Gillert

et al. 2024

Ecology and Evolution

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During past glacial periods, the land cover of Northern Eurasia and North America repeatedly shifted between open steppe tundra and boreal/temperate forest. Tracking these changes and estimating the coverage of open versus forested vegetation in past glacial and interglacial landscapes is notoriously difficult because the characteristic dwarf birches of the tundra and the tree birches of the boreal and temperate forests produce similar pollen grains that are difficult to distinguish in the pollen record. One objective approach to separating dwarf birch pollen from tree birch pollen is to use grain size statistics. However, the required grain size measurements are time‐consuming and, therefore, rarely produced. Here, we present an approach to automatic size measurement based on image recognition with convolutional neural networks and machine learning. It includes three main steps. First, the TOFSI algorithm is applied to detect and classify pollen, including birch pollen, in lake sediment samples. Second, a Resnet‐18 neural network is applied to select the birch pollen suitable for measurement. Third, semantic segmentation is applied to detect the outline and the area and mean width of each detected birch pollen grain. Test applications with two pollen records from Northern Germany, one covering the Lateglacial‐Early Holocene transition and the other covering the Mid to Late Pleistocene transition, show that the new technical approach is well suited to measure the area and mean width of birch pollen rapidly (>1000 per hour) and with high accuracy. Our new network‐based tool facilitates more regular size measurements of birch pollen. Expanded analysis of modern birch pollen will help to better understand size variations in birch pollen between birch species and in response to environmental factors as well as differential sample preparation. Analysis of fossil samples will allow better quantification of dwarf birch versus tree birch in past environments.

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Small shards and long distances — three cryptotephra layers from the Nahe palaeolake including the first discovery of Laacher See Tephra in Schleswig‐Holstein (Germany)

Krüger

Bogaard

2020

J Quaternary Science

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Investigations of Lateglacial to Early Holocene lake sediments from the Nahe palaeolake (northern Germany) provided a high‐resolution palynological record. To increase the temporal resolution of the record a targeted search for cryptotephra was carried out on the basis of pollen stratigraphy. Three cryptotephra horizons were detected and geochemically identified as G10ka series tephra (a Saksunarvatn Ash), Vedde Ash and Laacher See Tephra. Here we present the first geochemically confirmed finding of the ash from the Laacher See Eruption in Schleswig‐Holstein—extending the so far detected fallout fan of the eruption further to the north‐west. These finds enable direct stratigraphical correlations and underline the potential of the site for further investigations.

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In search of the Bølling-Oscillation: a new high resolution pollen record from the locus classicus Lake Bølling, Denmark

Cited by 25 publications

References 76 publications

Sequence completed – palynological investigations on Lateglacial/Early Holocene environmental changes recorded in sequentially laminated lacustrine sediments of the Nahe palaeolake in Schleswig-Holstein, Germany.

Sequence completed – palynological investigations on Lateglacial/Early Holocene environmental changes recorded in sequentially laminated lacustrine sediments of the Nahe palaeolake in Schleswig-Holstein, Germany.

First automatic size measurements for the separation of dwarf birch and tree birch pollen in MIS 6 to MIS 1 records from Northern Germany

Small shards and long distances — three cryptotephra layers from the Nahe palaeolake including the first discovery of Laacher See Tephra in Schleswig‐Holstein (Germany)

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