Browsing by Author "van Geel, B"

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    Bog burst in the eastern Netherlands triggered by the 2.8 kyr BP climate event
    (Sage Journals, 2014-11) van Geel, B; Heijnis, H; Charman, DJ; Thompson, G; Engels, S
    The nature and cause of the so-called 2.8 kyr BP event have been a subject of much debate. Peat sequences have provided much of the evidence for this event, but the process link between climate and peatland response is not well understood. Multiproxy, high-resolution analysis of a core from Bargerveen in the eastern Netherlands based on pollen, non-pollen palynomorphs, testate amoebae and geochemistry identified an abrupt shift from relatively dry to extremely wet conditions. Radiocarbon-based wiggle-match dating (WMD) and biostratigraphy based on the pollen record show that this shift in local hydrology occurred around 2800 cal. yr BP. We interpret an erosional hiatus lasting up to 950 years immediately prior to this, as the effect of a bog burst after excessive rainfall. This phenomenon was not limited to our sampling location but occurred over a large part of the former Bargerveen. Peat at the hiatus contains microfossils that reflect temporary eutrophication as a consequence of local fires and secondary decomposition because of increased drainage after the erosion event. Our data show how detailed multiproxy analyses can elucidate the past response of peatlands to changing climate and suggest that the climatic change in northwest Europe at this time caused major non-linear disruption to these ecosystems. © 2014, © SAGE Publications.
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    Bog burst in the eastern Netherlands triggered by the 2.8 kyr BP climate event
    (University of New South Wales and Australian Nuclear Science and Technology Organisation, 2015-07-09) Heijnis, H; van Geel, B; Charman, DJ; Thompson, G; Engels, S
    Not provided to the ANSTO Library.
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    Pollen-based quantitative reconstructions of holocene regional vegetation cover (plant-functional types and land-cover types) in Europe suitable for climate modelling
    (Wiley Online Library, 2014-10-22) Trodman, AK; Gaillard, MJ; Mazier, F; Sugita, S; Fyfe, RM; Neilsen, AB; Twiddle, C; Barratt, P; Birks, HJ; Bjune, AE; Björkman, L; Broström, A; Caseldine, C; David, R; Dodson, JR; Dörfler, W; Fisher, E; van Geel, B; Giesecke, T; Hultberg, T; Kalnina, L; Kangur, M; van der Knaap, P; Kuneš, P; Lagerås, P; Latalowa, M; Lechterbeck, J; Leroyer, C; Leydet, M; Lindbladh, M; Marquer, L; Mitchell, FJG; Odgaard, BV; Peglar, SM; Persson, T; Poska, A; Rösch, M; Seppä, H; Veski, S; Wick, L; Koff, T
    We present quantitative reconstructions of regional vegetation cover in north-western Europe, western Europe north of the Alps, and eastern Europe for five time windows in the Holocene [around 6k, 3k, 0.5k, 0.2k, and 0.05k calendar years before present (bp)] at a 1° × 1° spatial scale with the objective of producing vegetation descriptions suitable for climate modelling. The REVEALS model was applied on 636 pollen records from lakes and bogs to reconstruct the past cover of 25 plant taxa grouped into 10 plant-functional types and three land-cover types [evergreen trees, summer-green (deciduous) trees, and open land]. The model corrects for some of the biases in pollen percentages by using pollen productivity estimates and fall speeds of pollen, and by applying simple but robust models of pollen dispersal and deposition. The emerging patterns of tree migration and deforestation between 6k bp and modern time in the REVEALS estimates agree with our general understanding of the vegetation history of Europe based on pollen percentages. However, the degree of anthropogenic deforestation (i.e. cover of cultivated and grazing land) at 3k, 0.5k, and 0.2k bp is significantly higher than deduced from pollen percentages. This is also the case at 6k in some parts of Europe, in particular Britain and Ireland. Furthermore, the relationship between summer-green and evergreen trees, and between individual tree taxa, differs significantly when expressed as pollen percentages or as REVEALS estimates of tree cover. For instance, when Pinus is dominant over Picea as pollen percentages, Picea is dominant over Pinus as REVEALS estimates. These differences play a major role in the reconstruction of European landscapes and for the study of land cover–climate interactions, biodiversity and human resources. © 2014, The Authors Global Change Biology Published by John Wiley & Sons Ltd. Open Access CC-NC Licence.