Browsing by Author "Kuneš, P"

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    How old is the Tasmanian cultural landscape? A test of landscape openness using quantitative land-cover reconstructions
    (John Wiley and Sons, 2017-06-19) Mariani, M; Connor, SE; Fletcher, MS; Theuerkauf, M; Kuneš, P; Jacobsen, GE; Saunders, KM; Zawadzki, A
    Aim To test competing hypotheses about the timing and extent of Holocene landscape opening using pollen-based quantitative land-cover estimates. Location Dove Lake, Tasmanian Wilderness World Heritage Area, Australia. Methods Fossil pollen data were incorporated into pollen dispersal models and corrected for differences in pollen productivity among key plant taxa. Mechanistic models (REVEALS—Regional Estimates of VEgetation Abundance from Large Sites) employing different models for pollen dispersal (Gaussian plume and Lagrangian stochastic models) were evaluated and applied in the Southern Hemisphere for the first time. Results Validation of the REVEALS model with vegetation cover data suggests an overall better performance of the Lagrangian stochastic model. Regional land-cover estimates for forest and non-forest plant taxa show persistent landscape openness throughout the Holocene (average landscape openness ~50%). Gymnoschoenus sphaerocephalus, an indicator of moorland vegetation, shows higher values during the early Holocene (11.7–9 ka) and declines slightly through the mid-Holocene (9–4.5 ka) during a phase of partial landscape afforestation. Rain forest cover reduced (from ~40% to ~20%) during the period between 4.2–3.5 ka. Main conclusions Pollen percentages severely under-represent landscape openness in western Tasmania and this bias has fostered an over-estimation of Holocene forest cover from pollen data. Treeless vegetation dominated Holocene landscapes of the Dove Lake area, allowing us to reject models of landscape evolution that invoke late-Holocene replacement of a rain forest-dominated landscape by moorland. Instead, we confirm a model of Late Pleistocene inheritance of open vegetation. Rapid forest decline occurred after c. 4 ka, likely in response to regional moisture decline. © 2017 John Wiley & Sons Ltd
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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.