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Abstract: With global warming, the distribution of warmth through the year is likely to change in the future and comparable changes may have occurred over the course of the Holocene. Its effect on vegetation composition and species distribution can be compared to that of a continental versus an oceanic climate. The distribution of five major tree species along a continentality gradient was studied in Fennoscandia based on distribution maps and on their proportions of pollen in surface-sediment samples. Both analyses indicate that the five arboreal species show similar patterns of response to a continentality index in the order Ulmus glabra, Corylus avellana, Quercus robur, Tilia cordata, and Picea abies from the most oceanic to most continental. Continentality, growing degree days above 5°C, and January temperature were reconstructed quantitatively from four pollen diagrams using transfer functions based on a combined Fennoscandian pollen surface-sample data-set. Quantitative reconstructions indicate that the climate in Fennoscandia has become increasingly more continental over the last 7000 years, and this is largely an effect of winter cooling. Early Holocene vegetation composition has poor analogues to the present vegetation in Fennoscandia, which hampers quantitative reconstructions. Qualitative reconstructions suggest that the early Holocene in Fennoscandia was the most oceanic period, but probably with a high variability in temperature. [Copyright &y& Elsevier]

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. [ABSTRACT FROM AUTHOR]