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Pollen based landcover reconstructions help to reveal past climate–human–land-cover interactions in Europe (LANDCLIM2)
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Edité par CCSD -
International audience. Climate has been a major determinant of vegetation composition throughout geological history. However, during the last millennia, the effects of anthropogenic forcing have become prevalent in many areas. Quantitative landcover reconstructions are needed in order to better understand climate–human–land-cover interactions. A set of temporally and spatially continuous, continent -scale, pollen-based landcover reconstructions of Europe during the Holocene (last 11,700 cal yr BP) were recently produced by the LANDCLIM2 project. The 1°×1° maps representing percentage cover of 31 plant taxa assigned to 12 plant functional types and three land-cover types were compiled using Bayesian statistical models with the REVEALS (Regional Estimates of VEgetation Abundance from Large Sites) model reconstructions based on 1,128 pollen records across Europe (30° –75° N, 25° W–50° E). The reconstructed landcover in combination with ecosystem-model-derived climate inducedlandcover estimates were used as inputs to the RCM (Regional Climate Model) in order to determine the continent-scale impact of anthropogenic deforestation on climate at 6k, 2,5k and 0.02k. Results show that the anthropogenically induced land cover changes have beenstrong enough even during the time period before the industrial revolution to cause major changes in the physical properties of landcover and the induced biogeophysical changes vary considerably both geographically and seasonally. The albedo changes are the most 155prominent during winter in the boreal forest zone, with deforestation leading to increased reflection of solar radiation from snow covered fields causing a decrease in winter temperature. The deforestation of the Mediterranean has led to an increased albedo and decreased temperature during the summer season. The changes in evapotranspiration are most prominent during summer in the temperate broad-leafed forest zone with deforestation leading to increased summer temperatures. Most of the changes described above are more pronounced in the eastern, more continental part of Europe
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