Effects of land-use and climate on Holocene vegetation composition in northern Europe

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Marquer, Laurent | Gaillard, M.J. | Sugita, Shinya | Anneli, Poska | Trondman, A.-K. | Mazier, Florence | Nielsen, A.B. | Fyfe, Ralph | Maria Jönsson, Anna

Edité par CCSD -

International audience. Prior to the advent of agriculture, broad-scale vegetation patterns in Europe were controlled primarily by climate.Early agriculture can be detected in palaeovegetation records, but the relative extent to which past regionalvegetation was climatically or anthropogenically-forced is of current scientific interest. Using comparisons oftransformed pollen data, climate-model data, dynamic vegetation model simulations and anthropogenic land-coverchange data, this study aims to estimate the relative impacts of human activities and climate on the Holocenevegetation composition of northern Europe at a subcontinental scale.The REVEALS model was used for pollen-based quantitative reconstruction of vegetation (RV). Climate variablesfrom ECHAM and the extent of human deforestation from KK10 were used as explanatory variables to evaluatetheir respective impacts on RV. Indices of vegetation-composition changes based on RV and climate-inducedvegetation simulated by the LPJ-GUESS model (LPJG) were used to assess the relative importance of climate andanthropogenic impacts.The results show that climate is the major predictor of Holocene vegetation changes until 5000 years ago. Thesimilarity in rate of change and turnover between RV and LPJG decreases after this time. Changes in RV explainedby climate and KK10 vary for the last 2000 years; the similarity in rate of change, turnover, and evenness betweenRV and LPJG decreases to the present.The main conclusions provide important insights on Neolithic forest clearances that affected regional vegetationfrom 6700 years ago, although climate (temperature and precipitation) still was a major driver of vegetation change(explains 37% of the variation) at the subcontinental scale. Land use became more important around 5000-4000years ago, while the influence of climate decreased (explains 28% of the variation). Land-use affects all indicesof vegetation compositional change during the last 2000 years; the influence of climate on vegetation, althoughreduced, remains at 16% until modern time while land-use explains 7%, which underlines that North-Europeanvegetation is still climatically sensitive and, therefore, responds strongly to ongoing climate change.

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