Modelling carbon isotope fractionation in tree rings based on effective evapotranspiration and soil water status |
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Authors: | J-L DUPOUEY S LEAVITT E CHOISNEL S JOURDAIN |
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Institution: | Laboratoire de Phytoécologie forestière, INRA, 54280 Champenoux, France;Laboratory of Tree-Ring Research, The University of Arizona, Building #58. Tucson, Arizona 85721, USA;Meteo France, 2 Avenue Rapp, 75340 Paris Cedex 07, France |
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Abstract: | Environmental influences on carbon isotope fractionation in tree rings require further elucidation in order to use this parameter as a biological marker of climatic variations. δ13C values in tree-ring cellulose of beech (Fagus sylvatica L.) were analysed for the period from 1950 to 1990. A bioclimatic model of water balance was used to give the actual evapotranspiration as well as the soil water content on a daily basis. δ13C shows a significant decrease from –24·5‰ to –25‰ over this period. Internal CO2 concentration changes from 200 to 220 ppm in relation with the rise of atmospheric CO2. Beside a slight non-significant inter-individual variation, a large year-to-year variation exists. The relative extractable soil water of July, combined with the value of δ13C for the previous year, predicts as much as 70% of this variance. Air temperature or precipitation accounted for less variation. δ13C is strongly correlated with basal area increment, but appeared a more reliable indicator of water status at the stand level. |
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Keywords: | Fagus sylvatica L : Fagaceae beech δ13C tree ring water balance model internal CO2 concentration greenhouse effect |
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