Process based model sheds light on climate sensitivity of Mediterranean tree-ring width

[摘要] We use the process-based VS (Vaganov-Shashkin) model to investigate whethera regional Pinus halepensis tree-ring chronology from Tunisia can be simulated as a functionof climate alone by employing a biological model linking day length anddaily temperature and precipitation (AD 1959–2004) from a climate station toring-width variations. We check performance of the model on independent databy a validation exercise in which the model's parameters are tuned usingdata for 1982–2004 and the model is applied to generate tree-ring indicesfor 1959–1981. The validation exercise yields a highly significant positivecorrelation between the residual chronology and estimated growth curve(r=0.76 p<0.0001, n=23). The model shows that the average duration of thegrowing season is 191 days, with considerable variation from year to year.On average, soil moisture limits tree-ring growth for 128 days andtemperature for 63 days. Model results depend on chosen values ofparameters, in particular a parameter specifying a balance ratio betweensoil moisture and precipitation. Future work in the Mediterranean regionshould include multi-year natural experiments to verify patterns ofcambial-growth variation suggested by the VS model.

[学科分类] 地球化学与岩石