Articles | Volume 9, issue 3
Biogeosciences, 9, 965–972, 2012
Biogeosciences, 9, 965–972, 2012

Research article 09 Mar 2012

Research article | 09 Mar 2012

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

R. Touchan1, V. V. Shishov2, D. M. Meko1, I. Nouiri3, and A. Grachev2 R. Touchan et al.
  • 1Laboratory of Tree-Ring Research, The University of Arizona, P.O. Box 210058 Tucson, Arizona 85721-0058, USA
  • 2Siberian Federal University, Prospekt Svobodniy 79, Krasnoyarsk, 660041, Russia
  • 3National Institute of Agronomy of Tunisia, 43 Avenue Charles Nicolle, 1002 Tunis, Tunisia

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

Final-revised paper