VS-oscilloscope: A new tool to parameterize tree radial growth based on climate conditions

Abstract

tIt is generally assumed in dendroecological studies that annual tree-ring growth is adequately deter-mined by a linear function of local or regional precipitation and temperature with a set of coefficientsthat are temporally invariant. However, various researchers have maintained that tree-ring records arethe result of multivariate, often nonlinear biological and physical processes. To describe critical pro-cesses linking climate variables with tree-ring formation, the process-based tree-ring Vaganov–Shashkinmodel (VS-model) was successfully used. However, the VS-model is a complex tool requiring a consid-erable number of model parameters that should be re-estimated for each forest stand. Here we present anew visual approach of process-based tree-ring model parameterization (the so-called VS-oscilloscope)which allows the simulation of tree-ring growth and can be easily used by researchers and students.The VS-oscilloscope was tested on tree-ring data for two species (Larix gmeliniiand Picea obovata) grow-ing in the permafrost zone of Central Siberia. The parameterization of the VS-model provided highlysignificant positive correlations (p < 0.0001) between simulated growth curves and original tree-ringchronologies for the period 1950–2009. The model outputs have shown differences in seasonal tree-ringgrowth between species that were well supported by the field observations. To better understand sea-sonal tree-ring growth and to verify the VS-model findings, a multi-year natural field study is needed,including seasonal observation of the thermo-hydrological regime of the soil, duration and rate of tracheiddevelopment, as well as measurements of their anatomical features.