How Well Understood Are the Processes that Create Dendroclimatic Records? A Mechanistic Model of the Climatic Control on Conifer Tree-Ring Growth Dynamics - Dendroclimatology - page 37

Chapter 3
How Well Understood Are the Processes that
Create Dendroclimatic Records? A Mechanistic
Model of the Climatic Control on Conifer
Tree-Ring Growth Dynamics

Eugene A. Vaganov, Kevin J. Anchukaitis, and Michael N. Evans

Abstract We develop an observational and conceptual basis for modeling conifer
cambial processes as a direct but nonlinear and multivariate response to external
environmental conditions. The model, here termed Vaganov-Shashkin (VS), repro-
duces the critical features linking climate variability to tree-ring proxy formation.
We discuss recent test simulations of tree-ring width data from a variety of sites and
spatiotemporal scales. Our experiments demonstrate that the model skillfully repro-
duces observed patterns of tree-ring growth across a range of environments, species,
and scales. Model performance is found to be robust to parameter estimation. We
discuss present and future applications of the VS model, including exploration of the
biological basis of emergent phenomena and prediction of the influence of climate
change on conifer tree growth dynamics.

Keywords Tree growth · Biological basis · Cambium · Simulation · Process model

3.1 Introduction

Climatic variation is a major factor affecting tree-ring growth and wood forma-
tion. Accordingly, a significant amount of dendroclimatology research has been
focused on the extraction and validation of climatic variability from tree-ring data
series (Fritts 1966 ; Cook and Jacoby 1977 ; Fritts et al. 1979 ; Hughes et al. 1984 ;
more recently, see, for example, Stahle and Cleaveland 1992 ; Grissino-Mayer 1996 ;
Villalba et al. 1998 ; Briffaetal. 2001 ; Cook et al. 2002 ; Hughes 2002; Briffa et al.
2004 ; Pederson et al. 2004 ; Watson and Luckman 2004 ; Salzer and Kipfmueller
2005 ) . The main morphological and anatomical characteristics of tree rings bearing
the climatic signal have been described: tree-ring width, density profile, cell diame-
ter, and cell wall thickness (Vaganov 1996 a ). Although stable isotope methods and