Towards developmental modelling of tree root systems

Abstract

Knowledge of belowground structures and processes is essential for understanding and predicting ecosystem functioning, and consequently in the development of adaptive strategies to safeguard production from trees and woody plants into the future. In the past, research has mainly been concentrated on growth models for the prediction of agronomic or forest production. Newly emerging scientific challenges, e.g. climate change and sustainable development, call for new integrated predictive methods where root systems development will become a key element for understanding global biological systems. The types of input data available from the various branches of woody root research, including biomass allocation, architecture, biomechanics, water and nutrient supply, are discussed with a view to the possibility of incorporating them into a more generic developmental model. We discuss here the main focus of root system modelling to date, including a description of simple allometric biomass models, and biomechanical stress models, and then build in complexity through static growth models towards architecture models. The next progressive and logical step in developing an inclusive developmental model that integrates these modelling approaches is discussed.

Biomass models to estimate carbon stocks for hardwood tree species

“…Models for branch biomass presented a lower predictive ability, probably due to the high variability observed in this component resulting from differences in stand density and tree competition stage (Návar, 2009). Belowground biomass models only include diameter as independent variable, as stated in other studies (Drexhage and Colin, 2001;Tobin et al, 2007). Since most of the studied hardwood species are resprouters there is a greater degree of variability in belowground biomass, hence the efficiency of the model for this fraction is lower and, in addition, the number of root biomass samples was quite limited for some species, for these reasons more research about belowground biomass is needed to validate it.…”

Root system traits of Norway spruce, Scots pine, and silver birch in mixed boreal forests: an analysis of root architecture, morphology, and anatomy

“…The roots and root systems of trees are more difficult to study than tree shoots. This reflects in the restricted number of experimental studies on belowground structural and functional features, and root models are not therefore as advanced as their aboveground counterparts (Blaise et al 1999, Drouet and Pagès 2007, Tobin et al 2007. Fundamental questions such as the role of sink and source activity in plant growth and development, or how the belowground competition between trees, and between trees and other plants affects tree performance, largely await clarification (Schenk 2006, Fourcaud et al 2008.…”

“…Developmental and fractal modeling are the main approaches applied in the modeling of coarse root architecture (Tobin et al 2007). …”

Tree Root System Characterization and Volume Estimation by Terrestrial Laser Scanning and Quantitative Structure Modeling

“…As illustrated by the reviews in Tobin et al [7], Danjon and Reubens [8], and Danjon et al [9], knowledge of root system architecture is also of large importance in order to understand key ecosystem processes including tree stability, slope stabilization, erosion control, water and nutrient uptake through fine roots, and root competition. All of these processes affect a tree species' competitive performance and aid in the understanding of observed shifts in intra-and interspecific competition and the resulting forest dynamics across resource gradients [10].…”