Carbon-based models of individual tree growth:
A critical appraisal

[Abstract]

1. Introduction

2. General framework of carbon-based models of individual tree growth

2.1 Processes accounted for and common rationales used

2.2 Representing the effect of architecture on tree growth

2.3 Representation of tree structure: A problem of model objective?

2.3.1 Range of representations of tree structure

2.3.2 Link between the representation of tree structure and model objective

2.3.3 Conclusion

3. Range of approaches available to model carbon processes involved in tree growth

3.1 Modelling photosynthate production

3.1.1 Formulation of photosynthate production

3.1.1.1 Modelling photosynthate production without treatment of leaf photosynthesis

3.1.1.2 Empirical modelling of leaf photosynthesis

3.1.1.3 Mechanistic modelling of leaf photosynthesis

3.1.1.4 Choice of a formulation for photosynthate production: implications for model applications, parameterization and computation requirements

3.1.2 Representation of the distribution of photosynthate production within the tree crown, and associated radiation transfer modules

3.1.3 Summary

3.2 Modelling respiration

3.2.1 The two-component model

3.2.2 Practical application of the two component-approach in tree growth models

3.2.3 Potential extension of the two-component model

3.2.4 Simpler approaches to modelling respiration

3.2.5 Link between respiration formulation and time/space scale

3.3 Modelling reserve dynamics

3.4 Modelling carbohydrate allocation

3.4.1 Empirical allocation coefficient approach

3.4.2 Functional balance and other allometric relations

3.4.2.1 Shoot:root functional equilibrium

3.4.2.2 The pipe-model approach

3.4.2.3 Other growth relationships

3.4.2.4 A discussion of goal-seeking approach

3.4.3 Interactions among sinks with different demands and/or capacities

3.4.3.1 The proportional and hierarchical approaches

3.4.3.2 A mechanistic attempt to model interactions among sinks: Resistance model of sugar transport

3.4.4 Tentative classification of carbon allocation modules to assist the choice of a given formulation

4. Model outputs and implications for forestry and tree ecology

5. Critical issues for individual tree growth models to date

5.1 Carbon allocation and interactions between tree structure and function: Achilles' heel of most tree growth models

5.2 Carbon storage/remobilisation

5.3 Below-ground process and tree nutrient economy: The missing module of many tree growth models

5.4 Conclusion