PLATHO - A Dynamic Plant Growth Model Considering Competition between Individuals and Allocation to Carbon-Based Secondary Compounds

To explain patterns and variations in concentration of defence-related carbon-based secondary compounds in plant tissues, different complementary and in some parts contradictory plant-defence hypotheses were developed since several years. These conceptual hypotheses cannot be fully evaluated without a plant growth simulation model and consequently, the discussion about adequacy of plant-defence hypotheses neglects to a large extent the dynamics of plant growth. To get a more realistic view of the volatile dynamics of plant internal source and sink strengths of carbon and nitrogen during different phenological growth stages, a modelling approach for allocation of carbohydrates to a pool of carbon-based secondary compounds was integrated into the functional generic plant growth model PLATHO. In this paper, we explain the fundamental assumptions of our modelling approach and present the results of a simulation study for juvenile beech and spruce trees growing in mono- and mixed cultures under ambient and elevated atmospheric CO₂.