A root-morphology based simulation for plant/soil microbial ecosystem modelling

A simulation model is presented that produces and manipulates computer representations of plant root microbial ecosystems. The root system is described as a collection of nodes. A node records a position in three-dimensional space and may represent the origin of another root, a bend, or some change in the root's microbial status. Disease lesions, closely associated microbial populations such as mycorrhizal fungi, and free soil microbial populations may also be represented. A multi-dimensional matrix structure provides a useful conceptual framework for the numerous stochastic functions required by the model. Procedures for building the node-based root map, and for simulating root growth and microbial interaction, are presented in terms of such a matrix, in conjunction with the necessary manipulations of the node lists which represent the root system. This paper assesses the practicality of the approach described, which appears to be feasible and potentially useful. The model is considered as a step towards a generic framework for modelling root-architecture and the spatial structure of associated microbial ecosystems. The model has been successfully applied to a simulation of a Pinus radiata/Armillaria spp. pathosystem.