A generic approach to spatial individual-based modelling and simulation of plant communities

Abstract

A general framework is proposed for the formulation and simulation of spatially explicit individual-based models of plant communities. A software implementation, siplab, was developed using the R statistical programming language. The scheme is a synthesis that encompasses many approaches from the literature, making possible to compare and combine their different components. Relationships between plant growth and various competition or assimilation indices are discussed, together with the choice of state variables and statistical issues in growth equations. Modelling is extended to deal with environmental heterogeneity, specified as a given resource distribution in the plane. Plants exert competitive pressure over resources at each point, represented by size- and distance-dependent functions that emulate or generalize similar concepts used in existing models. The partitioning of resources where these functions overlap is parametrized in a way that includes the one-sided fully asymmetric allocation of tessellation models, as well as a continuum of symmetric and asymmetric resource sharing alternatives. Finally, the plant resource uptake is integrated over space, with an optional size- and distance-dependent plant response or efficiency weighting. The framework and software permit conducting simulation studies where results are less dependent on any specific model structure.