Ramet rules: merging mechanistic growth models with an individual-based approach to simulate clonal plants
Marine Biological Laboratory
Last modified: April 25, 2006
Existing individual-based models of clonal plants rely on simple rules of rhizome spacing, branching angle, and branching rate to predict colonization of space by asexually reproducing ramets. These models have provided unanticipated explanations for the emergence of nonlinear patch growth observed in real populations. However, no efforts have attempted to link these modelsí growth or morphological parameters with environmental conditions, relying instead on constant or stochastic values. In the case of seagrasses, widespread decline has prompted managers to ask for predictive tools that might provide better understanding of the landscape-level response of these clonal plants to water quality. The Virtual Eelgrass Meadow (VEM) was created to explore how the simple rules of a modular, clonal, architecture might be linked with environmental variables such as light, temperature, and nutrients to simulate eelgrass patch dynamics. A surprising insight gained from this modeling exercise has been the importance of leaf length in determining rhizome growth and branching rates. Moreover, the VEM suggests that changes to growth rates and resource allocation in response to the physical environment provides a mechanistic explanation for the morphological plasticity of ramets, which ultimately affects patch expansion rates.