Applications of organ-specific growth models; modelling of resource translocation and the role of emergent aquatic plants in element cycles

This paper presents and reviews the conceptual structure of several recently developed organ-specific growth models and discusses their applications, with particular emphasis on material translocation between above- and belowground systems and the role of aquatic plants in element cycles. The efficiency of the element cycling process in wetlands is closely related to the proportional biomass allocation to above- and belowground organs. Therefore, the framework of most macrophyte productivity models is usually similar, with a mass-balance approach consisting of gross production, respiration and mortality losses, and the translocation between organs. The paper delineates how these growth models are linked with decomposition models to evaluate the annual cycle of elements. The model formulating procedure and the material budget and translocation processes of two perennial emergent species, Typha angustifolia and Zizania latifolia, and the coupling of the validated partitioned growth model with the modules for decomposition based on a modified decomposition coefficient, are further discussed. Furthermore, the effect of differing water depth on the rhizomatous sedge species Eleocharis sphacelata was studied based on its responsive adaptation by apportioning additional resources to shoots.