Grassland ecosystems are the most widely distributed terrestrial ecosystems of the world. Many studies focus on aboveground grassland, but the belowground grassland is less explored because of the difficulty of sampling. Furthermore, the above-and-below ground biomass allocation mechanism of herbs is still disputed between the isometric growth hypothesis and the optimal partitioning hypothesis. In this study, a regrowth dynamic model, based on nutrient dynamics and stoichiometry, is proposed and analyzed to investigate the interaction between the aboveground and belowground herbaceous plants. The global dynamics of the belowground and aboveground biomass is well analyzed. Numerical simulations conclude that the herbaceous plant's biomass allocation mechanism for the aboveground and the belowground is in conformity with optimal partitioning at the beginning of growth, when the environment changes, it conforms to the constraints of isometric growth. Moreover, the dynamics of the model agree well with experimental data, which reveals that the model can express the relationship between aboveground and belowground biomass. Finally, a regrowth-herbivore model is established to explore the effects of nutrition and light intensity on the dynamics of plant and herbivore biomass.
Keywords: aboveground-belowground interaction; regrowth model; stoichiometric modeling.