Figure 6.
Fast dynamics of the root–shoot model, implemented with additional state variables for the shared surplus of nitrogen and carbon, and
. Biomass of root and shoot is kept constant. In the full system (with changing biomasses), this phase plane would change as the slow state variables evolve. The phase plane shown here reveals bistability of the fast dynamics. The system has three equilibria. The two outer (stable) equilibria correspond to states where
is high and where
is high (the other surplus sharing rate being zero). The equilibria characterize states where only the root growing and only the shoot growing. The two basins of attraction are separated by an unstable equilibrium and a separatrix. Brighter colors for the vectors indicate stronger attraction. Parameters:
,
,
,
,
,
and
. Root and shoot biomass are fixed:
and
.