Table 1.

Model parts of the root-shoot model

State variables
Symbol	Description	Typical units
	Root biomass (in carbon)	mol C
	Shoot biomass (in carbon)	mol C
Fluxes
Symbol	Description	Typical units
	Nitrogen assimilated by root	mol N d
	Carbon assimilated by shoot	mol C d
	Nitrogen shared by root	mol N d
	Carbon shared by root	mol C d
Parameters
Symbol	Description	Typical units
	Nitrogen assimilation rate of root	mol N mol C d
	Photosynthesis rate of shoot	mol C mol C d
	Nitrogen–carbon ratio of root	mol N mol C
	Nitrogen–carbon ratio of shoot	mol N mol C