The allocation of carbon as a linear function, exemplified by the root allocation response function for water stress. The dark blue line is the original parameterisation. The other two parameterisations are compared with this one. The green line shows the effect on the allocation function of a doubling of the parameter, rMc1, and the turquoise line a doubling of rMc2. This figure is analogous to the linear leaf response function and the other linear root response functions.