## 2 Materials and Methods
### DIMONA Platform and Model
#### 2.1.2. DIMONA Process-Based (PB) Model  
The main processes and relations in the _DIMONA_ PB model relevant to this study (Figure 7) are outlined below, with an emphasis on the simple process-oriented modifiers for plant water control on GPP through photosynthesis, plant growth, root/rhizoid respiration, and nutrient uptake. Model equations that are not explicitly stated in the manuscript are referred to by their numbers in the Supplementary Material, starting with the prefix S. All equation variables and parameters are explained in the Supplementary Material. Figure 6: A user’s personal account screen (**a**) and a user’s folder (**b**) with other folders (in blue) and files (in red), and various options to upload or download model and data files and execute model simulations. _DIMONA_ simulates the photosynthesis of vascular plants, e.g., coniferous and deciduous trees, evergreen and deciduous shrubs, grasses, agricultural crops, and bryophytes, e.g., _Sphagnum_ moss. Simulations are at the canopy level per each simulated plant species. Simulated C fixation of vascular plants is based on the Farquhar biochemical model for photosynthesis [30; 31], controlled by leaf temperature, T\({}_{\text{L}}\)[32; 33], and stomatal conductance through the ratio between internal and external leaf CO\({}_{2}\) concentrations [34], coupled to plant water status and external hydrological controls. The latter are the air relative humidity, RH, or atmospheric vapor pressure deficit (VPD), D\({}_{\text{VP}}\), represented by Ball-Berry- or Leuning-type equations, respectively [35; 36; 37]. Simulated C fixation of bryophytes is calculated by a rectangular hyperbola [20; 38] controlled by T\({}_{\text{L}}\). Simulated photosynthesis is driven by the incoming solar short-wave radiation, I\({}_{\text{swr}}\), partially reflected and attenuated through the canopy, ambient air temperature, T\({}_{\text{a}}\), RH, and wind speed, v\({}_{\text{w}}\), measured at 2 m above the canopy. It is also driven by soil hydrology through d\({}_{\text{WT}}\) or near-surface \(\theta\), directly for vascular plants and indirectly for bryophytes, as outlined below and in the Supplementary Material. Simulations are conducted at hourly or less than hourly time steps for modelling the diurnal cycle of the photosynthesis, daily aggregations are also calculated. _DIMONA_ can simultaneously simulate the photosynthesis and growth of a pre-set number of up to 10 plant species within the same canopy layer in up to 10 canopy layers (Figure 2a). The maximum numbers may be adjusted to \(>\)10 in the model code, if needed. With C3 vascular plants, relevant to this study, the ambient photosynthetic rate, A, is the minimum of the Rubisco-limited and the electron transport-limited CO\({}_{2}\) fixation rates A\({}_{\text{C}}\) and A\({}_{\text{J}}\), respectively (Equation (S.1.1.1)),A\({}_{\text{J}}\) (Equation (S.1.1.1.2)) depends  
Figure 7: Model schematic of main processes and relations through simulated soil–plant–atmosphere continuum in _DIMONA_ PB model. on the ambient electron transport rate, \(J_{m}\) (Equation (S1.1.1.3)), and is constrained by the ratio \(c_{x}\) between the CO\({}_{2}\) concentration in intercellular spaces at the carboxylation sites of Rubisco activity, \(C_{i}\), and the atmospheric CO\({}_{2}\) concentration, \(C_{a}\) (Equation (S1.1.5.1)). \(J_{m}\) is driven by \(I_{swr}\) attenuated through the canopy (Equations (S1.1.1.4) and (S1.1.2.2)), the effects of \(T_{L}\) (Equation (S1.1.1.5)), and plant water status (Equation (S1.1.1.6)). \(A_{C}\) (Equation (S.1.1.1.8)) depends on the ambient rate of carboxylation, \(V_{m}\) (Equation (S1.1.1.9)), and is constrained by \(c_{x}\), as defined above (Equation (S1.1.5.1)). \(V_{m}\) is determined by the effects of \(T_{L}\) (Equation (S1.1.1.10)) and plant water status (Equation (S1.1.1.6)). Foliar respiration, \(R_{d}\) (Equation (S.1.1.6.1)), is determined by the effects of \(T_{L}\) and plant water status (Equations (S.1.1.6.2) and (S.1.1.6.3)).