Summary:

## Numerical Scheme of LUNA Model

The LUNA model optimizes nitrogen allocation for maximum net photosynthetic carbon gain by incrementally increasing the nitrogen allocated for light capture (Nlc). This optimization only occurs when plants can grow (GPP > 0.0).

If GPP becomes zero under stress, the LUNA model assumes a daily decay rate of 0.1 for photosynthetic enzymes, considering their short half-life time of around 7 days. To avoid unrealistically low values of photosynthetic capacity, the decay is limited to 50% of the original enzyme levels.