Summary of the Article on Plant Nitrogen:

2.10.2.1. Plant Nitrogen

The LUNA model divides plant nitrogen at the leaf level (LNCa) into four pools: structural nitrogen (Nstr), photosynthetic nitrogen (Npsn), storage nitrogen (Nstore), and respiratory nitrogen (Nresp).

The photosynthetic nitrogen (Npsn) is further divided into nitrogen for light capture (Nlc), nitrogen for electron transport (Net), and nitrogen for carboxylation (Ncb).

The structural nitrogen (Nstr) is calculated as the product of leaf mass per unit area (LMA) and the structural nitrogen content (SNC).

The model assumes that plants optimize their nitrogen allocations to maximize the photosynthetic carbon gain, defined as the gross photosynthesis (A) minus the maintenance respiration for photosynthetic enzymes (Rpsn). The optimal nitrogen allocations are determined by solving the optimization problem.

The gross photosynthesis (A) is calculated using a coupled leaf gas exchange model based on the Farquhar et al. (1980) model of photosynthesis and the Ball–Berry-type stomatal conductance model. The maintenance respiration for photosynthetic enzymes (Rpsn) is calculated by multiplying the total photosynthetic nitrogen (Npsn) and the maintenance respiration cost for photosynthetic enzymes.