CASTANEA is a physiological multilayer process-based model designed to predict the carbon balance of an even-aged, monospecific deciduous forest stand. The main output variables are: (1) leaf area index (LAI), standing biomass, soil carbon content and water content, which are state variables; and (2) canopy photosynthesis, maintenance respiration, growth of organs, growth respiration, soil heterotrophic respiration, transpiration and evapotranspiration, which are flux density variables