For the simulations, we use the process- and individual-based model HETEROFOR implemented in the CAPSIS simulator. In the following, we present a brief overview of the model functioning while for a more in-depth description, we refer to Jonard et al. (2020) and de Wergifosse et al. (2020).
HETEROFOR determines the key phenological phases of the deciduous species (budburst, leaf yellowing and falling) from meteorological data. Then, the radiation intercepted by each tree is calculated with the SAMSARALIGHT library using a ray tracing approach. From the radiation intercepted by the foliage and the soil water potential (calculated with the water balance routine), the gross primary production (GPP) of each tree is estimated hourly with the biochemical photosynthesis model of the CASTANEA library.
The net primary production (NPP) is obtained empirically from the GPP through the Carbon Use Efficiency (CUE = NPP / GPP) concept. CUE varies with tree size and shape, competition for light and mean annual temperature.