MAIN PROCESSES OF FORMIND
The modelled processes are simulated on different levels: (i) area-level (e.g., 10 ha), (ii) patch-level (20m x 20m) or (iii) on the level of an individual tree.
For forests of high biodiversity, e.g. tropical rain forests, an aggregation of trees into functional groups is necessary. Depending on the site, we aggregate species richness up to 19 different plant functional types. Typically in FORMIND, we use two criteria for functional type grouping: light demands (e.g. shade intolerant pionner and shade tolerant climax species) and maximum tree height layer (e.g. understory, canopy, emergent). However, we are able to define any number of ecologically significant groups through parametrization (e.g. seed dispersal syndrome and water tolerance).
Within each time step, the following main processes can be calculated:
Seeds are distributed over the forest area. If light conditions are suitable, a new individual can establish and competes for light and space in its patch.
The growth of an individual is determined by its gross primary productivity (GPP), respiration and type-specific physiological parameters.
An individual can die due to a specific mortality rate. If one tree falls, neighboring trees of its patch can be damaged as well. Additional mortality can also be activated in relation for example, to tree density or growth rate.
The main driving factor of the model is light. Light decreases within the forest in order to include competition of light between individuals. Depending on its latitude, forest dynamics can be influenced by additional climatic variables like precipitation and temperature.
FORMIND enables to include different disturbance types like fire events, landslides, logging and fragmentation.
The model calculates the gross primary production, respiration and net primary production for each tree individually. Based on this the carbon balance for a whole forest area can be calculated (including soil respiration and net ecosystem productivity NEP).