Use of interactive forest growth simulation to characterise spatial stand structure

The forest stand growth simulator TRAGIC++ (tree response to acidification in groundwater in C++) which has been developed to serve as a decision support system and a visualisation tool for scientists and forestry practitioners is introduced. TRAGIC++ places an emphasis upon visualisation techniques while at the same time providing detailed information on tree physiology and related parameters. The model is calibrated numerically to growth history data from two different European sites. Next, due to the importance of the visual component of the model, its ability to reproduce forest stand spatial structure is investigated, using an application of the theory of marked point processes. This analysis is applied to different experimental data sets for stands of different age, revealing information on planting schemes and the extent of significant spatial correlations. The spatial structure of the two model calibrations is then explored with the same methods. The point process analysis turns out to be a powerful diagnostic for model quality assessments, since spatial distribution is an indirect result of competition between trees for light.