Modelling of competition for light in uneven aged-mixed forest stand

Today in science intensive research is conductedto develop various types of models of forest ecosystems, which is caused by the complexity of the object under study and long durationof time of the processes of their dynamics. To study the dynamics of tree communities and their successful management tools ofmathematical and computer modelling are widely used. This work offers the results of study and construction of an individual-basedmodel of the forest stands dynamics. Modelling the forest stand dynamics develops of its each tree growth modelling, by means of differentialequations and functions, which allow calculation of basic forest valuation characteristics: volume, height, trunk diameter andcrown. The trees are located in one space and influence each other through competition for light. The model allows computational experimentswith different sets of input data (different combinations of species and age structure of the stand). As the simulation resultsthe researcher can obtain various statistics presented in the form of graphs, tables. Visualization of trees on the coordinate plane allowsobserving the spatial-temporal dynamics of the forest. The simulation results showed that the species having approximately the samegrowth rate and size but varying degrees of light transmission can not coexist long in the same area. Under the same growth parametersof both species, but varying degrees of light transmission, the kind that has a stronger shadowing, over time begins to suppress the competitor.If to change the growth rate of the depressed type, in particular, to reduce the maximum rate of photosynthesis, then we can ensurethat the species will successfully coexist. The computational experiments carried out on modelling interspecific interactions of darkconiferous and light-loving species showed that the dark coniferous species of spruce, fir and cedar displace photophilous birch overtime. Modelling the dynamics of the interaction of dark coniferous species of spruce, fir and cedar showed their sustainable coexistence,this corresponds to the reality. The simulation results showed that competitive interactions in the community is largely determinednot only by the degree of shading, but largely depend on the rate of tree growth.

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