The structure of the forest covering is influenced very much by the endogenic factors. With the decrease in the amount of dark-coniferous forests the amount of fir-spruce seeds decreases as well, for the seeds of Siberian pines are not brought by birds any longer. The top soil is covered by turf, which results in hindering the process of the regeneration of dark-coniferous trees and in the long run there will appear “forested” meadows.

Such damages to the natural cycles of the regeneration of the fir communities and in some cases of pine communities change the structure of the redistribution of forest vegetation as well as the character of the carbon accumulation in forest ecosystems.

The conducted studies show that in a number of areas of the Lower Angara region the primary forest covering is destroyed to such a degree that, speaking about the dynamic balance between the spontaneous vegetation and the anthropogenic vegetation, we must admit that the anthropogenic vegetation prevails over the spontaneous one. There appear anthropogenic forest ecosystems as a result of a sharp change of ecological-geographical factors. And there appear a new “line” of the forest vegetation with the poor diversity as to the types of trees and with the less carbon accumulation. This forest vegetation is resistant to the recurrent anthropogenic disturbances.

The pine communities may appear in place of fire-sites in the fir forests. This process of substitution is of local character. In other words this process is not a regional regularity that perfects the biosphere function of forests or the carbon distribution among the biological components.

Conclusion
Studying the structure of the forest covering and the dynamics of this structure while mapping the forest vegetation in the south-eastern part of the Angara-Yenisei region has shown that before making the mathematical models to forecast the carbon circulation as to the main types of the boreal forests we must organise the obtained data into complex spatial-temporal cycles. These cycles must reflect the process of the formation of the most representative ecosystems that are “nuclei” for single landscapes of a different hierarchical level. The analysis of the map of the forest vegetation in the south-eastern part of the Angara-Yenisei region shows that at every high-altitude level there is an indigenous forest that is a “nucleus” for this particular belt of the forest vegetation. Accordingly for the middle mountainous belt (500-600 m. above the sea level) the “tree-soil” model must be considered using the example of the ecosystem of the larch whortleberry-lichen, whortleberry-herbaceous forest and for the convex watershed plains (250-400 m. above the sea level) - using the example of the Siberian-pine – spruce – fir, herbaceous – green-moss forest.

Adapting the models of the carbon circulation to the regional level will require a clear-cut mapping that will be able to give an idea not only about the up-to-date state of the forest vegetation, but also about the spatial-temporal dynamics of the forests, about their age structure and about the correlation between the areas as to the different types of communities.

References

• Kuzmenko, E.I.: 2001, ‘Up-to-date State and Transformation of the South-taiga Subzone Forests of the Right Side of Yenissei Region; There Biosphere Role‘, ESRI Library, New-York, http: //campus. esri. com/ campus. library/ Bibliography/ RecordDetail. cfm? ID=13343.
• Kuzmenko, E.I. and Smolonogov, E. P.: 2002 ‘Up-to-date state and transformation of the south taiga subzone forests’, 22 Annual ESRI International User Conference ( Track: Forestry, Wildlife and Fisheries Management). San-Diego, ESRI .- CD