To make a fragment of the map we used the topographical maps, the geo-morphological maps, the forest maps, the soil maps, the materials concerning the forestry, the taxation descriptions, the materials concerning the landscape-ecological researches and the stationary researches (Кrauklis 1979; Suvorov 1980; Каlashnikov 1987). The synthesised summer colour photos obtained from the Resurs-F satellite with the help of the MK-4 camera (9 – 11m.) were automatically processed.

For the forest communities the growing conditions and the relation to the landscape are determined. While making the dynamic taxonomic legend we took into consideration the high-altitude position of the forests. There are chosen the following 4 high-altitude belts: the middle mountainous belt with the larch mountainous taiga-forests (500-600 m. above the sea level), the low mountainous belt with the southern boreal fir - Siberian-pine (and Siberian-pine – fir) taiga-forests (400-500 m. above the sea level), the high mountainous watershed belt of plains with the southern Siberian-pine – spruce - fir taiga-forests (250-400 m. above the sea level) and the taiga-complex of the river plains, of the terraces and of the slope-valley areas. In every high-altitude belt there are 4 most typical orographic complexes: 1) watersheds or a plateau and adjacent top parts of the slopes, 2) sloped relief elements, 3) sloped concave watersheds and slopes (depressions accumulating water), 4) the river valleys. There is a third group of the ecological factors. It defines the peculiarities of the ecological regime of the territory and on the whole characterises the type of the growing conditions. It is connected with the structural relief elements, the exposure of the slopes, the moistening, and the characteristics of the soils.

To study the spatial-temporal dynamics the forest communities were grouped into the successive rows of the genetic forest types, the high-altitude belt, the orographic complex, the type of the growing conditions and the age of the trees being taken into consideration. In the process of preparing the computer-made map of the forest vegetation in the south-eastern part of the Angara-Yenisei region we used a multifunctional adaptive geo-informative МАGIS system which is manufactured by the Siberian scientific–publishing and manufacturing centre of the geo-information and the applied geodesy (the Sibgeoinform centre ) (The forest veg. 2002). During the first stage the map was digitised in the format А3. Then the digitised map was checked to find out weather it corresponds to the MAGIS model. It was also converted in the format HTML (the МАGIS system). And at last the МАGIS project was formed. Then a library of the conventional signs to be put on the map of the forest vegetation ( 1:200000) was elaborated. As well we began to form the structure of the represented information applying the qualifier of the digital information to the given fragment of the map. In the long run the computer-made map of the south-eastern part of the Angara–Yenisey region was recorded on 2 CDs using the inner format of the МАGIS system. The CDs contain as well the bases of the spatial data, the base of the semantic data, the libraries of the graphic attributes and the software. (The details of the software are given in the CD-manual.)

Subject matter and results of the research
The research of the dynamics of the forests in the landscape areas of the south-eastern part of the Angara-Yenisey region and along the Lower Angara river, the collation of the studied regions as to the way how the main forest-forming trees and the prevailing forest types spread themselves has shown that in the southern taiga-forest we can come across diverse ecological systems having the fragments of dark-coniferous, light-coniferous forests and their variants in the form of the shortly-derived, long-derived, stablely-derived birch-aspen forests. The state of the landscape structure can intensify or weaken the influence of the global tendencies in the environmental changes on the way how the dark-coniferous and light-coniferous trees take part in the forest forming process in this region.

The fragments of the maps make it clear that the structure of the forest covering is formed under the influence of the vertically organised high-altitude belts and that there are 4 levels of the spatial-functional interaction (from the mountainous, mainly larch, pine - larch, larch - pine taiga-forests in the belt of 500-600 m. above the sea level to the low mountainous fir – Siberian-pine and Siberian-pine - fir forests on the trapps in the belt of 400-500 m. above the sea level and to the forests situated on the convex watershed plains. These forests form the Siberian-pine – spruce – fir herbaceous green-moss communities. A special landscape structure is formed by the taiga-forest complex of the river valleys, the terraces and the slope-plain areas. This taiga-forest complex is characteristic of all high-altitude belts. In fact in all belts (including not shown in the fragments of the maps ( the region of the village of Kazachinsky) the plain complex of the spruce – Siberian-pine - fir forests on low loamy watersheds (150-250 m. above the sea level) there are fir forests that are independent genetic forest types and that greatly differ in the structure of the types of trees, in the species diversity, in the functional features, in the natural cycles of the age-regeneration dynamics and, consequently, in the types of the accumulation of the assimilated carbon and in the carbon biological circulation. After the anthropogenic impacts there appears a more complex picture of the temporal changes.

The collation of a fragment of the map of the forest vegetation with a fragment of the topographical map (О-46-83) (scale 1:100000) showed that for the last 40 years the area of the small-leaved forests, dark-coniferous small-leaved forests and light-coniferous small-leaved forests has increased up to 45-60 % as compared with 1953 when it was only 15-20 %. The great anthropogenic damage is characteristic of the other areas of the researched regions.

This allows us to draw a conclusion that the majority of the communities, consisting of the birch-aspen forests, are stablely-derived biogeocenoses in place of the damaged dark-coniferous forests. The analysis of a fragment of the GIS-map shows that such a transformation of the dark-coniferous forests into small-leaved ones is not only of local character but also of regional character under the influence of the changes in the landscape. Destroying the dark-coniferous forests that are a powerful forming factor of the environment brings about a sharp changing of the ecological situation. The climate becomes more continental. In spring and in early summer the air lacks moisture. It is at this time when the relative air moisture in the dark-coniferous communities is often lower than 20%. The process of the erosion and the degradation of top soils is under development. The global tendencies of the climate changes result in its warming in the northern hemisphere and in the increase of moisture in the mountains of the southern Siberia. Such warming can be traced from the 30s of the last century ( Vaganov and Shiyatov and Mazepa 1996). According to V. I. Vlasenko et al. (1999) such climate changes bring about the reinforcement of fir-trees in some areas of the Eastern Sayans. It is possible that such a tendency takes place in the middle mountainous belt of the south-eastern part of the Angara-Yenisey region. In this region there are still large areas of fir forests, but nevertheless in the Lower Angara region there is no spread of the fir-trees in spite of the improvement of the climatic conditions for this type of the forest.