Comparative analysis of two approaches to large-scale mapping of forest vegetation in the Southern Nechernozemye of Russia

The results of the comparative analysis of traditional forest typology data and the data of floristic classification by the J. Braun-Blanquet approach for large-scale mapping of forest vegetation from the Southern Nechernozemye of Russia are presented. 3 model forest areas located in the forestries in borders of different botanic-geographical districts with specific climatic and edaphic conditions have been chosen to make the comparative analysis of cartographic materials (Bryansk and Smolensk Regions). A comparison of existing afforestation plans and created geobotanical maps demonstrates the difference in the number of recognized typological units. In all cases, a smaller number of units are noted for the geobotanical maps with a scale 1 : 25 000. A decrease in the number of typological units can be explain by the lack of information on the age of tree stands. Another reason is, probably, the assignment of some forest stands with the predominance of different indigenous species to a single association. However, the same typological units, distinguished by the predominance of tree species, may correspond to different units of floristic classification, which may increase the number of typological units on the geobotanical map. Some features of the Braun-Blanquet approach such as the allocation of units, primarily based on a comparison of the floristic composition of plant communities, allows attributing both natural stands and forest cultures to a single syntaxon. This also reduces the number of typological units on the geobotanical map. The plans of afforestation show the present-day species composition and the age of the studied stands, but the dynamic interrelations of forest communities are not reflected there. Therefore, it is more effective to reflect the dynamics of vegetation of forest communities in accordance with the methodology adopted when creating geobotanical maps. In this case, the succession state of communities and their links to classification units of higher ranks has been taken into account by the allocation of temporary facies with the predominance of small-leaved species at the site of indigenous broad-leaved or coniferous forests. The deductive approach with the identification of non-rank «communities» also makes it possible to separate into separate syntaxa and time-unstable, unformed or poorly floristic communities. Typically, such forests are formed by coniferous cultures in the zone of deciduous forests. The unformed «semi-forest» communities in the lowland swamps are also placed into the same category. They are often formed after felling, initiating or intensifying bogging under conditions of fluctuating moisture. The use of a single colorimetric scheme for forest stands in different climatic and edaphic conditions, reflected in the TLU (forest conditions) system, can be considered not quite correct. Stands with the predominance of the same species can correspond to different zonal-conditioned TLUs. At the same time, communities of some syntaxomomical taxa of floristic classification can be formed in different TLUs and their diversity corresponds to the width of the ecological amplitude of the types of plant communities. The more stenotopic communities, the smaller number of TLUs corresponding to their habitats. The afforestation plans and geobotanical maps can be used by different ways in forestry. The traditional afforestation plans are widely used in forestry planning. However, the geobotanical map supplemented with information on the dynamic relationships of stands allows making more efficient prediction of scenarios of forest stand development under known forest conditions. In addition, cartographic materials on the proposed geobotanical basis reflect the general botanical and geographical trends of vegetation, and the syntaxa of the floristic classification always have a certain chorological content, thus, they can be used as zonal-climatic indicators. This feature is reflected in their compliance with TLU, which are specifically distinguished for different natural zones.