Downfall of meadow plants communities on the Left Bank Forest-Steppe Boundary in Ukraine

The research was carried out on the different types of grassland plant communities on the left-bank forest boundary in Ukraine. It was established that the supplies of downfall on the floodplaine meadows were within 37,3–1973,7 g/m2, upland medows – 21,8–627,3 g/m2, lowland medows – 70,0–1363,0 g/m2. The results of the research made it possible to identify three groups of indicators on the amount of downfalls. The first group consists of the areas with such amount of dawnfall as – 80.0 g/m2, the second one – 80,0–160,0 g/m2, and the third one – more than 160.0 g/m2. The change rate which depends on the part of the floodplain medows was considered. In the riverine area it was defined in the range of 31,8–663,6 g/m2, in the central area – 41,8–1973,7 g/m2, in the pre-terrace area – 37,3–1654,6 g/m2. The difference among minimal parameters is small but among maximum is significant. It is generally accepted that the results of the research are mainly supported by specific differences of floristic composition. The larger number of indicators (within the second group) are in the central parts of the investigated floodplains and rivers. In the central areas in general, there was a higher level of dry matter content. Combined with the increasing amount of downfall, to some extent, it is considered to be an indicator of higher crop level in this area. It was figured out that in some areas the upland meadows have got different number of the investigated indicators. The most important factors for this issue are the lower parts of the area but the minimum are the tops of the slopes. The difference can be quite significant. The comparison between the formation of downfall in the upland grasslands and the steppe area showed a certain regularity. In steppe areas the accumulation of the indicator was nearly one third less than the average one in the investigated meadows. The number of dry matter varied in the range of 31,8–95,7 %. The lower indicators as well as the upper ones differed in general not more than 10,0 %. In general the amount of dry matter content was the highest on the top of the slopes ant the lowest amount was on the bottom. In the overwhelming majority of surveyed lowland there was an increasing level of accumulation in the second and third groups.The comparison of the results about the accumulation of the downfall in the lowland meadows in the studied forest-steppe and steppe regions of Ukraine, which borders on the South, showed that its accumulation in the steppe regions was much less comparatively to the surveyed regions. Dry matter content of the downfall of this grassland areas was in the range of 31,9–94,4 %. We found that the energy storage of downfall meadow plant communities of the region is in the range of 0,4 × 106–37,1 × 106 Dzh/m2. Each type of medows has its own specific characteristics of the index and indicators. Thus, energy storage on the floodplaine was within 0,6 × 106–37,1 × 106 Dzh/m2, upland 0,4 × 106–12,1 × 106 Dzh/m2, lowland meadows – 1,3 × 106–25,7 × 106 Dzh/m2. Indicators of lowland meadows occupy an intermediate position between floodplain and upland areas. The comparison of borderline indicators allows us to see that they vary greatly both upper and lower. Minimal indicators are differe for 0,2 × 106–0,7 × 106 Dzh/m2 and maximum 7,3 × 106–16,1 × 106 Dzh /m2. The reduction of economic activity, in particular, the implementation of conservation as for all investigated meadow plant communities of the region leads to increasing amount of downfall in average. Weather conditions influences greatly the accumulation of the downfall. The analysis of climat map which was presented, shows us more favourable weather conditions during particular years. That is why the maximum storage of downfall was observed during this period.