Agronomijas v stis - Latvijas Lauksaimniecības universitāte

- substantiate a complex of measures to prevent and minimise negative environmentalchanges.We summed up and analysed the findings of researches on probable changes in plant resources topromote the development of a system of measures to be taken to prevent the decline in the resourcepotential of wild berry plants in Belarus.It is speculated that the global threshold level of consumption of primary produce has alreadyincreased many-fold, which generated the biosphere depletion and global ecological crisis(Loginov, 2004). The data obtained are indicative of the distinct relationship between globalchanges in the biosphere and anthropogenous factors (Loginov, 2003; Alexandrovich, 2003).About 11,500 plant species, including 2,100 higher plants and 9,000 to 9,400 lower plants, amongwhich are algae, lichens and fungi, are found naturally in Belarus (Loginov, 2004). Forestvegetation covers more than 38 percent of the territory of the republic.Belarus is located at the interface between two vegetation zones, namely, the boreal zone in whichconiferous forests predominate and the nemoral one in which deciduous summer broadleavedforests predominate. Here, therefore, three geobotanical subzones are recognised, namely, thesubzone of oak-dark coniferous southern taiga forests, the subzone of hornbeam-oak-darkconiferous sub-taiga forests and the subzone of mixed broadleaved-pine forests (Loginov, 2004).The last few years have been characterised by a large-scale dieback of spruce, oak and ash standsbrought on by droughts and heavy pest infestations. Forest fires, infectious tree diseases, windfalls,windbreaks, flooding and underflooding also cause grave damage to crops. Drainage reclamationthat brought on aridity in Polesye was one of the main factors extremely detrimental to theecosystems in Belarus. To date, the percentage of lichen, heath and bog moss forests has increasedby 1.5 – 2.0 percent. And this process will build up in the future (Loginov, 2004).In the context of global warming the monthly rise in temperature, the decrease in the depth of snowcover and freezing, and the increase in the probability of droughts are of paramount importance forforestry (Loginov, 2003; Alexandrovich, 2003). The increments therewith will most likely increaseby 5 % by 2020 and 10 % by 2050, fruits and seeds of forest trees and wild berries will presumablyripen 7 to 10 days and over earlier, and the silvicultural season will apparently begin 10 to 15 daysearlier (Loginov, 2004). Among the negative consequences of global warming are marked changesin the stand structure caused by the shift of the boundaries of the geographical ranges of spruce(Picea), hornbeam (Carpinus) and grey alder (Alnus incana), a longer fire danger period,favourable conditions for the reproduction of forest pests, the increase in probability of springfrosts, unfavourable growing conditions of stands owing to the decline of water table, higher ratesof evaporation and transpiration and unfavourable wintering conditions for plants due to unstablesnow cover. In Brest and Gomel Polesye the negative consequences will most likely be much morepronounced (Loginov, 2003; Loginov, 2004; Alexandrovich, 2003).Within the past fifteen years the percentage of pine formations dominated by the Vaccinium specieshas decreased by 6.4 percent. According to the data of scientific projections, global warming mayresult in an expansion of the distribution of mixed and broadleaved forests and forest-steppe and areduction in the area of coniferous stands.Forecasts of changes in the composition, productivity and resource potential of vegetation cover arerequired to take timely measures to adapt forestry and related branches of the economy of Belarusto the projected climate changes.The results of the 2006 – 2007 research done within the project on the climatically determinateforecasting of the typological structure of pineries suggest that by 2050 the transformation will verylikely bring about a decline in productivity of about 800,000 ha of pine forests, mainly at the costof upland pineries (Lazareva, 2007). More than 300,000 ha of mossy pine forests (Pinetapleuroziosa) will most likely grade into cowberry ones (Pineta vacciniosa); in this case the yieldclass may drop from 2 to 3. Around 700,000 ha of fresh mossy pine forests may grade into dryones; in this case the yield class may drop from 1 to 2. Also, the research points towards a probabledecline in productivity of around 40,000 hectares of bracken pineries (Pineta pteridiosa),particularly in the northern and central parts of the republic.The yield class for about 15,000 ha of wood sorrel pine forests (Pineta oxalidosa) in the northernand central parts of the republic may drop moderately from 1a to 1; in this case increasing aridity isnot a limiting factor for the growth of the pine stands. The yield class for cowberry pineries may32