SUCCESSIONS VEGETATION ON SOD-PODZOL SOILS OF A SUBTAIGA OF THE TOM-YAYSKY INTERFLUVE

In ecosystems of the southeast of Western Siberia's subtaiga two interesting dynamic phenomena can be observed in last decades. The first phenomenon is biodiversity restoration in ecosystems after the cessation of agricultural activity. It is related with agriculture degradation on low productive eutric podzoluvisols (by FAO 90) soils, especially after social and economic shocks at the end of the 20-th century. The second phenomenon is old growth dark coniferous forests dying (a fir is dominant) and photophilous sequences introduction. These phenomena are in the beginning and at the end of succession sequences. There are no researches that consider these phenomena in common. The succession sequences of the southeast of Western Siberia's subtaiga are not investigated.Therefore the purpose of the work was to investigate the succession sequences in subtaiga of the southeast of Western Siberia.To construct vegetation succession sequences the following method is used. We selected a row of ecosystems with similar soils and different succession status. The youngest, transitive links and mature. Then a spatial row convert in the temporal row. We studied succession sequences of vegetation within the area of eutric podzoluvisols with powerful albic horizons (more than 30-40 sm). The territory of research was the Tom-Yaysky interfluve. We chose a model range of ecosystems on the territory of the Larinsky wildlife preserve of Tomsk region, where they adjoin to each other and have various age. A spatial drawing of ecosystems of the Larinsky wildlife preserve reflects more than 150 year old summer history of wildlife management on this territory. In the center of the wildlife preserve old growth forests are located. Their formation is connected with the Larino village which used to be there from the middle of the 19-th century to the middle of the 20-th.Basing on the results of the research we made the following succession row of demutation vegetation. It is applicable to eutric podzoluvisols of the Tom-Yaysky interfluve. 1) Unstocked ecosystems (pasturable meadows, a plot of felled forest, arable lands, fires) are replaced by mixed or pure forests of aspens (pasturable meadows, a plot of felled forest), birches and pines (a fires (?), arable lands). 2) Mixed or pure forests of pines, aspens, birches with some fir-trees, cedars and fur-trees (with its domination in the understory of young regeneration on semi- and hydrogenic soils). 3) After coniferous species (fir-trees, Siberian cedars (though less) and spruces) getting into the first layer dark mixed forests are formed. Besides the second generation of aspens can join fir-trees on the Tom-Yaysky interfluve. 4) Firry, aspen-firry (on the interfluve), or cedarum-firry forests (in the valleys of rivers). In the beginning of a stage the admixture of old birches, aspens, pines can appear (in case of pine abundance variants of firry- and cedarumpinnum forests are formed). 5) Fir forests with gap-mosaic structure, rich in herbs and tallgrass and close to uneven-aged ones. The fifth stage is not the climax. In the absence of disasters the mosaic structure of firry forests is steady. At pathogenic disasters a firry forest stand collapses. Even-aged firry forests appear if there are no fires. If dry forests burn out, then demutation repeats. The last stage comes no less than in 200-250 years of spontaneous development.

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