The work represents the results of perennial studies of the structural-dynamic organization of the phytocoenoses, which are subjected during a long period to anthropogenic impact in different, for geographical conditions, areas of western and south-eastern Pre-Baikal. The composition of phytocoenoses, which form at cuttings of forests of different composition and typology is found out. The following parameters are determined: species composition, synfolial differentiation and dominant species of the soil cover reflecting the dynamics of reconstitutional stages of polydominant light-coniferous forests of Pre-Baikalian type. We noticed the peculiarities of transformation and reconstitution of the coenoses, which during a long period are used for haying and pasturage formed on the site of earlier cut timber stands at the boundary with the extrazonal steppe. During last decades, a gradual forestation of these territories is observed, the steppe plants species in the soil cover are replaced by forest species characteristic for the light-coniferous taiga. On the site of cuttings of dark-coniferous taiga in the first half of the last century in the southern part of Pre-Baikal, forests form with dominance of more hydrophilic trees species in undergrowth and young growth – fir and spruce replace cedar everywhere. This is probably due to secular forests dynamics with replacement of forest forming trees species on the background of climate changes during last decades. There are as well changes in the species composition of plants on the soil cover of forming dark-coniferous taiga.

Sizykh Alexander Petrovich, Doctor of Science (Biology), Leading Researcher, Laboratory of Ecosystems Bioindication, Siberian Institute of Plant Physiology and Biochemistry SB RAS, 132, Lermontov st., Irkutsk, 664003, Russian Federation, e-mail: alexander.sizykh@gmail.com

Sizykh A.P. Transformation and Reconstitution of Vegetation in the Pre-Baikal. The Bulletin of Irkutsk State University. Series Earth Sciences, 2021, vol. 37, pp. 86-102. https://doi.org/10.26516/2073-3402.2021.37.86 (in Russian)

Bezrukova E.V. Rastitelnost I klimat uga Vostohnoy Sibiri v pozdnem neopleystozene i golozena [Plants and Climate in the South of East Siberia During Late Neopleistocene and Holocene]. Abstr. Diss. Sci. Irkutsk, 2002, 46 p. (in Russian)

Belova V.A. Rastitelnost i klimat pozdnego kainazoay uga Vostochnoi Sibiri [Vegetation and climate of Late Holocene of South of Western Siberia]. Novosibirsk, Nauka Publ., 1985.159 p.(in Russian)

Geologicheskay karta uga Wostochnoi Sibiri i severnoi chasti Mongolii [Geological map of South of Eastern Siberia and Northern part of Mongolia]. Moscow, GUGK Publ., 1988, 1 p. (in Russian)

Voropai N.N., Gagarinova O.V., Ilicheva E.A., Kichigina N.V., Maksutova E.V., Balubina A.S., Osipova O.P. Gidrolimaticheskie issledovania Baikalskoi prirodnoi territorii [Gidro-climate researches on the Baikalian nature territories]. Novosibirsk, Nauka Publ., 2013, 187 p. (in Russian)

Grichyk M.P. K istorii rastotelnosti v basseine Angary [To history of vegetation in the basin of Angara river]. Doklady Academy of Science of USSR, 1955, vol. 102, no. 2, pp. 335-338. (in Russian)

Korrelaysionnaya ecologo-phytosenoticheskay karta [Correlation Ecological-Phytocoenotic map (scale 1: 500 000)]. Irkutsk, 1977, 1 sheet (in Russian)

Kuzavkova Z.O. Prostransvennya organizaciya geosistem zapadnogo makrosklona barguzinskogo chrebta [Spatial organization of geosistems of Barguzine ridge’ western slope]. Abstr. Dis. Sci. Irkutsk, 2019, 23 p. (in Russian)

Landshafty uga Vostochnoi Sibiri. Mastab 1:1 500 000 [Landscapes of the South of East Siberia, (Map. Scale 1:1 500 000)]. Moscow, State Department of Geodesy and Cartography Publ., 1977, 4 sheets (in Russian)

Metodu geobotanicheskich issledovanii [Methods of geobatanical researches]. Moscow, Association “Ecosystem” Publishing House, 1996, 21 p.

Peshkova G.A. Rastitelnost Sibiri. Predbaikale I Zabaikale [Vegetation of Siberia. Pre-Baikal and Trans-Baikal]. Novosibirsk, Nauka Publ., 1985, 145 p. (in Russian)

Polevaya geobotanika [Field Geobonany]. Vol. 3. Moscow, Leningrad, 1964, 530 p. (in Russian)

Polevaya geobotanika [Field Geobonany]. Vol. 4. Moscow, Leningrad, 1976, 336 p. (in Russian)

Prein Ya.P. Predvaritelnui otchet o botenicheskich issledovaniaych Balaganskogo okruga i okrestnostei g. Irkutska [Preliminary report about botanical research of Balagansk area and around of Irkutsk city]. Bulletin Western-Siberian branch of RGO, 1892, vol. 23, iss. 2, pp. 29-53. (in Russian)

Rastitelnost uga Vostochnoi Sibiri [Vegetation of the South of East Siberia (map, scale 1:1 500 000)]. Moscow, State Department of Geodesy and Cartography Publ., 4 sheet. (in Russian)

Sochava V.B. Geographycheskay zonalnost i polayrnay antisimmetriya.[Geographical zonality and polar anti-symmetry]. Bulletin AN USSR. Geographical Issue, 1963, no. 6, pp. 122-123. (in Russian)

Sochava V.B. Geotopologia kak razdel ucheniay o geosistemach [Geotopology as an research section about geosystems]. Topological aspects disciple about geosystems. Novosibirsk, Nauka Publ., 1974, pp. 3-86. (in Russian)

Sochava V.B. Rastitelni pokrov na tematicheskich kartach [Vegetation cover on the subject maps]. Novosibirsk, Nauka Publ., 1979, 189 p. (in Russian)

Stepi Evrasii [Steppe of Eurasia]. Leningrad, Nauka Publ., 1991, 145 p. (in Russian)

Stepi Centralnoi Asii [Steppe of Central Asia]. Novosibirsk, Nauka Publ., 2002. 296 p. (in Russian)

Maksutova E.V., Kichigina N.V., Voropai N.N., Оsipov O. P. Tendensii gidroklimaticheskich izmenenii na Baikalskoi prirodnoi territorii [Tendency of gidro-climate changes on the Baikalian nature territories]. Geography and natural resources, 2012, no. 4, pp. 72-81. (in Russian)

Tipy lesov gor Uzsnoi Sibiri [Types of Forests of Southern Siberia mountains]. Novosibirsk, Nauka Publ.,1980, 336 p.

Tishkov A.A. Sukcessi rastitelnosti zonalnuch ecosystem: sravnitelno-geographicheskii analis, znachenie dlay sochraneniay I vosstanovleniay bioraznoobrasiay [Successions of vegetation of zonal ecosystem: geographical analysis, important for conservation and restoration of biodiversity]. Bulletin of Samara scientific center of Russian academy of Science, 2012, vol. 14, no. 1(5), pp. 1387-1390. (in Russian)

Shmakin A.B. Klimaticheskie characteristiki sneznogo pokrova Severnoi Evrasii i ich izmeneniay v poslednie desaytiletya [Climate characteristics of snow cover of Northern Eurasia and its changes for last decades]. Ice and Snow, 2010, no. 1 (109), pp. 43-57. (in Russian)

Ashton D.H. Fire in tall open-forests (wet sclerophyll forest). Fire in the Australian Biota, 1981, pp. 66-339.

Pellegrini A.F.A, Andereg W.R.L., Paine C.E.T, Hoffmann W.A. et al. Convergence of bark investment according to fire and climate structures ecosystem vulnerability to future change. Ecology Letters, 2017, vol. 20, no. 3, pp. 307-316. http://doi.org/:10.1111/ele12725

Foster D.R. Disturbance, history, community organization and vegetation dynamics of the old-growth Pigah forests, south-western New Hampshire, USA. J. Ecology, 1988, vol. 76, pp. 34-105.

Franklin J.F., Hemstron M.F. Aspects of succession in the coniferous forests of the Pacific Northwest. Forest Succession: concepts and applications, 1981, pp. 212-229. http://doi.org/10.1007/978-1-4612-5950-3_14

Glitzenstein J.S., Harcombe P.A., Streng D.R. Disturbance, succession and maintenance of species diversity in an east Texas forest. Ecolog. Mongr., 1986, vol. 56, pp. 58-243.

Harmom M.E., Bratton S.P., White P.S. Disturbance and vegetation respons in relation to environmental gradients in the Great Smoky Mountains. Vegetatio, 1983, vol. 55, pp. 39-123.

Horn H.S. Succession. Theoretical Ecology: principles and application, 1976, pp. 187-204.

Peet R.K., Christensen N.L. Succession: a population process. Vegetatio, 1980, vol. 43, pp. 40-131.

Smirnova E., Bergeronm Y., Brais S. Influence of fire intensity on structure and composition of jack pine stands in the boreal forest of Quebec: live trees, understory vegetation and dead wood dynamics. Forest Ecology Management, 2008, vol. 255, no. 7, pp. 2916-2927. http://doi.org/:10.1016/j.foreco.2008.01.071

Veblen T.T, Lorens D.C. Anthropogenic disturbance and recovery patterns in mountains forests, Colorado Front Range. Physical Geography, 1986, vol. 7, pp. 1-24.