Состав фитоценозов на лесных гарях Бурятии

Data on the species composition and abundance of woody and shrubby vegetation in burnt areas of southern Transbaikalia are presented. The object of the study is a large burnt area in the forest fund of the Khorinsky forestry of the Republic of Buryatia. Phytocenoses are located on sandy soils, on various relief elements at an altitude of 676 to 845 m above sea level – from the foothills to the tops of gentle hills. The vegetation of all forest components has been recorded along free routes on circular survey sites with a radius of 1,785 m. Adjacent to each other, they have formed a counting tape. At least 30 survey plots have been established at each experimental site. It has been established that the vegetation composition and the proportion of species at the study sites differ. In the burnt areas 14–15 years old, the presence of 15–18 plant species in the living ground cover has been noted. The maximum projective cover – more than 5 % – is found in 6 species: Vaccinium vitis-idaea L., Calamagrostis arundinacea (L.) Roth, Carex pseudocyperus L., Avenella flexuosa (L.) Drejer, Lichenes sp. L., Bryidae sp. Engl. 6 species have been identified in the undergrowth, the most prevalent being Sorbus aucuparia subsp. Sibirica (Hedl.) Krylov, Viburnum burejaeticum Regel & Herder and Juniperus sibirica Burgsd. It has been shown that the range of variation in the number of undergrowth by study objects has been 190–673 pcs/ha. The young growth is formed by Scots pine in numbers ranging from 27 to 62 pcs/ha. It has been indicated that the main reason for the small number of self-seeding pine trees has been the extreme soil surface temperatures in the summer. The maximum temperature of 63 °C has been recorded in the mineralized part of the soil, which causes protein denaturation in the endosperm and loss of seed germination. Emphasis is placed on the large proportion of the mineralized surface as a consequence of wind and water erosion. In some experimental sites, the mineralized surface area has exceeded 18 %. The results obtained can be used in the design of reforestation measures, in geobotanical research and in the educational process.