DISTRIBUTION OF AN INVASIVE SPECIES OF HERACULUM SOSNOWSKYI MANDEN. (APIACEAE) IN THE LENINGRAD REGION

In the Leningrad Region, Heracleum sosnowskyi hogweed prefers well-developed fertile light and medium loamy sod-podzolic and sod-carbonate soils; it is practically absent in swamps and wetlands, in territories occupied by spruce forests, as well as pine forests with infertile low-power soils on sandy and rocky substrates. The most favorable hydrothermal, orographic, hydrological, soil, and ecological conditions for the development and spread of Sosnovsky hogweed are observed in the western, agriculturally developed areas (Slantsevsky, Kingisepp, Lomonosov, Volosovsky, Gatchina) with dismembered hilly relief, cultivated fields, occupying 7-13% of their territory, fallow lands. To the south, east and north of the area the conditions for development and spreading of hogweed become markedly worse that is stipulated mainly to the south and east by flat-low character of relief, its waterlogging, the spread of spruce and pine forests that are little and unfavorable for hogweed, low-power and poor soils on rocky substrates, especially to the north on the Karelian Isthmus and in the Podporozhsky district in the northeast.