Vol 7, No 1 (2016)

The verified list based on published reports and our own data and brief information on 78 alien plant species of the Yalta Mountain-Forest Nature Reserve are given. The recently revealed plant species are represented. The transformation rate of the vegetation in the protected area is evaluated on the basis of the analysis of the structure and dynamics of the adventive fraction. The species grouped accoding to the period of plant introduction, naturalization rate, and original range.

The flora of the Main Botanical Garden of the Russian Academy of Sciences (Moscow) was analyzed. It included 856 species from 407 genera, belonging to 95 families of vascular plants. The dynamics of the local flora within a significantly long period was analyzed for the first time. It was revealed that within a 65-year-long period, the local flora increased by 1.8 times: 62 wild species, 284 escapees from cultivation, and 36 alien weeds were added. For certain, Adenocaulon adhaerescens escaped from the Botanical Garden, and probably Geum macrophyllum did so. The taxonomic classification, life form, type of range, and invasive status of the species of the alien flora fraction were analyzed.

As a result of reintroduction of individuals of the Eastern European and Belorussian subspecies of European beaver populations, a Middle Irtysh population was formed. Five stages can be distinguished in its development: adaptation (1953–1966); recovery (1967–1975); stabilization (1976–1988); depression (1989–2000); and expansion (2001–2012, not finished). Each stage has its own individual statistical and mathematical characteristics. A complete restoration of the European beaver range has not been achieved in the oblast, since the introduction of commercial hunting led to a depression in the number and number dilution of the range. Therefore, the quantitative and spatial development of the Middle Irtysh European beaver population was delayed for 25 years.

This paper analyzes the secondary range and peculiarities of the early stages of development of Chaerophyllym aureum, an alien Umbelliferae species, which appeared in European Russia in the 20th century; one of the first herbaria (Moscow oblast) dates back to 1924. The species is most often found in the secondary range in anthropogenic habitats: near railways, on wastelands, more seldom in meadows and at edges of deciduous forests. In the regions represented by the herbaria, C. aureum is successively naturalized and creates stable self-supporting populations. It has a set of helio-mesomorphic structural features which permits it to take roots in relatively open moderately moist habitats and compete with aboriginal species. Such properties as the high rate of germination and significant polymorphism in morphology, size, and time of development of premature C. aureum individuals, which were revealed in this work, can promote the successful naturalization of the species in the secondary range.

The common hamster (Cricetus cricetus L., 1758) historically formed an extensive range covering much of Europe and Asia. However, in the last 50 years almost throughout the whole range, its number in natural habitats and agrocenoses dropped sharply. At the same time, the common hamster began to settle cities, which could be considered as a biological invasion. Now urban populations are found in Vienna (Austria) and several cities of Germany, the Czech Republic, Slovakia, Poland, and Russia. By example of Simferopol, where the largest urban population exists, we show what resources the species can use in the city and what changes in the ecology and behavior follow this. It is suggested that the major factors promoting the settling of cities by the common hamster are additional environmental resources associated with the specifics of the urban environment: the emergence of new shelters, food sources, etc. We assume that ecological opportunism, polyphagy, and high stress resistance could be crucial for the ability to settle urban environments.

This article presents results of the study of exotic woody plants producing self-seeding on the territory of St. Petersburg (Russia). According to our data, self-seeding is recorded in 227 species of 73 genera of 31 families in St. Petersburg. In 49 species of 28 genera of 19 families, self-seeding is observed for the first time. A number of species have potentially invasive properties, which is especially notable in recent years against the background of climate warming in St. Petersburg. Self-seeding emergence and maintenance depends on a number of factors, such as the presence of group plantings, level of soil turfing, degree of illumination, and presence or lack of treatment. It is urgent to constantly monitor all species producing selfseeding, since some of them may be potentially invasive.