Ecological Niches and Density of Cenopopulations of European Mountain Ash in Ekaterinburg Forest Parks
Introduction. In forest parks of modern cities, an anthropogenic transformation of forest plantations, performing habitat forming and environment regulation functions, is observed. The break of natural processes leads to the change in the composition of undergrowth species and supplantation of native species. The goal of this research is to monitor the anthropogenic transformation of old-aged pine stands in the urban wooodlands. Tasks: to reveal the cenotic role of European mountain ash (Sorbus aucuparia L.), define its ecological niches and cenopopulation density. The cenopopulations of Sorbus aucuparia L. of five forest parks of Ekaterinburg are the object of the research. These parks are the forest park named after Foresters of Russia, Nizhneisetskiy forest park, Shartashskiy forest park, Shuvakishskiy forest park, and Yugo-Zapadnyy forest park. The methodology included a route survey of forest parks located at different distances from the city and establishment of 16 study plots in order to determine the density (pcs/ha) of Sorbus aucuparia L. cenopopulations depending on the normality. Identification of ecological niches in the overmature pine plantations of Ekaterinburg forest-park zone was carried out under the “LesFond” program. Results. The dominant undergrowth species of Sorbus aucuparia L. is represented by fragments of populations of different age groups in 12 forest types. It takes the maximum areas in berry pine forests in remote from the city forest parks (Shuvakishskiy and Nizhneisetskiy forest parks). The stability of Sorbus aucuparia L. cenopopulations is confirmed by their high density and variety of ecological niches. The optimal ecological niche of Sorbus aucuparia L. in the overmature pine plantations is a berry pine forest and a herb pine forest. The highest density of Sorbus aucuparia L. cenopopulations, as an indicator of the development of an ecological niche, was found in the berry pine forest of Shartashskiy forest park with 0.7 density of pine. Malus baccata (L.) is a chief competitor of Sorbus aucuparia L. in capturing the undergrowth area of the studied forest parks. Conclusion. Scots pine stand is a phytocenotic protection for native undergrowth species from invasive cenopopulations of Malus baccata L. and other woody introduced species.