Invasive plants of urban forests of Berlin - economic problems associated with selected species and methods of their control.
With increasing globalization, increasing numbers of plant species are being moved from their areas of natural occurrence to new ecosystems and parts of the world. Several species belong to the invasive alien species with more or less negative impacts on their surrounding environment. In the urban forests of Berlin, we can already find five plants from the "List of Invasive Alien Species Recognized as Threatening the European Union" (Ailanthus altissima (Mill.) Swingle, Asclepias syriaca L. Elodea nuttallii H. St. John, Heracleum mantegazzianum Sommier & Levier, Impatiens glandulifera Royle), and a dozen plant species considered invasive and potentially invasive by the German Federal Office for Nature Conservation (Bundesamt für Naturschutz). However, not all of them are subject to eradication. The Berlin Forestry Administration and the Berlin Senate have focused on two groups of plants: species that have a significant negative impact on forest management, and species that threaten human and animal health and/or life. The aim of this paper is to present the history of invasive species in the urban forests of Berlin. Furthermore, it discusses which invasive species pose the biggest problems from a natural and economic point of view, and describes the measures to reduce and control them that have been taken so far in Germany. The paper discusses the significance of such important species as Prunus serotina Ehrh., Heracleum mantegazzianum and Ambrosia psilostachya L., as well as measures which have been taken so far to limit their populations.