Changes in the structure of ant assemblages in broad-leafed forests with domination of Impatiens parviflora Dc. (Balsaminaceae) in herbaceous layer

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In June–August of 2012–2013, changes in the structure of multispecies ant assemblages caused by invasive plant species Impatiens parviflora in deciduous forests of the green zone of Kiev, Ukraine, were studied. This species–transformer is able to penetrate into ecosystems and change their shape by forming single–species thickets. Data on ant’s attendance of each of the 7 species of herbaceous forest plants were compared. The comparison showed that I. parviflora is the most attended herbaceous forest plant by ants. Fourteen ant species were found in the areas where I. parviflora dominated in the grass layer. Three species of ants, Formica rufa, Lasius fuliginosus, and L. emarginatus, are dominants. When becoming a dominant species in the grass layer of forests, I. parviflora is attended mainly by influent ant species. The main resource provided by I. parviflora to ants is the sugary excretions of aphids Impatientinum asiaticum colonies. Dominant ant species, except for L. emarginatus, do not attend I. parviflora plants, which gives the ability of creating high dynamic density in the grass layer to influent species without the influence of dominants. Influents prefer to attend the herbaceous layer, whereas dominants prefer the ground layer. Influence of I. parviflora on quantitative parameters in multispecies ant assemblages is generally estimated positively. In plant communities, where I. parviflora dominates in the grass layer, the assemblages of ants are characterized by maximum values (ant species number and medium number of ants per sample) compared with other communities formed by native herbaceous plants.