Invasive goldenrods affect abundance and diversity of grassland ant communities
Solidago gigantea and S. canadensis (Asteraceae, EPPO List of Invasive Alien Plants) are a major threat to semi-natural habitats in Central Europe having been introduced as garden ornamentals from North America in the first half of the nineteenth century. Their success can be attributed to their high colonisation ability, rapid growth rates and high propagule pressure (plants can produce thousands of seeds which are wind dispersed). The present study evaluated the impact of the presence of S. gigantea and S. canadensis on ant (Hymenoptera: Formicidae) populations in ten semi-natural wet grasslands located in the south-eastern part of Kraków (Poland). Ants are considered a keystone species in many natural habitats, playing an important role in modifying the physico-chemical properties of the soil. Ants are sensitive to environmental changes making them useful bioindicators of the environment. At each of the ten sites, six 5 x 5 m square plots were selected where three plots were dominated by S. gigantea and S. canadensis and three were control plots (free from the non-native species). The cover of vegetation in each plot was estimated using the Braun-Blanquet Cover-Abundance Scale method. In each plot the total number of ant nests was recorded and the ant species present were identified. A total number of 1 087 ant nests belonging to seven species were observed during the study. Myrmica spp. were the most common species collected and were more numerous in the control sites compared to the invaded sites. The number of ant nests was significantly lower in invaded plots compared to the controls with more than a 50 % reduction in invaded plots. The number of ant species was also lower in invaded plots compared to the controls, with the results of a NMDS ordination plot suggesting differences in the structure of the ant community between invaded and uninvaded plots.
Kajzer-Bonk J, Szpilyk D, Woyciechowski M (2016) Invasive goldenrods affect abundance and diversity of grassland ant communities (Hymenoptera: Formicidae). Journal of Insect Conservation 20, 99–105.