Differing impacts of two major plant invaders on urban plant-dwelling spiders (Araneae) during flowering season

Abstract Plant invasions can have major impacts on ecosystems and influence global species diversity. In Central Europe, Himalayan balsam ( Impatiens glandulifera ) American goldenrods Solidago canadensis S. gigantea are important invaders often establishing dense homogeneous stands, especially in urban other disturbed habitats. We investigated their plant-dwelling spiders (abundance, family structure, guild structure) potential spider prey items during flowering season within an urbanized landscape using a paired design comparing invaded native reference vegetation plots. general, had no significant the composition. Invasion of further effect total abundance item abundance. contrast, showed significantly increased crab (Thomisidae) while being less inhabited by web builders. negatively influenced free hunters running (Philodromidae) abundance, we found effects groups For balsam, was higher than stands. Notwithstanding that our results only represent snapshot system, they suggest large-scale removal goldenrod stands might local spiders. Management efforts should therefore be accompanied compensation measures to avoid disruptive communities.