Impacts of an Invasive Non-Native Annual Weed, Impatiens glandulifera, on Above- and Below-Ground Invertebrate Communities in the United Kingdom

Abstract

Vegetation community composition and the above- and below-ground invertebrate communities are linked intrinsically, though few studies have assessed the impact of non-native plants on both these parts of the community together. We evaluated the differences in the above- (foliage- and ground-dwelling) and below-ground invertebrate communities in nine uninvaded plots and nine plots invaded by the annual invasive species Impatiens glandulifera, in the UK during 2007 and 2008. Over 139,000 invertebrates were identified into distinct taxa and categorised into functional feeding groups. The impact of I. glandulifera on the vegetation and invertebrate community composition was evaluated using multivariate statistics including principal response curves (PRC) and redundancy analysis (RDA). In the foliage-dwelling community, all functional feeding groups were less abundant in the invaded plots, and the species richness of Coleoptera and Heteroptera was significantly reduced. In the ground-dwelling community, herbivores, detritivores, and predators were all significantly less abundant in the invaded plots. In contrast, these functional groups in the below-ground community appeared to be largely unaffected, and even positively associated with the presence of I. glandulifera. Although the cover of I. glandulifera decreased in the invaded plots in the second year of the study, only the below-ground invertebrate community showed a significant response. These results indicate that the above- and below-ground invertebrate communities respond differently to the presence of I. glandulifera, and these community shifts can potentially lead to a habitat less biologically diverse than surrounding native communities; which could have negative impacts on higher trophic levels and ecosystem functioning.

Evolution of plant defences along an invasion chronosequence: defence is lost due to enemy release – but not forever

“…; Tanner et al . ). A previous experiment has shown that this inhibition could be attributed to allelopathic effects on seed germination of U. dioica , from either leaf extracts or root leachates (Gruntman et al .…”

Invasive success and the evolution of enhanced weaponry

“…In a second set of experiments, we examined the predictions of the NWH by evaluating the germination success of U. dioica seeds collected at both the native and invasive ranges of I. glandulifera in response to either leaf extracts of –or soil trained with– invasive I. glandulifera . In all experiments, we used U. dioica as a target species because it not only shares similar habitats as I. glandulifera at both ranges and has been shown to be highly inhibited by it at its invasive range (Tickner et al , Tanner et al ), but also because it is a fierce competitor often dominating plant communities not occupied by I. glandulifera (Hejda and Pyšek , Taylor ). Urtica dioica therefore presents a preferable test species, whose response to I. glandulifera could represent a more general effect compared to poorer competitors (Vilà and Weiner ).…”

Weed biological control in the European Union: from serendipity to strategy

“…Himalayan balsam can tolerate a wide range of environmental conditions, enabling the plant to rapidly form dense monocultures on wasteland, woodland, railways lines and particularly in riparian habitats. As well as directly reducing biodiversity (Hulme and Bremner 2006), especially amongst invertebrate communities (Tanner et al 2013), Himalayan balsam also lures pollinators away from native plants, decreasing the fitness of native species (Chittka and Schürkens 2001). River banks are laid bare by the weed after it dies back in the winter, which renders them more prone to erosion (Greenwood and Kuhn 2014).…”