Chapter 2 Raw Data

Plant invasions likely impact entire arthropod communities but most research focuses either on insect controls or select target plant species. In Western Montana, USA, vegetation and arthropod communities were compared between intermountain grassland habitats uninvaded by spotted knapweed (Centaurea stoebe) and habitats corresponding with increasing levels of invasion. Arthropods were sampled using a diverse array of sampling methods. Arthropod data were analyzed both at the community and trophic level. Native plant species richness and percent cover values were significantly different between uninvaded and invaded habitats, but no differences were observed in plant diversity and evenness. Invasion by C. stoebe did not reduce arthropod morphospecies diversity estimates. Overall arthropod abundance however and proportional abundance by trophic level were significantly influenced by extent of invasion. Arthropod detritivores, predators, and biological control herbivores were positively re...