Both plant invasions and subsequent management efforts can change vegetation structure and composition, but how these impacts affect other resident communities, such as arthropods, is uncertain. To evaluate how vegetation change relates to shifts in other trophic groups, we are tracking arthropod community composition as part of a long-term experiment evaluating the consequences of invasive shrub removal and plant community restoration. Russian olive (Elaeagnus angustifolia L.) is a nitrogen-fixing shrub or small tree invading riparian zones of western North America. Originally introduced for shelterbelts and wildlife habitat in dryland areas, it remains a popular agricultural species. Balancing its cultural value against increasing investments in managed removals requires teasing apart the links between Russian olive’s ecological costs and benefits to wildlife and ecosystem services. We compared arthropod communities before Russian olive removal to those two and five years after removal and to proximate non-removal reference plots. We sampled multiple habitat dimensions using a combination of sweeps, pitfalls, and malaise traps, and identified arthropods to the family level.
Results/Conclusions
Arthropod communities diverged two years after Russian olive removal, and differences persisted as vegetation re-established five years post-removal. These shifts resulted primarily from subtle changes in the relative abundance of community members (e.g., spiders, ants, hemipterans, and coleopterans), rather than overall differences in richness or diversity. Ground sampling with pitfalls showed the strongest compositional shift, as well as a nearly eight-fold higher arthropod abundance in removal plots relative to reference (Russian olive) plots. Removal pitfalls had more diverse and abundant assemblages of families from key orders, such as Araneae, Orthoptera, and Coleoptera, that constitute important functional components within our riparian system. Arthropods in removal and reference areas also significantly differed in the vegetation understory (from sweeps) and in the canopy (from malaise traps), though these communities were less distinct. Native shrubs and trees providing alternative equivalent vegetation structure have only recently begun to fill the canopy formerly occupied by Russian olive. Over time, this succession will allow us to better relate removal impacts to arthropod community change, and inform management decisions benefiting multiple dimensions of target communities.