With or without you: A global meta-analysis of resilience of native faunal communities in response to invasive Spartina species and its removals in coastal ecosystems

Zhonghua Ning, School of Environment, Beijing Normal University, Beijing, China

Background/Question/Methods: Coastal ecosystems worldwide are being threatened by invasive species in the context of global changes. Especially the invasive plants often bring ecological consequences, such as disruption of trophic interactions, reorganization of native communities and losses of ecosystem functions. However, how the invasive plants influence the native faunal communities and whether native faunal communities could be recovered following the invader removals with different measures across global coastal ecosystems are still poorly understood. Here, we presented the first global meta-analyses to quantify the impacts of Spartina invasions on coastal faunal communities and further to evaluate the outcomes of Spartina removals on their recovery based on 74 independent studies.
Results/Conclusions: We found that invasive Spartina species generally decreased the biodiversity, but increased coastal faunal abundance and fitness, though the effect on abundance was insignificant. The pattern of influence was context-dependent that these effects strongly depended on habitat types, faunal taxa, trophic levels and feeding types. Specifically, Spartina species invaded to mudflats caused greater impacts than that invaded to vegetated habitats. Insects and birds at higher trophic levels were strongly affected by invasive Spartina species, indicating that invasive plant effects can cascade upward along with the food chain. Additionally, impacts of Spartina invasions were more obvious on food specialists such as herbivores and carnivores. Furthermore, our analyses revealed that current removal measures were overall beneficial for native faunal communities to recover from the displacement caused by Spartina invasions (i.e., resilience), but this recovery process depended on specific removal measure and time. For example, the long-term waterlogging had strong negative impacts on faunal recovery that should not be encouraged for controlling invasive plants. Our findings suggest that invasive plants could have contrasting effects on functional responses of native faunal communities. Although invasive plant removals could enhance the resilience of native faunal communities, future functional restorations of invaded ecosystems should take the legacy effects of invasive species on native communities into account. These findings provide insightful implications for future scientific controls of invasive species and the recovery of natural ecosystems under intensifying global changes.