Does the wetland invader, Alternanthera philoxeroides cause different ecological impact compared to the native Typha angustifolia? A comparison of sediment stoichiometry and microbial pattern between urban and periurban rivers

AbstractBackground and AimsPlant invasion can modify habitat characteristics for instance soil stoichiometry and microbial pattern. However, few studies concerned the effects of plant invasion on the soil properties in the urban ecosystem. The present study aims to explore the impact of aquatic plant invasion on sediment properties within the urbanization context.MethodsFirst, population density and impervious surface area, were used to construct an urbanization gradient of river wetlands and divide the two rivers of Qingdao City, China – Zhangcun River and Wenquan River into urban and periurban types. Second, sediment samples were collected from the plots invaded by the aquatic plant invader,Alternanthera philoxeroidesand its native neighbor,Typha angustifoliain urban and periurban rivers. Lastly, sediment properties were determined and a comparison was performed.ResultsFirst, a general similar fertility and stoichiometry was found between the sediment derived from the invasive and that from the native. Second, a higher bacterial diversity was found in the sediment derived fromA. philoxeroidesmerely in the periurban river, while the higher bacterial diversity was merely shown for the Shannon’s diversity index ofA. philoxeroidesin the urban river. Third,A. philoxeroidesshaped a novel soil microbial structure since more microbes relevant with nutrient cycling were accumulated compared to the native. Lastly, urbanization gradient affected the comparison between the invasive and native plants on soil properties. Conclusion The invasion of exotic aquatic plant altered the sediment microbial pattern to some extent and the potential plant-soil feedback needs further investigation.