Relationship of the heavy metals distribution in sediments to vegetation diversity and macroinvertebrate communities in riparian wetlands

River habitat integrity plays a key role in maintaining the safety and health of environment, ecology, and hydrology of rivers. To investigate the relationship of the distribution of heavy metals in sediments to vegetation diversity and macroinvertebrate communities in riparian wetlands, the surface sediments, vegetations and benthic invertebrates were sampled in Luanhe River. Six heavy metals, including Ni, Cr, Zn, Cu, Pb and Cd, were measured. Effects range-median quotient and integrated potentially ecological risk index were calculated to evaluate the pollution characteristics of heavy metals. The biological communities were assessed with the application of vegetation diversity index and benthic macroinvertebrate-based index of biotic integrity(B-IBI). The results showed that the surface sediments of Luanhe River were at clean status, but the distribution of heavy metals varied substantially in different sections. Along the river, the ecological harm index and potential ecological index were the highest at the lower reaches. A total of 219 vascular plant species and 105 macroinvertebrate species were collected in Luanhe River. The plant diversity and benthic macroinvertebrate integrity was lower in the downstream than in the middle and up stream. Overall, heavy metals in sediments of the downstream showed a high potentially biological toxicity on biological communities in Luanhe River, reducing the vegetation species diversity and benthic community integrity in the riparian wetlands. The B-IBI reflects the change of the structural characteristics of benthic macroinvertebrate communities effectively and has significant implications in assessing ecological health of riparian wetlands.