Traceability of heavy metals and their effects on the species diversity of plant communities in Caizi Lake wetland, China

Abstract This study assessed the effects of heavy metals on plant community species diversity in the restoration and reconstruction area of Xinjian Dyke in Caizi Lake National Wetland Park. Using a positive matrix factorization (PMF) model, principal component analysis (PCA), regression, and correlation analysis, our study determined that the main sources of soil heavy metals in the study area were organic fertilizer, transportation and agricultural activities, and natural sources. Hg, Cd, Zn, As, Cr, and Cu were the main heavy metals in the study site. The Shannon-Wiener, Margalef, and Simpson indices were used to evaluate plant diversity. Our findings indicated that Hg was not significantly correlated with any of the three indices, Cr and As were positively correlated with the indices, and Cd and Zn were negatively correlated with the indices. Furthermore, Cu was positively correlated with the Shannon-Wiener and Simpson indices, and negatively correlated with the Margalef index. These findings indicated that the uniformity of the individual distribution among species was an important factor of community diversity, and the differences in the community diversity indices were related to the heavy metals in the soil . To improve the difference and functional complementarity between coexisting individuals, single superior species must be avoided and niche differentiation must be maintained as much as possible. Soil pH value, SOM, and other conditions should be improved to inhibit the migration and diffusion of heavy metals, improve their bioavailability, and give priority to local pioneer plants instead of functional redundant species.