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

Abstract

This study investigated the effects of heavy metals on the species diversity of the Xinjian Dyke Wetland, an ecosystem where reclaimed farmlands are being transformed back into wetlands through the introduction of indigenous plants. The sources of soil heavy metals were analyzed, and correlation analyses were conducted to assess the relationships between heavy metal content and biodiversity indices. The results indicated that (1) the mean contents of Hg, Cd, Cu, Zn, As, Cr, and Pb were higher than the control values, with the content of Hg, Cd, Cu, and Zn exceeding the national standard; (2) the soil heavy metals mainly came from pesticides, chemical fertilizer, transportation, sewage irrigation, and the soil matrix; and (3) Hg and As were not significantly correlated with the diversity indices, but there was a highly positive correlation for Cu, Cr, and Pb, and a significant negative correlation for Zn and Cd. Collectively, our findings indicated that heavy metals have different effects on the plant species diversity inXinjian Dyke reconstruction area. The ecological restoration of wetlands from reclaimed farmlands should reasonably increase tolerant species and maximize the ecological niche differentiation of the species. Moreover, functionally redundant species should not be planted.