Phosphorus is more effective than nitrogen in restoring plant communities of heavy metals polluted soils. (November 2020) - Huang, Jingxin
Abstract: Heavy metal pollution is widespread, and has an increasing trend in some countries and regions. It can be easily accumulated in plants, leading to plant species loss and affecting plant community composition. Artificial restoration can conserve plant diversity in contaminated soils and accelerate the recovery of polluted ecosystems. The application of nitrogen (N) and phosphorus (P) is inexpensive and convenient, which can increase the resistance of plants to adversity and promote the growth of plants in heavy metal polluted soils. In order to examine the effect of N and P nutrition on the conservation of plant community, we conducted a comparison experiment in greenhouse using soil with low N and P concentration, and set five treatments: C (soil with no heavy metals and fertilizer addition), H (soil with heavy metals addition but with no fertilizer), HN (soil with heavy metals and N addition), HP treatment(soil with heavy metals and P addition), HNP treatment (soil with heavy metals, N and P addition). Our results showed that heavy metal pollution reduced plant species by 300%, and significantly decreased plant diversity ( P < 0.05). N addition increased the richness of plant species and increased the dominance of Euphorbia peplus, but had no significant effect on plant diversity and community structure, while reduced the evenness of plant species. P addition of HP and HNP treatments restored plant species richness and increased plant diversity under heavy metal pollution. The plant community structures of these two treatments were more similar to that of group C. Compared with N addition, P addition had a better performance to restoring the species composition and relative dominance of plant communities. Our results provided a guidance for the restoration of plant communities and the conservation of plant species in low N and P concentration soils with the context of heavy metal pollution. Graphical abstract: Soil heavy metals pollution decrease plant diversity, evenness, change plant community composition. Nitrogen and phosphorus fertilizer increased soil N and P available, it further positively affected plant diversity, and P had a higher effect than N. Fig.1 Results of structure equation model analysis examining effects of N, P addition and soil heavy metals content on Richnness, Pielou Index, Shannon wiener Index, Simpson Index. Orange and blue lines indicated positive and negative relationship, respectively. Width of lines represented proportional to the strength of the relationship. Solid and dashed lines represented significant positive ( P < 0.05) and negative pathways respectively. Image 1 Highlights: Soil heavy metals pollution decreased plant diversity. Nitrogen and phosphorus addition both restored richness, diversity of plant species of heavy metals polluted soil. Phosphorus addition had a better performance to restoring the plant communities than nitrogen.