[Influence Mechanism of Restoration Years on the Inter-root Soil Environment and Bacterial Community of Robinia pseudoacacia：A Case Study of the Iron Tailing Pond Governance Area in Northern Hebei， China].

Abstract

To elucidate the succession pattern of the inter-root soil environment and microbial community structure of Robinia pseudoacacia in the process of mine restoration through time， the inter-root soil of Robinia pseudoacacia in six restoration years （5a， 9a， 12a， 15a， 20a， and ck） was selected as the object of study. High-throughput sequencing， Mantel analysis， molecular ecological network analysis， and other methods were employed to investigate the change pattern of soil environmental factors， as well as the stability of the bacterial community and the influence of underlying mechanisms. The study produced several important results： ① The inter-root soil factors of Robinia pseudoacacia exhibited significant differences across the various restoration years. The contents of SOM， TN， AN， and AK were higher in the restored soil than in ck. AN， TN， and MBC increased each year， while pH and AP decreased each year. ② Significant differences in the diversity and richness levels of soil bacterial communities were observed at different restoration years. The dominant phyla were Proteobacteria （39.7%-65.2%）， Acidobacteria （5.3%-31.8%）， Actinobacteria （5.4%-10%）， and Green Chloroflexi （4.1%-9.8%）， which collectively accounted for more than 83% of the total community. The diversity of species was higher under the different treatments than under ck， with high microbial diversity at 9a and 12a. The bacterial network aggregation was lowest at 9a and highest for ck. The Robinia pseudoacacia bacterial community was most stable at 20a and least stable at ck. ③ Significant correlations were found between soil physicochemical properties and bacterial communities at different restoration years， and highly significant correlations （P < 0.01） were found between bacterial diversity and the number of OTU and MBN， pH， and so on. The structure of the bacterial community at the phylum level showed highly significant correlations （P < 0.01） with MBN， TK， and others. The phyla Ascomycota and Bacteroidetes showed significant positive correlations （P < 0.01） with factors such as pH and TN. The results of the study provide a scientific basis and reference for environmental remediation and ecological restoration for sustainable development in the mining areas of northern Hebei.