Succession of bacterial community structure and diversity in soil along a chronosequence of reclamation and re-vegetation on coal mine spoils in China.

Yuanyuan Li,Tingting Yin,Longqian Chen,Hongyu Wen,Daniele Daffonchio

doi:10.1371/journal.pone.0115024

Abstract

The growing concern about the effectiveness of reclamation strategies has motivated the evaluation of soil properties following reclamation. Recovery of belowground microbial community is important for reclamation success, however, the response of soil bacterial communities to reclamation has not been well understood. In this study, PCR-based 454 pyrosequencing was applied to compare bacterial communities in undisturbed soils with those in reclaimed soils using chronosequences ranging in time following reclamation from 1 to 20 year. Bacteria from the Proteobacteria, Chloroflexi, Actinobacteria, Acidobacteria, Planctomycetes and Bacteroidetes were abundant in all soils, while the composition of predominant phyla differed greatly across all sites. Long-term reclamation strongly affected microbial community structure and diversity. Initial effects of reclamation resulted in significant declines in bacterial diversity indices in younger reclaimed sites (1, 8-year-old) compared to the undisturbed site. However, bacterial diversity indices tended to be higher in older reclaimed sites (15, 20-year-old) as recovery time increased, and were more similar to predisturbance levels nearly 20 years after reclamation. Bacterial communities are highly responsive to soil physicochemical properties (pH, soil organic matter, Total N and P), in terms of both their diversity and community composition. Our results suggest that the response of soil microorganisms to reclamation is likely governed by soil characteristics and, indirectly, by the effects of vegetation restoration. Mixture sowing of gramineae and leguminosae herbage largely promoted soil geochemical conditions and bacterial diversity that recovered to those of undisturbed soil, representing an adequate solution for soil remediation and sustainable utilization for agriculture. These results confirm the positive impacts of reclamation and vegetation restoration on soil microbial diversity and suggest that the most important phase of microbial community recovery occurs between 15 and 20 years after reclamation.

Highlights

Mining activities result in extensive soil damage, causing drastic disturbances in landscape, altering the ecological environment of soil microorganisms, thereby disrupting the functional stability of the microbial community [1]
Similar amount of Soil organic matter content (SOM), Total N, P and Available K were present in undisturbed reference (UND) and reclaimed sites (REC)-20, both of which were significantly greater than REC-1, suggesting that long-term reclamation practice and revegetation greatly improved physicochemical properties of degenerated soil to nearly pre-disturbance levels
The color of each site in small pie charts displayed the relative abundance of bacterial community group in different samples sites. All these analyses suggested that the dominant bacterial phyla observed in our older reclaimed soils (REC-20 and REC-15) and control soils were present in similar relative abundances, and the 20-yr-old reclaimed soil were more similar to the undisturbed soil than other soils

Summary

Introduction

Mining activities result in extensive soil damage, causing drastic disturbances in landscape, altering the ecological environment of soil microorganisms, thereby disrupting the functional stability of the microbial community [1]. Because of the important ecosystem functions mediated by microorganisms in the soil, recovery of the soil microbial community is a critical step in achieving the goal of soil restoration for its sustainable and beneficial use [4]. Changes in microbial community can precede detectable changes in soil physicochemical properties, thereby providing early signs of environmental stress or ecological environment evolution in the mining area [9]. There are few studies on general soil microbial community recovery and these studies have revolved around the effects of soil reclamation on microbial populations, microbial biomass and activity [9, 12, 13, 14]. In case of mine soils, recovery of soil bacterial diversity and structure in disturbed and reclaimed lands is not well understood

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Results

Discussion

Conclusion