Soil properties under different ecological restoration modes for the quarry in Yanshan mountains of Hebei province, China

Abstract

The ecological environment of quarry mining area is fragile, and the vegetation restoration cycle is long and difficult, so scientific and appropriate artificial vegetation is of great significance to ecological restoration. The purpose of this study was to evaluate the herbaceous and woody vegetation restoration, including Medicago sativa (Me), artificial miscellaneous grass (Mg), Rhus typhina (Rh), fruit orchard (Or) and Pinus tabulaeformis (Pi), to investigate the soil physicochemical properties and the structure of the microbial communities, and to reveal the correlation between them. The results addressed that Medicago sativa and artificial miscellaneous grass had significant effect on soil remediation, which were conducive to scientific and efficient ecological restoration, and could promote ecological restoration in the damaged ecosystems. While, the modes of Rh and Pi were not suitable for ecological restoration in this study area because they had strong allelopathy. Another arborous restoration mode of Or showed a better improvement effect (including soil nutrients, soil microbial diversity, etc.) than that of Rh and Pi. The findings also indicated that the herbaceous vegetation restoration modes of Me and Mg significantly increased the relative abundance of Proteobacteria, Acidobacteria, Actinobacteria bacteria, Ascomycota and Mortierllomycota fungi, and reduced the relative abundance of Firmicutes bacteria and Basidiomycota fungi. This study also revealed that the trend of bacterial localization in the fruit orchard, artificial miscellaneous grass and Medicago sativa was more obvious. Among many soil abiotic factors, the contents of organic matter, available nitrogen and pH were the most important factors affecting soil microbial community.

Keywords: Quarry mining; Soil microorganisms; Vegetation restoration; Yanshan mountains.

Figure 1. (A–H) Soil physicochemical properties in different sample plots.

The different letters indicated significant differences between treatments according to ANOVA and Tukey’s test (n = 7, P < 0.05). The white line segments in each box indicated the average of the data group. The tops and bottoms of boxes represent the 75th and 25th percentiles, respectively. The upper and lower vertical bars extend to the maximum and minimum values, respectively.

Figure 2. Venn diagram of soil bacterial OTUs (A) and fungal OTUs (B).

The OTUs not unique to a single sample or common to all samples were not shown in the diagram.

Figure 3. NMDS plots of the soil bacterial (A) and fungal (B) OTUs.

Non-metric multidimensional scaling (NMDS) of the soil bacterial (A) and fungal (B) community composition (Bray–Curtis distance). Ellipses indicate 95% confidence intervals around centroids for each site.

Figure 4. Diversity of the soil bacteria (A–D) and fungi (E–H).

Alpha diversity of the soil bacteria (A–D) and fungi (E–H). The white horizontal bars inside each box indicates the mean value. The tops and bottoms of boxes represent the 75th and 25th percentiles, respectively. The upper and lower vertical bars extend to the maximum and minimum values, respectively. The numbers of replicated samples in this figure are n = 7. Letters are used to distinguish whether there are significant differences between groups. Different letters indicate that there are display differences between groups (P < 0.05).

Figure 5. The relative abundances of dominant soil bacterial (A–D) and fungal (E–H).

Communities at the phylum level. Letters are used to distinguish whether there are significant differences between groups. Different letters indicate that there are display differences between groups (P < 0.05, ANOVA).

Figure 6. The relative abundances of soil bacterial (A) and fungal communities (B).

With the relative abundance >1% at the genus level.

Figure 7. VPA of the effects of soil environment factors on soil bacterial (A) and fungal (B) communities.

The percentages in the figures were the variation of the bacterial/fungal community structure explained by the eight sets of environmental factors. The external percentages were the single interpretation rate of environmental factors, the internal percentages were the common interpretation rate of two environmental factors, and the relative abundances of OTUs were used as input in the analysis.