Microbial Functional Diversity as Affected by Different Engineered Eco-Restoration Methods at Xiangjiaba Hydropower Station

Abstract

To select and improve techniques capable of eco-restoration and reconstruction of soils, it is vital to determine the impacts of different engineered eco-restoration techniques on communities of soil microbes. For this purpose, slopes of four engineered eco-restoration techniques [thick layer base material spraying technique (TBS), vegetation concrete base spraying technique (CBS), external soil spray seeding technique (ESSS), and frame beam + external soil (FBES)] were studied and compared with slopes of natural forest (NF) at Xiangjiaba Hydropower Station in China. The results indicated that the engineered eco-restoration techniques had different effects on the physical and chemical properties of the soil and the structure and functional diversity of the microbial community. Phosphorus content and potential of hydrogen (pH) were higher in soil of all artificially restored slopes than those in soil of the natural forest. Whether it was soil physicochemical properties and microbial utilization of carbon source or average well color development (AWCD) reflecting soil microbial metabolic functional diversity, the soil of TBS was significantly better or closer to soil of the natural forest. However, the soil’s AWCD values, microbial utilization carbon source capacity, and diversity index of the other three technologies were lower than those of natural forests. Among them, the soil of CBS had the lowest AWCD value and McIntosh diversity index (U). The redundancy analysis and correlation analysis indicated that the content of available phosphorus (AP) and total phosphorus (TP) showed a negative correlation with most carbon sources’ utilization and McIntosh diversity index and were significantly positively correlated with the evenness index. The content of total nitrogen (TN) was positively associated with the utilization of the most carbon sources and the diversity index. In addition, there was a positive correlation between the content of soil organic carbon (SOC) and the utilization of most carbon sources. These results suggest that the high phosphorus content and low nitrogen content in the substrates of engineered eco-restoration techniques would inhibit the microbial activity.