Response characteristics of soil microorganisms under strong disturbance conditions in the riparian zone of the three Gorges reservoir Area

Abstract

The normal operation of the Three Gorges Reservoir, which involves periodic water storage and discharge, has led to strong disturbances in environmental conditions that alter soil microbial habitats in the riparian zones. Riparian zones are an important part of controlling pollution in the Three Gorges Reservoir area, since they act as a final ecological barrier that intercepts pollutants. Meanwhile, monitoring the health of microbial communities in the riparian zone is crucial for maintaining the ecological security of the reservoir area. We specifically investigate the Daning River, which are tributaries of the Three Gorges Reservoir and have typical riparian zones. Soil samples from these areas were subjected to high-throughput sequencing of 16S rRNA genes and 18S rRNA genes, in order to obtain the characteristics of the present microbial communities under strong disturbances in the riparian zones. We studied the characteristics and distribution patterns of microbial communities and their relationship with soil physicochemical properties. The study results indicate that microbial communities exhibit high diversity and evenness, and spatial heterogeneity is present. The ASV dataset contains many sequences not assigned to known genera, suggesting the presence of new fungal genera in the riparian zone. Redundancy analysis (RDA) revealed that pH and ${\mathrm{NH}}_4^{+}$ -N were the primary environmental factors driving bacterial community variation in the riparian zone, while pH, total carbon (TC) content, and ${\mathrm{NO}}_3^{-}$ -N were identified as the main drivers of soil archaeal community variation.

Keywords: Microbial community; Riparian zone; Three Gorges Reservoir Area; Variation.

Figure 1

Study area and periodic water impoundment and release. Location of the study area in the Three Gorges Reservoir (a) and recent water level changes in the riparian zone (b).

Figure 2

The extent of deforestation zones and sampling locations.

Figure 3

Change of soil physicochemical parameters among different altitudes. (The different letter presents significant difference in the soil indices in each soil altitude.)

Figure 4

The alpha diversity (Chao1 index (A), Simpson index (B) Shannon index (C) and Pielou index(D)). ("***" and "**" indicate significant differences at the level of P < 0.001 and P < 0.01, respectively).

Figure 5

Composition and structure of prokaryotic microbe communities in soils at the different elevations. The microbial kingdom in different sampling elevations (A) dominant phyla/classes for bacterial (B) and Archaeal(C), respectively.

Figure 6

Composition of Prokaryotes (A) and fungi communities at the top ten genus level (B).

Figure 7

Redundancy analysis (RDA) between microbial biomass and soil properties in soil. (A) Bacteria (B) Archaea. (Arrows indicate soil physicochemical properties and different coloured spheres indicate microbial communities at different elevations. ("***" and "**" indicate significant differences at the level of P < 0.001 and P < 0.01, respectively) .

Figure 8

Correlation matrix between isolated species and physicochemical variables. Red indicates positive correlation and blue negative correlation. “*, **” represent P < 0.05 and P < 0.01, respectively.

Figure 9

Redundancy analysis (RDA) between microbial biomass and soil properties in soil. (Arrows indicate soil physicochemical properties and different coloured spheres indicate microbial communities at different elevations. ("*" indicate significant differences at the level of P < 0.05, respectively).