Microbial community diversity and assembly processes in the aridification of wetlands on the Qinghai-Tibet Plateau

Abstract

This study investigates soil microbial community dynamics in high-altitude wetlands on the Qinghai-Tibet Plateau under drought conditions. It compares the composition, structure, and assembly mechanisms of microbial communities in water-rich and water-deficient wetlands. The results show that while α diversity remains stable after aridification, the community undergoes significant phylum reorganization. Aridification leads to increased sensitivity in the β diversity of archaea and bacteria to environmental and geographic factors, while fungal β diversity remains unchanged. Co-occurrence network analysis reveals a more complex and denser microbial network in aridified wetlands. Hub microbial groups are found only in bacteria and fungi, and their richness decreases after aridification. The study suggests a shift from a neutral to a partially deterministic assembly process, marked by reduced dispersal limitations and stronger heterogeneous selections. These findings contribute to understanding microbial community evolution in response to global environmental changes.

Keywords: Aquatic biology; Aquatic science; Environmental science; Microbiology.

Graphical abstract

Figure 1

α diversity and community composition of soil microorganisms under wetland drought (A) α Diversity; (B) ANOSIM analysis of species composition differences; (C) Differential abundance of major microbial phylum (relative abundance >0.005%) under different moisture conditions. Abbreviations: F indicates water-rich wetland; IF indicates water-deficient or dry wetlands. Outer ring in sub-figure(c) heatmap colors indicate the relative abundance score of microbial phyla across various sites, where red represents high abundance and blue represents low. The middle ring denotes inter-site clustering trees. The inner ring represents the significance of differences in abundance of each phylum under different moisture conditions. The length of the bars indicates the relative abundance of each phylum, and the letters highlighted on the bars represent the t-test results.

Figure 2

Relationship between wetland soil microorganisms and environmental factors The legend shows the meaning of the main symbols in the figure. In addition, asterisks in the figure indicate the significance level of Pearson correlations, ∗: p < 0.05; ∗∗:p < 0.01; ∗∗∗:p < 0.001.

Figure 3

Relationship between soil microbial β-diversity and environmental characteristics based on Bray-Curtis distance analysis Red color in the figure indicates water-rich wetlands and blue color indicates water-deficient or dry wetlands; asterisks indicate the significance level of the linear fitness, ∗: p < 0.05; ∗∗:p < 0.01.

Figure 4

Co-occurrence network analysis (A and B) (A) Soil microbial co-occurrence network in water-rich wetland; (B) Soil microbial co-occurrence network in water-deficient or dry wetlands; in the network diagram, circles represent nodes, the color of the circle represents the clustering features, and the size of the circle represents the node’s high or low degree of degree value; the connecting lines represent the edges, and the darker the edges represent the higher their weights. (C and D) (C) Node-level topological feature parameters; (D) hub taxa analysis.

Figure 5

The assembly process of soil microbial communities in alpine wetlands (A) Differentiality of βNTI under different moisture conditions; (B) Contribution of different ecological processes to the assembly of eukaryotic microbial communities; (C) Neutral community model. In the neutral model, blue and green circles represent species with occurrences higher or lower than predicted by the model; solid black line indicates best fitness with the neutral community model, while the dashed black line represents the 95% confidence interval. “m” represents the estimated migration rate, and “R²” represents the goodness of fitness with the neutral community model. ∗: p < 0.05.

Figure 6

Location of sample sites Well-watered wetlands (F) and 6 sites in water-deficient or drought-prone wetlands (IF).