Diversity and distribution of methanogen communities in the riparian wetlands of the Nam Co basin

doi:10.17520/biods.2024247

Abstract

Abstract:

Aims: Alpine riverine wetland ecosystems are significant sources of methane emissions. Methanogenic archaea, which act as the sole producers of methane in wetland environments, play a critical role in global carbon cycling. However, their community composition and distribution patterns in alpine riverine wetlands remain unclear. Here, our study aims to: (1) investigate the diversity and compositional changes of methanogen communities in a riverine wetland, and (2) elucidate the assembly mechanisms and sources that drive their community distribution.

Methods: Our study site was located in the riparian zones of the Niyaqu basin in the Nam Co basin of the Qinghai-Tibetan Plateau. Using mcrA gene amplicon sequencing, we analyzed methanogens in soils across two dimensions: Lateral dimension (riparian wetland, transitional zone, and alpine meadow) and longitudinal dimension (at four elevation gradients: 4,980 m, 4,843 m, 4,777 m, and 4,752 m).

Results: Methanogen community α diversity of methanogens was the highest in riparian wetland, followed by the transitional zone, and then to the alpine meadow ecosystem. With community composition, the riparian wetland was significantly different from that of the transitional zone and alpine meadow. Among all sampling sites, hydrogenotrophic methanogens were the most abundant and Methanobacterium was the most predominant. In particular, the average relative abundances of alpine meadows, transitional zone, and riparian wetland was 45.78%, 42.90% and 34.17%, respectively. Neutral community models also indicated that community assembly in the wetland was primarily driven by stochastic processes. However, these processes contributed less to the communities in the alpine meadow and transitional zone. Additionally, FEAST source tracking analysis indicated that in the lateral dimension, alpine meadow and transitional zone contributed 17.62% and 13.04%, respectively, to the methanogen communities in the riparian wetland. In the longitudinal dimension, methanogen communities in low elevation riparian wetlands (S4) were primarily sourced from upstream riparian wetlands (49.71%) and alpine meadows (21.45%).

Conclusions: This data suggests that the alpine meadows serve as a significant species reservoir for methanogens that funnel to the riparian wetland. Ultimately, our work described the diversity and distribution patterns of methanogen communities in alpine river basin soils, which holds significant importance to understand the functionality of alpine ecosystems.

Key words: riparian wetlands, methanogens, community assembly, microbiological sources

Yuan Liu, Jianqing Du, Liyuan Ma, Gang Yang, Jianqing Tian. Diversity and distribution of methanogen communities in the riparian wetlands of the Nam Co basin[J]. Biodiv Sci, 2025, 33(1): 24247.

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URL: https://www.biodiversity-science.net/EN/10.17520/biods.2024247

https://www.biodiversity-science.net/EN/Y2025/V33/I1/24247

Figures/Tables 5

Fig. 1 Sample collection and α-diversity of methanogen communities in soils of different ecological types. (A) Schematic diagram of sampling locations in the Niyaqu basin of Nam Co basin on the Qinghai-Tibetan Plateau; (B) Differences in the Shannon index of methanogens across different soil types (mean ± SE); (C) Variations in the Shannon index of methanogens in different soil types along the altitudinal gradient (mean ± SE). Different letters indicate significant differences (P < 0.05). S1-S4 indicate sample plots.

Fig. 2 Analyses of methanogen community structure, compositional changes, and distance-decay relationships. (A) Differences in methanogen communities based on Bray-Curtis distances; (B) Distance-decay curve showing the relationship between Bray-Curtis similarity and geographical distance (data converted to natural logarithm); (C) Methanogens composition at each sample site across different soil types. The dashed ellipse in Figure A and the shaded area in Figure B indicate 95% confidence intervals, and the solid line in Figure (B) indicates ordinary least squares linear regression.

Table 1 Permutational multivariate analysis of variance of methanogen community structure differences in soils of different ecological types

类型 Type	R²	P
高寒草甸 vs. 过渡带 Alpine meadow/Transitional zone	0.055	0.353
高寒草甸 vs. 岸边带湿地 Alpine meadow/Riparian wetland	0.117	0.001
过渡带 vs. 岸边带湿地 Transitional zone/Riparian wetland	0.105	0.004

Fig. 3 The neutral community model fits the relationship between the frequency and relative abundance of OTUs in methanogenic archaeal communities in different soil types. R2 represents the overall goodness of fit of the neutral community model, with a negative R2 indicating a poor fit of the neutral community model. Nm is the product of the metacommunity size (N) and the mobility (m). The solid blue line in the figure represents the best-fit value of the neutral community model, the blue dashed line represents the 95% confidence interval of the model (estimate obtained by 1000 bootstrap), green indicates OTUs that occur more frequently than predicted by the neutral community model, and red indicates OTUs that occur more frequently than predicted by the neutral community model.

Fig. 4 Contribution of different source communities to methanogen communities in riparian wetlands (lateral and longitudinal dimensions). (A) Overall contribution of microbial communities from alpine meadows and transition zone soils to riparian wetlands; (B) Source analysis of riparian wetland communities at each sample site; (C) Overall contribution of methanogen communities in soils from the three different ecological types to the terminal riparian wetland (S4) community; (D) Contribution of the three soil community types to the terminal riparian wetland (S4) community at each site.

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