[Response of Soil Bacterial Community Assembly to Depth in Grassland Ecosystems of Arid and Semi-arid Regions].

Authors

Sheng-Gang Chen, Ming-Yue Bai, Jun Ma, Ya-Qi Zhang, Lin Chen, Jian-Bin Guo

Published in

Huan jing ke xue= Huanjing kexue. Volume 47. Issue 10. Pages 7307-7317. Oct 15, 2026.

Abstract

Soil bacterial communities play a crucial role in ecosystem processes， yet their assembly dynamics across different soil horizons remain poorly understood. Elucidating the co-occurrence networks and assembly patterns of soil bacterial communities in grassland ecosystems is essential for comprehending microbial ecosystem processes. Using high-throughput sequencing of 16S rRNA and ITS amplicons， we investigated the effects of soil depth gradients in grassland ecosystems on bacterial community assembly. The results indicated that Actinobacteria， Proteobacteria， Verrucomicrobia， and Acidobacteria were dominant bacterial phyla across different grassland soils. Bacterial diversity decreased progressively from surface to deep soil layers. Co-occurrence network topology parameters （edges， nodes， and clustering coefficients） diminished with increasing soil depth， while surface soil bacterial communities exhibited higher modularity and more positive correlations between communities. Zero-model analysis revealed that deterministic processes （particularly uniform selection） dominated bacterial community assembly， though their influence weakened with depth， while stochastic processes （e.g.， diffusion limitation） progressively strengthened from surface to deep soils. Segmented structural equation modeling indicated that both abiotic factors （climate and nutrients） and biotic factors （interspecies interactions） exerted depth-dependent effects on bacterial community assembly. This study provides a novel perspective on the vertical stratification of soil bacterial communities in grassland ecosystems of arid and semi-arid regions， deepening our understanding of soil formation processes under climate change and microbial adaptation strategies in heterogeneous soil environments.

PMID:
42935431
Bibliographic data and abstract were imported from PubMed on 27 Oct 2026.

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