Soil may look quiet, but beneath the surface lies a highly connected microbial world. A new study across China's Loess Plateau shows that different groups of soil bacteria play sharply different roles in building complex and stable microbial communities, offering new insights into how belowground ecosystems may respond to environmental change.
Researchers analyzed 117 soil samples collected across broad climatic and ecological gradients on the Loess Plateau, including forests, shrublands, and grasslands. Using high-throughput DNA sequencing and ecological network analysis, the team divided bacteria into core, abundant, and rare groups and examined how each group was assembled and how it contributed to the wider microbial network.
"Our findings show that microbial abundance alone does not determine ecological importance," said Xing Wang, co-corresponding author of the study. "Core bacteria help organize the complexity of the microbial network, while rare bacteria make an especially important contribution to its stability. These groups respond differently to environmental change, but together they help maintain soil microbial communities."
The study found a striking imbalance between abundance and diversity. Rare bacteria represented about half of all detected bacterial sequence variants, yet accounted for only 4.24% of total abundance. In contrast, abundant bacteria represented less than 1% of the detected variants but accounted for 31.48% of total abundance. Core bacteria were even fewer, with only 0.34% of variants occurring in more than 80% of samples.
Despite their small numbers, core bacteria occupied influential positions in microbial networks. The researchers found that core and abundant taxa were more highly connected than rare taxa, while core bacteria showed the strongest relationship with overall network complexity.
Rare bacteria, however, appeared to perform another critical job. The analyses showed that rare taxa were particularly important for maintaining microbial network stability, potentially because their high diversity provides ecological and functional redundancy that helps communities cope with environmental disturbances.
The researchers also discovered that the three bacterial groups were shaped by different ecological forces. Deterministic processes, particularly environmental selection, primarily governed the assembly of core bacteria, while stochastic processes played a larger role in shaping both abundant and rare bacteria.
Environmental drivers also differed. Climate was the main factor influencing core and abundant bacterial communities, whereas rare bacteria responded more strongly to soil properties. This suggests that environmental change may reshape different components of the soil microbiome through separate pathways.
These distinctions could be important for understanding how soils respond to climate change, land management, and ecosystem restoration. Rather than treating the soil microbiome as a single community, the findings suggest that researchers may gain a clearer picture by considering the different ecological functions of widespread, abundant, and rare microorganisms.
Together, the results provide regional-scale evidence that core, abundant, and rare bacterial communities have distinct but complementary roles in maintaining microbial complexity and stability. The authors note that future research covering deeper soil layers and multiple seasons or years will be needed to determine whether these patterns persist over time.
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Journal Reference: Wang Z, Zhou Z, Hu R, Lu S, Zhang Q, et al. 2026. Core and rare microbiota enhance bacterial community complexity and stability along environmental gradients on the Loess Plateau. Agricultural Ecology and Environment 2: e022 doi: 10.48130/aee-0026-0020
https://www.maxapress.com/article/doi/10.48130/aee-0026-0020
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Agricultural Ecology and Environment (e-ISSN 3070-0639) is a multidisciplinary platform for communicating advances in fundamental and applied research on the agroecological environment, focusing on the interactions between agroecosystems and the environment. It is dedicated to advancing the understanding of the complex interactions between agricultural practices and ecological systems. The journal aims to provide a comprehensive and cutting-edge forum for researchers, practitioners, policymakers, and stakeholders from diverse fields such as agronomy, ecology, environmental science, soil science, and sustainable development.
