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Divergence From Temperate Models: Pollution Dominance and Stochastic Assembly in a Continental Freshwater System
Xu Zhao1,2,3, Lingjie Huang1,2, Yu Ma1,4
1China National Environmental Monitoring Centre, Beijing, China.
Global Change Biology
|July 4, 2026
Summary
Organic pollution, not habitat or climate, significantly impacts freshwater biodiversity in China. Stochastic processes dominate community assembly, challenging biodiversity frameworks from temperate regions.
Area of Science:
- Freshwater ecology
- Macroecology
- Environmental science
Background:
- Continental-scale biodiversity patterns are often based on temperate regions, potentially misrepresenting rapidly developing areas.
- Understanding multiple stressors is crucial for freshwater ecosystem management.
Purpose of the Study:
- To test the universality of established macroecological patterns in China's diverse freshwater ecosystems.
- To identify key drivers of benthic macroinvertebrate diversity across continental scales.
Main Methods:
- Standardized field survey of benthic macroinvertebrates at 502 sites across China.
- Analysis of taxonomic, functional, and phylogenetic diversity.
- Assessment of environmental variables including chemical pollution (COD, BOD, N, P), land use, and climate.
Main Results:
- Organic pollution (COD, BOD) was the primary driver of biodiversity variation, overriding habitat and climate.
- Chemical stressors (N, P) also significantly influenced diversity.
- Community assembly was dominated by stochastic processes (~86%), suggesting a 'stochastic trap' hypothesis.
Conclusions:
- Established biodiversity frameworks from temperate regions may not apply to developing areas with rapid environmental change.
- Reducing chemical pollution is critical for freshwater resilience in the Anthropocene.
- Stochastic processes, potentially driven by frequent disturbances, shape communities in these dynamic systems.
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