Phosphorus addition ameliorates soil micro-food web simplification due to nitrogen enrichment but does not restore nematode community composition
Soil Biology and Biochemistry(2024)
摘要
Nitrogen (N) inputs to terrestrial ecosystems are increasing faster than phosphorus (P) inputs, causing N:P imbalances and substantial changes in the diversity and structure of plant, soil microbial, and fauna communities. The responses of the soil micro-food web to N:P imbalances remain unclear but are crucial to understanding the impacts on ecosystem functioning. We investigated the effect of N and P additions on plant communities, edaphic properties, and nematode species diversity and composition, and assessed shifts in soil micro-food web complexity using nematode-based indices and structural equation modeling (SEM) in a nine-year nutrient addition experiment in an alpine meadow on the Tibetan Plateau. We found that N addition decreased the structure index (SI) and enrichment index (EI), indicating that N enrichment led to a simplification of the soil micro-food web. The addition of P alleviated the negative effect of N on soil micro-food web complexity but did not restore nematode community composition. The SEM supported the hypothesis that N addition simplified soil micro-food webs through increases in the N:P ratio and associated reductions in plant species richness, while P addition ameliorated the effect of N by decreasing the soil N:P ratio and increasing plant species richness. Our results highlight the positive effects of plant diversity in maintaining the complexity of the soil micro-food web. Our findings provide information that can be used to guide sustainable management and restoration of grasslands to alleviate the projected effects of future N:P imbalances on the soil micro-food web. However, efforts should be made to avoid nutrient deposition given the observed effects on both plant and nematode communities that could not be restored by alleviating the N:P imbalance through P addition.
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关键词
Alpine meadow,complexity,N:P imbalances,restoration,soil nematode,species richness
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