Differential Effects of Nitrogen Chemical Forms on Soil Bacterial Communities and Ecosystem Multifunctionality in a Temperate Meadow Steppe
Bibliographic record
Abstract
ABSTRACT Understanding the impact of nitrogen (N) enrichment on soil microbial community and its associations with ecosystem functionality is crucial, given rising global atmospheric N deposition and even greater agricultural inputs. Most previous studies simulating N deposition used single N species, yet the specific effects of different N forms are not fully understood. This limitation hinders our capacity to link changes in soil microbial communities with ecosystem multifunctionality and to assess the impact of atmospheric N deposition on ecosystem services. To bridge this knowledge gap, our study, conducted from 2016 to 2018 in a typical temperate grassland in Inner Mongolia, China, evaluated the differential effects of the addition of four N forms—ammonium bicarbonate (AC), ammonium nitrate (AN), ammonium sulfate (AS), and urea (UR)—on soil bacterial community structure and function, taxonomic interactions, and ecosystem multifunctionality. These forms were applied at five levels (0, 2, 10, 20, and 50 g N m −2 year −1 ) with five replicates as part of a long‐term experiment. Our findings reveal that N forms in combination with increased N loading differentially influence bacterial community structure and functional characteristics, and co‐occurrence networks, alongside ecosystem multifunctionality. Notably, AN/AS significantly reduced bacterial taxonomic and functional diversity and network complexity, unlike AC, which showed minimal changes. The alteration in bacterial community structure and function under AN/AS was more significantly linked to changes in ecosystem multifunctionality than those under AC/UR, with AC having minimal connections. Additionally, keystone taxa responded differently to N levels and showed varied correlations with ecosystem multifunctionality. These results underscore the distinct effects of different N forms on soil bacterial communities and their cascading influence on ecosystem multifunctionality, emphasizing the need for management practices targeted to the specific chemical species of N deposition and fertilization.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".