Distinct Microbial Strategies to C and N Limitation Along an Aridity Gradient in Rhizosphere and Bulk Soils of <scp> <i>Caragana microphylla</i> </scp> Plantation
Bibliographic record
Abstract
ABSTRACT Soil extracellular enzymes and microbial functional genes play essential roles in regulating carbon (C), nitrogen (N), and phosphorus (P) cycling by mediating nutrient transformations and maintaining soil biochemical balance. However, how functional genes modulate enzyme stoichiometry in response to microbial nutrient demands under drought conditions remains poorly understood. In this study, we integrated metagenomic sequencing with extracellular enzyme activity (EEA) analysis to explore how microbial C‐, N‐, and P‐cycling genes and extracellular enzyme stoichiometry (EES)‐specifically the vector length (an indicator of microbial C limitation) and angle (an indicator of microbial N vs. P limitation)‐respond across an aridity gradient in the rhizosphere and bulk soils of Caragana microphylla plantations. Our results demonstrate that microbial communities in both rhizosphere and bulk soils experience C and N limitations under arid conditions. In the rhizosphere, increasing aridity intensified microbial C limitation but alleviated N limitation, likely due to reduced root exudation and enhanced nitrogen fixation by C. microphylla . In bulk soils, microbial nutrient limitations exhibited threshold‐type responses to aridity: N limitation intensified under low aridity but was alleviated beyond a critical threshold (aridity index: AI < 0.24), while C limitation emerged only under higher aridity levels (AI < 0.285). These dynamics likely reflect buffered organic inputs and enhanced microbial nitrogen turnover, emphasizing the nonlinear and context‐dependent nature of nutrient constraints in dryland ecosystems. Partial least squares path modeling (PLS‐PM) revealed that N‐cycling enzymes were the primary predictors of microbial nutrient limitation in both compartments. However, C‐cycling enzymes exerted a stronger influence in the rhizosphere, while C‐ and N‐related functional genes played a greater role in bulk soils, reflecting compartment‐specific microbial strategies under drought stress. This study advances understanding of C‐N‐P cycling and microbial C‐N limitations in C. microphylla plantations, offering new insights into land degradation mechanisms and a scientific basis for vegetation and soil management in arid regions.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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 teacher head, 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".