Earthworms regulate soil microbial and plant residues through decomposition
Bibliographic record
Abstract
• Earthworms exert negative effects on microbial cellular and extracellular residues. • Earthworms’ have no effect on slow-decaying plant residues. • Earthworms’ effects on fast-decaying plant residues depend on species. • Earthworms regulated the balance between microbial and plant residues. Earthworms are keystone regulators of carbon exchange between terrestrial ecosystems and the atmosphere. However, exactly how earthworms regulate the composition of microbial and plant-derived carbon in soil organic matter remains poorly understood. Here we conducted a microcosm experiment with two species of endogeic earthworms ( Drawida gisti and Metaphire guillelmi ) to investigate their effects on cellular and extracellular-microbial residues versus fast and slow-decaying plant materials. We found that both species of earthworms reduced microbial residues (amino sugars or the protein content of extracellular polymeric substances (EPS)) and facilitated the decomposition of microbial residues rather than their formation. Neither earthworm species affected slow-decaying plant residues (lignin phenols). However, their effects on the fast-decaying fraction of plant residues (particulate organic matter (POM)) depended on the earthworm species. Principal component analysis (PCA) revealed that earthworms mediated two gradients between microbial and plant residues. The first gradient was between the nitrogenous fraction of microbial residues (e.g., amino sugars and EPS-protein) versus slow-decaying plant lignin, while the second gradient was between the fast-decaying POM versus EPS-polysaccharide. Our results suggest that earthworms play vital roles in mediating plant and microbial residue fractions in soil through their multifaceted mechanisms in regulating the chemical composition of organic carbon, and in understanding biological control of the global soil carbon cycle.
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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) | 0.001 | 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".