Suppression of hydrolytic enzyme activities by short-term aeration of periodically anoxic soils: Evidence from upland ecosystems
Bibliographic record
Abstract
• Aeration suppressed hydrolase activities in upland soils under anoxic conditions. • A lower proportion of small pores enhanced the suppression of in situ activities. • Enzyme activity suppression by aeration was stronger in cropland than in forest soil. Land-use change and duration of agricultural practice cause shifts in the soil physical structure and porosity. These changes, in turn, may hamper soil aeration, restrict gas exchange, and therefore, cause establishment of anoxic conditions in upland soils. Such periodic fluctuations of aeration control the activity of microbial extracellular hydrolytic enzymes. Earlier studies revealed a clear suppression of key hydrolytic enzymes due to a short-term aeration (i.e., oxygen exposure) of established anoxic ecosystems such as rice paddies. However, it remains unclear whether the suppression also occurs in upland soils with periodic anoxicity. This key gap was addressed by measuring the kinetic parameters and in situ activities of hydrolytic β-glucosidases and acid phosphatases under oxic and anoxic conditions in forest, grassland, and cropland mineral soil after 3–5 days of anoxic pre-incubation. Short-term (2 h) aeration suppressed β-glucosidase and acid phosphatase activities by up to two times as compared with activities under anoxic conditions. The suppressive effects of aeration on the maximum reaction rate of enzymatic activity (V max ) were more pronounced in the cropland (by 1.6–2.4 times) than in the forest (by 1.3–1.7 times) soil. Our findings indicate the importance of fluctuations in redox conditions in the soil organic matter transformation catalyzed by hydrolytic enzymes, particularly in scenarios where the frequency and/or severity of flooding events increase due to changes in land use and/or climatic conditions. The mechanism of the suppression of hydrolytic enzyme activities has been demonstrated to be sustainable in lowland and upland ecosystems, yet further studies are required to elucidate the biogeochemical basis for this phenomenon.
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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 | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 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".