Photosynthetic carbon allocation to live roots increases the year following high intensity defoliation across two ecosites in a temperate mixed grassland
Bibliographic record
Abstract
Livestock grazing is an important driver of the carbon (C) cycle in grasslands and could be a decisive factor determining whether grasslands are a net sink or source of C. However, short-term C dynamics in grassland ecosystems and its response to different grazing intensities remain unclear, especially under field conditions. Here we test the hypothesis that photosynthetic C allocation in the plant-soil system of grasslands is differentially affected by the intensity of grazing that occurred in the prior growing season. We studied the fate of new C assimilates, using a 13CO2 pulse-labeling technique, as they move from shoots to roots and soil in vegetation previously exposed to different defoliation (emulated grazing) intensities in two semiarid Mixed Prairie grassland ecosites having contrasting soil textures (sandy vs. loamy). Within 24 h after photosynthetic uptake, 34.5% of the labeled C was translocated out of shoots, with 21% of the labeled C found in the mineral soil. Plant communities treated with high intensity defoliation during the previous growing season had more of the newly fixed 13C translocate into live roots at both ecosites throughout the 25-day chase period, indicating a higher demand for photosynthetic C by the root system of heavily defoliated plants. Twenty-five days after labeling, 13C transfer into the top 30 cm mineral soil was consistently greater at the loamy (26% of total 13C remaining) than at the sandy ecosite (10.4% of 13C remaining). We conclude that conditioning with high intensity defoliation the prior growing season stimulated short-term C allocation to roots in these semi-arid grasslands. Although this response was independent of soil texture, more C was translocated belowground overall in the loamy ecosite. The effect of defoliation intensity and ecosite in regulating short-term C allocation in the plant-soil system in temperate grasslands should be incorporated into future models describing C cycling in grasslands when predicting C dynamics under different management strategies employing contrasting grazing intensities.
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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".