Two grasses differ in their absorptive root physiological traits and rooting depth under drought in an alpine steppe
Bibliographic record
Abstract
BACKGROUND AND AIMS: Absorptive root traits play important roles in acquisition of water and nutrients from soil by plants. Despite numerous reports on the changes in species dominance under long-term drought in grassland communities, few studies have specifically investigated absorptive root traits of these dominant species in grasslands, especially in alpine grasslands. METHODS: Here, two grass species (Leymus secalinus and Stipa purpurea) differing in their responses to drought were selected from an alpine steppe. A series of absorptive root traits were examined under drought in a 3-year glasshouse experiment. KEY RESULTS: We found that drought had no effects on root morphological and architectural traits, whereas root physiological traits and rooting depth differed in their responses to drought. Specifically, drought significantly reduced root respiration and enhanced organ carbon (C) exudation rate, carboxylate exudation rate, acid phosphatase activity and rooting depth of L. secalinus. In particular, L. secalinus released more citrate into the rhizosphere under drought than S. purpurea. In contrast, these root traits of S. purpurea remained relatively unchanged in response to the drought. These differential responses would render L. secalinus more competitive in acquisition of nutrients and water, thus contributing to its dominance in the community under drought. Moreover, root respiration was negatively correlated with organic C exudation rate, carboxylate exudation rate and acid phosphatase activity, indicating a trade-off between root respiration and root exudates to acquire nutrients and water by optimizing C allocation under drought. Additionally, all root traits exhibited two independent dimensions in root economic space for both species under drought. CONCLUSIONS: These results indicate that the plant species with great capacity to acquire water and nutrients in soil by optimizing C allocation under drought will be dominant in the community of the alpine grasslands. These findings provide an important insight into species re-ordering under drought on the Tibetan Plateau.
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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".