Effects of recent fire on soil conditions and nutrient use of a native and an invasive grass in the Brazilian savanna
Bibliographic record
Abstract
In fire-influenced savanna ecosystems, native and invasive exotic plants may use different abilities to coexist and compete for nutrients available in post-fire soil. The availability and uptake of nitrate by two C4 grasses (Urochloa brizantha (exotic invasive) and Axonopus siccus (native)) were characterized in an unburned area and in a recently burned area in the Cerrado of Southeastern Brazil. Ecophysiologic tests were performed to measure Nitrate Reductase Activity (NRA) and nitrate content in leaves and roots. Soil fertility was also analyzed. In the unburned area, organic matter (25.3 ± 2.4 g kg−1), phosphorus (19.0 ± 2.0 mg dm−3), and nitrate (19.9 ± 7.4 mg dm−3) levels were higher than in the recently burned area, which had 27% less cations in the soil. In comparison with soils from the recently burned and unburned areas, ashes of the recently burned area had higher pH, electrical conductivity and nitrate, potassium, and calcium contents. In both areas, the aboveground part of U. brizantha was more responsive to nitrate compared to A. siccus and both had low belowground NRA. This confirms the working hypothesis that the two species undergo distinct ecophysiologic processes and indicate the adaptive potential of U. brizantha to bypass soil nutrient limitation.
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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".