The evolution of a tropical rainforest/grassland mosaic in southeastern Brazil since 28,000 <sup>14</sup>C yr BP based on carbon isotopes and pollen records
Why this work is in the frame
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Bibliographic record
Abstract
Abstract The lack of paleoecological records from the montane Atlantic Rainforest of coastal Brazil, a hotspot of biological diversity, has been a major obstacle to our understanding of the vegetational changes since the last glacial cycle. We present carbon isotope and pollen records to assess the impact of the glaciation on the native vegetation of the Serra do Mar rainforest in São Paulo, Brazil. From ca. 28,000 to ∼ 22,000 14 C yr BP, a subtropical forest with conifer trees is indicative of cool and humid conditions. In agreement carbon isotopic data on soil organic matter suggest the presence of C 3 plants and perhaps C 4 plants from ∼ 28,000 to ∼ 19,000 14 C yr BP. The significant increase in the sedimentation rate and algal spores from ∼ 19,450 to ∼ 19,000 14 C yr BP indicates increasing humidity, associated to an erosion process between ∼ 19,000 and ∼ 15,600 14 C yr BP. From ∼ 15,600 14 C yr BP to present there is a substantial increase in arboreal elements and herbs, indicating more humid and warmer climate. From ∼ 19,000 to ∼ 1000 14 C yr BP, δ 13 C values indicated the predominance of C 3 plants. These results are in agreement with studies in speleothems of caves, which suggest humid conditions during the last glacial maximum.
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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 | 0.002 | 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 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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 it