Past century changes in <i>Araucaria angustifolia</i> (Bertol.) Kuntze water use efficiency and growth in forest and grassland ecosystems of southern Brazil: implications for forest expansion
Bibliographic record
Abstract
Abstract Araucaria angustifolia (Bertol.) Kuntze is an indigenous conifer tree restricted to the southern region of South America that plays a key role in the dynamics of regional ecosystems where forest expansion over grasslands has been observed. Here, we evaluate the changes in intrinsic water use efficiency (iWUE) and basal area increment (BAI) of this species in response to atmospheric CO 2 , temperature and precipitation over the last century. Our investigation is based on tree‐rings taken from trees located in forest and grassland sites in southern Brazil. Differences in carbon isotopic composition ( δ 13 C), 13 CO 2 discrimination (Δ 13 C) and intracellular carbon concentration ( C i ) are also reported. Our results indicate an age effect on Δ 13 C in forest trees during the first decades of growth. This age effect is not linked to an initial BAI suppression, suggesting the previous existence of nonforested vegetation in the forest sites. After maturity all trees show similar temporal trends in carbon isotope‐derived variables and increasing iWUE, however, absolute values are significantly different between forest and grassland sites. The iWUE is higher in forest trees, indicating greater water competition or nutritional availability, relative to grassland, or both. BAI is also higher in forest trees, but it is not linked with iWUE or atmospheric CO 2 . Nevertheless, in both forest and grassland sites A. angustifolia has had growth limitations corresponding to low precipitation and high temperatures observed in the 1940s.
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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".