Soil and tree ring chemistry as indicators of changes in atmospheric environments in the oil sands region of Alberta, Canada
Bibliographic record
Abstract
The impact of increased CO₂ and NO x emissions on soil and tree ring chemistry of Pinus banksiana (jack pine) and Populus tremuloides (trembling aspen, aspen) stands in the Athabasca oil sands region in Alberta, Canada was investigated in watersheds NE7 and SM8. Watershed NE7 was exposed to greater amounts of acid deposition due to its closeness to the mining area. The δ 15 N in the forest floor was lower (p＜0.05) in NE7 (ranged from -1.42 to -0.87 ‰) than in SM8 (-0.54 to 1.43 ‰), implying a greater amount of recent deposition of 15 N-depleted N in NE7. Tree ring δ 13 C gradually decreased over time for both tree species/watersheds, indicating the influence of 13 C-depleted CO₂ emitted from industrial sources. Tree ring N concentration and δ 15 N were not different between watersheds and did not significantly change with time. Interestingly, however, the difference between watersheds (NE7?SM8) that is expressed as Diff_N (for N) increased with concomitant decreases in Diff_δ 15 N over time, implying greater increases in 15 N-depleted N input in NE7 than in SM8. Such trends were stronger in aspen stands (R²=0.64 and P＜0.001 for Diff_N and R²=0.44 and P＜0.01 for Diff_δ15N between 1964 and 2009) than in jack pine stands. We conclude that δ 15 N in the forest floor and differences in N and δ 15 N of tree rings between watersheds are useful indicators reflecting the impact of spatial variations of air pollution on forest stands in the Athabasca oil sands region in western Canada.
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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 | 0.001 | 0.002 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 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".