Autotrophic and heterotrophic respiration rates across a chronosequence of hybrid poplar plantationsin northern Alberta
Bibliographic record
Abstract
Distinction of autotrophic (root, Rr) versus heterotrophic (Rh) soil respiration is important to understanding C balance in forest ecosystems and the contribution of both respiration components to total soil respiration (Rs) may change as stands mature. We studied Rr and Rh in a chronosequence of hybrid poplar plantations that were 4, 6, 8, and 13 yr old in summer 2005. We hypothesized that Rr will become increasingly larger and will also represent a greater proportion of Rs as plantation age increases. Our results showed that both Rs and Rh showed significant seasonal variations; however,Rr were much more variable. No significant differences among plantation ages were observed for any of the respiration parameters (Rr, Rh and Rs) measured throughout the summer. No significant differences were found for the contribution of Rh to Rs between plantation ages or between sampling dates. The average proportion of Rh to Rs across all sites and sampling dates was 0.63 ± 0.026 (mean ± standard error), indicating that heterotrophic respiration dominated total soil respiration in the studied hybrid poplar plantations.The power of the statistical tests in this study was likely quite low due to the inclusion of only two replicates for each plantation age. Key words: Autotrophic, heterotrophic respiration, root exclusion, trenching, hybrid poplar, chronosequence
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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 | 0.001 |
| Science and technology studies | 0.000 | 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) | 0.001 | 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".