Component respiration, ecosystem respiration and net primary production of a mature black spruce forest in northern Quebec
Bibliographic record
Abstract
We measured respiratory fluxes of carbon dioxide by aboveground tree components and soil respiration with chambers in 2005 and scaled up these measurements over space and time to estimate annual ecosystem respiration (R(e)) at a mature black spruce (Picea mariana (Mill.) B.S.P.) ecosystem in Quebec, Canada. We estimated periodic annual net primary production (NPP) for this ecosystem also. R(e) was estimated at 10.32 Mg C ha(-)(1) year(-)(1); heterotrophic respiration (R(h)) accounted for 52% of R(e) and autotrophic respiration (R(a)) accounted for the remainder. We estimated NPP at 3.02 Mg C ha(-1) year(-1), including production of bryophyte biomass but not including shrub NPP. We used these estimates of carbon fluxes to calculate a carbon use efficiency [CUE = NPP/(NPP + R(a))] of 0.38. This estimate of CUE is similar to those reported for other boreal forest ecosystems and it is lower than the value frequently used in global studies. Based on the estimate of R(h) being greater than the estimate of NPP, the ecosystem was determined to emit approximately 2.38 Mg C ha(-1) year(-1) to the atmosphere in 2005. Estimates of gross primary production (GPP = NPP + R(a)) and R(e) differed substantially from estimates of these fluxes derived from eddy covariance measurements during 2005 at this site. The ecological estimates of GPP and R(e) were substantially greater than those estimated for eddy covariance measurements. Applying a correction for lack of energy balance closure to eddy covariance estimates reduces differences with ecological estimates. We reviewed possible sources of systematic error in ecological estimates and discuss other possible explanations for these discrepancies.
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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 | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 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".