From forest to lake: effect of hydroelectric reservoir impoundment on the net ecosystem exchange of carbon dioxide
Bibliographic record
Abstract
The purpose of this research was to determine the magnitude and direction of carbon exchange resulting from a boreal forest being flooded for hydroelectric purposes and to determine the net reservoir effect. In this study, carbon dioxide fluxes were measured from March 29th 2007 to November 30th 2008 in a mature black spruce forest and a flooded forest in Eastmain-1, James Bay, Quebec, Canada using eddy covariance towers. The unburned mature boreal forest was selected to act as a pre-flooded analogue site to the newly impounded hydroelectric reservoir. Flux tower measurement of the net ecosystem exchange (NEE) showed that the forest was a carbon sink during the growing seasons (DOY 102-304 in 2007 and 104 to 305 in 2008) with a similar cumulative NEE for both years, varying from -115.6 g C m-2d-1 in 2007 to -122.5 g C m-2d-1 in 2008. When compared to the pre-flooded site, flux measurement over the reservoir revealed that this flooded environment was a constant emitter of CO2 throughout the study period. Two seasonal peaks of emissions were identified during the year defined as December 2007 to November 2008. The first occurred during the ice break up in the last week of May 2008 (DOY 143-152) with 1.78 ± 0.09 g C m-2d-1 and the second corresponded to the reservoir turnover at the end of August and September 2008 (DOY 229-274) with 1.27 ± 0.03 g C m-2d-1. Overall, the net reservoir effect was estimated to be 1.75± 0.07 g C m-2d-1 for the ice free period and of 289.2 ± 144.6 g C m-2yr-1for the entire annual period.
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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 | 0.000 | 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) | 0.001 | 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".