Carbon in Canada’s boreal forest — A synthesis
Bibliographic record
Abstract
Canada’s managed boreal forest, 54% of the nation’s total boreal forest area, stores 28 Pg carbon (C) in biomass, dead organic matter, and soil pools. The net C balance is dominated by the difference of two large continuous fluxes: C uptake (net primary production) and release during decomposition (heterotrophic respiration). Additional releases of C can be high in years, or in areas, that experience large anthropogenic or natural disturbances. From 1990 to 2008, Canada’s managed boreal forest has acted as C sink of 28 Tg C year −1 , removing CO 2 from the atmosphere to replace the 17 Tg of C annually harvested and store an additional 11 Tg of C year −1 in ecosystem C pools. A large fraction (57%) of the C harvested since 1990 remains stored in wood products and solid waste disposal sites in Canada and abroad, replacing C emitted from the decay or burning of wood harvested prior to 1990 and contributing to net increases in product and landfill C pools. Wood product use has reduced emissions in other sectors by substituting for emission-intensive products (concrete, steel). The C balance of the unmanaged boreal forest is currently unknown. The future C balance of the Canadian boreal forest will affect the global atmospheric C budget and influence the mitigation efforts required to attain atmospheric CO 2 stabilization targets. The single biggest threat to C stocks is human-caused climate change. Large C stocks have accumulated in the boreal because decomposition is limited by cold temperatures and often anoxic environments. Increases in temperatures and disturbance rates could result in a large net C source during the remainder of this century and beyond. Uncertainties about the impacts of global change remain high, but we emphasize the asymmetry of risk: sustained large-scale increases in productivity are unlikely to be of sufficient magnitude to offset higher emissions from increased disturbances and heterotrophic respiration. Reducing the uncertainties of the current and future C balance of Canada’s 270 Mha of boreal forest requires addressing gaps in monitoring, observation, and quantification of forest C dynamics, with particular attention to 125 Mha of unmanaged boreal forest with extensive areas of deep organic soils, peatlands, and permafrost containing large quantities of C that are vulnerable to global warming.
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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 | 0.001 | 0.003 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.009 | 0.022 |
| Science and technology studies | 0.002 | 0.002 |
| Scholarly communication | 0.005 | 0.002 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.011 | 0.001 |
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".