Carbon cycling at a post-extraction restored peatland: Small-scale processes to global climate impacts
Bibliographic record
Abstract
Peatlands store large amounts of organic carbon (C) and are an important component of the global climate system. Climate and peatland land surfaces are closely coupled through land-atmosphere exchanges of greenhouse gases (GHG), such as carbon dioxide (CO2) and methane (CH4). When undisturbed, peatlands exert a long-term (millennia) negative radiative GHG forcing (climate cooling) through CO2 removal from the atmosphere, and a short-term (decades) positive forcing (climate warming) with the addition of CH4 to the atmosphere. Peatland drainage and extraction, however, results in mineralization of stored peat, releasing large amounts of CO2 while generally reducing CH4 to minimal levels. Rewetting and actively restoring vegetation is now a restoration approach used to reduce CO2 emissions from degraded peatlands. However, the timeframe needed for restoration to re-establish the C sink function of an undisturbed peatland remains poorly constrained due to a lack of multi-year measurements. In this thesis, I analyze three years of eddy covariance flux measurements from a post-extraction restored peatland in eastern Quebec, Canada that was restored 14 years prior. I link these measurements with flux footprint modelling, stable isotope fractionation data and pore water concentrations to characterize how belowground C cycling and fluxes are impacted by restoration. I combine a series of flux towers at post-extraction unrestored and restored peatlands in eastern and western Canada with an atmospheric perturbation model to further reveal how after-use management is affecting the global climate.The post-extraction restored peatland was a C sink of 78 ± 17 g C m-2 yr-1 within fourteen years of restoration, due to strong CO2 uptake and small CH4 emission and dissolved organic carbon export. A comparison with an undisturbed reference peatland (Mer Bleue) revealed annual NEE at the restored peatland was most similar to wetter, more productive years at the reference peatland. A mapping of post-extraction (1980 onwards) canopy structure changes showed broad comparability between the restored peatland and surrounding intact peatland within five years of restoration. The enhanced vegetation index results suggest that the developing vegetation in general had a normal response to environmental factors and was not experiencing any enduring stress from the underlying cutover peat. While the processes behind the surface net CO2 flux appear successfully recovered, approximately two thirds of the restored peatland was a minimal source of CH4, suggesting a lag in the recovery of belowground C cycling processes. Carbon turnover in the cutover peat beneath the new Sphagnum layer was slow and appeared to occur only with E. vaginatum substrate input and plant-mediated transport. The C isotopic fractionation factor for CH4 and CO2 in the restored field pore water exhibited a dominance of acetoclastic methane production, even deeper in the cutover peat profile. In contrast, isotopic fractionation in the former drainage ditches showed a balance of acetoclastic and hydrogenotrophic methanogenesis deeper in the profile, indicating that some bulk peat C turnover was occurring. Over time (decades), C turnover of the new peat is expected to limit the impacts of the cutover peat on the surface CH4 flux.Flux measurements at unrestored sites in eastern and western Canada reveal that not restoring post-extraction peatlands leads to decades of CO2 addition to the atmosphere, with low CH4 emission. The after-use decision to not restore results in a positive radiative forcing seven times more powerful than the negative forcing achieved by active restoration after 500 years. Prompt active restoration achieves a neutral climate impact about 155 years earlier than restoration after a 20-year delay. In contrast, IPCC Tier 1 emission factors based on a wide range of rewetting activities display a continually positive radiative forcing, even with prompt rewetting
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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 | 0.001 |
| 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".