Drainage as a model for long-term climate change effect on vegetation dynamics and carbon cycling in boreal peatlands
Bibliographic record
Abstract
Peatlands are important components of the global carbon cycle, storing one-third of the global soil carbon.The accumulation of peat depends on two main interacting factors: the wetness and vegetation composition of a peatland.Previous studies have looked at the impact of a water table lowering on carbon fluxes in different types of peatlands.However, these studies were conducted within a time frame that did not allow the examination of vegetation changes due to the water table lowering.To be able to predict the fate of peatlands with changing climate and potentially lower water tables, the effect of a change in vegetation has to be considered.To bridge this gap, I conducted a study along a drainage gradient resulting from the construction of a drainage ditch 85 years ago in a portion of the Mer Bleue bog, located near Ottawa, Canada.According to water table reconstructions based on testate amoeba, the drainage dropped the water table by approximately 18 cm.On the upslope side of the ditch, the water table partly recovered and the vegetation changed only marginally.However, on the downslope side of the ditch, the water table stayed persistently lower and trees established (Larix and Betula).The importance of Sphagnum decreased with a lower water table, and evergreen shrubs were replaced by deciduous shrubs.The water table drop and subsequent vegetation changes had combined and individual effects on the carbon functioning of the peatland.Methane fluxes decreased because of the water table lowering, but were not affected by vegetation changes, whereas respiration and net ecosystem productivity were affected by both.The carbon storage of the system increased because of an increase in plant biomass, but the long-term carbon storage as peat decreased.Several steps need to be taken to allow for the appropriate representation of water table disturbances in peatland carbon modelling.The modelling of the effect of water table drop, along with vegetation changes using the Holocene Peatland Model revealed that the model captured the general behaviour of the peatland; however, the evaluation version is more resilient than the system is.The inclusion of the feedback effect that vegetation has on the carbon functioning of a peatland when a disturbance occurs is crucial to model the carbon balance of this ecosystem.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".