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Record W7115824456

Restoration and CH4 dynamics in a cutover peatland

2003· dissertation· en· W7115824456 on OpenAlexaboutno aff

Bibliographic record

VenueMacSphere (McMaster University) · 2003
Typedissertation
Languageen
FieldEnvironmental Science
TopicPeatlands and Wetlands Ecology
Canadian institutionsnot available
Fundersnot available
KeywordsPeatAtmosphere (unit)MethanogenesisMethaneCarbon dioxideWetlandWater tableHydrology (agriculture)
DOInot available

Abstract

fetched live from OpenAlex

Peatlands cover 3% of the earth's surface, with approximately 110 to 130 million hectares in Canada and are important in terms of the long-term sequestration of atmospheric carbon. In contrast to their removal of CO2 from the atmosphere, peatlands represent 15 to 30% of the total methane emissions to the atmosphere with Canadian wetlands emitting approximately 0.1 to 1 x 1010 g yr^-1. Drainage and harvesting of peatlands generally reduces CH4 emissions to the atmosphere and increases CO2 emissions by up to 400%. However, recent studies have suggested that drained peatlands may represent a larger source of atmospheric CH4 than undisturbed peatlands. In the first part of this study, potential CH4 production and oxidation was determined from natural, harvested and recently restored peat. Total depth integrated CH4 production decreased with time post harvest where CH4 production at 2-yr > 7-yr > 20-yr cutover peat. This decrease in CH4 production was a result of a decreased source of labile carbon, a decrease in the methanogenic population, and an increase in the concentration of alternative electron acceptors. Restoration has altered CH4 production processes so that total depth integrated CH4 production was 2-yr > 7-yr >RESTORED> 20-yr cutover peat. Depth dependent trends in potential CH4 oxidation and production from each peat were dependent on the water table position while substrate quality was the main difference production values between the Lac St. Jean and Bois-des-Bel peat. Comparison of CH4 fluxes over the four field seasons showed restored site bare peat and mosses did not play a significant role in CH4 emissions from the peatland. However, the overall CH4 function of the peatland was directly related to the increase in CH4 emissions from vascular vegetation, remnant ditches and newly constructed ponds which were directly attributed to an increase in labile carbon for methanogenesis provided by vegetation. CH4 fluxes from ditches and ponds suggest that these features are the largest sources of CH4 from the peatland. However, when weighting the fluxes to the areal extent of each feature, ditches become secondary to vascular vegetation in total CH4 emissions while the ponds had a minimal impact on the amount of CH4 emitted from the peatland. Furthermore, ebullition from ditches and ponds was insignificant in comparison to the diffusive fluxes. When comparing CH4 emissions from this site to natural peatland systems (~10 g CH4 m^-2 a^-1), it is evident that the site is still a much smaller source of CH4 and that the carbon and CH4 process are still changing as the pool of labile carbon increases (develops). Vegetation succession is still occurring and more time and monitoring is needed in order to determine if this site will return to similar CH4 functions as natural peatlands.

Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.

How this classification was reachedexpand

Full frame machine prediction

Teacher imitation

Not 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.

metaresearch head score (Codex)0.000
metaresearch head score (Gemma)0.000
Version: metacan-v3-hybrid-931329e0061cValidation status: machine_predicted_unvalidated
Candidate categoriesnone
Consensus categoriesnone
DomainCandidate signal: none · Consensus signal: none
Study designCandidate signal: Observational · Consensus signal: none
GenreCandidate signal: Empirical · Consensus signal: Empirical
Teacher disagreement score0.022
Threshold uncertainty score0.045

Distilled classifier scores by category (both heads)

CategoryCodexGemma
Metaresearch0.0000.000
Meta-epidemiology (narrow)0.0000.000
Meta-epidemiology (broad)0.0000.000
Bibliometrics0.0000.000
Science and technology studies0.0000.000
Scholarly communication0.0000.000
Open science0.0000.000
Research integrity0.0000.000
Insufficient payload (model declined to judge)0.0000.000

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.

Opus teacher head0.006
GPT teacher head0.188
Teacher spread0.182 · how far apart the two teachers sit on this one work
Validation statusscore_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it

Classification

machine, unvalidated

Machine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.

The models applied no category: nothing in the taxonomy fit this work.
Study designObservational
Domainnot available
GenreEmpirical

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".

Quick stats

Citations0
Published2003
Admission routes1
Has abstractyes

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