Controls on terrestrial carbon and nutrient cycling in Arctic permafrost environments
Bibliographic record
Abstract
High latitude regions are being disproportionately affected by changes induced by climate warming. The direction of global environmental change will largely depend on the response of Arctic ecosystems to positive and negative feedbacks, which has implications for the global climate system and the people that inhabit the Arctic region. Improving our understanding of the biogeochemical cycles that influence Arctic terrestrial systems will help improve models predicting future changes in northern latitudes. This research aims to determine the environmental controls on nutrient status and greenhouse gas exchange by assessing the relationships between environmental conditions, soil nitrogen availability, and greenhouse gas exchange under ambient and experimental conditions. At the Cape Bounty Arctic Watershed Observatory on Melville Island, Nunavut, varying land cover types exist across a naturally occurring moisture gradient, allowing us to investigate these relationships in wet and mesic tundra. Soil moisture, as opposed to soil temperature, was the main driver of inorganic nitrogen availability; ammonium was dominant under wetter conditions, while nitrate prevailed in drier conditions. In the wet tundra, soil moisture and ammonium availability together played an important role in mediating the carbon dioxide balance of the wet sedge meadow and ultimately contributed to the wetland being a net carbon dioxide sink across all three study years. While moisture and ammonium availability also played an important role in methane release, with drier conditions favouring nitrous oxide release via nitrifier denitrification, the strong carbon dioxide uptake offset the methane and nitrous oxide release, allowing the wetland to be a net greenhouse gas sink. The experimentally warmed mesic tundra site demonstrated a sustained warming effect on ammonium availability and ecosystem respiration 10-years after experiment establishment, and these effects were mediated by moisture. An enhanced snowfall and warming interaction increased nitrate availability, which corresponded with higher rates of N2O release. Temperature is often thought to be the key driver of changes in high latitude processes, but this dissertation finds that the future greenhouse gas balance of High Arctic systems will largely depend on the response of soil moisture and subsequent nitrogen availability to climate change.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| 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 teacher head, 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".