Soil organic matter dynamics along a long-term soil warming gradient in a subarctic forested ecosystem
Bibliographic record
Abstract
Global warming will lead to a temperature rise of the soil, with a stronger effect in high latitude areas as compared to the global average. Soil warming could cause positive carbon-climate feedback, but this is still subject to many uncertainties. To enhance the understanding of how warming impacts underlying biogeochemical processes in top – and subsoils, our study makes use of a century-scale geothermal warming gradient. It is located in an aspen-dominated subarctic forest in the southern Yukon-Territory, Canada. A previous study at the site showed the SOC-stock to be reduced with warming, while the N-stock remained mainly unchanged. Thus, the C:N ratio was reduced, which was particularly pronounced in subsoils. Moreover, N shifted from the particulate-organic matter (POM) pool to the mineral-associated organic matter (MAOM) pool. We hypothesize the shift to be related to a higher microbial contribution to the MAOM fraction. In addition, the contribution of plant-derived OM in the subsoil might have decreased. This might be due to a change of root biomass distribution along the soil profile, as it is assumed that warming enhances N availability and the distribution of soil moisture. Furthermore, we hypothesize the soil structure to be a relevant factor for the distribution and loss of SOC, as the fraction of sand and stable aggregates (S+A) might be reduced with warming.To understand the coupling- or decoupling of C- and N cycles, we will determine biogeochemical parameters at four warming intensities up to a warming of +10 °C to a depth of 80 cm. This design allows us to identify potential non-linear responses and it includes different warming scenarios. We will measure C- and N stocks of the POM, S+A and MAOM fraction. To moreover address the warming effect on the relative organic matter turnover, δ13C and δ15N values will be analyzed. For soil structural changes, the mean weight diameter of water-stable aggregates is evaluated. Furthermore, the coarse- and fine root biomass is assessed along the soil profiles. This comprehensive study will gain valuable biogeochemical insights and first results of ongoing evaluations will be presented.
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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 | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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".