Effect of varying oceanicity on early- to mid-Holocene palaeohydrology, Kola Peninsula, Russia: isotopic evidence from treeline lakes
Bibliographic record
Abstract
The stable-isotope stratigraphy of sedimentary organic matter and algal cellulose in cores from two lakes near treeline on the Kola Peninsula indicate changes in water and nutrient balance that correlate with inferred expansion of Pinus sylvestris during the early to mid-Holocene. Trends in cellulose-inferred lakewater δ18O values for both lakes suggest that moist conditions after deglaciation were followed by progressive drying from about 9500 to between 8000 and 7500 14C yr BP. Although pine appeared in the area by 8000 14C yr BP, the maximum density of trees locally, as suggested by stomate evidence, occurred during subsequent moistening between 7500 and 6000 14C yr BP. This is c. 1000 years later than in other regions of northern Russia and is possibly attributable to limitations on seedling establishment and survival due to root desiccation during dry winters. Changes in nutrient balance and productivity in the lakes, as inferred from variations in sediment carbon and nitrogen elemental abundances and their respective stable-isotope signatures, are also consistent with expected changes in hydrological and edaphic conditions. Development of moister conditions at about 7000 14C yr BP on the Kola Peninsula is in harmony with evidence for increased oceanicity at this time in central Siberia, which is thought to reflect enhanced propagation of warm, moist air masses across northern Eurasia due to increased sea-surface temperatures and reduced sea-ice cover in the Nordic Seas.
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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 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| 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".