A 130 0-year history of vegetation and environmental change at Jan Lake, east-central Alaska
Bibliographic record
Abstract
Pollen, stomates and macrofossils were analysed from a 3.63 m sediment core at Jan Lake, eastcentral Alaska, in order to improve spatial resolution of patterns of vegetation history in this region. The chronology was based on 19 AMS 14 C dates on plant macrofossils and concentrated pollen. Zone Jan-I (12400-11 600 yr BP) records a unique herb-tundra pollen assemblage, particularly high in Chenopodia ceae, adding supporting evidence for a spatial mosaic of lateglacial vegetation in east-central Alaska. Unexpected pollen of Picea, Betula and Alnus in lateglacial sediments appears to arise from reworking of older pollen-bearing deposits, according to a radiocarbon date of 22180yr BP on a pollen sample. Shrub Betula tundra dominates zone Jan-Il (11 600-10000 yr BP), with indications of climatic amelioration. Tree species (Populus, Picea glauca, Betula papyrifera) began to arrive in zone Jan-Illa (9200-6600 yr BP), and the modern boreal forest, including Alnus and Picea mariana, became established during zone Jan-IIlb (6600-0 yr BP). Fossil stomates appear to be an effective indicator of initial local occurrence of Picea at Jan Lake. Picea arrival at Jan Lake is within 300 years of its arrival at other AMS-dated sites across eastern and central Alaska. A migration route into Alaska through the drainages of the Tanana or Yukon Rivers is hypothesized. Evidence is found for a slight mid-Holocene Picea decline at Jan Lake, intermediate in magnitude between Picea pollen records showing no decline to the east and a larger decline to the west in Alaska.
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 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) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| 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) | 0.001 | 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".