A Stable Isotope Investigation Of Pollen From Pinery Provincial Park, Southwestern Ontario, Canada
Bibliographic record
Abstract
Pollen is a useful proxy for reconstructing paleoclimate; however, the relationship between its stable isotopic composition and the environment in which it forms is still poorly understood. We examine the stable oxygen, carbon, and nitrogen isotope compositions of pollen from tree (coniferous and deciduous), grass (C3 and C4), and marsh species from Pinery Provincial Park, Ontario, and its environs, and maple and oak tree species from eight localities across the United States of America, to (i) determine the major environmental influences on pollen δ18O, δ13C, and δ15N values, (ii) examine the causes of stable isotopic variability of pollen from different plant species from the same location, and (iii) assess whether the isotopic composition of pollen corresponds to that of plant cellulose.\nAssuming a cellulose-water fractionation factor of +27‰, δ18O values of T. latifolia (cattails) closely match δ18Oprecipitation values at the time of sugar synthesis in the area, suggesting little to no isotopic enrichment. Grass species differ from δ18Oprecipitation values at the time of sugar synthesis by +3.5 to +5.8‰, and tree species by +10.2 to +13.2‰, indicating increased levels of transpiration, and its attendant effects on δ18Oleaf water values, prior to pollen synthesis. Bulk leaf cellulose δ18O values differ by +0.6 to +2.1‰ relative to pollen in tree species versus up to +5.2‰ in grass species. These results suggest that the biochemical pathway used by sugars during translocation in grass species results in mixing of 18O-poor source water with leaf water. The δ13C value of pollen is likely controlled by a combination of factors such as photosynthetic pathway, and relative humidity (water stress) at the time of the formation of sugars used in pollen formation. The nitrogen isotope composition of pollen reflects a complex array of parameters, which were not resolved in this study, but likely reflects site-specific conditions affecting the more open versus more closed nature of the nitrogen cycle.
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 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 | 0.002 |
| Science and technology studies | 0.003 | 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".