A transplant experiment on the factors preventing lichen colonization of oak bark in southeast England under declining SO<sub>2</sub> pollution
Bibliographic record
Abstract
To investigate the factors responsible for limited lichen recolonization on oak with declining SO2 concentrations, Parmelia caperata (L.) Ach. and Parmelia saxatilis (L.) Ach. were transplanted to five stations along a transect running from central London (U.K.) into the surrounding countryside. Healthy thalli were transplanted onto young and mature Quercus robur L. (pedunculate oak) and Betula pendula Roth (silver birch), and some were moved with their original bark attached to investigate the importance of bark acidification. Relative growth rates and visible injury were monitored over 2 years, along with concentrations of atmospheric SO2 and NO2, measured using diffusion tube samplers and bark chemistry. SO2 concentrations were low in central London in comparison with the situation in previous decades, but they remain sufficiently high to harm the most sensitive lichens. NO2 concentrations increased sharply on approaching London, and levels were higher in winter than in summer. Bark pH was lower in mature oak than in birch or young oak at the two innermost stations, and levels of bark Mg also declined in London. Transplants of P. caperata survived on birch and young oak at all transect stations except Hyde Park, whereas P. saxatilis failed to grow over a wider range of the transect stations. We conclude that modest SO2 levels, interacting with low bark pH, still inhibit recolonization of oaks by P. caperata in central London. Parmelia saxatilis, in addition, appears to be limited by another factor such as the high NO2 concentrations that now characterize urban and suburban London, rather than through an inherently poor dispersal potential.Key words: atmospheric pollution, bark acidification, epiphytic lichens, NO2, recolonization, SO2.
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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) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 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 | 0.001 |
| 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".