Calculating long‐term fire frequency at the stand scale from charcoal data
Bibliographic record
Abstract
Fire frequency is a statistical metric used to evaluate long‐term fire activity at stand and landscape scales. Fire frequency is defined as the number of fires occurring per unit time in a given area. In this study a method to calculate fire frequency at the stand scale is described, based on direct fire evidence of radiocarbon‐dated macrocharcoal fragments (>2 mm diameter) at the soil surface and buried in the mineral soil. A jack pine ( Pinus banksiana Lamb.) stand was used as a model site to calculate the long‐term fire frequency. The number of fires recorded at the soil surface is a function of fire activity and residence time of charcoal, the fewer fires occurring in the site the longer the residence time of charcoal. The residence time of charcoal at the surface of the study site totals 1710 calibrated years (calibrated age in years before 2010). Fourteen fire events occurred over the last 1000 years, i.e., an average fire interval of 75 years, a situation facilitating the long‐term maintenance of jack pine. When considering the late Holocene period covered by the dated charcoal in the surface and soil compartments, the average fire interval was 165 years over the last 3565 cal. years. Botanical identification of dated charcoal fragments indicated the arrival of jack pine about 2400 cal. years ago, i.e., the minimum arrival date of the species near its northeasternmost limit in North America. Although longer fire intervals prevailed before the last millennium, jack pine was able to maintain in the site or nearby, given that most fire intervals where shorter than the species maximum lifespan. Self‐perpetuation of jack pine illustrates the effectiveness of recurrence dynamics over the last thousand years. It is concluded that detailed analysis of radiocarbon‐dated macrocharcoal fragments at the surface and in the soil allows the calculation of the long‐term fire frequency and reconstruction of fire history at the stand scale. Given the long residence time of charcoal in fire‐prone sites, there is an opportunity to reconstruct local fire histories when focusing only on macrocharcoal fragments at the soil surface.
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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 | 0.001 | 0.003 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.003 | 0.002 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.001 |
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".