Limited tree mortality in unburned areas linked to bark beetle spillover from wildfires
Bibliographic record
Abstract
Increased fire activity in the western United States since 2000 has produced an abundance of fire-injured trees at risk to lethal attack by bark beetles. Large populations of bark beetles reproducing in fire-injured trees may disperse (or spillover) from inside the fire perimeter to adjacent, unburned forests, potentially causing extensive tree mortality. In the western United States and Canada, fire-injured Douglas-fir (DF; Pseudotsuga menziesii) are frequently colonized by Douglas-fir beetle (DFB; Dendroctonus pseudotsugae), prompting concern among land managers about elevated risk of spillover. We investigated spatiotemporal patterns of DF tree mortality from DFB in unburned areas surrounding 61 wildfires (2000-2017) with a high likelihood for spillover in the Northern Rocky Mountains, USA. We developed a multiple-scale analytical framework to examine tree mortality potentially associated with spillover following fire. Synchronous fluctuation in the amount of DF mortality within and beyond the flight distance of DFB in the region and surrounding individual fires (0-10 km) suggested that DFB activity primarily responded to a broader scale process, such as drought, rather than proximity to burned trees. Using shorter and longer range dispersal scenarios, we estimated that at <0.25 km from the fire perimeter, the dominant source of DFBs transitioned from burned to unburned sources due to the closer proximity of DFBs from unburned sources. Some fires (8%-15%; range of fires from sensitivity analysis) did exhibit evidence of DFB spillover, but spillover occurred <1 km from fires (based on our criteria) and DF tree mortality associated with spillover was 0.2%-0.3% of total DF damage area during the study period. Spillover was not associated with climate conditions that increase host tree stress, rather it was associated with greater DF mortality from DFB in the prior year in the same area (i.e., poorly linked to spillover). Site-specific monitoring of post-fire DFB populations in susceptible, unburned DF forests adjacent to fires by land managers may be necessary to determine the risk of DFB emigrating from burned areas. Our findings inform post-fire planning and the ecological implications of disturbance interactions that occurred in the early 21st century during a period of amplified wildfire and DFB activity.
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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 | 0.001 |
| 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) | 0.004 | 0.002 |
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; both teacher heads agree on what is shown here.
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".