Thread by @PhilipHiguera, 1/7 @TJTimberlake asks: "Could you (or another #FireEcology) expert provide some context [...]

1/7 @TJTimberlake asks: "Could you (or another #FireEcology) expert provide some context on the debate regarding beetle-kill affecting fire behavior/severity/extent? Gray stage versus red stage and all that..." Well studied in past 15+ yr; not really a debate in sci. community.

2/7 Short answer: major driver of size of #EastTroublesomeFire = extremely dry fuels + high winds. Mountain pine beetle (MPB) mortality likely affected fire behavior, including tree torching and fire intensity, but TBD if it impact severity - it may not. Here’s the basis:

3/7 Good framework for this Q provided by Jeff Hicke et al., who divide post-MPB stands into 3 categories: red, grey, and old phase. Based on changes in canopy and surface fuels, each phase has diff. expected impacts on

behavior.
https://www.sciencedirect.com/science/article/pii/S0378112712000746

3/7 Good framework for this Q provided by Jeff Hicke et al., who divide post-MPB stands into 3 categories: red, grey, and old phase. Based on changes in canopy and surface fuels, each phase has diff. expected impacts on behavior. https://www.sciencedirect.com/science/article/pii/S0378112712000746

4/7 Areas of #EastTroublesomeFire (not all) impacted by MBP, up to c. 80% mortality.

from 2007, looking west towards Grand Lake, from @RockyNPS. This area's just south of the

, but looking out towards fire-affected areas.

4/7 Areas of #EastTroublesomeFire (not all) impacted by MBP, up to c. 80% mortality.from 2007, looking west towards Grand Lake, from @RockyNPS. This area's just south of the , but looking out towards fire-affected areas.

5/7 Stands would now be in "Old" phase, suggesting

surface fire intensity and individual tree torching. Active crown fire potential

– BUT photos, InciWeb & rate of spread indicate extreme

behavior: large flame length and rapid spread.

Andrew Lussie via InciWeb

5/7 Stands would now be in "Old" phase, suggesting surface fire intensity and individual tree torching. Active crown fire potential – BUT photos, InciWeb & rate of spread indicate extreme behavior: large flame length and rapid spread. Andrew Lussie via InciWeb

6/7 Overall... high winds + record-setting dry fuels, & everything else becomes less influential. No doubt studies will look at this in depth for #EastTroublesomeFire. @Brian_J_Harvey D. Donato & @MonicaGTurner have a robust study on this Q in N. Rockies: https://www.pnas.org/content/111/42/15120

Recent mountain pine beetle outbreaks, wildfire severity, and postfire tree regeneration in the US...

Understanding how multiple disturbances may interact to affect ecosystems is important for ecosystem management as climate-driven disturbance activity increases. Recent severe bark beetle (Circulio...

https://www.pnas.org/content/111/42/15120

7/7 Last but not least: @HartsTrees @taniaschoe @ThomasTVeblen T. Chapman: "Contrary to the expectation that an MPB outbreak increases fire risk...[we] show no effect of outbreaks on subsequent area burned during years of extreme burning across the West." https://www.pnas.org/content/112/14/4375

Area burned in the western United States is unaffected by recent mountain pine beetle outbreaks

Across western North America, abundant susceptible pine hosts and a suitable climate during the early 21st century have promoted widespread mountain pine beetle (MPB) outbreaks, leading to concern...

https://www.pnas.org/content/112/14/4375

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