[MCN] The standard prediction is that beetle kill -> more fires

[Lance Olsen]

Robert A. Andrus, Thomas T. Veblen, Brian J. Harvey, and Sarah J. 
Hart In press. FIRE SEVERITY UNAFFECTED BY SPRUCE BEETLE OUTBREAK IN 
SPRUCE-FIR FORESTS IN SOUTHWESTERN COLORADO. Ecological Applications. 
http://dx.doi.org/10.1890/15-1121.1

Abstract
http://www.esajournals.org/doi/abs/10.1890/15-1121.1

Recent large and severe outbreaks of native bark beetles have raised 
concern among the general public and land managers about potential 
for amplified fire activity in western North America. To date, the 
majority of studies examining bark beetle outbreaks and subsequent 
fire severity in the U.S. Rocky Mountains have focused on outbreaks 
of mountain pine beetle (MPB, Dendroctonus ponderosae) in lodgepole 
pine (Pinus contorta) forests, but few studies, particularly field 
studies, have addressed the effects of the severity of spruce beetle 
(Dendroctonus rufipennis Kirby) infestation on subsequent fire 
severity in subalpine Engelmann spruce (Picea engelmannii) and 
subalpine fir (Abies lasiocarpa) forests. In Colorado, the annual 
area infested by spruce beetle outbreaks is rapidly rising, while MPB 
outbreaks are subsiding; therefore understanding this relationship is 
of growing importance. We collected extensive field data in subalpine 
forests in the eastern San Juan Mountains, southwestern Colorado, to 
investigate whether a gray-stage (<5 years from outbreak to time of 
fire) spruce beetle infestation affected fire severity. Contrary to 
the expectation that bark beetle infestation alters subsequent fire 
severity, correlation and multivariate generalized linear regression 
analysis revealed no influence of pre-fire spruce beetle severity on 
nearly all field or remotely sensed measurements of fire severity. 
Findings were consistent across moderate and extreme burning 
conditions. In comparison to severity of the pre-fire beetle 
outbreak, we found that topography, pre-outbreak basal area, and 
weather conditions exerted a stronger effect on fire severity. Our 
finding that beetle infestation did not alter fire severity is 
consistent with previous retrospective studies examining fire 
activity following other bark beetle outbreaks and reiterates the 
overriding influence of climate that creates conditions conducive to 
large, high-severity fires in the subalpine zone of Colorado. Both 
bark beetle outbreaks and wildfires have increased autonomously due 
to recent climate variability, but this study does not support the 
expectation that post-beetle outbreak forests will alter fire 
severity, a result that has important implications for management and 
policy decisions.

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" The increase in interaction diversity with the beetle outbreak adds 
to growing evidence
that insect outbreaks can increase components of biodiversity in 
forest ecosystems at various
temporal scales."

Kristina L. Cockle and Kathy Martin. Temporal dynamics of a commensal 
network of cavity-nesting vertebrates: increased diversity during an 
insect outbreak. Ecology, 96(4), 2015, pp. 1093-1104






















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