native bark beetles in the western united states: who ... · 1925. mountain pine beetle -killed...
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Forest and Woodland Ecosystem Research
Native Bark Beetles in the Western United States: Who, Where, and Why
Barbara J. Bentz Rocky Mountain Research Station
USDA Forest Service Logan, UT
Photo Ryan Bracewell
Douglas fir beetle D. pseudotsugae
Spruce beetle D. rufipennis
Western pine beetle D. brevicomis
Arizona fivespined ips Ips lecontei
Pinyon ips Ips confusus
Mountain pine beetle Dendroctonus ponderosae
Native Western US Bark Beetle Species That Can Cause Landscape-Wide Tree Mortality
Pine engraver Ips pini
Southern pine beetle D. frontalis
Western balsam bark beetle Droycoetes confusus
Jeffrey pine beetle D. jeffreyi
Roundheaded pine beetle D. adjunctus
1925. Mountain pine beetle-killed lodgepole pine in Yosemite National Park, CA
Photo M Furniss
Photo JM Miller
1925
1984
Year
19992000
20012002
20032004
20052006
20072008
2009
Mill
ion
Acre
s Af
fect
ed
0
2
4
6
8
10
Native bark beetles have affected > 63 million acres in the western US over the past decade (USDA Forest Health Protection).
High elevation ecosystems
1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009
Mill
ion
Acr
es A
ffect
ed
0
.5
1.0
1.5
2.0
2.5
3.0
3.5
Alaska
Year
1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009
Mill
ion
Acr
es A
ffect
ed
0
.5
1.0
1.5
2.0
2.5
3.0
3.5
Washington
Year
1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009
Mill
ion
Acr
es A
ffect
ed
0
.5
1.0
1.5
2.0
2.5
3.0
3.5
Oregon
Year
1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009
Mill
ion
Acr
es A
ffect
ed
0
.5
1.0
1.5
2.0
2.5
3.0
3.5
California
Year
1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009
Mill
ion
Acr
es A
ffect
ed
0
.5
1.0
1.5
2.0
2.5
3.0
3.5
Idaho
Year
1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009
Mill
ion
Acr
es A
ffect
ed
0
.5
1.0
1.5
2.0
2.5
3.0
3.5
Nevada
Year
1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009
Mill
ion
Acr
es A
ffect
ed
0
.5
1.0
1.5
2.0
2.5
3.0
3.5
Utah
Year
1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009
Mill
ion
Acr
es A
ffect
ed
0
.5
1.0
1.5
2.0
2.5
3.0
3.5
Arizona
Year
1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009
Mill
ion
Acr
es A
ffect
ed
0
.5
1.0
1.5
2.0
2.5
3.0
3.5
Montana
Year
1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009
Mill
ion
Acr
es A
ffect
ed
0
.5
1.0
1.5
2.0
2.5
3.0
3.5
WyomingYear
1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009
Mill
ion
Acr
es A
ffect
ed
0
.5
1.0
1.5
2.0
2.5
3.0
3.5
South Dakota
Year
1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009
Mill
ion
Acr
es A
ffect
ed0
.5
1.0
1.5
2.0
2.5
3.0
3.5
Colorado
Year
1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009
Mill
ion
Acr
es A
ffect
ed
0
.5
1.0
1.5
2.0
2.5
3.0
3.5
New Mexico
Bark Beetle-Caused Tree Mortality in 13 Western US States: 1999 to 2009
Data source: USDA Forest Service, Forest Health Protection, Aerial Detection Surveys
Photo Diana Tomback Photo Diana Tomback
Exotic Native
Cronartium ribicola White pine blister rust
Mountain pine beetle
Whitebark pine Pinus albicaulis
Photo Wally MacFarlane
Whitebark pine is currently being considered for Threatened or Endangered Status, USFWS
• Legacies of past management created large expanses of susceptible-aged & homogenous forests. • lodgepole pine
Multiple factors are influencing recent mountain pine beetle outbreak dynamics:
• Legacies of past management created large expanses of susceptible-aged & homogenous forests. • lodgepole pine
Multiple factors are influencing recent mountain pine beetle outbreak dynamics:
• Environmental Changes - • precipitation • temperature
Source: http://data.giss.nasa.gov
Thresholds and positive feedback processes at multiple scales contribute to the eruptive, outbreak nature of ‘aggressive’ bark beetle populations.
Raffa et al. 2008, Bioscience
Mountain pine beetle Cold Tolerance 1961-1990 Normals, CRCM v. 4.2.0 IPPC A2 scenario
Probability of Survival
Régnière & St-Amant. 2007
Future Predictions
Bentz et al. 2010
Mountain pine Beetle Cold Tolerance 2001-2030
Probability of Survival
Mountain pine Beetle Cold Tolerance 2071-2100
Probability of Survival
What can be done?
• Tree protection in high value recreation areas and near homes is possible with:
• insecticides • semiochemicals – verbenone
• Bark beetle-killed tree removal in recreation areas and near power lines.
© Senator Mark Udall
What can be done? (cont.)
• Optimal management strategies for a forest and a wildland urban interface are not the same.
• Optimal management strategies will differ across ecosystems and geographic locations. • Reducing tree mortality in forests after a bark beetle outbreak has started is not feasible.
• Silvicultural manipulations can be used to reduce susceptibility of some forest types to bark beetle attack prior to outbreak initiation.
• Create a diverse forest landscape through modifications to species and age classes at a regional scale.
• Forest management strategies should incorporate projections of climate-change on both forests and beetle population dynamics.
“Using Landsat satellite data, University of Wisconsin forest ecologist Phil Townsend and his team are discovering that pine beetle damage appears not to have a significant impact in the risk of large fires. In fact, it might even reduce fire risk in some instances.” Source: www. nasa.gov
Do bark beetle outbreaks influence other forest disturbances such as wildfire? Research suggests there is NOT a direct correlation between bark beetle-caused tree mortality and large wildfire. The relationship is dynamic and an ignition source and ‘fire weather’ are important drivers.
FIRE
HAZARD
hig
h
low
TIME
Live, water-stressed conifer forest
Extensive tree mortality, dead needles still on trees
Dead needles drop, Fine surface fuels , Surface fuels drier
Surface Fire
Canopy Fire
Dead trees start to fall. Herb and shrub and tree re-growth, Coarse woody surface fuels
bar
k bee
tle
outb
reak
– fore
st die
bac
k
From: Bentz et al. 2010