Mountain Pine Beetle Outbreak in the
Warner Mountains: Implications for
Whitebark Pine
Danny Cluck
Entomologist
Forest Health Protection
Susanville, CA
Mountain Pine Beetle Outbreak in the
Warner Mountains
Why here, why now?
Climate Change
• The Warner Mountain region has not exhibited a
significant change in mean or minimum
temperatures in the last 80 years based on local
weather station data and the PRISM climate
model shows some Warner Mountain areas are
cooler
• The northeastern California climate zone has
exhibited a general increase in annual
precipitation by an average of 3 inches since 1931
Merriam and Safford 2011
Do cold winter temps control mountain pine
beetle populations in California?
• -30°F must be sustained for at least five days for a
large number of MPB larvae to be killed during
the middle of winter
• The ability of MPB to acclimate to colder
temperatures is likely sufficient to prevent a
significant winter mortality event in California as
temperatures in forested areas rarely if ever drop
to lethal levels for an extended time (Yuill 1941)
• Cold-induced caused MPB mortality may not play
as big a role in California as in northern latitudes
(Bentz 2013)
Does a warmer climate result in more mountain
pine beetle generations per year?
In this warm environment (Southern California), MPB is living at or very
close to it’s optimal temperature. Small increases can have negative
impacts on fitness. The thermal “safety margin” is small. Hotter is not
always better
Evolved adaptations reduce MPB capacity to take full advantage of
increased thermal heat at warmest sites, limiting potential for
bivoltinism (two generations/year) within current realized distribution
At higher latitudes and elevations, populations are currently living at
environmental temperatures cooler than their optimal temperatures,
such that climate warming may enhance fitness
2013 California Forest Pest Council presentation:
Phenology and Life History Characteristics of Mountain Pine Beetle and Jeffrey Pine Beetle - Barbara J. Bentz,
RMRS
Mountain Pine Beetle
in the Warner
Mountains
• Generally one generation per
year (some may need two years
to complete development)
• Attacks from July through
September
Short-term changes in temperature
Average Temperature - June/July/August
California Division 3 (Great Basin)
65
64
Degrees Farenheit
63
62
61
60
59
58
57
56
1987
1989
1991
1993
1995
1997
1999
2001
Year
2003
2005
2007
2009
2011
2013
Average Annual Temperature (F)
Year
2010
2007
2004
2001
1998
1995
1992
1989
1986
1983
1980
1977
1974
1971
1968
1965
1962
1959
1956
1953
1950
1947
1944
1941
1938
1935
1932
1929
1926
1923
1920
1917
1914
1911
1908
1905
Temperature (F)
Average Annual Temperature 1905 - 2012 (Oct - Sept), California Division 3 (Great Basin)
49
48
47
46
45
44
43
42
41
• Whitebark pine is more widespread and occurs in denser
stands than it did 150 years ago (Figura 2006 and Vale
1977).
• Episodic recruitment at low elevations and continuous at
higher elevations
Figura 2006
Whitebark pine diameter distribution
Based on 18 FHP plots – est. 2010
800
700
600
TPA
500
400
300
200
100
0
<1.0
1.0 - 4.0
4.1 - 8.0
8.1 - 12.0 12.1 - 16.0 16.1 - 20.0 20.1 - 24.0 24.1 - 28.0 28.1 - 32.0 32.1 - 34.0 34.1 - 38.0
DBH (in)
Precipitation and Drought
Palmer Hydrologic Drought Index (PHDI) 1896 - 2013
Water Year (Oct-Sept), California Division 3 (Great Basin)
4
2.83
Palmer Hydrologic Drought Index
3
2.81
1.77
2
1
0.57
0
-1
-0.84
-0.94
-1.02
-1.3
-1.61
-2
-1.92
-3
-2.57
-2.75
-3.14
-3.42
-4
2000
2001
2002
2003
2004
2005
2006
2007
Year
2008
2009
2010
2011
2012
2013
Mountain Pine Beetle Outbreak
2005 - present
Forest Health Protection
Aerial Detection Survey
2006 - 2007
Forest Health Protection
Aerial Detection Survey
2006 - 2009
Forest Health Protection
Aerial Detection Survey
2006 - 2011
Forest Health Protection
Aerial Detection Survey
2006 - 2013
Forest Health Protection
Aerial Detection Survey
2006 - 2007
Forest Health Protection
Aerial Detection Survey
2006 - 2009
Forest Health Protection
Aerial Detection Survey
2006 - 2011
Forest Health Protection
Aerial Detection Survey
2006 - 2013
Mt. Bidwell 2007
Mt. Bidwell 2011
Mountain pine beetle impacts to cone production
100.0%
3.8%
5.5%
16.7%
90.0%
23.4%
80.0%
4.6%
70.0%
10.0%
Dead >5 years
60.0%
MPB killed <5 years
50.0%
92.7%
40.0%
Green Infested
77.0%
Green Trees
62.8%
30.0%
20.0%
10.0%
0.0%
< 4.0" dbh (2.2% producing
cones)
2013 - 12% mortality
4.0 - 8.0" dbh (43.4%
producing cones)
> 8.0" dbh (84.1% producing
cones)
27% mortality
34% mortality
Plot #
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
% of BA Age of dominant/
Stems/Hectare
suitable host
codominant
94
99
93
93
90
97
85
95
93
94
91
98
97
97
97
88
97
96
>80
>80
<60
>80
>80
>80
>80
>80
>80
>80
>80
>80
>80
>80
>80
>80
>80
>80
780
1899
1159
1139
1799
1199
1259
1079
880
520
880
720
920
760
1100
2139
1259
820
Susceptibility
Rating
Observed %
mortality
94
79
9
93
72
97
85
95
93
47
91
49
97
97
97
44
97
96
34
67
0
82
0
0
14
6
0
13
0
20
0
0
15
75
53
57
Future of whitebark pine in the
Warner Mountains?
• Most larger diameter LPP and WBP stands
that helped facilitate the current outbreak are
or will likely be decimated
• Most large diameter LPP and WBP will likely
be thinned from mixed size class stands
• There may be an extended period of reduced
cone production and Clark’s nutcracker
facilitated reforestation
Future of whitebark pine in the
Warner Mountains?
• Large areas of small diameter whitebark pine
should have high levels of survival
• WBP regeneration exists in nearly all MPB
killed stands and should survive (and thrive?)
• It does not appear that white pine blister rust
will significantly impact whitebark pine
regeneration in the near future
White pine
blister rust
•
•
•
•
WPBR confirmed or suspected on 9 plots
Confirmed infection on 0.6% of WBP stems
Confirmed/suspected on 1.7% of WBP stems
No mortality attributed to WPBR infections
Pityogenes spp. and Pityophthorus spp.
Found attacking:
• small diameter WBP within clumps where
MPB is killing larger stems
• limbs and tops of MPB attacked WBP and
LPP (even large diameter LPP)
• Individual small diameter WBP growing at
lower elevations on poorer sites.
Pityogenes spp. and
Pityophthorus spp.
Pityophthorus spp.
• Uncommon in plots and most of
Warner Mountains
• Heavy infestation reported in 2009
on over 150 acres of whitebark
pine at north end of wilderness
• Elevated levels on west slope of
Eagle Peak in 2012
Shoot Moth
(Possibly Rhyacionia sp.)
• Twigs tend to break off
at point of attack
• Might be reducing cone
production on individual
trees
Limber Pine Dwarf Mistletoe
(Arceuthobium cyanocarpum)
•Uncommon; only
observed in one small
area in south Warners
Thank you!
Acknowlegments:
Rachel Simons, Botanist/Forester, Modoc NF
Judy Perkins, Botanist, Modoc NF
Krystina Smith, Forester, Modoc NF
Amanda Grady, Entomologist, FHP
Rueben Mahnke, Biological Technician, FHP
Meghan Woods, GIS Analyst, FHP
Cynthia Snyder, Entomologist, FHP