USDA Forest Service
Monitoring Forest Insects
and their Impacts in a
Changing Climate
John E. Lundquist
Region 10 Forest Health Protection
USDA Forest Service, Anchorage AK
Evidence accumulating that climate changing…
(www.gi.alaska .edu/AtmoSci/Research/climate.html)
In Alaska…0.9 to 1.8 °F in the past 100
years …3.0 to 5.0 °F since 1950.
A changing climate can impact many things…
Glaciers melting
Polar bears dying
Flowers
blooming
later
Insect outbreaks…
Butterflies
migrating
Oceans rising
(Holsten 2000)
“the ultimate integrated science”…
We all have our own stories… if we don’t now we will…
1976
Photo credits -- U of Alaska Library
2006
Portage Glacier, Alaska
Photo credits -- Gary Brassch
What can insect pests tells about monitoring
the effects of climate change?
Point 1. Forest insects interact/react with climate in
many ways.
Point 2. Effects on forests are expressed in many
ways.
Point 3. Determining cause and effects is complex.
Point 1. Forest insects interact with climate in many ways…
Direct
Effects
Change in Host
Resistance
(host switching, host
distribution, inducible defense
responses)
(phenology,
winter
mortality)
Climate
Change
Impacts
on Insect
Populations
Indirect
Effects
(predators/prey,
symbiotic fungi,
forest
structure)
Spatial and
Temporal
Synchrony
(decoupling insect
and host
phenologies)
…how do these interactions relate to impacts on forest health??
Point 2. Effects on forests are expressed in different ways.
Northward
expansion.
Change in
Host
Resistance
Indirect
Effects
Incidence/severity
increase.
Direct
Effects
Climate
Change
Impacts
on Insect
Populations
Spatial and
Temporal
Synchrony
… how can these responses be used as a basis for monitoring?
Some observations from Alaska.
25
Severity
20
warming
History of Spruce Beetle
Outbreaks on the
Kenai Peninsula, Alaska
15
10
5
0
2010
1995
1975
1955
Year
1935
1915
1895
1875
1855
1835
1815
-5
(Berg 2006)
…could this be due to climate change?
Some observations from Alaska.
Northward migration
of outbreaks
Based on previous reports/aerial surveys
…could this be due to climate change?
Some observations from Alaska.
800,000
Aspen Leaf Miner
700,000
600,000
500,000
400,000
300,000
200,000
100,000
2004
2001
1998
1995
1992
1989
1986
1983
1980
-100,000
Year
0
…could this be due to climate change?
Some observations from Alaska.
Northward migration of spruce
budworm based on first reports
65
22
286
762
1630
357
78 54
8
12
o
ooo
oo
oo
o
o
Limit line by 2008
Limit line by 2000
Limit line by 1990
Limit line by 1980
Limit line by 1960
Limit line by 1950
…could this be due to climate change?
Number (standardized)
Some observations from Alaska.
1.0
Latitudinal
distribution of
spruce
budworm…
2008
2009
0.8
0.6
0.4
0.2
0.0
60 61 62 63 64 65 66 67 68 69
LATITUDE
…could this be due to climate change?
Climatic pattern changes that with latitude…
Longer growing season
Ave Temperature, F
60
40
Earlier,
warmer
spring
20
0
-10
-20
JAN
JUN
DEC
Milder winter
Month
…are these patterns similar under a changing climate?
Point 3. Determining cause and effects is complex.
Climate Change
+ TIME
+ SPACE
Host
Direct
Effects
Change
in Host
Resistan
ce
Climate
Insect
Change
Impacts
on
Populations
Insect
Populati
ons
Indirec
t
Effects
Spatial and
Temporal
Synchrony
?
Environment
Impact
… cause/effect relationships are difficult to track.
Case Study -- the spruce beetle.
Dendroctonus rufipennis (Kirby)
19
80
19
82
19
84
19
86
19
88
19
90
19
92
19
94
19
96
19
98
20
00
20
02
20
04
20
06
Infested Area (acres)
Spruce Beetle Infested Area
1200000
1000000
800000
600000
400000
200000
0
Year
Course of the 1990s outbreak…
(Forest Conditions Report 2003)
Hypotheses about the connection with climate…
“The summer temperature hypothesis…“… a run of two or
more warm summers (exceeding 51 o F) would generate a
detectable level of Spruce beetle activity…” (Berg 2006)
… but this doesn’t tell us much about the mechanisms.
Mechanisms of climate influences…
Winter Mortality
Hypothesis
Moderate winter
temperatures and
abundant snowfall
Low winter mortality
Early Spring
Hypothesis
Early increasing
spring temperatures
Early emergence,
attack, oviposition,
and egg hatch
2- to 1- Year Life
Cycle Hypothesis
Early increasing
spring temperatures
Switch from 2- to 1year life cycle
Summer Stress
Hypothesis
Increasing summer
temperatures
Transpiration deficit
causing tree stress
and increased
susceptibility
Frozen Root
Hypothesis
Cold soil, frozen
roots while
temperatures warm
in the spring
Reduced host rate
increasing
susceptibility
Growth Season
Length Hypothesis
Lengthened growth
season
Longer time to
cause damage
… all of these probably play a role.
Abundant beetle
population Pre-1990s
beetle
outbreaks
Various
disturbance
agents
Increasing population
growth & development
on the Kenai
Fires of the 1870s
destroyed large areas
Abundant spruce
regeneration of
suitable host spp
during recovery
Increasing
Intra specific
competition
Increasing
breeding material
Windfall
and other
small
scale
disturbances Over
mature
forest
Initial
attack
Susceptible
host
population
transpiration
deficit
Spatial &
temporal
synchrony
Low winter
mortality
Condition of
neighboring
stands
?
Beetle
Genetics
Natural
biocontrol
activity
Reduce host
growth rate
Attractants
released
Contributing
beetle
population
Blue stain
fungi
Mature, heavily
stocked stands of
suitable hosts.
Stress
physiology
Reduced
oleoresin
pressure.
Increasing
beetle
population
Fire management
Time,
increasing age
Endemic
beetle
population
s present
?
?
Early
emergence
and attack,
oviposition,
egg hatchl
?
Host
Genetics
Increasing
summer
temperatures
2- to 1-year
Life cycle
Moderate winter
temperatures and
abundant snowfall
Early,
Increasing
spring
temperatures
Cold soil, frozen roots
while temperatures start
warming in early spring
Changing
atmospheric patterns
= Climate Change
Enabling
Environment
What can managers do?
Alter forest structure
Alter patterns across landscapes
Alter species composition
Control/reduce invasive species
Rapid response to introductions
Plant late successional species.
Add diversity
Others…
To deliver good science,
we will need good science to deliver…
The Future is a Moving Target…
…will require a new paradigm
How can we measure these changes in meaningful ways?
Why do we want to make these measurements?
Are there any existing programs that can be used as
benchmarks?
What existing data can be used to answer questions?
How can we design studies that overcome the difficulties
of climate change?
Goal – Examine how we can develop a
framework for monitoring the effects of
climate change on the health of our forests