Climate Change as a Driver in Mountain Pine Beetle Outbreaks in Eastern

Washington

Washington State Climate Change Impacts Assessment Conference

Seattle, WashingtonFebruary 12, 2009

Elaine E. Oneil1, Jeffrey A. Hicke2, Donald McKenzie3, and James A. Lutz1

1College of Forest Resources, University of Washington

2Department of Geography, University of Idaho3Pacific Wildland Fire Sciences Lab, U.S. Forest

Service

J. Hicke

Photo credit: Don Hanley

Photo credit: Don Hanley

MPB and host as co-drivers of MPB epidemics with climate change

Host Susceptibility a function of changes in summer VPD Linked to the likelihood of a tree, or stand, being attacked

as a function of poor vigor. Warmer and drier summers leading to increased moisture stress and

reduced vigor within pine forests Warmer and/or drier winters reducing snowpack and effective moisture

retention into late spring/early summer

Risk of MPB attack linked to changes in annual temperature regimes Linked to the likelihood of MPB attack as a function of MPB

population dynamics and proximity to host trees Climate change enhancing insect survival and reproduction at higher

elevations and leading to asynchronous development at lower elevations

Acres affected by Mountain Pine Beetle in Washington State

YearYearYearYear

19991999

20002000

20012001

20022002

20032003

20042004

00

5050

100100

150150

200200

250250

300300

350350

400400

450450

500500

19101910 19301930 19501950 19701970 19901990 20102010An

nu

al A

cre

s (1

000’

s) a

ffec

ted

by

MP

B i

n E

aste

rn W

ash

ing

ton

Oneil, 2006

Mortality by MPB in ponderosa and lodgepole pine in eastern Washington from 1979-2004 (tallied 1980-2005)

0

500,000

1,000,000

1,500,000

2,000,000

2,500,000

3,000,000

3,500,000

4,000,000

4,500,000

1979 1984 1989 1994 1999 2004Year

Total Mortality (# trees)

0.0

2.0

4.0

6.0

8.0

10.0

12.0

Mortality/acre (Trees/Acre)

# Trees killed by MPB # Trees/acre killed by MPB

1979-1999 Mortality Rate = 2.2 TPA

2000+ Mortality Rate 8.4 TPA

Adapted from Waring and Running (1998)

'Dryness' increases exponentially with increasing temperature

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

0 3 6 9 12 15 18 21 24 27 30

Temperature (C)

Vapor Pressure (kPa)

Humidity

100%

60%

30%

Vapor Pressure Deficit (VPD)

Predictor p-value1) MaxVPD (when exceeds 2 kPa) 0.1672) Pre-growing season PPT 0.3933) Average VPD (Jun, Jul, Aug) 0.0314) DaysVPD exceeds 1.5 kPa 0.0005) First Day VPD (exceeds 1.5 kPa) 0.0006) Interaction of #1 and #3 0.0247) Interaction of #4 and #5 0.000

Climate predictors for MPB attack 2000-03

Summer Water Deficit as a precursor to tree stress

as a percentage of pre-2000 period

Scenario YearAverage Water

DeficitAnnual

PPTSummer

PPTHistorical 1980-99 100% 100% 100% 2 0.1%Historical 2000-03 199% 82% 51% 33 2.0%B1 2020 193% 171% 75% 27 1.7%

2040 236% 187% 60% 18 1.1%2080 326% 235% 25% 116 7.1%

A1B 2020 294% 132% 29% 116 7.1%2040 367% 206% 15% 228 14.0%2080 432% 302% 11% 442 27.1%

# Plots exceeding

deficit of 250

% Plots exceeding

deficit of 250

Higher Elevations get hit harder

Historical 2000-03 B1 2020 MPB attacks

Adapted from: DeLucia, E. H., H. Maherali, et al. (2000). "Climate-driven changes in biomass allocation in pines." Global Change Biology 6(5): 587-593.

Leaf/sapwood area relationships for pine species

Average Summer VPD

MPB and host as co-drivers of MPB epidemics with climate change

Host Susceptibility a function of changes in summer VPD Linked to the likelihood of a tree, or stand, being attacked

as a function of poor vigor. Warmer and drier summers leading to increased moisture stress and

reduced vigor within pine forests Warmer and/or drier winters reducing snowpack and effective moisture

retention into late spring/early summer

Risk of MPB attack linked to changes in annual temperature regimes Linked to the likelihood of MPB attack as a function of MPB

population dynamics and proximity to host trees Climate change enhancing insect survival and reproduction at higher

elevations and leading to asynchronous development at lower elevations

Research Questions • Do Tmax and Tmin increase in lock step?

– future VPD’s are likely underestimated

• Improve predictions of Tdew in increasingly arid environments– future VPD’s are likely underestimated.

• Determine if, and how quickly, leaf area – sapwood area ratios might change in response to changing VPD – Keys into increasing vulnerability to MPB and likelihood

of loss of the species altogether

• Will other phenotypes/genotypes of MPB invade low elevation sites

Blue Print for Management Action

Determine a stress index for lodgepole in their current niches

Refine estimates of future stress based on climate scenarios

Determine if LP can modify its LA/SA ratios in response to the change in VPD (aka research)

Determine how stand carrying capacity changes in response to climate shifts and manage stands to stay within the carrying capacity of the site

• Determine how habitat types will move and change in their constituency with climate change

• Determine how to model that change to increase forest ecosystem resilience

Refine our estimation of disturbance rates