Climate Change and Douglas-fir

Dave Spittlehouse, Research Branch, BC Min. Forest and Range, Victoria

Outline

• Climate changes for PNW• Implications for Douglas-fir• Management – vulnerability

assessments and adaptation

Future Climate(s)?Increase in Global Mean Temperature

Tem

pera

ture

diff

ere

nce

fro

m 1

980-1

999

(C

)

1

-1

0

2

3

4

1900 2000 2100

Historic

Large reduction in emissions – B1Medium reduction in emissions – A1B

Minimal reduction in emissions - A2

Total cut in emissions now

(Adapted from IPCC - Climate Change 2007: The Physical Science Basis)

Change in Summer Maximum Temperature from Current

Conditions, CGCM2-A2

http://pacificclimate.org

2080s2050s

Change in Winter Minimum Temperature from Current

Conditions, CGCM2-A2

http://pacificclimate.org

2080s2050s

http://pacificclimate.org

Change in Summer Precipitation from Current Conditions, CGCM2-

A22080s2050s

Change in Winter Precipitation from Current Conditions, CGCM2-

A2

http://pacificclimate.org

2050s 2080s

(Little 1971)

Climate change and Douglas-fir

Change in Douglas-fir climates in US 4C warming

(Rehfeldt et al. 2006)

Current 2020s

2050s 2080s

Douglas-fir climate in BC

Current

Climate range 2080s 4C warming

(Hamman and Wang 2006)

<5% 5-10% >10%

Douglas-fir Seed Planning Zones

Mean annual temperature

Current C

3

4

5 7 8 9

Douglas-fir Seed Planning Zones

Mean annual temperature

Current C

3

4

5 7 8 9

2050 C

5.5

6.5

7 9 10 11

Environmental factors

• Photosynthesis – light, nutrition, soil water, temperature, CO2

• Respiration – temperature, soil water, photosynthesis

• Physiology (e.g., carbon allocation, bud set) – temperature - chilling, frost

• Genetics • Disturbance – fire, insects, disease,

harvest/reforestation, weather (wind, frost)

Net ecosystem productivity = Photosynthesis - Respiration

Douglas-fir, Vancouver IslandPhotosynthesis = F(PAR, Air temperature)

Respiration = F(Air temperature)

Respiration = Tree + Soil

Net primary productivity

Monthly relationships derived from 1998 to 2005 data (Morgenstern et al. 2004, Jassel et al. 2007, Schwalm et al. 2007)

Calculate historic (1976-2007) and future (2008-2056) NEP, G, R for a 50-yr-old forest

Annual air temperature

0

2

4

6

8

10

12

14

1976 1986 1996 2006 2016 2026 2036 2046 2056

Year

Tem

pera

ture

(C

)

MinimumMaximum

Annual PAR

7500

8500

9500PA

R (

mol m

-2 y

-1)

Warming trend

Photosynthesis, Respiration and Net Ecosystem Productivity for a 50-y-old

Douglas-fir stand

0

500

1000

1500

2000

2500

1976 1986 1996 2006 2016 2026 2036 2046 2056

gC

m-2y

-1

PhotosynthesisRespirationNEP

Warming trend

Water availability and growth

• Precipitation in fall, winter and early spring >> evaporative demand

• Amount of water in May through July to meet evaporative demand

• Summer water availability = (May, June & July Rainfall) + 60% of water storage capacity of the root zone

• Water storage capacity = f(texture, stone content, depth)

Summer water availability (mm)

Tree height and water - Coastal Douglas-fir

(Spittlehouse 2003)

10

15

20

25

30

35

40

150 170 190 210 230 250 270 290

Sit

e In

dex @

50

y (

m) 800

900

600

400

500

700

Volu

me @

harv

est

(m

3 h

a-1)

May-July evaporative demand

Influence of climate change

Temperature Evaporative Summer water °C demand (%) balance (mm)

1 3 2 7 3 10 4 15

(Spittlehouse 2003)

ppt -10% -20%

-20 -32 -25 -40

-30 -45 -40 -53

Change in growth by 2050 for the CGCM2-A2 scenario

• Evaporation + Precipitation: 10% reduction in volume

• Temperature: 15% reduction in NPP

Total: 25% reduction over 50 y

Reforestation

• Increased risk of failure due to drier summers

Possible offsets?

• CO2 fertilization

• Increased water use efficiency

Disturbance

• Fire: +4C temperature - Increase length fire season 4 to

20 days- Increase severity ratio by 0 to

50% (Flannigan et al.

2005)

• Insects and disease - ?

Vulnerability to climate change

• Timber supply for the next 50 years• Reforestation and trees for >50

years• Forest operations• Water quality and quantity• NTFP • Wildlife habitat• Conservation

Adaptation

• Reduce vulnerability - Minimise negative effects - Take advantage of opportunities

• Biological - Adapt the forest to the changing climate

• Societal - Adapt to the response of forests to the changing climate

Challenges

• When will we know enough to respond?

• Which climate scenario?

• Species/provenance climate sensitivity

• Developing interim adaptive actions

• Who manages the risk?

• Scale

Summary• Significant change in the area of

climate suitable for Douglas-fir• Provenances and optimum climate• Reductions in productivity -

increase in respiration - increase in water restriction to photosynthesis

• Increase in fire, reforestation failure• Vulnerability assessments