Potential Change in Lodgepole Pine Site Index and Distribution

under Climate Change in Alberta

Robert A. MonserudPacific Northwest Research Station,

Portland, Oregon, USA

Yuqing Yang & Shongming Huang Ministry of Sustainable Resource Development,

Edmonton, Alberta, Canada

Nadja TchebakovaSukachev Forest Institute, Krasnoyarsk, Russia

Western Mensurationists 2007

Objectives

• Examine variation in both LPP site productivity and species range under future climate change scenarios across Alberta

Lodgepole pine (Pinus contorta)

• Alberta’s most important & common forest tree

• 20% of mature stems, 40% of annual harvest

• Wide ecological amplitude– Best on moist rich sites with long warm

growing season– Also grows on dry, nutrient poor sites with

short growing season– Can tolerate frost pockets and cold air

drainage

Steps

1. Map LPP site productivity (SI) across Alberta

2. Map climate across Alberta

3. Connect SI and climate (GDD5)

4. Connect species range and climate (DI)

5. Interpolate climate change scenarios onto Alberta Climate Map

6. Calculate potential SI and species range under climate change scenarios

Productivity Data:

1145 Stem analysis plots

•Mean SI = 14.4 m•Range = 4.3 to 26.5 m

Step 1

•ANUSPLIN map of site index across the natural distribution of lodgepole pine

•Residual Mean = 0•Residual S.Dev.=1.24 m

Step 1b: Map SI

Step 2: Alberta Climate Model

• Basis: network of 1260-1433 weather stations

• Period: 1961-1990 (30-yr climate normals)

• Buffer: 2o around Alberta

• Mapping tools: ANUSPLIN & ArcInfo– Thin-plate 4-D smoothing splines– Uses Latitude, Longitude, Elevation to predict 4th variable– (Hutchinson, Australian Nat’l Univ)

•Growing degree days >5oC (GDD5)

5

365

1

5 )( GDDdtTT

Step 2: Map Climate

Step 3

• Connect Alberta Climate Model to the network of 1145 Site Index plots for LPP across Alberta

• Variables in common:

Latitude, Longitude, Elevation

Step 3 Results: SI=f(GDD5)

• Strongest correlations with Site Index: Measures of Heat– Julian date when GDD5 reaches

100 (D100)– Growing degree days >5oC

(GDD5)– Mean temperature of July, the

warmest month• Explains 26% of variation• All 3 are highly

intercorrelated (r=0.98)

Step 4: Connect species range and climate

• Connect species range and climate using Dryness Index (DI)

• DI is the ratio of GDD5 to annual precipitation

• 99% DI limits on natural range of LPP are 0.9-2.6 oC mm-1

Step 5: Climate Change Scenarios• Used 3 General Circulation Models (GCMs) from IPCC

– Hamburg– Hadley– Canadian

• Used new SRES A2 emissions scenarios – (“Business-as-usual”)

• Used all three 30-yr time periods:– 2020s (2011-2040) – 2050s (2041-2070) – 2080s (2071-2100)

• Scenarios are monthly anomalies (differences) in temperature and precipitation from current climate

• Anomalies must be added to Alberta current climate map

Step 5: Interpolate Anomalies

• Interpolate climate change scenarios onto Alberta Climate Map (2 km x 2 km)

• GCMs are very coarse resolution: 2.5o to 3.75o

• Weighted average of 5 closest anomalies for each of 166,000 pixels (weight = inverse distance squared)

• Add weighted anomalies to current climate map

Current climate vs. 2080 GDD5

Step 6: Potential SI

• Calculate potential SI and species range under climate change scenarios

• SI = 2.4 + 0.012 GDD5

• Species range: Dryness Index 0.9 to 2.6oC mm-1

CCM Predicted SI: Current & 2020

CCM Predicted SI: 2050 & 2080

Current Climate SI

Hadley: 2020, 2050, 2080 SI

Current Climate SI

Hamburg: 2020, 2050, 2080 SI

Results• Similar results across all 3 GCM scenarios:• Increasing warming but no increase in

precipitation (hotter and drier)• Potential productivity (SI) increasing steadily

1 m/decade• Potential range expands in 2020s (40-70%),

but shrinks greatly in 2050s & 2080s (40-70% reduction in potential area)

Discussion• Increased risk of forest fire• Increased risk of mountain pine beetle outbreaks

(warmer winters)– Potential for MPB to bridge east to the Atlantic

• Reforestation (planting) should consider populations adapted to future climates

• Northern populations might already be adapted to future warm climates (Rehfeldt’s BC work on LPP)

That’s all, folks

• Thanks