Ecological Impacts of the Mountain Pine Beetle on Pine Forests of the Southern Foothills, Alberta A Case Study in Waterton Lakes National Park Jodi Axelson (University of Victoria, Department of Geography, Victoria BC)
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Ecological Impacts of the Mountain
Pine Beetle on Pine Forests of the
Southern Foothills, Alberta
A Case Study in Waterton Lakes National Park
Jodi Axelson (University of Victoria, Department of Geography, Victoria BC)
Background
• Over the last decade researchers at the Pacific Forestry Centre have conducted a number of studies in lodgepole pine stands in BC and Alberta to examine the effects of the mountain pine beetle (MPB) on stand dynamics.
• Results of these studies have been used in decision support models such as TASS: Tree and Stand Simulator
• In 2008/09 did dendroecological research in the west-central Foothills as part of the Foothills Growth and Yield project “Monitoring and Decision Support for Forest Management in a Mountain Pine Beetle Environment” (Alfaro et al. 2009).
• In 1981 permanent sample plots (PSPs) were established in five stands in Waterton Lakes National Park to study effects of the 1970s MPB outbreak.
• In 2002 stands were re-measured to evaluate the affect of the outbreak on stand dynamics.
• In 2010 stands were once again re-measured project to fill a key regional gap in the southern Rocky Mountains. In addition, detailed dendroecological samples collected to determine the disturbance history at each stand.
Waterton Lakes National Park
East Slopes sites
Objectives
• Develop ecological baselines of biotic disturbances in Waterton Lakes National Park using a dendroecological approach → reconstructing past MPB outbreaks and the mortality and regeneration dynamics post-disturbance
• Examine how biotic disturbances affect future forest structure and composition → overstorey, understorey and fuels
• Integrate dendroecological data collected in this project with previous surveys in the central and northern Rocky Mountains to provide a comprehensive picture of disturbance regimes ands stand dynamics for the east slopes
• Variable radius plots were used to measure
overstorey metrics with a 2 m2/ha BAF prism (all
years)
• Fixed area plots were established to tally
advance regeneration and seedlings by height
class and species (2002, 2010)
• Coarse and fine fuels were measured along 30
metre transects (2002, 2010)
PSP methods
• In 2010 dendroecological samples were collected
from overstorey, understorey and CWD
Dendroecological methods
Results
• The degree of lodgepole pine mortality
was highly variable between plots and
between stands
• Lodgepole pine density has decreased in
all stands from 1981 to 2010
• Lodgepole pine volume decreased in all
stands from 1981 to 2010, with exception
of stand 1
Overstorey lodgepole pine density
Stand
No.
1981
(sph)
Pl - % Live
(% Dead)
2002
(sph)
Pl - % Live
(% Dead)
2010
(sph)
Pl - % Live
(% Dead)
1 1393 90 (10) 1203 72 (28) 1029 84 (16)
2 1180 45 (55) 727 39 (61) 361 76 (24)
3 1523 68 (32) 765 60 (40) 482 67 (33)
4 724 7 (93) 174 35 (65) 78 49 (51)
5 1163 71 (29) 739 65 (35) 487 80 (20)
Average 1197 56 (44) 721 54 (46) 487 71 (29)
Lodgepole pine mortality 1981
0
200
400
600
800
1000
1200
1400
1600
1 2 3 4 5
Stand No.
To
tal
tre
es
/ha
Dead Pl
Live Pl
0
200
400
600
800
1000
1200
1400
1600
1 2 3 4 5
Stand No.
To
tal
tre
es
/ha
1981
2002
2010
Overstorey lodgepole pine density
Overstorey lodgepole pine volume
Stand
No. 1981
(m3/ha)
Pl - % Live
(% Dead) 2002
(m3/ha)
Pl - % Live
(% Dead) 2010
(m3/ha)
Pl - % Live
(% Dead)
1 123.74 83 (17) 132.95 78 (22) 133.92 0.89 (0.11)
2 201.62 32 (68) 130.34 50 (50) 86.96 0.78 (0.22)
3 222.42 56 (44) 155.23 80 (20) 77.60 0.77 (0.23)
4 148.19 5 (95) 26.71 30 (70) 14.17 0.50 (0.50)
5 171.01 61 (39) 132.62 78 (22) 71.81 0.85 (0.15)
Average 173.39 47 (53) 115.5 63 (37) 76.89 75 (25)
Overstorey lodgepole pine volume
Results
• While there has been a decline in lodgepole pine
density there has been an increase in non-host
species such as spruce and fir from 1981 to
2010
• With the exception of stand 1, sapling and
seedling densities have increased in all stands
from 2002 to 2010
– High degree of variability in stocking between stands
– Composition made up almost entirely of shade tolerant species
Overstorey Saplings Regeneration
Saplings Regeneration
Saplings Regeneration
Saplings Regeneration
Results
• Fine fuels have remained relatively
constant between 2002 and 2010
– Stand 2 had increase as standing dead
decreased by 32% between 2002 and 2010
• Coarse fuel mass and volume has
increased in all stands from 2002 to 2010
as MPB killed trees have fallen to the
ground
Fuels: Mass and Volume
Disturbance History
• Overstorey pine ages ranged from 83 to 125 years
old, and non-host species ranged between 51 to
104 years old
• MPB was detected in all PSPs via stand-wide
growth releases in the survivors (co-dominant and
intermediate at time of attack)
• Growth release data is supported by death dates for
CWD and lagged regeneration pulses
Tree-ring data integration
• Have collected a total of 28 lodgepole pine
chronologies on the east slopes
• Chronologies represent sites spanning 5
degrees of latitude
– West-central region:15 chronologies
– South-western region:11 chronologies
• Objective of studies was to evaluate mountain
pine beetle (MPB) impacts on lodgepole pine
Tree-ring data integration
• How homogenous is tree-ring variability along a north-south transect on the east slopes of the Rocky Mountains in Alberta?
• How sensitive is tree-ring variability to stand disturbances (e.g., mountain pine beetle outbreaks) versus climate and/or climatic teleconnections?
• Do chronologies from southern Alberta, in areas of known mountain pine beetle outbreak, group with chronologies collected farther north where there are no documented outbreaks?
Research questions
Factor Analysis
FC4
FC1
FC2
FC3
Factor Eigenvalue Percent total variance
Cumulative percent
1 7.41 28.5 28.5 2 4.81 18.5 47.0 3 3.18 12.2 59.2 4 2.26 8.7 67.9
Factor chronologies (FCs)
FC1 loaded by low elevation Grande
Prairie chronologies in Lower Foothills
natural sub-region.
FC2 loaded by high elevation chronologies
in Nordegg and Banff area in Subalpine
natural sub-region.
FC3 based on two Waterton Lakes NP
chronologies in the Montane natural
sub-region at mid-elevation.
FC4 loaded by two Jasper NP
chronologies also in mid-elevation
Montane natural su-region.
Factor chronology 2 (Nordegg-Banff) The Pacific Decadal Oscillation and FC2
1910 1920 1930 1940 1950 1960 1970 1980 1990 2000-3
-2
-1
0
1
2
3
Sta
nd
ard
ize
d In
de
x
March PDO
FC2r = 0.56
• Strong geographical and sub-regional groupings
• Variance was spread amongst each retained FC
• Some factors chronologies had strong correlations to climatic variables and/or climatic indices, whereas others had weak correlations with climate but strong regime shifts possibly indicative of stand disturbance dynamics
• Chronologies in the west-central region did not group with chronologies in the south with documented MPB outbreaks, suggesting that disturbances detected arise from other agents
Inferences
Take Home Messages
• Stands in Waterton Lakes National Park show remarkable resilience
• Thirty years post-MPB outbreak and stands are more heterogeneous
• In face of uncertainty managers can use this type of information in a more natural disturbances based management framework
Acknowledgements
Questions?
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