Modelling stand dynamics after partial harvesting
in eastern Canadian boreal mixedwoods
Arun K. Bose,
Brian D. Harvey,
Dave K. Coates,
Suzanne Brais,
Yves Bergeron
9th IUFRO International Conference on Uneven-aged Silviculture,
WSL, Zurich, Switzerland
17-19th June, 2014
Introduction to the eastern boreal mixedwood
Introduction to the eastern boreal mixedwood
Early successional species
Trembling aspen
Populus tremuloides
Jack pine
Pinus banksiana
White birch
Betula papyrifera
Introduction to the eastern boreal mixedwood
Early successional species
Mid- to late-successional species
Trembling aspen
Populus tremuloides
White spruce
Picea glauca
Jack pine
Pinus banksiana
Black spruce
P. Mariana
White birch
Betula papyrifera
Balsam fir
Abies balsamea
Eastern white cedar
Thuya occidentalis
Introduction to the eastern boreal mixedwood
Early successional species
Mid- to late-successional species
Woody shrub
Trembling aspen
Populus tremuloides
White spruce
Picea glauca
Mountain maple
Jack pine
Pinus banksiana
Black spruce
P. Mariana
White birch
Betula papyrifera
Balsam fir
Abies balsamea
Eastern white cedar
Thuya occidentalis
Acer spicatum
Natural dynamics of mixedwood stands
Succession
1st cohort
Intolerant broadleaves
2nd cohort
Mixedwood
3rd cohort
Tolerant conifers
6
Natural dynamics of mixedwood stands
Fire
Succession
1st cohort
Intolerant broadleaves
2nd cohort
Mixedwood
3rd cohort
Tolerant conifers
7
Natural dynamics of mixedwood stands
Spruce
Budworm
Fire
Gaps
Tent
caterpillar
1st cohort
Intolerant hardwoods
2nd cohort
3rd cohort
Mixedwood Tolerant softwood
Partial harvesting, a tool of Natural Disturbance
Based Management
8
Study site
Vancouver Calgary
Halifax
Study site, Lake Duparquet Research & Teaching Forest
≈ 48° N 79° W
Source: Baldwin et al. (2013)
Montréal
Toronto
Lake Duparquet Forest
study sites
SAFE 3
(1910)
SAFE 1
(1923)
Initial stand condition
Aspen
SAFE 1
140
(1923)
100
Birch
Fir
Spruce
Jack pine
120
80
Basal area (m2/ha)
Aspen: 41
Spruce:1
Birch: 1
Fir: <1
J. pine: <1
60
40
Acer spicatum
20
0
5
10
14
18
22
26
30
34
38
DBH class (cm)
Aspen
SAFE 3
(1910)
Birch
Fir
Basal area (m2/ha)
Aspen: 34
Spruce: 6
Fir: 2
Birch: <1
Spruce
140
120
100
80
60
40
20
0
Abies balsamea
5
10
14
18
22
26
DBH class (cm)
30
34
38
Short-term results of the experiment
3 years after,
Brais, S. et al. 2004. Testing forest ecosystem management in boreal mixedwoods of
northwestern Quebec: initial response of aspen stands to different levels of harvesting.
Can. J. For. Res. 34: 431-446.
6 years after,
Harvey, B.D. and Brais, S. 2007. Partial cutting as an analogue to stem exclusion and
stand break-up in aspen (Populus tremuloides) dominated boreal mixedwoods : implications
for deadwood dynamics. Can. J. For. Res. 37: 1525-1533.
12 years after,
Bose, A. K. et al. 2014. Recruitment and mortality dynamics following partial harvesting in
aspen-dominated mixedwoods in eastern Canada. For. Ecol. Manag. In press.
Bose, A. K. et al. 2014. Trembling aspen (Populus tremuloides Michx.) volume growth in the
boreal mixedwood: Effect of partial harvesting, tree social status, and neighborhood
competition. For. Ecol. Manag. 327: 209-220.
Simulator
The SORTIE-ND
http://www.sortie-nd.org/research/pubs.html
A spatially explicit individual-based model
Originally developed and parameterized for hardwood forests in the
northeastern United States (Pacala et al., 1993, 1996)
Re parameterized for British Columbia forests (Coates et al. 2003)
105 peer-reviewed publications since 1993 (SORTIE-website)
SORTIE-ND Model
• Spatially-explicit
– position of each tree defined
– growth
– recruitment
– mortality
• Permits simulation of
– complex mixed-species stands
– partial cuts
– all forms and types of openings
(gaps, patch cuts)
Model calibration
• Growth, mortality and recruitment functions were
tested for each individual species
• Mortality by spruce budworm was implemented using
knowledge of published literatures (Morin et al, 1993;
Bergeron and Leduc,1995 and Blais 1981)
• Field data were used to set starting conditions of
simulations
Objectives
1. To evaluate whether SORTIE-ND capture short and long
term stand dynamics
2. To identify partial harvesting prescriptions that accelerate
the development of multi-cohort complex stands
3. To assess whether mixedwood stands of different
composition respond similarly to partial harvesting
treatments over a period of 100 years after harvesting
Testing partial cutting scenarios
Initial condition:
empirical data, n=15
Control
Dispersed partial cuts
33% BA
61% BA
80% BA
Gap cuts
400 m2 (37% BA)
900 m2 (43% BA)
1600 m2 (54% BA)
Results (Model validations)
1. Short term (12 years) validation, empirical and simulated
results showed excellent agreements for un-harvested
controls and low-light intensity partial harvesting
treatments
2. However, disagreements appeared with high-heavy
intensity partial harvestings on overstory aspen survival
3. Higher uncertainties appeared with long-term (78 years)
model validation, particularly on aspen recruitment and
spruce survival
Results (Trembling aspen dynamics)
Gap cuts
& 80% dispersed
Gap cuts
& 80% dispersed
Gap cuts
& 80% dispersed
Gap cuts
& 80% dispersed
Results (Balsam fir dynamics)
Spruce budworm outbreak incidents
Spruce budworm outbreak incidents
Results (White spruce dynamics)
Simulation results at year 100
SAFE-1
Treatments
Stand BA
SAFE-3
% of Conifers
Stand BA
% of Conifers
Control
27.1±2.5
51.3
23.7±1.2
78.5
33% dispersed cut
26.9±2.4
44.6
22.9±1.1
79.5
61% dispersed cut
27.9±2.5
35.8
23.1±1.9
78.4
80% dispersed cut
32.7±2.1
17.7
24.9±2.8
66.3
400 m2 gap cut
32.6±1.9
29.8
28.7±1.2
47.0
900 m2 gap cut
33.8±1.6
21.6
30.8±1.4
38.6
38.0±0.8
17.6
34.1±1.9
27.6
1600 m2 gap cut
Conclusions
1. Model validation
o Good short-term validation for controls and low
intensity partial cut
o Long-term validation,
o Aspen: problems with recruitment
o Spruce: juvenile recruitment and survival too high
o SORTIE-ND does project feasible outcomes that appear
to incorporate influences of different treatments and
stand conditions
Conclusions
Objective-2
Layout of the harvesting is the KEY
 Gap cut would promote both conifers and intolerant
hardwood regeneration
 Gap cut would allow higher basal area retention
 Higher basal area retention would also provide
greater habitats for animals
Objective-3
Starting condition is the KEY
 Age of the overstroy trees
 Seed trees of desired conifer species
 Stock of advanced regeneration of desired conifer
species
 Presence of woody shrubs
SORTIE-ND for the boreal mixedwood forest:
a work in progress....
Thank you for listening !!
Acknowledgements
NSERC-FQRNT-BMP Scholarship
BC Forest Service, Bulkley Valley Research Center
Lora Murphy, Albanie Leduc, Danielle Charron, Marc Mazerolle, Mario Major, Manuella Strukelj, Jeanne
Therrien, Suzie Rollin, Hannah Brais-Harvey, Elizabeth Turcotte, Alfred Coulombe