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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 birchBetula papyrifera
Introduction to the eastern boreal mixedwood
Early successional species
Trembling aspen Populus tremuloides
Jack pine
Pinus banksiana
White birchBetula papyrifera
Mid- to late-successional species
White spruce Picea glauca
Black spruceP. Mariana
Balsam firAbies balsamea
Eastern white cedarThuya occidentalis
Introduction to the eastern boreal mixedwood
Early successional species
Trembling aspen Populus tremuloides
Jack pine
Pinus banksiana
White birchBetula papyrifera
Mid- to late-successional species
White spruce Picea glauca
Black spruceP. Mariana
Balsam firAbies balsamea
Eastern white cedarThuya occidentalis
Woody shrub
Mountain maple
Acer spicatum
6
Natural dynamics of mixedwood stands
Intolerant broadleaves Tolerant conifers1st cohort 3rd cohort2nd cohort
Mixedwood
Succession
7
Natural dynamics of mixedwood stands
Intolerant broadleaves Tolerant conifers1st cohort 3rd cohort2nd cohort
Mixedwood
Succession
Fire
Intolerant hardwoods Tolerant softwood1st cohort 3rd cohort2nd cohort
Mixedwood
Fire
8
Tent caterpillar
Spruce Budworm
Natural dynamics of mixedwood stands
Gaps
Partial harvesting, a tool of Natural Disturbance Based Management
Study site
Source: Baldwin et al. (2013)
Thermoboreal (Mixedwood)
Mesoboreal (Continuous conifer)
Supraboreal (Taïga)
Study site, Lake Duparquet Research & Teaching Forest ≈ 48° N 79° W
Vancouver
EdmontonCalgary
Toronto
MontréalOttawa
Halifax
Lake Duparquet Foreststudy sites
SAFE 1(1923)
SAFE 3(1910)
Acer spicatum
5 7 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40+0
20
40
60
80
100
120
140
Aspen Birch Fir Spruce Jack pine
DBH class (cm)
Basal area (m2/ha)Aspen: 41Spruce:1Birch: 1Fir: <1J. pine: <1
SAFE 1(1923)
5 7 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40+0
20
40
60
80
100
120
140
Aspen Birch Fir Spruce
DBH class (cm)
Basal area (m2/ha) Aspen: 34 Spruce: 6Fir: 2Birch: <1
SAFE 3(1910)
Abies balsamea
Initial stand condition
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.
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.
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)
• 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)
SORTIE-ND Model
• 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
Model calibration
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
33% BA 61% BA
Control
80% BA
400 m2 (37% BA) 900 m2 (43% BA) 1600 m2 (54% BA)
Dispersed partial cuts
Gap cuts
Initial condition: empirical data, n=15
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)
SAFE-1 SAFE-3
Treatments Stand BA % of Conifers Stand BA % of Conifers
Control27.1±2.5
51.323.7±1.2
78.5
33% dispersed cut26.9±2.4
44.622.9±1.1
79.5
61% dispersed cut27.9±2.5
35.823.1±1.9
78.4
80% dispersed cut32.7±2.1
17.724.9±2.8
66.3
400 m2 gap cut32.6±1.9
29.828.7±1.2
47.0
900 m2 gap cut33.8±1.6
21.630.8±1.4
38.6
1600 m2 gap cut38.0±0.8
17.634.1±1.9
27.6
Simulation results at year 100
Conclusions
1. Model validationo Good short-term validation for controls and low
intensity partial cuto 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
ConclusionsObjective-2Layout 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-3Starting 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
AcknowledgementsNSERC-FQRNT-BMP ScholarshipBC Forest Service, Bulkley Valley Research CenterLora Murphy, Albanie Leduc, Danielle Charron, Marc Mazerolle, Mario Major, Manuella Strukelj, Jeanne Therrien, Suzie Rollin, Hannah Brais-Harvey, Elizabeth Turcotte, Alfred Coulombe
Thank you for listening !!
SORTIE-ND for the boreal mixedwood forest: a work in progress....