Stand Development Modelling
Development Modelling Information
Current Focus Areas
Research and Development
Extension and Consultations
Recent Publications and
The Ministry of Forests and
Range is responsible for ensuring a balance between economic, social, and
environmental values. Success rests upon our ability to predict the state of
future forests and develop legislation, policy, and regulations that are based
The Stand Development
Modelling group contributes to the sustainable management of British Columbia’s
forest resources by developing reliable growth
and yield decision support tools and scientific information. As the provincial
government faces critical issues such as the impacts of the
mountain pine beetle infestation and
climate change, the Stand Development Modelling group continues to develop
new model applications to support changing forest management and policy, forest
research, and sustainable timber supply projections.
Modelling group personnel conduct a wide variety of long-term model development
projects to increase our understanding of complex stand structures. Recent
examples include studies of light and tree growth interactions, and of windthrow.
New knowledge and data from permanent sample plots are integrated into our
models to refine forecasted yields.
The Stand Development
Modelling group is at the leading edge of complex stand modelling. The Tree and
Stand Simulator (TASS)
model, for example, allows forest managers to predict tree growth and the
dynamics of stand development. Researchers are currently refining and testing
the next version (TASS III) that models complex structures found in uneven-aged
and mixed-species stands. TASS and other components such as the Table
Interpolation Program for Stand Yields (TIPSY),
and a suite of linked modules that evaluates the effect of
Treatments on Yield, Lumber Value, and Economic
estimate the size, volume, and wood quality of second-growth stands.
Thus, the economic alternatives of various management regimes can be compared.
The information provided improves the competitiveness of the forest industry by
ensuring that management investments are cost-effective.
PrognosisBC predicts growth and yield for complex forests of the
southern interior and could be linked to economic modules in the future.
With increasing emphasis
in the Ministry on understanding ecosystem resilience and forest values such as
habitat, biodiversity, and visual quality, stand development models provide
integrated information for priorities such the
Future Forest Ecosystems Initiative, implementation of the
Forest and Range Practices Act (FRPA), and
Timber Supply Reviews. They also support second-growth management,
Forest Stewardship planning and evaluation, and
ecosystem-based management implementation on the coast.
This web site is intended to
provide resource professionals involved in growth and yield projections with
relevant background information necessary to select an appropriate growth and
yield system for a particular application.
Stand Development Models
Model Comparison and Selection
Links to Models Not
Supported by the Research Branch:
- Validating and calibrating growth and
yield models against independent data to ensure the accuracy and precision
- Increasing the applicability of
models to local conditions by incorporating additional species, stand types,
environmental factors, biogeoclimatic zones, and a broad range of growing
conditions and factors that affect yield.
- Providing high-quality, responsive,
and focused services to internal (Executive, Forest Practices Branch, Forest
Analysis Branch, Economics and Trade Branch, and Regions) and external
(academia and forest practitioners in industry and consulting) client
groups. Extension activities include providing convenient and free access to
models, training and supporting model users, disseminating new information
and improvements at meetings and workshops, and advising decision-makers.
- Refining models to incorporate new
information and capabilities, such as light–moisture interactions, hardwood
and mixedwood modelling, light estimates, windthrow, and crown, wood, and
- A trial version of
the third generation Tree and Stand Simulator (TASS III) was introduced in
2008 with new capabilities of modelling tree growth in pure and
mixed-species stands for selected combinations of conifers. This newest
version of TASS simulates management of complex stand types, including
stands with structural diversity and with multiple coniferous and broadleaf
species, such as boreal mixedwood ecosystems. TASS III allows users to test
complex silvicultural treatments and harvesting patterns. The new model
includes revised computer architecture that permits simulation of multiple
canopy layers, has a user-friendly graphical interface, and will run on a
Parameterizing existing models to predict variables other than tree growth,
such as: optimum light conditions for
non-timber forest products (e.g., berry and mushroom production),
range forage, or caribou lichen growth; forest carbon budgets; genetic worth
(percent elevated gain); and the economic impacts of forest health outbreaks
such as mountain pine beetle, spruce weevil, and Armillaria root rot.
Completed a second season of understorey regeneration measurements at two
sites in order to understand the development of residual trees and
regeneration following mountain pine beetle attack in thinned lodgepole pine
- Compiled and
analyzed over 10 years of permanent plot data collected at the Pothole Creek
Study Area. This research studies uneven-aged stand development in interior
Collaborated with the U.K. Forestry Commission in Edinburgh, Scotland to
incorporate their windthrow model ForestGALES into TASS.
Initiated destructive sampling projects designed to provide data to support
TASS tree-level parameterization for new tree species such as red alder and
trembling aspen, and further refinement of previously calibrated species
such as white spruce and lodgepole pine.
Re-measured and analyzed long-term research trials to provide data for the
development of custom TASS model projections of operational silviculture
site preparation and vegetation management prescriptions. Several projects
are collaborating with the B.C. Ministry of Forests and Range, Forest
Practices Branch, and the Pacific Forestry Centre, Canadian Forest Service.
Conducted field research to explore light dynamics, tree growth, and
interspecific competition between lodgepole pine, white spruce, and aspen
found in boreal and sub-boreal mixedwood stands of interior British
- Collected field
micro-climate data across a variety of partial-cutting regimes and forest
types to capture baseline data on light, temperature, and moisture for
future model development.
- Incorporating coastal balsam fir data into TASS III to improve the model
fidelity for this species, in support of the Coastal Forest Action Plan.
- Adding biomass equations into TASS III and TIPSY to generate biomass and
carbon storage information relevant for addressing questions concerning
- Assembling data from permanent sample plots to investigate the causes of
tree mortality for coastal Douglas-fir, western redcedar, and western
hemlock, and developing a component for TASS III to predict the probability
of tree mortality in complex stands, under a wide range of stand conditions.
- Upgrading TASS III with new growth functions for Interior Douglas-fir.
- Developing TASS components for wood quality of interior spruce and
lodgepole pine to inform decisions regarding silvicultural management of
- Assessing the effects of different levels of residual growing stock and
structure on overstorey tree growth, stand development, recruitment, and
natural ingress that have emerged 15 years after single-tree selection
harvesting treatments in uneven-aged Douglas-fir stands, to provide data for
improving growth and yield simulation models.
- Conducting field work and analysis to extend coverage of the PrognosisBC
model to the SBS and SBPS Biogeoclimatic Ecosystem Classification zones.
- Extending PrognosisBC to incorporate coarse woody debris, snags, and
decay components to facilitate reporting on carbon accumulation in live and
dead biomass and assessing the impacts of various silvicultural practices on
forest biomass and carbon storage.
- Consulting with the
Forest Practices Branch on the development of partial-cutting guidelines for
the FRPA Forest and Range Evaluation Program.
Future Forest Ecosystems Initiative,
on projecting forest development under changing climate scenarios; assisting
with identifying priority research projects associated with the Initiative
Forest and Range Practices Act Forest Resource Evaluation Program (FRPA/FREP),
ways to evaluate the impacts of proposed Forest Stewardship Plans and new
results-based management techniques.
Forests For Tomorrow, Technical Support—TASS
III will be used to grow advanced regeneration to determine whether there
will be a viable timber source in the future and to better understand and
predict the quality of wood from post-harvest and post-beetle stands,
particularly in areas managed for spruce.
- Presentations on TASS III to forest
practitioners in a variety of venues, including the Complex Stand Modelling
Conference, February 2007 and the Timber Growth and Value Conference,
February 2008, both in Smithers, British Columbia.
- Formed part of the scientific
organizing committee for the International Union of Forest Research
Organizations (IUFRO) Conference on Wind and Trees, University of British
Columbia Forest Sciences Centre, Vancouver, B.C., August 2007. [link]
- Presented results and
management implications of a study on Douglas-fir tree biology and stand
development at the Pothole Creek Study Area to 100 forestry practitioners at
the Southern Interior Silviculture Committee in September 2007.
- Presented the keynote address at the
IUFRO Conference on Ecological Complexity and the Applications of Stand
Development Models in Sault Ste. Marie, Ontario, July 2007.
- Presented a paper at the IUFRO
conference on Forest Growth and Timber Quality: Crown Models and Simulation
Methods for Sustainable Forest Management in Portland, Oregon, August 2007.
- Data use agreements with a wide
variety of research institutions, universities, stand management
co-operatives, provinces, and states to obtain PSP and experimental plot
datasets for model development, calibration, and validation efforts.
- Providing research, modelling, data analysis, quality control, and
support in areas of growth and yield, site productivity, stand development,
wood quality, and financial analysis.
- Designing, developing, and implementing computer tools, field guides,
diagrams, and reports, to transfer growth and yield information to clients
for use in AAC determinations, silviculture planning, operational planning,
and other resource management decision-making.
- Providing training, extension, advice, and interpretation on the use and
application of growth and yield information and computer tools to Ministry
of Forests and Range management, professional, and technical staff, and to
Bealle Statland, C.A. 2008. The Pothole Creek study area:
Dry uneven-aged Douglas-fir stand development. B.C. Min. For. Range, Res. Br.,
Victoria, B.C. Exten. Note 85.
Byrne, K.E. and C.M. Di Lucca. 2007. Incorporation of
windthrow modelling into TASS and TIPSY and its application into STEMS
(Silviculture Treatments for Ecosystem Management in the Sayward). Presentation
given at the Coastal Silviculture Committee Summer Field Tour, Campbell River,
B.C., Jun. 21-22.
Byrne, K.E., S.J. Mitchell, T. Shannon,
and C.M. Di Lucca. 2007. Integrating ForestGALES_BC with TASS/TIPSY growth and
yield model. Conference on Wind and Trees, IUFRO, Univ. British Columbia Forest
Sciences Centre, Vancouver, B.C., Aug. 5-9, 2007.
Comeau, P., P. Fielder, G. Harper, and K.
Thomas. 2007. Assessing the competitive effects of red alder on coastal
conifer plantations. FORREX Forest Research Extension Partnership. LINK
Newsletter 9(1): 12-13.
Di Lucca, C.M. and J.W. Goudie. 2007.
Variable retention yield adjustments in TIPSY. In Overcoming Obstacles to
Variable Retention in Forest Management: Science to Management Forum Proc., Sep.
25-27, 2007. B.C. J. Ecosystems Manage. 8(3):69-72.
Di Lucca, C.M., S.J. Mitchell, and K.E.
Byrne. 2006. Using TIPSY to evaluate windthrow effects on regeneration in
variable retention harvests. B.C. Min. For. Range, Res. Br., Victoria, B.C.
Exten. Note 77.
Goudie, J. and C.M. Di Lucca. 2007. Tree
and Stand Simulator (TASS): History, structure, applications and future
developments. Presentation given at: Science Seminar: Forecasting Change:
Ecological Modelling and Ecosystem Productivity. CFS, Pacific Forestry Centre,
Victoria, B.C. Jun. 7, 2007
Goudie, J., C.M. Di Lucca, K. Mitchell, R.
Parish, C. Bealle Statland, K. Polsson, and D. Simpson. 2007. Tree and Stand
Simulator (TASS): History, structure, applications and future developments.
Seminar given to biometrics and forest mensuration professors and graduate
students. University of British Columbia, Vancouver, B.C. Jan. 2007.
Goudie, J.W., K.R. Polsson, and P.K. Ott. 2009. An
empirical model of crown shyness for lodgepole pine (Pinus contorta var.
latifolia [Engl.] Critch.) in British Columbia. For. Ecol. Manag. 257(1):
Goudie, J.W. and S. Stearns-Smith. 2007. TASS-TIPSY advance growth and yield
modelling in British Columbia. Link. 8(3): 7-8.
Goudie, J. and S. Stearns-Smith. 2008.
BC’s forest professionals get TIPSY (and TASS III). B.C. For. Professional.
Harper, G. 2008. Quantifying the branch, crown and bole
development of Populus tremuloides
Michx. from north-eastern British Columbia. For. Ecol. Manage. 255(7):
Harper, G., R. Astrup, and D. Simpson.
2006. TASS III boreal mixedwood modelling: light and understorey tree growth.
Poster presented at the Canadian Weed Science Society Annu. Gen. Meet. and
Forestry and Industrial Symp., Nov. 29, 2006, Victoria, B.C. and at the Post
Harvest Stand Development Conf., Jan. 31–Feb. 1, 2006, Edmonton, Alta.
Harper, G. and K. Polsson. 2007. Modelling
boreal mixedwoods with the Tree and Stand Simulator (TASS). B.C. Min. For.
Range, Victoria, B.C.
Exten. Note 80.
Harper, G., K. Polsson, and J. Goudie. 2008. Modelling
vegetation management treatments with the Tree and Stand Simulator. The For.
Chron. 84: 53-59.
Mansfield, S.D., R. Parish, M. Di Lucca, J.W. Goudie, K.-Y.
Kang, and P. Ott. . Revisiting the transition between juvenile and mature
wood: A comparison of fibre length, microfibril angle and relative wood density
in lodgepole pine. Holzforschung 63. In press.
Mansfield, S.D., R. Parish, J.W. Goudie,
K.-Y. Kang, and P. Ott. 2007. The effects of crown ratio on the transition from
juvenile to mature wood production in lodgepole pine in western Canada. Can. J.
For. Res. 37: 1450-1459.
Suárez, J.C., B.A. Gardiner, B. Nicoll, A.
Achim, S.J. Mitchell, C.M. Di Lucca, and J.W. Goudie. 2006. The next generation
of wind risk models for managing upland forests in Britain. Geographic
Information Science - Fourth International Conf., GIScience 2006, Münster,
Thomas, K.D., G.J. Harper, P.G. Comeau,
and P. Fielder. 2006. Effects of red alder on stand dynamics and nitrogen
availability (EP1121.01). B.C. Min. For. Range Victoria, B.C.
Exten. Note 76.
Jim Goudie, Stand Modelling Research Leader
Please direct questions
regarding webpage to For.Prodres@gov.bc.ca
Updated April 2009