Stand Development Modelling

Additional Stand Development Modelling Information
Current Focus Areas
Research and Development Highlights
Extension and Consultations
Recent Publications and Presentations
Ministry Contact


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 on science.

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.

Stand Development 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 Silvicultural Treatments on Yield, Lumber Value, and Economic Return (SYLVER), 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.Top

Additional Stand Development Modelling Information

Stand Development Models

Model Comparison and Selection


Links to Models Not Supported by the Research Branch:


Current Focus Areas 

  • Validating and calibrating growth and yield models against independent data to ensure the accuracy and precision of models.
  • 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 fibre characteristics.Top

Research and Development Highlights

  • 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 laptop computer.
  • 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 stands.
  • 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 Douglas-fir forests.
  • 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 Columbia.
  • 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.Top
  • 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 carbon sequestration.
  • 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 interior forests.
  • 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.Top

Extension and Consultations 

  • 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, Technical Role—Advising on projecting forest development under changing climate scenarios; assisting with identifying priority research projects associated with the Initiative objectives.
  • Forest and Range Practices Act Forest Resource Evaluation Program (FRPA/FREP), Technical Support—Determining 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 industry clients.Top

Recent Publications and Presentations 

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): 321–331.

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. Jan.-Feb. 2008. 

Harper, G. 2008. Quantifying the branch, crown and bole development of Populus tremuloides Michx. from north-eastern British Columbia. For. Ecol. Manage. 255(7): 2286-2296.

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. [2009]. 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, Germany. 

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.

Ministry Contact

Jim Goudie, Stand Modelling Research Leader


Ministry contact: Jim Goudie.
Please direct questions regarding webpage to

Updated April 2009