Growth & Yield Modelling

The Government of British Columbia develops and maintains a suite of stand-level models and tools to predict the growth and yield of the province’s future forests. These predictions play a key role in supporting sustainable forest management decision making by government and its forest licensees in many areas, including:

  • Forest and timber-supply analysis
  • Forest inventory
  • Silviculture planning

A Review of the Growth and Yield Modelling Systems for BC

This review assessed the current GY models used in BC and models with potential for use in BC. Models were evaluated on how well they currently address GY needs in BC and their potential to be adapted to address GY needs in BC.

Growth and Yield Modelling Systems for BC  A Review

Models and Tools

Tree and Stand Simulator (TASS) is the foundation for much of this suite. TASS III, the newest version, now supports multiple species and complex stand structures for lodgepole pine (Pinus contorta var. latifolia) and white spruce (Picea glauca), and is the first publically distributed, MS-Windows ™ version of TASS.

Table Interpolation Program for Stand Yields (TIPSY) provides TASS-generated, managed-stand yield tables, which support many operational applications in B.C.

Variable Density Yield Projection (VDYP) is an inventory-based model producing natural-stand yield tables.   VDYP and TIPSY are both used extensively in sustainable forest management planning and timber supply analyses.

Financial Analysis of Silviculture Investment and Economic Return (FAN$IER) supports economic analysis of silviculture options based on product-based yield predictions (logs, lumber, carbon, biomass) from TASS and TIPSY, within the SYLVER (Silviculture impacts on Yield, Lumber Value and Economic Return) framework.

Site Index Tools (SiteTools) is a comprehensive Site Index calculator for BC tree species.


The Government of British Columbia strives to balance financial, social and environmental values. Success rests on predicting the future state of forests and developing science-based legislation, policy and regulations.

On-going scientific research enables the continuous improvement of growth and yield models and tools, which enable the continuous improvement of sustainable forest management practices.   Consequently, growth and yield research and modelling have been long-term provincial stewardship responsibilities since establishment of the BC Forest Branch in the early 1900’s, which evolved into the current ministry.

This suite of growth and yield tools enables comparison of the economic alternatives of various management regimes. The information provided improves competitiveness and ensures management investments are cost effective.  The tools support management of forest values such as habitat, biodiversity, resilience, and visual quality. They provide direct support for government priorities and activities including the Forest and Range Practices Act and Timber Supply Reviews.  The tools also support second-growth management, forest stewardship planning and evaluation, and ecosystem-based management initiatives.

Research and development activities are currently focused on:

  1. Validating and calibrating growth and yield models against independent data to ensure accuracy and precision of models
  2. Broadening the applicability of models to diverse conditions by incorporating more tree species, stand types, environmental factors, and forest health agents.
  3. Providing high-quality, responsive and focused services to provincial government and external client groups through extension activities such as:
    • Providing convenient and free access to models and tools
    • Supporting model users
    • Presenting new information and improvements at meetings and workshops
    • Advising decision makers
  4. Refining models to incorporate new information and capabilities, addressing such things as:
    • Broadleaves and mixedwoods
    • Light interception
    • Windthrow
    • Crown, wood and fibre characteristics
    • Carbon sequestration and biomass yields
    • Climate change impacts

Interagency and international collaborators and supporters (past and present) that have contributed data, research, or funding include:

Forest Industry

  • Crown Zellerbach
  • International Paper
  • Rayonier Inc.
  • Weldwood Canada
  • Western Forest Products
  • Weyerhaeuser


  • University of British Columbia, Faculty of Forestry
  • University of Idaho, College of Forestry, Wildlife and Range Sciences, USA
  • Yale University, School of Forestry and Environmental Studies, USA

Agencies & Organizations

  • Alberta Ministry of Agriculture and Forestry
  • British Forestry Commission
  • Forest Investment Account (FIA), Forest Science Program
  • Forest Renewal BC
  • FPInnovations:  Wood Fibre Centre (Canadian Forest Service) and FORINTEK
  • Intermountain Forest Tree Nutrition Cooperative, University of Idaho, USA
  • New Zealand Forest Research Institute
  • Stand Management Cooperative, University of Washington, USA
  • United States Forest Service, Department of Agriculture
  • Washington State Department of Natural Resources, USA