2022 Growth Model User’s Group (GMUG)

April 5, 2022, 9am – 5pm PT

Growth Model User’s Group: Did you hear that GMUG will get a “reboot” in 2022?  The Growth Model User’s Group (GMUG) was first organized in the year of Y2K to bring together many of the leading regional characters and first-time users to discuss and learn about building, improving, and applying growth models in their work. With many decades of forest modeling experience and a network of collaborators, LandVest’s Weikko Jaross and Woodland Creek’s Kevin Ceder are teaming up to host the virtual reboot on April 5th, 2022. The Western Forestry and Conservation Organization will be sending out communications requesting input on topics of interest ahead of the meeting as Weikko and Kevin finalize the agenda and venue.  We are looking forward to a stellar line up of presenters, relevant topics and participation.

Sponsored by:


Click on any of the section titles below to view the recording of that section.

09:00 – 09:45 Logistics and Introductions
10:00 – 10:45 Growth Model Updates (15-Minutes Each)

  • FVSOnline: New Features and ToolsMichael Vandyck, Forest Vegetation Simulator Group, USFS
    • FVSOnline, which has been in full production for over 2 years, work continues with improved analysis, training, and updates with new growth and mortality functions.
  • Forest Projection System: What’s New Dan Opalach, Forest Biometrics Research Institute
    • A “What’s New” briefing on the direction of the Institute, staffing, updates to the Forest Projection and Planning System (FPS), and more.
  • Within-stand variability: modelling of variability in tree heightsJim Flewelling
    • Tree height imputation is an often overlooked step in growth modeling. Jim will present a newly co-developed approach with Jacob Strunk for preserving the observed variance and co-variance in imputed tree heights. Can growth model users safely ignore this and other sources of variation?

10:45 – 11:00    Break

11:00 – 11:30    Growth Model Updates – continued (15-Minutes Each)

  • FVS-BC for FVSOnline – Donald Robinson, ESSA Technologies Ltd.
    • FVS-BC is being updated, in cooperation with the University of British Columbia, including integration into FVSOnline.  These updates will improve modeling results and usability.
  • CIPSANON – Doug Mainwaring, Center for Intensive Planted-forest Silviculture
    • Updates on the CIPSANON growth model and supporting R&D.
  • Open Discussion Model Updates, Q&A, Kevin Ceder, Moderator

11:45 – 12:45   Lunch

12:45 – 1:30      Growth model assessments, validation, and adjustments (15-Minutes Each)

  • FVS Growth Calibration – Peter Gould
    • Peter Gould asks Is there a general approach to localized FVS diameter growth calibration to improve performance of FVS? Working on behalf of LandVest, FIA plot data were used to develop an approach to calculate FVS diameter growth multipliers and assess improvements in diameter growth. Through a carbon inventory reconciliation project in Northern California, we noted the importance of localized height increments for the large tree growth models of tan oak, Douglas fir, and coast redwood. We found that calibrating volume and carbon increments is not as simple as using average diameter and height growth adjustments.
  • Small Tree, Site Index, and Total Height Imputation – Kevin Ceder, Woodland Creek Consulting
    • Seedling and saplings , site index and total tree heights, which are important for growth modeling, are often missing in typical timber cruise data in the Northeast and Lake States regions, were estimated from FIA and USGS data for use in FVS simulations. The results improved  biomass and carbon estimates of forests managed and marketed by LandVest.
  • Even-aged Site Index from Uneven-aged Forests – Logan Wimme, Intermountain Forestry Cooperative
    • Even-aged site potential (site index) was predicted from uneven-aged forests managed by LandVest in Northern California using a two-point approach. Logan will present his sampling design, modeling approach, and thoughts on the practical use of a two point site index estimation in FVS, which may lead to improved growth estimates.
  • Open Discussion – Improvements, Q&A – Weikko Jaross, Moderator

1:45 – 2:45          Data Processing Tools, Model I/O (15-minute each)

  • Operationalizing Carbon Inventories – Weikko Jaross, Landvest
    • A working carbon inventory was operationalized for modeling timber volumes and carbon in the FVS-CA variant using a grid of permanent carbon plots, a wall-to-wall coverage of predicted stocking and heights from remote sensing models, and imputed tree lists for stands in Northern California.
  • Merchandizing an FVS Database – Doug Larmour, Mason, Bruce and Girard
  • New strategies for calculating biomass-carbon from tree lists – Dehai Zhao, Warnell School of Forestry and Natural Resources
    • Structures and estimation methods for developing additive biomass components and biomass allocation equation systems to meet the needs of diverse clients.
  • Log Scale Volumes, Biomass, and Carbon from Growth Model Outputs – Kevin Ceder, Woodland Creek Consulting
    • Harvest volume, biomass, and carbon yields produced by forest growth models may not reflect requirements of local markets and verifiers. LandVest’s Merchandizer and Carbonator systems were developed to provide better estimates of harvest volumes and forest carbon through integration of the National Volume Estimator Library and bucking algorithm into SQL Server.

2:45 – 3:30          Open DiscussionKevin Ceder, Moderator

  • New models and modeling frameworks not yet discussed

3:30 – 4:00          House Keeping ItemsWeikko Jaross, Moderator

  • Words from our GMUG 2022 sponsor, LandVest
  • Feedback on agenda and venue
  • Ideas for new topics to discuss in 2022
  • When next to meet again?

If you have any questions related to the program, please contact Weikko Jaross or Kevin Ceder .


  • Regular Registration: $100
  • Presenter Registration: $50
  • Student Registration: Free, but please register to receive the Zoom meeting information. (Student registrations are sponsored by LandVest)

If you have any registration questions, please contact Melinda in the WFCA office.

SAF CFE Credits
2022 GMUG attendees are eligible for 4.5 Cat 1 SAF credits.