fvs_remodeling

FVS Remodeling Project Repository

Maintainers:

• Greg Johnson
• David Marshall
• Aaron Weiskittel

This repo holds scripts and supporting files to re-model Forest Vegetation Simulator (FVS) component growth and imputation models for CONUS.

Our objective is to grow any tree list from plots in CONUS in a single, variant-free model.

Our principles:

• Use parsimonious, biologically consistent model forms for all species,
• Reduce or eliminate site index as a productivity measure, and
• Require no calibration when verified against FIA data.

A presentation delivered to the Western Mensurationists on June 23, 2026 summarizes our work to date.

Progress

We have preliminary equations developed for:

• Diameter Growth
• Height Growth
• Mortality

and we have in development equations for:

• Change in Crown Length
• Height imputation
• Maximum Crown Width

Work has not begun or is continuing on:

• Crown dimensions imputation
• Species mapping for species with low sample sizes
• Improvement in site (location) effects
• Refine height growth equation for consistency across species.
• Explore parameter clustering techniques (perhaps at the genus level) for species mapping.
• Build (or rebuild) imputation equations for:
  • Δℎ𝑡𝑙𝑐
  • ℎ𝑡
  • ℎ𝑡𝑙𝑐
  • 𝑑𝑏ℎ???
  • 𝑙𝑐𝑤 (largest crown width)
  • Build a testing simulation framework and a growth verification system to evaluate bias and precision

Documentation

Documentation of equation fitting and model testing can be found here

Related Projects

• fvs-conus

• fvs-modern

ontacts:

• greg@nosnhoj.org
• davidkathymarshall@comcast.net
• aaron.weiskittel@maine.edu