Outdated cost estimates embedded in the US Forest Service’s primary timber appraisal tool are deterring contractors from bidding on mechanical thinning projects, leaving overgrown national forests exposed to worsening wildfire conditions across the American West.
That is according to researchers at Northern Arizona University’s Ecological Restoration Institute (ERI), whose analysis of the Transaction Evidence Appraisal (TEA) method — published in the Journal of Forestry — is the first systematic examination of the tool’s bid-participation mechanics in the US Southwest.
For nearly 40 years, TEA has set the fair market value of timber on Forest Service sales, building estimates from felling and haulage costs for each project it prices. ERI research associate Tucker Herbert, the study’s lead author, found that the tool’s core vulnerability is the lag between when market conditions change and when TEA data is refreshed — a gap that leaves contractors unable to determine whether a project will cover their costs before they decide whether to bid at all.
“The better we understand where the big costs are, whether that’s cutting and loading trees or hauling them long distances, the more transparent TEA can be,” Herbert said. “That helps contractors plan and keeps their margins from getting too thin.”
Cutting and trucking account for more than 90 per cent of total thinning sales costs in the study’s dataset — a share that shifts dramatically with mill density. Across the Rocky Mountains, where mills are scarce, and distances between harvest sites and processing facilities are long, transport costs drove individual projects beyond what many operators could absorb, compressing bid numbers and lifting the probability of unsold sales, whilst in northern Colorado, denser mill infrastructure kept costs lower and contractor participation consistently stronger.
In the Southwest, bidder competition proved to be the single most decisive variable: projects attracting multiple companies were significantly more likely to proceed, whilst those drawing fewer bids faced a sharply higher probability of no sale and further delay, and sales requiring longer in-forest skidding distances deterred smaller operators unable to absorb the added haulage cost.
“When people don’t understand how the price for trees is set, sometimes no one ends up bidding,” Herbert said. “And that slows everything down, including the restoration work.”
Each unsold thinning project leaves another section of national forest carrying accumulated fuel loads through another fire season — in landscapes where the Forest Service is under sustained political and operational pressure to accelerate hazard reduction across tens of millions of acres. The Biden and Trump administrations have each committed to expanding mechanical thinning as a core wildfire mitigation strategy, yet the pace of treatment has remained constrained by the contractor-availability problem that TEA’s data lag produces.
A TEA system updated to reflect current mill capacity and real haulage distances would change that calculus, the ERI researchers found, because contractor participation in Arizona and New Mexico responds directly to whether appraisal figures reflect what operators actually face on each project. “The tricky thing about TEA is that markets are dynamic,” Herbert said. “The system has to be updated frequently to reflect mill capacity, haul distances, and changing product demand.”
With felling and haulage accounting for more than 90 per cent of total thinning costs, accuracy in just those two line items determines whether a project draws competitive bids or sits unsold, Herbert said.
For More Information
The full study — An Analysis of the Process and Attributes Used in the Transaction Evidence Appraisal Method for USDA Forest Service Timber Sales in the US Southwest by Charles Tucker Herbert et al — is published in the Journal of Forestry (2026) and available via the NAU Ecological Restoration Institute research repository.
