Validation of the OpCost logging cost model using contractor surveys

ABSTRACT

OpCost is a harvest and fuel treatment operations cost model developed to function as both a standalone tool and an integrated component of the Bioregional Inventory Originated Simulation Under Management (BioSum) analytical framework for landscape-level analysis of forest management alternatives. OpCost is an updated implementation of the Fuel Reduction Cost Simulator (FRCS). However, neither FRCS nor OpCost have been formally validated. Validation of simulation models using data that are independent of those used for model development is important for building user confidence in model predictions. This is particularly true when models are embedded in decision support systems and deployed regionally to inform policy. To evaluate the quality of OpCost predictions in fuel reduction treatments, a mixed method survey was conducted in Oregon, Washington, and Idaho. Professional logging contractors were asked to estimate the production rates and costs of common logging systems using timber sale prospectus data generated using GIS and the FVS model. Comparing survey results to production and cost estimates generated by OpCost for the same stand and site conditions facilitated evaluation of prediction error for both entire harvest systems and their individual equipment components. Model predictions were not different from expert estimates of total costs for harvest systems, but there were differences between predicted and expert estimates of production rates for individual pieces of equipment.

KEYWORDS:

• Logging cost
• forest operations model
• OpCost
• fuel treatments
• Forest Vegetation Simulator
• BioSum

Acknowledgements

Assistance with the research was provided by Nick Crookston and Terrie Jain from the Rocky Mountain Research Station.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

Financial support for this project was received from the Joint Fire Science Program [JFSP Project no. 13-1-03-8] under grant number 13-JV-11261979-056 from the USFS PNW Research Station with additional support from USDA National Institute of Food and Agriculture McIntire-Stennis project [IDAZ-MS-0103] and the Idaho Forest Utilization Research (FUR) program.