Validation of Fuel Consumption Models for Smoke Management Planning in the Eastern Regions of the United States

Project Description

Fuel consumption was measured during prescribed burn operations in southern pine forest and pine scrub fuelbed types in the southeastern United States and mixed hardwoods and pitch pine fuelbed types in the northeastern and north-central United States. The data was used to create a validation dataset and to test current fuel consumption models.

Purpose and Scope

Land managers use fire to maintain and restore ecosystems, reduce fuel loading, expose mineral soil, improve wildlife habitat, and reduce the hazard of wildfire. As understanding of forest ecosystems has increased, forest managers have become more discriminating in their use of prescribed fire and managing wildland fire. Fires are now applied to satisfy land management objectives and benefit forest ecosystems as a whole.

Fuel consumption is a key variable in fire effects modeling and understanding when and how fire should be applied to meet site and landscape objectives, while at the same time reducing air quality impacts. Until recently, much of the considerable research on fuel consumption focused on prescribed burning following logging in forested ecosystems.

Methods

• Collected a set of prefire fuel characteristics, fuel consumption, and environmental input data for developing a fuel consumption validation set
• Determined the uncertainties, biases, and application limits of applying Consume 3.0 to wildland fires for two fuelbed types found in the eastern regions of the United States
• Determined Consume and FOFEM fuel consumption predictive uncertainties, biases or application limits in the eastern United States
• Modified Consume 3.0 as needed and conduct a regional fuels workshop 5. Provided datasets

Implementation

Data from all burns were compiled and analyzed. Consumption models were built for fuel categories within the following fuelbed types: black and white spruce/hardwoods, longleaf and loblolly pine, ponderosa pine, grasslands, and sagebrush. Improvements to the software included the following:

• Validating fuel consumption predictions
• Refining forest floor reduction models to provide more reasonable predictions
• Creating consumption models for new vegetation types, including a new shrub consumption model for southern pine forests and consumption models for eastern mixed hardwood forests types

Key Findings

• Consume and FOFEM predictions of shrub consumption correlate strongly with measured shrub consumption
• FOFEM and Consume accurately predicted herbaceous fuel consumption for 18 of the 29 units that contained a herbaceous vegetation layer.
• Both models tend to overpredict 1-hr fuel consumption, particularly for the mixed hardwood sites
• Both models overpredict 10-hr fuel consumption and are better at predicting the fuel consumption for the southern pine sites than the mixed hardwood sites
• Consume predictions of 100-hour fuel consumption have a better fit with measured consumption values (R2 = 0.81) than FOFEM predictions (R2 = 0.66)
• Consume predictions of large wood consumption are strongly correlated with measured consumption (R2 = 0.99) with a nearly 1:1 model fit across all units and were found to be equivalent with measured consumption at α = 0.1
• Neither model does a good job at predicting litter consumption
• Consume and FOFEM predicted 0 pecent duff consumption for the majority of mixed hardwood and pitch pine units

Project Deliverables

Consume v. 4.2 is embedded within the Fuel and Fire Tools (FFT) program. The earlier version, Consume v. 3.0, is available as a stand-alone downloadable file.