Angeles National Forest

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FETM Application: Angeles National Forest

Introduction

FETM was applied on the Angeles National Forest (ANF) as part of the Pacific Southwest Research Station's "Risk-Based Comparison of Potential Fuel Treatment Tradeoff Models" . The objectives of this Joint Fire Science Program-funded research program were to perform a comprehensive sensitivity analysis of three landscape disturbance models−including FETM, VDDT, and SIMPPLLE/MAGIS (model descriptions)−at seven different sites around the U.S. to determine the reliability of each model, and to document the performance of their algorithms.

The Angeles National Forest assessment focused on the SW section of the Forest, an area encompassing 578,000 acres. The Forest boundary is located approximately 15 miles from downtown Los Angeles.

The vegetation of the ANF is predominantly chaparral, in four different species groups: northern mixed chaparral, semi-desert chaparral, chamise chaparral, and montane chaparral. Roughly half of the remaining vegetation is conifer woodlands, and the rest is in other vegetation types.

The fuel treatment scenarios comprises four levels of prescribed burning in northern mixed chaparral, the most common chaparral type. The scenarios ranged from zero to 92 percent of the available northern mixed chaparral acres treated per decade.

14-year old northern mixed
chaparral stand

55-year old northern mixed
chaparral stand

Source: Natural Fuels Photo Series. Volume IV, Southwestern US, NFES 1084

FETM Application 1: Economic Tradeoff Analysis

One application of FETM was to evaluate the economic tradeoffs of three fire protection strategies, including:

	High suppression (large organization) / no prescribed (Rx) fire treatment
	High suppression (large organization) / low Rx fire treatment
	Low suppression (small organization) / high Rx fire treatment

The results indicated that the use of prescribed fire reduced the total annual wildfire acres burned considerably. However, the total costs of fuel treatment, resource loss and suppression costs were similar (within 2 percent of each other). This result was mainly due to a tradeoff between fire suppression costs and fuel treatment costs.

FETM Application 2: Smoke Impact Analysis

The second application was to demonstrate FETM's capability in evaluating the changes in wildfire acres burned and smoke emissions following alternative prescribed burning strategies. The different fuel treatment strategies consisted of different levels of prescribed burning in Northern mixed chaparral:

	Zero acres per year
	7,500 acres per year (2.3 % of initial)
	15,000 acres per year (4.7 % of initial)
	30,000 acres per year (9.3 % of initial)

The results of this study were as follows:

Annual wildfire acreage decreased with increasing prescribed fire acreage, but stabilized at 15,000 prescribed fire acres per year.

As prescribed fire acreage increased, the fuel loading of northern mixed chaparral shifted to lower fuel loading classes.

As prescribed fire acreage increased, PM_2.5 emissions from wildfire decreased due to a decrease in wildfire acreage and average fuel loading. However, total PM_2.5 emission increased due to emissions from prescribed fire.

View more information on the Angeles National Forest ( ANF Web Site) or the FETM application (ANF Publication)

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