14 Mar 2008, 6:42pm
by admin

The Forest Carbon and Emissions Model (FCEM)

Bonnicksen, Thomas M. The Forest Carbon And Emissions Model. 2008. The Forest Foundation, Auburn, CA

FCEM Report No. 1 — Overview and technical information (beta version). Full text [here]

FCEM Report No. 2 — Greenhouse Gas Emissions from Four California Wildfires: Opportunities to Prevent and Reverse Environmental and Climate Impacts. Full text [here]

Review with selected excerpts by Mike Dubrasich:

The Forest Carbon and Emissions Model (FCEM) is a mathematical method (model) for estimating the amount of greenhouse gases (CO2, CH4, N2O) emitted by forest fires. FCEM requires minimum input of stand data, the number of acres burned, and the percent understory and overstory mortality. From those FCEM computes carbon stored and the emissions from fire combustion and from subsequent decay of dead wood.

FCEM is based on the (scientifically) reported biomass for various forest types and species, and the reported partitioning of that biomass into above-ground and below-ground components, as well as into trees and shrubs. Other components include equations that estimate the biomass lost to combustion and subsequent decay, the carbon stored in harvested trees, and the biomass stored in post-fire forest regrowth.

At this time FCEM (the beta version) is a deterministic model. That is, it outputs a value, not a range of probable values. However, by adjusting the inputs a user may generate a range of output values.

FCEM also provides a comparison of the output value to passenger car per year equivalents, megawatts of coal-fired power plant equivalents, as well as comparing them to total greenhouse gas emissions in California.

From FCEM Report No. 1

FCEM is a Rapid Estimation Model (REM) that requires a minimum of input data. It fills the need for quickly estimating forest carbon storage, sequestration, and greenhouse gas (GHG) emissions. FCEM is a deterministic biomass-based model that uses an Excel spreadsheet to compute estimates.

Forests and forestry are playing an increasingly important role in sequestering carbon and reducing greenhouse gas emissions, especially during a period of rising concerns about global warming. FCEM provides quick estimates to inventory carbon storage and assess the consequences of wildfires and insect infestations to climate change. This can help improve decision making when information is limited and budgets are restricted.

This version of FCEM applies to California. Future changes to FCEM could include expanding the list of species and vegetation types to other regions of the United States, updating equations and coefficients as scientific and technical information advances, and converting the Excel spreadsheet to a Windows program to enhance the model?s flexibility and helpfulness to users.

This report [FCEM Report No. 1] provides an overview of FCEM, input requirements, and example applications and outputs. It also includes information on the structure of the model and lists scientific and technical references.

FCEM Report No. 2 provides examples of the application of the model to four California forest fires: the Angora (2007), Fountain (1992), Moonlight (2007), and Star (2001) Fires. From FCEM Report No. 2:

The Angora Fire: The Angora Fire burned from June 24 to July 10, 2007, sweeping across 3,100 acres of dense forest largely on national forest land west of South Lake Tahoe. The fire killed about 80 percent of the big trees and destroyed 254 homes. As of March 2008, the U.S. Forest Service has not taken action to remove dead trees and plant young trees to restore the forest.

The Fountain Fire: Recognized as one of the worst fires in California history, the Fountain Fire destroyed 59,840 acres of mostly private forestlands and more than 300 homes in the Sierra Nevada, about 40 miles east of Redding in August 1992. Unlike many other burned forests, this forest is well on its way to a full recovery because private forest landowners harvested fire-killed trees and planted young trees.

The Star Fire: The Star Fire burned 16,171 acres (about 11,930 acres of public land and 4,241 acres of private land) in September 2001 in the Tahoe and Eldorado National Forests in the northern Sierra Nevada. Fire-killed trees were harvested on 93 percent of private forestlands and young trees were planted on 52 percent. The Forest Service removed dead trees on 39 percent of their burned land and planted young trees on 19 percent.

The Moonlight Fire: The Moonlight Fire burned 65,714 acres (47,174 acres of public lands and 18,540 of private lands) in September 2007 in the Plumas National Forest in the northern Sierra Nevada, spreading smoke throughout the Sacramento Valley. Private forest landowners are removing dead trees and planting young trees, but as of March 2008, the Forest Service hasn’t released a plan to restore public forestlands.

The various inputs for each of the forests involved were made, and the greenhouse gas (GHG) emissions and passenger car equivalents were estimated by the model:

Table 5. FCEM estimates of greenhouse gas emissions from combustion by wildfire.

Greenhouse Gases (tons/acre)

Angora Fire: 46.2
Fountain Fire: 53.4
Star Fire: 76.7
Moonlight Fire: 74.7

Total Wildfire Greenhouse Gases (tons)

Angora Fire: 143,129.0
Fountain Fire: 3,196,172.2
Star Fire: 1,240,688.5
Moonlight Fire: 4,910,941.6

The emissions in Table 5 are large and difficult to interpret without comparisons. Therefore, Table 6 shows how many cars would be added to California’s highways for one year, each spewing tons of greenhouse gases out of the tailpipe, to equal combustion emissions. Seen another way, it shows how many cars in total and cars per acre burned that would have to be taken off the road and locked in a garage for one year to make up for the global warming impact of these four wildfires.

Table 6. FCEM estimates of passenger car equivalents for combustion emissions by wildfire.

Passenger Car Emission Equivalents* for Combustion (cars/acre)

Angora Fire: 9
Fountain Fire: 11
Star Fire: 15
Moonlight Fire: 15

Total Wildfire Passenger Car Emission Equivalents* for Combustion (cars)

Angora Fire: 28,166
Fountain Fire: 629,294
Star Fire: 244,284
Moonlight Fire: 966,880

To add to this, the model uses a factor of 3.67 times the combustion emissions to account for subsequent CO2 emissions from post-fire decay, and compares those estimates to the total annual passenger car emissions in California:

Table 7. FCEM estimates of CO2 emissions from combustion and decay and passenger car equivalents by wildfire.

Proportion of Annual Passenger Car Emissions (%)

Angora Fire: 0.75
Fountain Fire: 17.19
Star Fire: 5.89
Moonlight Fire: 25.9

The interpretation is that one of the many fires in California last summer, the Moonlight Fire, has and will produce as much GHG’s as a quarter of all the passenger cars driven in the state during the entire year.

The National Interagency Fire Center reported that 8,881 wildfires burned 1,059,923 acres in California last year. The Moonlight Fire (65,714 acres) was just one of those (about 6% of total acres). It is easy to compute that wildfires out-emitted all the cars in California in 2007 by a factor of 3 or 4 times.

Dr. Bonnicksen included these thoughts in FCEM Report No. 2:

The catastrophic wildfires that ravage California each year don’t resemble the historic fires that took place in these forests for millennia. Natural fires set by lightning and Native people were frequent and light, burning mainly surface fuels and igniting only scattered small groups of trees (Bonnicksen 2000, 2007). They didn’t sweep across landscapes destroying whole forests, killing wildlife, destroying habitat, baking soils into hardened clay that can’t absorb rainwater, and causing massive erosion as modern wildfires do today. Unlike the overcrowded and unhealthy forests we see now, most historic forests were open, diverse, and more resistant to catastrophic fires. …

Clearly, we must make every effort to reduce the amount of excess biomass in forests to prevent catastrophic wildfires. That means thinning trees to restore the natural health and diversity of forests and to make them more resistant to crown fires. Reducing wildfires maybe the single most important action we can take in the short-term to reduce greenhouse gas emissions and fight global warming.

I would add that regardless of global warming, catastrophic wildfires destroy our shared heritage and natural ecosystems, as well as pollute our air and water to a enormous degree. The Forest Carbon and Emissions Model is a new tool that will assist us in turning that destruction into comparative numbers, and those numbers should shock and horrify. No individual can witness the actual destruction everywhere. The FCEM adds some perspective otherwise unattainable.

  • Colloquia

  • Commentary and News

  • Contact

  • Topics

  • Archives

  • Recent Posts

  • Meta