Homebuilding on Forest-City Interface Raises California Fire Risk

More than 200,000 forested acres burned on average annually between 2001 and 2005, the five years covered in the report.

Forests cover about a third of California's 100 million acres, and of that forested area, about 19 million acres is publicly managed, the report shows.

More than 13 million acres of forest land is privately held - about five million acres is owned by industry, and seven percent of this acreage is managed by a timber investment management organization or real-estate investment trust.

Foresters inventory trees in the Pacific Northwest. (Photo courtesy U.S. Forest Service)

Released to the public on Wednesday, the California report was produced by the U.S. Forest Service's Pacific Northwest Forest Inventory and Analysis Program. Based in Portland, Oregon, the program conducts forest inventories in Alaska, California, Oregon, Washington, Hawaii, and the Pacific Islands.

The five year frequency of reporting was set by Congress through language in the 1998 Farm Bill, says ecologist Joseph Donnegan, a member of the Forest Inventory and Analysis Program.

"Instead of the 10 year timber reports we used to produce, we now post data annually and write a report every five years that covers a much broader range of topics that regularly appear in the news," he said.

"The idea was not only to provide data on an annual basis, but to be nationally consistent in how we conduct inventory and monitoring. Previously, different FIA regions were using different methodologies," explains Donnegan.

"The results were specific for that region or part of the country, but comparisons and analyses weren't easily made owing to the variety of techniques used. The national Forest Inventory and Analysis Program now uses standard measurement and analysis techniques," he said.

The five year report shows that insects, diseases, air pollution, and fire shape the forested California landscape.

California trees are useful for absorbing the greenhouse gas carbon dioxide. Carbon storage for live and dead trees, and downed wood are highest in redwood and Douglas-fir forest types when evaluated on a per-acre basis, according to the report.

Modeling crown fire potential under extreme weather conditions showed that fire would occur as a surface or conditional surface fire in 72 percent of forests, and as a passive crown fire in only 20 percent of forests.

In most cases, fuel treatment may require only the removal of smaller diameter trees rather than thinning mature trees in the upper canopy.

The capacity of bioenergy facilities using wood has increased over the five years between 2001 and 2005, resulting in California facilities being able to generate over 470 megawatts of electricity.

The data from the Forest Inventory and Analysis reports are used by state, federal, and private land managers and investors for purposes that include the assessment of fuels and potential fire hazard, biomass and carbon storage, the effects of insects and disease, growth and mortality, wildlife habitat, plant diversity, and the supply of goods and services.

Since the 1930s, the U.S. Forest Service has conducted inventories of private lands throughout the United States. In the early days, inventories focused primarily on trees - how much timber was out there?

Today's inventory is still about measuring and counting trees, but it also accounts for understory vegetation, down woody material, lichens, damage caused by insects and disease, biomass, carbon stocks, wood volume, biodiversity, and disturbances.

Standardization and the move to annual data availability occurred through the efforts of client input via blue-ribbon panels. Congress responded with Farm Bill directives and by allocating partial funding to begin progress toward a Forest Inventory and Analysis system that is national in scope.

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