Task force report: Trees are not a Primary Fire Hazard

David Maloney, a member of the Task Force investigating the 1991 Oakland Hills fire confirms that even there – in Oakland’s climate of more extremes and less humidity than Mt Sutro’s cloud forest – trees were not the primary problem. Not even eucalyptus trees.

This letter was also published in the Contra Costa Times.

(Emphasis has been added.)

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Task force report confirms trees are not primary fire hazard

By David Maloney

Posted: 07/30/2009 10:42:02 AM PDT

I retired from the Oakland Fire Department in 1988. In 1989 I began working for the Department of Defense as chief of fire prevention at the Oakland Army Base. In 1991 I was appointed to the Oakland-Berkeley Mayors’ Firestorm Task Force. Our job was to investigate the causes of the 1991 Hills Fire and make recommendations to prevent its recurrence.

The Task Force Report concluded that the spread of the fire was mostly due to the radiant heat generated by burning houses. A burning house has a sustained radiant heat transmission of 2,500-3,000 degrees. The spread of the fire was not due primarily to burning trees — eucalyptus or any other species.

The July 17 article failed to mention another crucial fact. There are two species of eucalyptus that predominate in the East Bay Hills: The blue gum, which is highly fire-resistant, and the dwarf blue gum.

The characteristics that determine the fire resistance of any tree are how high from the ground its branches begin and the thickness of the tree’s bark. The blue gum has a very thick bark, enabling it to withstand fire, and its branches begin about 25 feet from the ground, — a ground fire will blow past it without catching its leaves on fire. An example of the blue gum is the copse of trees on the University of California campus close to Oxford Avenue.

The dwarf blue gum has a thick bark but its branches are low to the ground. A ground fire will transmit relatively easily to its leaves, thereby causing the tree to burn. Many native California trees, such as oak, also have branches low to the ground.

In the late 1990s the federal government clear-cut blue gum eucalyptus from Angel Island. The eucalyptus canopies that provided shaded avenues for countless hikers and bikers were replaced by grass, brush and shrubs. In 2008 the worst fire in modern Angel Island history occurred, and consumed 400 of the island’s 740 acres. It burned much of the grass, brush and shrubs that had taken the place of the clear-cut eucalyptus. Blue gum eucalyptus is a dominate species. It precludes grass, brush and shrubs from growing around it. If the blue gum eucalyptus had not been cut down, the grass, brush and shrubs could not have survived, and the fire would not have been as extensive as it was.

My experience on the task force was that many people who wanted only native California plants and trees on our hillsides seemingly deliberately ignored the facts of the major cause of the fire, and the difference between the blue gum and dwarf blue gum.

The Hills Conservation Network is correct in its support of thinning out the East Bay Hills wooded areas. It would be a waste of taxpayers’ money to clear-cut the East Bay Hills of trees that are highly fire-resistant, and it could lead to another devastating fire. Because of our conclusions, new fire prevention codes relative to housing construction were promulgated by the State of California and various cities throughout California. There were no new fire codes promulgated relative to the species of trees that would populate the East Bay hills.

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(The Hills Conservation Network operates in the East Bay to find fire-safety solutions that are cost-effective and not destructive of forests.)

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