Robert Ingram: Killer fires, the ugly truth
December 25, 2018
About 2 percent of California wildfires occur during catastrophic high-wind events. These are the fires that kill people and destroy communities, like Santa Rosa, Redding, Paradise (maybe Nevada City, Grass Valley, Alta Sierra or Banner Mountain will be next or all four at once).
These are the types of fires we must protect against.
What has changed, California's Mediterranean climate or fire weather? Neither appreciably.
Every year by late summer through fall all sizes and types of forest fuels lose moisture becoming more available to burn. During this same time period Northern and Southern California experience periodic episodes of high winds. High-wind fires consume virtually all available fuel in their path regardless of whether eight tons or 80 tons per acre (or more) resides on the forest floor. High-wind fires push super-heated air flat across the landscape desiccating and pre-heating live and dead fuel way ahead of the flames. Billions of hot embers (fire brands) travel through this hot corridor starting new fires (spot fires) ahead of the main fire. Massive fuel ignition consumes so much oxygen, it creates a void. As air rushes in to fill the vacuum, the fire creates its own fire winds. Heavily fuel loaded landscapes burn much hotter, spews far more fire brands and can create higher fire winds than lower fuel loaded landscapes. All basic fire physics.
We cannot stop high-wind events, but we can remove the unnaturally volatile fuel load that we created.
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Has the ecosystem changed? Yes, dramatically in the last 100 years.
For countless millennia, repetitive fire occurred in the Northern California foothills, through the yellow pine (Ponderosa Pine) belt up to around 5,000 feet elevation. On a seven to 15-year cycle, every acre received a ground cleansing fuel reduction. Young trees and brush would burn or desiccate, leaving the forest far more open. All that started to change around 1910, when the newly created U.S. Forest Service decided all fires on federal lands would be extinguished.
At the same time, up until the 1970s, most of timber harvests on federal lands removed the larger and/or high value trees. All the limbs, tops and debris remained on the forest floor to rot away. But our hot dry summers and cold wet winters do not provide the proper medium for rapid decay.
Until 1973 California annually taxed private forest landowners on their standing timber (Ad Valorem tax). However if you harvested every tree over 18 inches in diameter you could avoid the tax for 10 years. To keep their land, many landowners heavily cut their forests, left it a mess, but avoided the onerous tax.
After 1973, California instituted a yield tax. Landowners would only pay a timber tax following harvesting (2.5 percent of the gross value, paid out of the landowner's net value, so ultimately more like 6 percent). If the landowner's logger lops and scatters the limbs and tops, the material can be legally left on the ground.
In the late '60s, '70s and '80s developers purchased large and small ranches and forest lands to subdivide. People poured out of the cities to live in the foothills and mountains. Every Sierra and coastal county now contain tens of thousands of structures in high fire risk locations as decade after decade of forest fuel growth continued unchecked in between the homes.
Now local and state politicians, environmentalists and fire agency leaders want a simple solution to this every growing liability. Their focus, mastication and chipping live material and shooting it back on the ground. The already heavily fuel loaded forest floor, that has already miss seven to 10 fuel reducing ground fires, now gets a new layer. Plus, every hardwood species and virtually every brush species sprouts vigorously when severed or masticated. Without constant maintenance, in a few years, an even thicker fuel ladder returns over the additionally fuel loaded forest floor making the condition worse.
The physics of the fire problem stares us all in the face. We cannot stop high-wind events, but we can remove the unnaturally volatile fuel load that we created. Sickly forests of 400 trees per acre exist today where 60 to 90 trees used to thrive. Forest fuel loads 6, 8, 10 times the natural condition sit like a powder keg. But it will take actual fuel reduction. That means more burning, more logging, more 18-wheeler chip vans rolling down the highway, all on a massive scale.
Or not, we can chip and masticate and avoid removing one ounce of fuel until a high wind event turns our little piece of heaven into … Paradise.
Robert G. Ingram lives in Grass Valley.
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