Editor's Column

Guest Columns

Forest Facts

By: Jim Petersen

The immediate causes of the Southwest’s wildfires vary: lightning strikes, careless campers and arson. But there are underlying factors— reasons why these fires are so large and so much more ferocious than any for which evidence exists in natural history—that add up to real problems for communities, firefighters and the nation.

Of all these factors, none looms larger than the fact that there are too many trees crowded into the West’s forests. And more are sprouting every year. The chart opposite compares the number of trees counted in Southwest forests in 1998 with the number that was counted in a 1910 survey. The increase is astonishing. In some areas, ponderosa groves that once held no more than a dozen or two large trees now contain more than 2,000 stems per acre. Picture a solid block of wood the length and width of a football field stretching a mile into the sky. That’s how much new wood fiber is added to Arizona and New Mexico forests every year. The block in your mind’s eye contains 185 million cubic foot block of wood—enough to build 1,800 square foot homes for 90,000 families.

The moisture, nutrient reserves and growing space needed to sustain such mind boggling growth don’t exist in Southwest forests— and never has. The fires we are witnessing are nature’s long predicted reaction to a set of forest conditions put in motion by starcrossed circumstances involving public policy, weather and plain old dumb luck.

Begin with this: the 1919 ponderosa pine seed crop was one of the best ever in the Southwest. And it grew like crazy thanks to an unusually wet spring. Millions of these trees are still standing in southwestern forests. Most are no bigger around than your forearm despite the fact that they are more than 80 years old.

This is one of the most recognizable faces in the world. And the Forest Service’s fire prevention program embodies one of the most successful advertising campaigns in history. Who cannot recite Smokey’s admonition by heart, “Only you….”

Historically, wildfires would have killed most of the trees that sprouted from the 1919 seed crop in their first or second years, allowing the survivors to grow quite large in the much less crowded forests of that era. But by 1919 the gentle under-burns that kept the region’s forests open and relatively free of insects and diseases were disappearing from the landscape. Three factors contributed to their disappearance, laying the groundwork for the ferocious and increasingly frequent stand-replacing wildfires that have dominated the Southwest since the 1980s.

First, 400 years of grazing. Dry grass easily carried ground fire through the open savannah-like ponderosa pine stands that dominated much of the forested Southwest before post-Civil War European settlement began. But by the late 1880s livestock had consumed so much of it that ground fire lost its most immediate fuel source.

Second, the nation’s 19th century Indian policy. For eons, Indians burned their forests and rangelands annually, mainly to promote growth in grasses and forbs that were important food sources for game animals. But once Indians were driven onto reservations so-called “native fire” vanished from the landscape.

Third, the nation’s still widely supported commitment to ridding the West of its wildfires. As awful as our fire seasons have become, they pale when compared to what westerners endured 50 and 60 years ago. In 1930, one of the worst fire years since 1910, more than 53 million acres burned. But it was the Great 1910 Fire that steeled public resolve against fire. On Saturday, August 21, some 3,000 small fires burning in northern Idaho and western Montana were blown together by gale force winds. Over the next 24 hours, three million acres of timberland were leveled. Armed only with hand tools, 86 firefighters perished, many still wearing the same street shoes they had on when they were recruited from skid row bars in nearby Spokane, Washington. An enraged Gifford Pinchot, then the first chief of the newly formed U.S. Forest Service, blamed Congress.

“For want of trails the finest white pine forests in the United States were laid waste and scores of lives lost,” he told a reporter for Everybody’s Magazine. “It is all loss, dead irretrievable loss, due to the pique, the bias and the bullheadedness of a knot of men who have sulked and planted their hulks in the way of appropriations for the protection and improvement of these national forests.”

The rest is history. Congress ratified the Clarke-McNary Act in 1924, the Forest Service went into the firefighting business and development of the West’s national forest timber resources proceeded on course—with strong public support. It would be another 25 years before foresters first noticed that both forest density and species composition were changing. Millions of small ponderosa pines were crowding into forests historically kept open by frequent ground fires that would have killed perhaps 90 percent of these seedlings and saplings. Worst yet, white fir, a prolific re-seeder that tolerates shade but not drought, was beginning to push shade intolerant ponderosa and aspen from their native habitats. But unlike drought resistant ponderosa, which can withstand the heat of moderate fire once its bark thickens, or aspen, which following fire quickly resprouts from its own roots, thin-barked white fir is easily killed by fire.

 

 

But now, aided by the nation’s wellintended fire policy, white fir was overtaking ponderosa and aspen habitat—more than a million acres of it between 1962 and 1986. And now, stressed beyond their endurance by four years of drought, these dead and dying fir, ponderosa and aspen stands are fueling wildfires whose explosive behavior is unlike anything that veteran firefighters have ever observed. Entire watersheds, vital to the region’s communities and economy, are in serious trouble. So too are countless thousands of rare and common species: mammals, birds, amphibians, reptiles, insects and plants.

But step back from this drama for a moment. Recognize that evidence abounds that the number of trees growing in national forests in Arizona and New Mexico has been increasing steadily since both wildfire and Indians were excluded from the landscape. You can read all about it in a fine peerreviewed article published by the prestigious Journal of Forestry nearly ten years ago. [“Changes in Southwestern Forests: Stewardship Implications”] The article, by Marlin Johnson, Assistant Director of Forestry for the Forest Service’s Southwestern Region, revealed that the number of trees of every size, except the very largest, increased steadily between 1962 and 1986, the two most recent years in which trees per acre were counted in sample plots.

During the 26-year period between surveys, the number of trees one to 4.9 inches in diameter increased from 130 to 160 per acre, while the number from five to 16.9 inches in diameter increased from 70 to 120 trees per acre. For perspective sake, consider this from history: a survey crew working in Arizona’s North Kaibab region in 1909 estimated there were 91 trees per acre three inches or less in diameter. When the survey was repeated in 1989 surveyors counted 1,100 trees per acre.

Even more surprising, data from the 1962 and 1986 surveys reveals that, despite a sawtimber harvest of 2.2 billion board feet during the 26-year period, the number of trees over 17 inches in diameter remained virtually unchanged at eight per acre, a statistic supported by separate Forest Service growth, harvest and mortality records which reveal that, for the period, regional sawtimber harvest was about 34 percent of net growth— well below the volume that could have been harvested without exceeding annual growth.

 

Had the Forest Service reintroduced fire in the 1950s— intentionally setting some fires and allowing others set by lightning or errant campers to run their course—the tree density problem might well have reversed itself over time, but there was woefully little public support for such action. By 1960, the face of Smokey Bear—which drew its inspiration from a bear cub rescued from a 1950 fire on New Mexico’s Lincoln National Forest— was one of the most recognizable in the world. School kids everywhere could recite his admonition [Go ahead Baby Boomers, “Only you…”]

Now, a half-century later, it is too late to safely re-introduce fire—a hard lesson learned at Los Alamos. There are too many dead trees and there is too much debris on the forest floor. In some places it is knee deep. There is great concern for the future of the oldest of the region’s ponderosa pines. Thought their bark is thick enough to withstand the heat of low intensity ground fires, the 2,000- degree heat of today’s infernos is more than any living thing can tolerate. These big trees are also threatened by encroaching white fir and ponderosa thickets, which rob them of soil nutrients and moisture, adding to the danger that—in their weakened condition—they will fall prey to insects, diseases and ultimately fire.

Of course, it would be easy to blame our ancestors for not recognizing fire’s beneficial role in fire-dependent ecosystems. But making the West a safe place to put down new roots—paving the way for prosperity’s eventual arrival —was more important to them. And to many, it still is.

So we are left with these facts. National Forests in the Southwest— and elsewhere in the Interior West— are in deep, deep trouble. They have far too many trees in them and they are burning to the ground because of it. Nature is not going to solve this problem in a publicly pleasing way. But we can.

"We must always consider the environment and people together, as though they are one, because the
human need to use natural resources is fundamental to our continued presence on earth."