Rim fire's effects likely to last for decades to come

"We have … miles and miles of mortality," said botanist Jennie Haas, who has worked in the Stanislaus for more than three decades. She has seen some seeds floating through the ghostly landscapes — what she called "little rays of hope."

"But if we don't intervene, it will convert to brush," she added.

Intervening means salvage logging, clearing out the charred trees that are of no value and replanting. The process is opposed by many environmentalists who point out that a thriving post-fire ecosystem emerges in burn areas, drawing bird and other species found only in blackened forests.

Allen Johnson, a retired fire management officer for the Stanislaus, and Morris Johnson, a research fire ecologist with the Forest Service, stood on a ridge overlooking a large bowl. It had burned in the 1973 Granite fire, was salvage-logged and then replanted with ponderosa pines. The nearly 4-decade-old trees now resembled an army of black sticks marching across the slopes.

"You look right here and it killed everything," said Allen Johnson. Then he gestured behind him to a stand in which the pines still had their needles, although they were almost entirely brown, scorched by the fire's heat and unlikely to survive.

In the scorched stand, the flames had been only a few feet high. In the bowl, which resembled the inside of a doused campfire, the fire had been much more intense, consuming the tree crowns.

The difference, at least in part, could be explained by the fact that about six years ago, the scorched stand was thinned to reduce tree density. "Did it change the fire behavior? Yes, it did," said Allen Johnson. "Did it save the trees? No."

The two men had spent days driving in smoky haze around the Rim burn area to examine stands that had previously been thinned or had undergone prescribed burns to reduce fuel levels. They will prepare a report as part of a new Forest Service program that is evaluating the effectiveness of such treatments in wildfires across the country.

The Rim is the latest in a string of fierce blazes that have hit the Sierra and the Southwest in recent decades, the result of what scientists say is a combination of factors.

Extensive logging in the last century and late 1800s removed most of the big, old-growth trees that are the most fire resistant. The government's war on forest fires, launched in the early 1900s, put an end to the frequent, low-intensity wildfires that for millennia had kept fuel levels in check in much of the Sierra. Warming temperatures and drought are lengthening the fire season and drying out fuels, leaving wild lands more flammable.

Analyzing fire scars in the stumps of ancient giant sequoias in the Sierra, Thomas Swetnam has compiled fire records going back 3,000 years showing that wildfire frequency plummeted with the arrival of the settlers.

"What's missing in these forests really has been the surface fires," said Swetnam, director of the University of Arizona Laboratory of Tree-Ring Research. "It's true enough that high severity, stand-replacing fires are not totally abnormal. But it's the size of them and the extent of them that is unusual."

Safford expects more Sierra fires like the Rim.

"We're going to see a bigger one than this at some point," he said.

bettina.boxall@latimes.com