10 Years after Fires, Yosemite Showing its Resilience by Dorothy Korber Sacramento Bee - September 11, 2000 YOSEMITE -- After the devastating fires of 1990 finally were controlled, tourists drove across Yosemite's scorched western flank and grieved for the lost greenery. But park ecologist Sue Fritzke surveyed the acres of charred forest with a sense of grim satisfaction. "Personally, I think it looks better than it did before the fire," Fritzke said in 1991." After 100 years of fire suppression, we had a completely dead forest underneath the conifers. Where there should have been wildflowers, we had 2 feet of 'duff' -- dead material." Lightning lit the fuse Aug. 10, 1990, sparking 55 fires in a four-hour period. Fed by duff, drought and low humidity, the Arch Rock firestorm generated its own weather, triggering cyclonic winds and columns of smoke and flames 40,000 feet high -- tall enough to divert cruising jetliners. The fires that summer devoured 24,000 acres of woodland and left the burned-out village of Foresta a sad parody of its name. A decade later, though, Yosemite shows its resilience. After the fires, the lovely harlequin lupine -- previously rare in Yosemite -- flowered on more than 18,000 acres. Oaks resprouted within weeks above their singed root systems. Golden eagles nest in the dead treetops, hunting the denizens of the brush below. "The deer are going gangbusters," Fritzke said in a recent interview. "They're browsers, and they love the shrubs and sprouting trees. And, thanks to the deer, the mountain lion population is rebounding." Yosemite's scars are healing. But there was a surprise buried in the ash: It turns out that nature needs some human help if the park is to return to a natural state. While the woods still smoldered, Fritzke, a specialist in ecological restoration, saw an Eden in the embers. Periodic small fires would clear out duff under the trees, she predicted, and wildflowers would bloom freely, happy creatures would eat seeds -- and each other -- in a balanced ecosystem. "That's nature at work," she explained. Today, however, her enthusiasm is tempered by a worrisome reality. Over the decade, a couple of invasive species -- botanical hitchhikers -- have been sneaking into Yosemite: cheat grass and yellow star thistle. "The exotic invaders put a different spin on things," Fritzke said. "This is the beginning of something that could be very bad. We can't just walk away and let the forest grow on its own. It needs help." Cheat grass is aptly named. It lacks nutrients, burns readily and does not impede erosion. A major factor in wildfires across the West this summer, the weed is a newcomer to Yosemite and has already spread across nearly 6,000 acres in the 1990 burn area. Inside her crisp park service uniform, Fritzke is an easygoing woman with a ready smile. Ask her about yellow star thistle, though, and her eyes narrow and her brows knot. "Yellow star thistle is the scourge of the earth," she growled. "It's the very worst non-native plant species. It now covers 18 million acres in California -- including about a thousand acres in Yosemite. It has a huge impact on grazing and timber -- it takes over the land, crowding out other plants." Yosemite will fight fire with fire in the battle against cheat grass, setting prescribed burns in the autumn that should kill the seeds of the stubborn weed. The war on the yellow star thistle, however, requires hand-to- hand combat. "We mow it, we weed-whack it, we hand-pull it," Fritzke said. "Potentially, we might have to spray it. We're weighing that." The mighty Ponderosa pines that once towered 200 feet high are gone, but young pines -- some 10 feet tall -- are replacing them. And the duff is cleaned out. "Naturally, we have an ecosystem here on Yosemite's western flank that would burn every 15 to 20 years," Fritzke said. "A typical fire would be a 100-acre fire, and you'd have a mosaic of burned patches. That's what we're aiming for. "You suppress fires for a century, and you get a 30,000-acre fire. That's the problem. We can use the 1990 fires to justify really pushing to use prescribed burning to clean out the forest periodically." But prescribed burns themselves can get out of hand. The disastrous fires that burned 80 square miles in New Mexico last spring were fanned by a prescribed burn lighted on a windy day. Fritzke acknowledged that prescribed burns are controversial. "We're seeing huge fires this summer, and people point fingers and say we aren't doing the right thing," Fritzke said. "People want instant fixes, but they don't understand that these things took a hundred years to develop."