Devastating Fire Ignites Flurry of Research at Forest Lab

Throughout its 70-year history, the San Dimas Experimental Forest has taught researchers many valuable lessons.

The 17,000-acre tract, part of the larger Angeles National Forest set aside in 1933, has provided fertile ground for experiments in hydrology, soil science and botany. It has yielded important clues about how water and fire can transform the landscape around us.

Now, in its death and phoenix-like rebirth, the Experimental Forest has new wisdom to impart.

It has been more than a year since the Williams fire inhaled 38,000 acres of the San Gabriel Mountains, leaving behind scorched hillsides, the charred carcasses of trees and the smoldering ruins of the Experimental Forest.

For the owners of the 62 homes destroyed by the fire, the last 15 months have been a time of grieving, coping and adjusting. But for the researchers who claim the Experimental Forest as their living laboratory, it has been a time of jubilation, of new beginnings and rediscovery.

Eventually, the researchers hope, their work will help foresters decide how to respond to more devastating firestorms, such as the ones that swept through San Bernardino, San Diego, Ventura and Los Angeles counties in the fall.

Scientists have spent the months since the Williams fire, which destroyed 85% of the Experimental Forest, instigating new long-term research projects and turning up old structures, discarded equipment and abandoned projects buried by overgrowth long ago.

“It was almost like Christmas,” said Pete Wohlgemuth, a hydrologist with the U.S. Forest Service’s Riverside Fire Lab who serves as the forest’s manager. “You know, rediscovering new things on the watershed we had come to know and love. All of a sudden, there’s all this new stuff out there we didn’t know was out there.”

To enter the San Dimas Experimental Forest means traveling through the Angeles Forest along Glendora Mountain Road, a long stretch of winding asphalt that eventually touches the northern edge of the forest.

Although it is open now, access to the forest was limited for much of 2003, closed to the public by Los Angeles County officials who feared that rocks and debris might tumble onto the road in a heavy rainstorm. Heavy metal gates secured the route.

When they did squeak and groan open, the gates revealed a secret world: a forest that was absolutely still, and seemingly uninhabited, except for an occasional coyote darting across the road or a hawk circling above. Landscapes that once had been rich with an artist’s palette of green were studies in neutral, dominated by black, beige and brown. Trees once bushy and prosperous were mere wraiths, shivering in a heavy wind.

Researchers had always expected that a fire of this scale would envelop the forest eventually.

They regularly had conducted small-scale burns in the forest, using their data to examine how fires could be battled and how the hills and canyons would be affected by the burns and the rains and flooding that would inevitably follow.

So, after the Williams fire swept through in September and October of 2002, it was time for researchers to get to work. Proposals were prepared, grants sought. Forest aficionados tracked the researchers’ progress.

“The new experiment,” one person wrote in an Internet news forum, “is recovery after the fire.”

Though most research done in the forest in the last few decades had been surprisingly low tech, the first studies out of the forest after the Williams fire seemed cutting edge and focused on testing ways to help charred hillsides recover.

In 2002, before the first rains of the winter season, a chemical known as P.A.M. was sprayed on some of the forest’s slopes. Scientists hoped to test how it would bind soil particles together into clods to minimize water runoff and thus prevent flooding and erosion.

In other places, Lincoln Log-like structures -- built with crisscrossed, prefabricated wood pieces -- were set into stream channels to see whether the structures could disperse water sideways and over a wide area. Otherwise, the water might build up force as it rushes down a narrow channel, possibly reshaping the mountainside.

The chemical did not perform as researchers had hoped, but the structures, Wohlgemuth said, “did a pretty good job.” Those experiments were conducted in areas of the forest where long-term records have been kept on rainfall and water runoff.

Last winter “wasn’t Noah’s flood,” Wohlgemuth admitted. But the normality of the rainfall was actually a helpful gauge.

It did, however, create one major problem: Monitoring stations in Bell Canyon, which were used to measure stream flow through the forest, were buried in mudslides thick with rocks and boulders. Those stations had already collected decades’ worth of data, and scientists wanted to be able to use the information as a reference point.

So, forest officials spent almost $100,000 -- most of their funding for the year -- cleaning out the monitoring sites.

“Now we’re poised to continue our record collection.... It’s an exciting time to be doing research,” said Wohlgemuth, who has spent much of his career studying the forest.

The next project, he said, will focus on plant regrowth -- comparing certain areas of the current forest with detailed surveys of the vegetation planted there in an experiment years ago.

For anyone seeking information about how that pattern might play out, Monroe Canyon, at the experimental forest’s northern edge, will be pivotal.

Before the fire, the canyon’s floor was ripe with an array of shallow-rooted grasses, planted in 1965 by scientists who had hoped that using the plantings would allow more water to flow into reservoirs below and eventually better sustain residents of the burgeoning San Gabriel Valley.

Those efforts had failed after heavy rains blanketed the forest and the hillsides -- without their native, deep-rooted vegetation -- turned to mud. Equipment was buried; it took 20 years to dig out one bridge in the canyon. And though the grasses returned, the experiment ended there.

Scientists had done little research in Monroe since then. But after the Williams fire, questions arose. What kinds of vegetation would return to the canyon? The shallow-rooted plants and grasses, bromes and clovers that had inhabited the hillside for four decades? Or native plants, like the chaparral that peppered the surrounding hillsides?

“It’s an interesting question,” Wohlgemuth said. “The idea here is that the vegetation is going through this fundamental change, moving toward some goal.”

Soon after the fire, in November 2002, a howling wind echoed off the mountains, kicking up dust clouds that swirled, funnel-like, as they crept across the landscape and through the Experimental Forest.

The northern floor of Monroe Canyon was covered with that dust, a silky, fine substance, rich with ash, that left stains on hands and invaded clothing and shoes. Stepping down the canyon’s steep slope left footprints that recalled an astronaut’s first steps on the moon.

Water drops from above, used by firefighters in battling the Williams fire, had buried vegetation. Sumac trees rose from the ground like people trying desperately to escape quicksand. Darkened, charred limbs seemed to reach desperately skyward. Few leaves remained on branches; those that did had been burned to a rust-colored crisp.

Here and there, small green sprouts pushed out of the ground, giving no indication of what they might become.

By February 2003, the canyon ground, baked by a fierce sun, was firmer, more clay-colored; the hills were sprinkled with green. Vines wrapped their tendrils around the branches of dead trees.

Mustard flowers had sprouted. So too had yucca plants, some of which were beginning to flower.

At the bases of the trees that months earlier had seemed dead beyond repair, leaves were pushing toward the sky.

If this were a garden, many of the small sprouts poking through the ground, resembling baby mint and spurge, would be identified as weeds and eliminated. In the forest, they were a symbol of renewal.

Wohlgemuth said that, in the months after a fire, it is typical for herbaceous species to appear -- plants whose seeds lie dormant in the ground until they are “liberated” by the fire. These fire-following annuals, he said, are common and not always an indication of the kind of landscape that will dominate eventually.

Indeed, by last month, the floor of Monroe Canyon was carpeted anew in green, silver and brown. Unfriendly brambles of wheat-colored plants made walking down into the canyon -- something easily accomplished months earlier -- nearly impossible.

Yucca, mustard and buckwheat -- all of which could be found elsewhere in the forest -- dominated the landscape, and so Monroe Canyon looked very much like the rest of the Angeles. Birds chirped in the background.

Only burned sumac trees, now almost entirely enveloped by fresh, green leaves, gave a hint of the massive trauma suffered by the experimental forest. Few other obvious signs of the fire remained.

But how the next stage of regrowth will play out remains to be seen.

“To tell you the truth, nobody knows,” Wohlgemuth said. “But in a few years, we will be able to answer that question ... whether it will follow the natural pattern or whether it will become something different we haven’t thought about or whether it will go to the grass it was before.

“It’s this giant, outdoor laboratory experiment, and we have no idea what the results will be, exactly. Which actually is very exciting for those of us in the field.”