A Living Lab on the Edge of Suburbia

It’s more than three times the size of Santa Monica, but it has only two residents.

Although close to suburbia, it somehow manages to go largely undetected. Skiers and hikers seeking adventure in Angeles National Forest often pass its northern border without ever noticing its simple entry gate or the “no trespassing” sign posted nearby.

But anonymity is an asset. It might even be the greatest strength of San Dimas Experimental Forest.

The intriguing name, a throwback to when the forest was established in the 1930s, captures its mission well: to act as a giant, living laboratory.

Its 17,153 acres stretch across the San Gabriel Mountains--above the cities of Claremont, Glendora, LaVerne and San Dimas--representing a perfect specimen of chaparral forest and watershed land. Eighty-three members of the asteraceae family--a kind of flowering plant--reside within its boundaries, as do 14 kinds of bats and three types of lungless salamanders.

“You have this large area that represents the mountain front, and that mountain front impacts all the urban areas below,” said Robert Graham, a professor of soil science at UC Riverside who has been conducting experiments in the forest since the mid-1980s.

The experiments have added to our knowledge of how we can protect, and perhaps harm, the mountains around us and all that dwells in them. The unexpected events of 1965 offer an extreme example of what the experimental forest can teach researchers.

“That was a landmark year for the forest. We learned a lot,” said Pete Wohlgemuth, a hydrologist with the U.S. Forest Service’s Riverside Fire Lab who serves as the forest’s interim manager.

In the mid-1950s and ‘60s, scientists experimented with changing the vegetation of an area, a process known as type conversion, to manipulate its water output.

By 1965, research had been underway in Monroe Canyon, at the forest’s northern edge, for almost 10 years. Scientists hoped that replacing the native, deep-rooted vegetation would free up more water for residents of the burgeoning San Gabriel Valley. Two reservoirs lie at the south end of the forest.

“Monroe Canyon was established as a giant outdoor hydrological lab to test how water works in a steep land environment,” Wohlgemuth said.

Researchers put in rain gauges, stream gauges and evaporation areas to measure how much water was taken in by plants.

“The idea was, if we can get rid of the deep-rooted plants, replace them with shallow grasses, then we can have more water coming out of the canyon,” Wohlgemuth said. “They found that it worked initially, but by changing the vegetation, they disturbed the landscape.”

And then the rains came.

Without trees and deep-rooted plants, Monroe Canyon’s hillsides quickly turned to mud in what was the wettest year of the 20th century. Equipment to measure water flow, installed at the bottom of the canyon, was buried under 25 feet of mud. One bridge was covered so deep it took 20 years to dig it out.

“We learned,” Wohlgemuth said quite simply, “not to do type conversions anymore.”

Lessons Enhance Scientific Understanding

The lessons learned from the San Dimas Experimental Forest have enhanced science’s understanding of diverse topics, from soil erosion and pollution to post-fire sedimentation--something biologists call “small mammal community dynamics.”

But don’t expect high-tech wizardry. Some equipment is surprisingly simple, such as the rain gauges. Mike Oxford, the forest’s technician, checks them by hand at least once a week during the rainy season. But since the research stretches back decades, the simple measurements provide researchers valuable tools today.

“I think the main benefit of the forest is its use as a long-term monitoring site,” said Enoch Bell, assistant director of the Pacific Southwest Research Station, which oversees the forest. “It provides an undisturbed baseline that can be used for comparisons of what is happening.”

The aim of the research has changed since the forest was established in 1933, with early studies often focusing on how to exploit the land. A report from 1936 was titled “Water for the year 2000: a fifty-year experiment at San Dimas for industry and agriculture.”

But by the 1980s and 1990s, research had shifted to preservation and restoration. The titles of more recent research papers can be tongue-twisters such as a 1988 study, “Enhanced biogenic emissions of nitric oxide and nitrous oxide following surface biomass burning.”

In 1996 came another catchy title, “Distribution, accumulation and fluxes of soil carbon in four monoculture lysimeters at San Dimas Experimental Forest.”

80 Experimental Forests in U.S.

The U.S. Forest Service maintains more than 80 experimental forests, watersheds and ranges in the United States, including Hubbard Brook Experimental Forest in New Hampshire and H.J. Andrews Experimental Forest in western Oregon. But most of these locations are less than half the size of San Dimas Experimental Forest.

The expanse of its landscape, which varies from 1,300 to 5,700 feet in altitude and encompasses two major watersheds, makes it unique. So, too, do its proximity to urban areas and its status as the one of the nation’s most polluted wilderness sites, according to the Environmental Protection Agency.

“Because it is nestled in the growing urban areas,” Bell said, the forest “provides that sort of monitoring site not available everywhere else. There’s not another one like it. Anywhere.”

Like many of the nation’s other experimental forests, the San Dimas site was established in the early 1930s. Works Progress Administration and Civilian Conservation Corps crews built the 20 structures that still stand at the heart of the forest in a wooded area called Tanbark Flats, including residences, a mess hall, a laboratory-office building and other storage areas.

A bunkhouse spans the small creek that runs through the area. It housed scores of workers who once helped gather information from the gauges and measuring devices throughout the forest. Now, only two people--forest technician Oxford and another Forest Service employee--live in the forest.

“It’s like Sleepy Hollow,” said Graham, the UC Riverside professor. “Those buildings were put to sleep. It’s like going back in time.”

The buildings at Tanbark Flats, like the rest of the forest’s infrastructure, have fallen into disrepair. Research facilities that once were state of the art are now symbols of a bygone era. Forest managers complain that their limited operating budget, which hovers between $10,000 and $20,000, not including staffing, isn’t enough to maintain, let alone upgrade, the facilities.

“The forest is at a crossroads,” said Wohlgemuth, who has worked there since 1980 and wrote his graduate thesis at Cal State Northridge on research done in the forest. “We need an infusion of money, or we need to think about closing at least the buildings. What’s important are the lab and the residences. We need to make it ready for the computer age here. Right now, we make do with chewing gum and baling wire.”

Economic Problems Prove to Be Vexing

Congress has provided some additional funding to go into the maintenance of recreational sites, but it is unclear whether the forest will benefit from that money.

In the meantime, Wohlgemuth said, “We are exploring partnerships to make ends meet and make improvements: volunteer groups, trail builders, Boy Scouts looking to earn merit badges. That’s all nickel and dime stuff, though. We’ve been unsuccessful at getting university funding.”

The economic problems are vexing, but for Wohlgemuth the forest remains a private, peaceful space devoted to science and all that he loves.

On a recent sunny morning, before descending into the heart of the forest, he stopped his Jeep Cherokee at the northern edge, at a point overlooking Monroe Canyon. He spread his arms wide across the forest, breathed in the mountain air and said, “It’s a beautiful day, isn’t it?”