Just a Few Bugs in the System : Forestry: Grasshoppers deliver serious blow to attempt to help the Engelmann oak make a comeback.


It was fine until the grasshoppers came.

Up to that point, the state was finally managing on a gentle slope of forest--after two failed attempts--to grow the imperiled Engelmann oak, whose seedlings no longer seem to mature in nature.

Caltrans has launched a planting program of 780 oaks that employs a solar-powered drip irrigation system similar to one used by marijuana growers. The project one day could become a model statewide, officials said.

But, although foresters thwarted the seedlings' traditional enemies--parched earth and the gnawing teeth of cattle, deer and gophers--they neglected to plan for an unusual seasonal guest: Grasshoppers.

In Love Valley, a meadow of Cleveland National Forest dotted with mature oak trees, occasional deer saunter by and squirrels zigzag amid the grass browned by summer. Large yellow and black spiders, called argiopes, spin webs that glint in the sun. In this isolated niche in the park, 7 miles south of Palomar Mountain, you hear no traffic, only crickets and mourning doves.

The valley seemed completely still when Roger Wong of the U.S. Forest Service recently surveyed the 20 acres of foot-tall Engelmann oak and coastal live oak seedlings planted this May. But, as Wong stepped forward, a small cloud of grasshoppers sprang up out of the tall grass--the result of a wet winter. And clearly, the voracious insects have wrought havoc, stripping bare some seedlings, leaving half-eaten leaves on others.

Wong can only groan. Before the grasshopper infestation hit last month, he had estimated that about 95% of the tiny oak trees would survive--a startling success rate considering the past.

The two previous attempts were dismal failures. The first effort by the U.S. Forest Service managed to grow 10% of the trees planted. Foresters at UC Agriculture Extension tried it again in 1989, planting more than 600 seedings and giving them a squirt of water and fertilizer, Wong said. That time, none survived.

So for this latest effort, foresters coddled the trees with protective mesh screens and a drip irrigator.

"We thought of everything, everything. Except grasshoppers," Wong said. "I never had to deal with grasshoppers before. I never thought that would be a problem."

The bugs are only the latest bad hand dealt the oaks.

Centuries ago, the Engelmann oaks grew throughout southeastern California, Arizona and Baja California. But, as civilization and urbanization spread, the territory of the Engelmann oak has diminished further and further.

Today, the Engelmann oak persists in scattered groves, 93% of which are in San Diego County and 6% in Riverside County, all in the general area of the national forest. They occupy the smallest range of any mainland tree oak. But, perhaps scariest of all for oak enthusiasts and conservationists, the Engelmann oak has become extremely vulnerable because it is not restocking itself--the population of older Engelmann oak trees is not being replenished by young saplings.

"It's very much a case of dwindling numbers in terms of Engelmann oaks," said Jim Dice, president of the San Diego Chapter of the California Native Plant Society. "We don't know what we are losing when we wipe something out. We do know we are losing open space and things we once took for granted, like the Engelmann oak."

Conservationists worry about whether the public will rally to help preserve trees that are less spectacular than sequoias and redwoods but play an important environmental role by supplying food to insects and animals.

"The species we tend to think about are a handful of charismatic mega-flora and mega-fauna, whatever is the biggest or the furriest," said Bruce Pavlik, associate professor of biology at Mills College. "But others are as important, if not more important. Maybe we have chosen to preserve the biggest at the expense of what's ecologically important."

Experts say there are a number of reasons why the Engelmann oak is not replacing itself. Pocket gophers, mice, ground squirrels and other rodents that enjoy munching acorns and tender young oak roots have proliferated in the growing absence of their natural predators, bobcats, gray fox, coyotes and badgers, said Pavlik, author of "Oaks of California."

Throughout the Southland, the indigenous grasses have been overtaken by non-native weeds that form a thick herbaceous carpet. The dense layer of growth vies with oak seedlings for the soil's nutrients, often choking the young Engelmann oaks.

"No matter where the acorns fall, if they are not eaten by critters, they are going to be competing with these weedy grasses," Pavlik said. "We think it's a major factor."

Historically, grass fires opened up the weed layer, enabling oak seedlings to poke through. But the reluctance to burn areas in recent years has allowed the weeds to become firmly entrenched in many regions, Pavlik said.

Widespread grazing and cattle travel have packed the soil, making it difficult for rainfall and oak roots to penetrate. The livestock also enjoy nibbling oak leaves.

Indeed, a number of animals--as well as insects--chomp oak leaves. Studies in Carmel Valley have shown that, even when the oaks are protected from cattle and deer, fewer than 1% escape consumption by pocket gophers. In a San Luis Obispo study, less than 1% of unprotected blue oak seedlings survived three growing seasons, according to Pavlik.

To further complicate the picture, about 80% of the state's oak woodlands are on private land, putting them out of reach of conservationists, Pavlik said. Today, foresters are realizing that they have omitted the oak in their preservation efforts.

"The state spent so much time and effort on conifers. Protecting hard woods is something we neglected for a long time. Only now are we beginning to realize we've eliminated a lot of hard wood," Wong said. "We didn't look into regenerating oaks until now. Oaks are very difficult to regenerate--that's another one of our problems."

Under existing state law, Caltrans is obligated to replace native plants destroyed for roads or facilities. The mitigation law has created an environmental 'Let's Make a Deal,' in which Caltrans officials negotiate, for instance, the number of trees they will provide to replace the ones wiped out.

Mitigation, however, is a concept that some environmentalists oppose, saying that replanted baby trees are no replacement for the mature trees in their original environment.

"We don't want to get into the mitigation game--if you start mitigation in the forest, it's as good as dead," said Duncan McFetridge, president of Save Our Forests and Ranchlands in Descanso. "It's like shifting chairs on the deck of the Titanic. You have already lost."

Indeed, the replanted portion of Love Valley today hardly looks au naturel. The seedlings, encased in wire mesh cages that protect their leaves from errant livestock, are planted in corn rows across the meadow. Once it becomes clear which trees are destined to survive, Wong said, the remaining trees will be thinned "to create a natural oak woodland appearance."

The $20,000 project, funded by Caltrans and planned since 1989, is the first mitigation project that the Forest Service has agreed to conduct at Cleveland National Forest, Wong said. And officials only approved it after weighing what appears to be the bleak fate of the oaks.

Thirty miles west of Love Valley, at Interstate 15 just south of Temecula, construction is almost completed on a Caltrans maintenance station, California Highway Patrol and U.S. Border Patrol inspection facilities.

To compensate for the oaks cut down to make room for these buildings, Caltrans promised the Department of Fish and Game that it would plant three oaks for every one lost, which Caltrans is expected to honor within five years, said Jim von Dohlen, an associate landscape architect at Caltrans.

To maintain the genetic purity of the species, Von Dohlen had acorns collected from Cleveland National Forest's oaks and dispatched these to a nursery where they could be germinated and tended until they were a year old. This May, the seedlings were planted, with their mesh cages sunk 12 inches into the soil to ward off root eaters.

Jim von Dohlen himself set up the drip-irrigation system for the planting in Cleveland National Forest. Such systems were first used in the Middle East. In the United States, the system became popular with marijuana growers because it requires no electrical power, employs one solar power panel and gravity to drip water on the plants from pipes just below the surface of the soil.

Every other morning, just as the sun rises, each foot-tall oak seedling gets watered from a spring-fed, 750,000-gallon tank at the top of the valley.

The young trees had begun to flourish. For Wong, the buds on the baby trees signaled a triumph. In 1989, more than 600 oaks were planted and all died. In another major effort, only 10% survived.

Then the grasshoppers showed up. So far, although the baby trees have clearly been munched on, they are still producing buds, which shows they are fighting to survive. Only about 10% have been killed, estimated Laura D. Merrill, a U.S. Forest Service entomologist who examined the damage.

Since the oaks are on public land, there will be no spraying. Merrill said, "We just have to wait and see."

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