But the 16-year-old plans to spend a month this summer camping in the backcountry while working six days a week building hiking trails in a program organized by the Student Conservation Association, a nonprofit group that trains hundreds of young people across the nation in land stewardship each year.

"I'm totally from the city. But I love getting out and learning about the environment,'' said Billy, a junior at Oakland High School. "I'm from East Oakland and until I took hikes at Mount Lassen and some other places, I had no idea what it was like out there."

Billy was among 30 high school student volunteers from around the Bay Area who spent Martin Luther King Jr. Day pulling weeds and hacking brush on a very steep Oakland hillside near the Caldecott Tunnel.

The students, who also planted more than 100 oak trees in a 22-acre area destroyed by the 1991 hills fire, are the Bay Area contingent of the Student Conservation Association. Like Billy, many of the SCA volunteers grew up in the city with little background in hiking or camping.

The students are part of a year-long program in which they perform monthly service projects in parks or other undeveloped areas and spend one month in the summer camping and working -- typically building trails or restoring habitat -- in remote national parks or forests in all 50 states.

Founded in 1957, the private group is based in New Hampshire and has regional offices in Oakland; Seattle; Pittsburgh; Washington, D.C.; Boise, Idaho; and New Paltz, N.Y. Nearly two-thirds of the 40,000 people from around the world who have participated in the program have become conservation professionals.

Many of the students, like Julie Chunne of Oakland's Skyline High School, returned for a second year to help lead conservation crews. Julie, 16, spent last summer building trails and planting trees at Sleeping Bear Dunes National Lakeshore in Michigan.

"The good part was that we were camping and working right on the beach every day for a month last summer,'' Julie said. "The bad part was that we really worked hard and the mosquitoes there are as big as birds. Trying to go to the bathroom, you totally get attacked."

Julie and other volunteers also pulled weeds at San Francisco's Presidio and rebuilt a washed-out trail at Sugarloaf Ridge State Park in Sonoma County.

Last Monday, the students were targeting broom -- often called French or Scottish broom -- a nonnative plant known for its yellow flowers that carpet many Bay Area hillsides in the early spring.

"These volunteers are great,'' said Robert Sieben, a Hiller Highlands activist who helped plan where the trees were planted. "It's a huge job. They're covering a lot of ground."

The volunteers worked in many steep areas where brush can be difficult to clear. Unlike goats or sheep, the students are selective about what plants they target, leaving desirable native plants unscathed.

Most of the Bay Area SCA volunteers come from San Francisco, Oakland and Berkeley with a couple coming from suburban communities.

"We intentionally mix kids of different backgrounds,'' said Jenny Seiler, an SCA administrator based in Oakland. Often in the summer program, each member of a team of six to 10 workers is from a different state.

For Julia Mead, a 17-year-old senior at Berkeley High School, that "mixing" last summer during a month at Natchez Trace Parkway in Mississippi, Alabama and Tennessee was a source of amazement -- and some irritation.

"I'd never really met a Republican before last summer,'' Julia said. "Our group split into factions and argued about politics for a month. ... I mean these two guys didn't even believe in evolution."

Despite the differences, Julia conceded that she became friends with the "Republican faction" after a month together.

"You can't help it," she said, laughing. "You're together almost 24 hours a day. You work that hard together, and you kind of bond."

Like Julie Chunne and many other students involved in the program, Julia hopes go into an environmental career after college.

Some participants who plan other careers talk about the program's profound effect on their lives.

Mylan Trang, 22, spent two summers with the program while attending Balboa High School in San Francisco. She stayed with the program as a part- time coordinator while majoring in education and childhood development San Francisco State University.

"It really changed me," said Trang. "I'm still a city person. But I really appreciate and respect nature now."

At Alaska's Denali National Park in 2000, Trang's crew saw bald eagles daily and often had encounters with foxes and bears. One day, they all stopped working to watch a bear chasing a moose in circles. The exhausted bear eventually gave up but the moose was also too tired to run any more so both animals just stopped.

"I couldn't believe I was really watching this,'' she said. "You grow up in a city like San Francisco, and you wonder if this is for real. I never thought I'd ever see anything like that.".

For more information on the Student Conservation Association, go to the group's Web site at www.thesca.org or call the group's Oakland office at (510) 832-1966. E-mail Jim Herron Zamora at## jzamora@sfchronicle.com.