Studios Set the Stage for Trek : Benefit: More than 10,000 people, including stars, are expected for the Earthwalk fund-raiser. Back lots will be open on the six-mile route.

For the first time, four major movie and television studios in the San Fernando Valley will open their back lots to their neighbors Saturday as part of Earthwalk, a fund-raiser for environmental causes.

The New York Streets at Universal, Mickey Mouse Lane at Disney, the “Growing Pains” set of Warner Ranch and the Carson and old “Laugh-In” studios at NBC-TV are among areas scheduled to be open along a six-mile route. Fox and Sony studios--which have lots over the hill--plan large displays with props and sets from their back lots. The studios are also planning many surprises.

More than 10,000 people are expected to join such celebrities as Valley residents Bruce Davison, Ed Begley Jr., Melanie Mayron, Edward Asner, Charlie Fleischer, Neil Patrick Harris and Danica McKellar. Other actor activists and their families expected to stroll along with the crowd include Ted Danson, Pierce Brosnan and Richard Moll.

Already, as many as 600 people a day have registered for the walk, which is co-chaired by actor and director Leonard Nimoy and his activist wife, Susan Bay Nimoy. People from as far as Santa Barbara and San Diego are expected to attend the event.

Studio executives are extending a special welcome to neighbors who may have had to put up with the traffic, noise and bright lights of the back lots but may never have ventured inside the gates. Those neighbors include residents of Studio City, Toluca Lake, Burbank, Glendale, North Hollywood and Universal City.

“I started getting some consciousness-raising in the 1960s, while working on ‘Star Trek,’ ” said Nimoy, who played the stoical, logical Vulcan character Mr. Spock on the popular TV show and in six feature films. “I remember when it was not unusual to see the mountains in Los Angeles and when it was OK to swim along all the beaches. I remember a very different California.”

Nimoy, who moved to Pasadena from the East Coast in 1949, recalled a panoramic view for miles in every direction from a rooftop cafe at the Pasadena Playhouse. Twenty years later, when returning to the same area to shoot a scene for the TV series “Mission: Impossible,” the crew was red-eyed and tearing up because of the thick smog.

“You could almost feel the stuff in the air around you,” said Nimoy, sitting on the steps of the “Back to the Future” town square set on a recent smoggy day at Universal Studios. “I thought it was terribly unhealthy, yet it used to be a paradise here.”

As he witnessed the deterioration of the environment, he became more politically involved. Nimoy and his wife now co-chair the Environmental Leadership Corps, a branch of the California League of Conservation Voters, which monitors the voting records of legislators. It is the oldest conservation group in the state.

Eventually, his concern sparked Nimoy to create and direct the popular motion picture “Star Trek IV: The Voyage Home,” which is filled with environmental messages and is to date the highest-grossing “Star Trek” movie, amassing more than $110 million.

“Suddenly the stories that I did in science fiction that seemed so outlandish--people having to leave a planet because they made it uninhabitable--was becoming a reality,” Nimoy said with a dry chuckle. “You stop and say, ‘Wait a minute, what are we doing here?’ ”

The Nimoys recycle, car-pool and conserve around their home. Their son attends an environmentally aware Valley school that teaches families to reuse plastic wrappers for school lunches. During outings with friends, the Nimoys drive a seven-seat van that gets good gas mileage; they have a bucket in the shower to collect water that is later used for their plants, and they even cut up old scripts and use them as note pads.

“The tough one for me is to remember to take a canvas shopping bag to the market,” Nimoy confessed. “When I was a kid, I clearly remember that my parents and grandparents always carried a cloth shopping bag. Today, we go to the market and use a bag for the smallest item, and meanwhile, trees are disappearing.”

Nimoy credits the entertainment industry with making people aware of ecological problems. He said, “The problems often seem insurmountable, but there are intelligent and professional people who have devoted themselves to figuring out what to do, and those are the people who deserve our support.”

Many celebrities are concerned about environmental causes and speak intelligently about the issues, Susan Bay Nimoy said. “A celebrity may get people to pay attention to something that will change their lives, and if a favorite actor or actress is giving them direction, that’s terrific.”

Danica McKellar, 17, who plays Winnie on “Wonder Years,” a TV show set in the 1970s when concern about conservation was less prominent, is one of the celebrities who will help out in Earthwalk. She has been involved with Heal the Bay for two years and spoke to the U.N. General Assembly last month to plead for a worldwide environmental conference.

“It’s a very slow process, and it’s frustrating because you’re not going to see things solved right away,” Danica said. She said she grew up in San Diego, where her family recycled, used a composter and grew organic vegetables. “I still tell people it’s important to get involved in any way they can.”

Getting celebrities together for Earthwalk wasn’t as difficult as opening up the studio back lots, said Lisa Paulsen, president of Permanent Charities, the umbrella organization for Earthwalk. Movie production--usually a highly secretive process done behind tall fences and thick bushes--will be open for public viewing, and the studios have donated more than $100,000 in staff, free gifts and services for the walk, Paulsen said.

Permanent Charities was formed by entertainment heavyweights such as Sam Goldwyn and Humphrey Bogart to raise money within the industry for many causes. The group, which has raised more than $85 million since its formation 50 years ago, identified the environment as a main concern three years ago. Earthwalk has since become a major fund-raiser for the organization.

Proceeds will be split among seven local environmental groups: Earth Communications Office, Heal the Bay, TreePeople, Environmental Media Assn., American Oceans Campaign, Natural Resources Defense Council and Kids for Saving Earth.

The first two Earthwalks, limited to industry employees and their families, were held in the 20th Century Fox back lot. They attracted about 3,000 people each.

Anyone--the public or celebrities--who raises $50 or more in donations will receive a free T-shirt. Most walkers are expected to average $100 in pledges.

Not all studio managers are thrilled about the public access to their back lots, said Dan Slusser, MCA Universal senior vice president and general manager and Permanent Charities chairman.

He said the walk will be controlled and closely monitored by security personnel.

Slusser helps manage the world’s most-visited back lot: the one at Universal, which opened to the public in 1915 and now averages 5 million visitors a year. But even Universal’s tour usually has visitors ride in trams instead of allowing them to walk through the sets.

“Anytime you have something as big as a studio situated in a residential area, you have to be concerned about the feelings of the neighbors,” Slusser said. “This is one of our ways to open up to them and say thanks.”

Earthwalk begins at 10 a.m. Saturday on the back lot of Universal Studios. To register for the two-hour walk, call (818) 763-2784.