McDonalds Corp., which destroys a small forest every year to wrap its burgers and buns, is going to extraordinary lengths to preserve one for a new corporate home.

More than 1,500 trees have been documented and 600 transplanted in the 80-acre, 100-year-old Hickory Oak woodland. Construction firms are being kept environmentally conscious by McDonalds' threat of a fine of up to $20,000 for each tree lost to carelessness. Exposure to a "save-the-trees" film and pamphlet, and a signed pledge to preservation are demanded of each worker to insure that does not happen.

Crews are prohibited from driving over exposed roots, from storing construction materials under trees, and from entering any of the environmentally sensitive areas bounded by three miles of fence.

In a paper before the Society of American Foresters convention last year, McDonalds forestry consultant Charles A. Stewart said the company's four years of planning to complement construction with conservation is unsurpassed.

The forester noted later that most businesses call him only after the damage has been done:

"What's wrong with my trees? They're dying."

The answer, typically, is, "Well, you never should have built that road there," he said.

Stewart's enthusiasm is buttressed by letters of praise from the state Environmental Protection Agency and by an award to the project in April by the National Arbor Day Foundation, which said it leads the way for other corporations.

So far, 10 major businesses preparing new corporate headquarters have studied McDonalds' plans, according to the architect, Joseph Antunovich, of the firm of Fujikawa, Conterato, Lohan and Associates, Inc. TRW is developing a similar tree training film for construction workers on its Lindhurst, Ohio, site.

Having won the approval to build over the additional objections of Oakbrook's polo pony set, McDonalds' Office Campus Director Kim Pardue said the project proves a commercial development can preserve more of the foliage in a pristine area than low-density, high-priced, single-family residential construction.

Although the site will contain 1.15 million square feet of floor space by the year 2005, only 15 percent of the land will be occupied by buildings.

The complex is being ringed by a two-mile-long bike and jogging path. A national training center, a 150-room lodge and all of the landscaping are scheduled to be completed in 1983. A national meeting center and a new corporate headquarters with a 1,000-car underground parking facility will be constructed later on.

Currently, two man-made lakes are being dug. One, Lake Fred, is being named after McDonalds' chairman of the board, Fred Turner, a fact Antunovich hoped would be emphasized as little as possible.

While there were some raised eyebrows from prospective construction firms over the proposed fines and conservation restraints, McDonalds said they made no objections.

This may be largely because the company spent considerable time weeding out the firms it thought environmentally unsuitable to do the work.

Pardue said it took him three months to choose a general contractor. He avoided the largest because he wanted to deal with a principal of a company that would be working directly on the project, a "hands-on" approach McDonalds seeks in most companies it does business with.

Antunovich said he didn't want an outfit used to building interstate highways to lay its heavy hands on the delicate roads threaded throughout the woods:

"This is not a major earth moving project," he explained.

In keeping with that, they have tried to use smaller pieces of construction equipment.

After nearly a year of construction, no fines have been assessed, but workers seen without an oak-tree sticker on their helmets, signifying that they've seen the film, have been sent back to the site office.

In one case, workers decided to save a large tree that the planners thought would have to go.

No one at McDonalds would estimate how much the conservation precautions add to the cost of project. Pardue said this development of the forest--once owned by Chicago suburban Oakbrook founder Paul Butler--never would have been done any other way.

McDonald spokesman Steve Leroi said the public will have access to the grounds, and he expects McDonalds won't be able to turn down requests from Boy Scout and Girl Scout groups once the project is completed. He also guessed that McDonalds employes and their families would choose to spend leisurely weekends at the lodge.