Barbed Wire Hides an Irvine Co. Jewel : Environment: Undisturbed for more than a century, the breathtaking scenery of Limestone Canyon may be opened to the public in a few years.

The red and white no-trespassing signs that warn visitors away from Limestone Canyon are as worn as the rusted barbed wire fence that holds them. The white iron gate is locked, and it creaks loudly when it opens, having been used over the years by only a handful of visitors and cattle ranchers.

Behind the gate, shady glens stretch gently away from the road and over ridges draped in wildflowers. Groves of oak trees, some of them hundreds of years old, break up the fields and line the creek beds, their dark green set off by the lighter splashes of sycamores.

For more than a century, passers-by have paused near the entrance to the canyon, straining to see around its bluffs. But they’ve had to do it from behind the fence.

The Irvine Co. bought 5,477 acres in and around the canyon in 1868, and since that time, the few adventurers who wandered onto the property did so at their own risk, knowing that the company’s security patrols could loom just over the next ridge, waiting to run them off the property.

That could soon change. The company, Orange County’s largest landowner, announced Thursday that it hopes to open up vast expanses of its private properties that have been set aside for future parks.

Most of the areas, including Limestone Canyon, were not expected to become parks for more than a decade. But if all goes as planned, Limestone Canyon, the largest of the properties to be affected, could open to the public within a few years.

When it does, Orange County residents will get their first look at one of the county’s most spectacular natural areas, an expanse of fields and peaks that have been protected for decades by the same company that is busily building out the valleys dropping away on all sides.

Behind the barbed wire, birds and small animals skitter in the fields, foraging for food. A dirt road dips into rolling pastureland, richly green in the spring.

Most of the year, the land strains for water, but for a few months about this time, the mustard blooms bright yellow and the California lilacs open in clusters of pale purple.

“We had rain last week, and it’s greened it all up,” said Mike Stockstill, the company’s senior director for corporate communications. “The wildflowers are really in full bloom.”

Rick Cermak, senior director of urban planning and design, nodded from behind the wheel of his four-wheel drive during a tour of the land Friday. “Look at this little drainage,” he said, pointing to a shady creek bed just off the road. “Look at the luxuriousness with which the oaks are chockablock.”

But if the bulk of Limestone Canyon is in its thick groves of oaks and rolling, almost-Irish pastures, the jewels in its crown are the sharp ridgelines with views across the entire county and the breathtaking limestone ravine known as “the Sinks.”

The Sinks sit about a mile from busy Santiago Canyon Road, but the canyon mouth faces south and west, cutting off any traffic noise. Limestone deposits in the Sinks have eroded over the centuries, leaving a sharp cliff face pocked with wear. The cliffs are dusty brown and drop more than 100 feet into a green meadow.

“This is the only one of its kind in this area,” Cermak said. “It is really something, isn’t it?”

Friday, hawks rode the updrafts that blow up the canyon walls, circling and searching for prey. Limestone Canyon, in fact, represents one of the most treasured homes for birds of prey, also known as raptors, left in Orange County, where development has destroyed the habitats for most of the avians.

“This is one of the very finest raptor habitats that we have left,” said Ginny Chester, a former president of the Sea and Sage Audubon Society. Chester was active in the effort to secure Limestone Canyon as a park in return for developments that the Irvine Co. was allowed to build in Orange and Irvine.

“It has the trees that are necessary for their nesting sites. It has the fields where they hunt . . . and it has the updrafts they need to soar,” she added.

With the company now apparently committed to allowing public access into this area for the first time, the challenge before environmentalists and company officials is to allow people into the park without exposing it to damage.

“On the one hand, the company has kept people out of this land for years, for business reasons and other reasons,” Stockstill said. “But on the other hand, this land has been protected as a result. Now that’s going to change.”

In order to protect the land at the same time that it opens it, the company has indicated that it plans to consult with environmental groups for advice on areas that should remain closed to the public. The process is supposed to begin within a few weeks.

Exactly when the land will actually open is still undecided, but company officials hope to have a plan completed by the end of the year.