A few years ago, Mahlon B. Wallace III of Ladue, a retired pencil company executive, rancher, wildlife art collector and philanthropist, purchased a small bronze statue by the noted wildlife sculptor Kent Ullberg. “Reaching Elephant,” it was called, an African bull elephant browsing in an acacia tree.

Mr. Wallace was so taken by the piece that he asked the St. Louis Zoo if it would like to have a life-sized version of it. As it happens, said Zoo President Jeffrey Bonner, the Zoo was looking for an iconic symbol to grace its new front entrance.

And that explains why, at his studio in Loveland, Colo., Mr. Ullberg has molded a 19-foot-tall African bull elephant in clay. That model now is being cast in bronze, and sometime in the next two years, it will be installed at the south entrance to the St. Louis Zoo close to the present entrance of the parking lot. It will be a gift of the Wallace family’s Casa Audlon Charitable Trust.

The elephant won’t have a bronze acacia tree, though; that proved too difficult to reproduce at the larger scale. Instead, it will be browsing in a real locust tree, pruned to look like an acacia, a thorny species common to the African veldt.

The Zoo parking lot will look different by then. Acres of asphalt will have been landscaped and grass will grow in the medians. And the south entrance will have been transformed into The South Arrival Experience.

Assuming the plan is approved by the Missouri Department of Transportation and the Forest Park Advisory Commission, work could begin this fall when the Hampton Avenue entrance to Forest Park is closed as part of the Highway 40/Interstate 64 reconstruction project.

When St. Louis “reopens” in 2010, Mr. Bonner said — that is, when the 40/64 work is done — traffic to the Zoo may be funneled directly to the “arrival experience.” Visitors will get out of their cars and walk past the elephant, maybe stopping to photograph the kids patting its knee. Mr. Ullberg’s elephant could well claim a place among the icons of St. Louis.

Visitors then will stroll along a landscaped, gently curving pedestrian ramp over Wells Avenue and into the Zoo. No more dodging cars on the street. Money for this has been provided by one of those infamous congressional “earmarks;” in this case, $5 million inserted in the 2006 Transportation, Treasury, Housing and Urban Development appropriations bill by Sen. Christopher S. “Kit” Bond and Rep. Jo Ann Emerson of Cape Girardeau, both Missouri Republicans.

The big concrete pylon with the vertical block “ZOO” will be moved south into the parking lot.

The bronze elephant will be the first and most visible sign that big changes are underway at the Zoo, which will celebrate its 100th anniversary in 2010. Some will be noticeable: the renovation and expansion of the venerable bear pits and sea lion pool and a big yard for non-bronze elephants to walk around in. Those still are in the design stage and will be completed sometime after 2010.

Many other changes already are underway, but they will be much less obvious: better lighting, security, drainage and climate control and salt water instead of fresh water for marine mammals. “The Zoo is going to be 100 years old,” Mr. Bonner said. “If you want it work for the next 100 years, you have to start tackling those projects that aren’t so glamorous.”

More significantly, the Zoo’s work beyond the borders of Forest Park will continue to expand. It may be, as Simon and Garfunkel suggested, that it’s all happening at the Zoo. But the Zoo also is happening all around the world.

American zoos have changed profoundly in the last three decades. Mr. Bonner dates the change to the Endangered Species Act of 1973, which required institutions that wanted to bring wildlife into the country to demonstrate that they are doing conservation work in the animals’ home nations.

“At the same time, there was a developing movement where zoos moved away virtually entirely from being what you might call ‘consumptive users’ of wildlife — [the idea that] ‘We can always get more’ — toward managing conservation. That happened essentially during my adulthood,” said Mr. Bonner, 54. Simultaneously, he said, “there was a crash in the population size of many species and a growing awareness that zoos had to be a safety net.”

Zoos around the world began concentrating on scientific management of species and sustaining wild populations. For many species today, he said, there are larger, more genetically viable populations in zoos than there are in the wild.

So as the St. Louis Zoo developed its new strategic plan, it also was developing “a vision of what the role of institutions like the Zoo will be in 25 years,” Mr. Bonner said. The conclusion: “Animals may be safe in zoos, but they’re not saved in zoos. They’re saved if they can continue to live their lives relatively unmolested in the wild.

“We see zoos and aquariums 25 years from now as primarily field conservation organizations. Obviously, the zoo that you see will never go away, nor should it. For many species there is no wild.”

The challenge is how to link what’s inside the fence to what’s outside the fence, as they say in the zoo business. Taxpayers in St. Louis and St. Louis County contribute about $20 million a year to the Zoo through the Zoo-Museum District. That supplies roughly a third of its operating budget. Another third comes from donations and gifts and the final third from parking and concessions.

The tax money all stays “inside the fence,” Mr. Bonner said. One goal in the next 25 years is to “connect fence to field” — to make exhibits that underscore and support the conservation mission. Thus, when the bear exhibit is rebuilt, it may feature a glass wall at which visitors can come “nose to nose with a major carnivore,” Mr. Bonner said. The plight of the polar bear, whose wild habitat is shrinking drastically because of global warming, will become personal.

“Exhibiting is an important step,” Mr. Bonner said. “In many ways, it begins with that. The first step is to get people to care about living things. For many people, that’s not a given. . . . As a society, I’m not sure that we do a very good job of taking the affinity for living things and making it real, making it part of people’s lives. And that’s the role of zoos.”

Watch this video about the Zoo’s plans.