There was no rumble of traffic from the Beltline because the Beltline did not exist. To the south was nothing but more farmland. There were a few housing developments nearby but mostly the city and the Arboretum's parent university were miles away across more fields and woodlots.

Were he to come back and take a stroll today, Leopold would not recognize the place.

And, with the Arboretum's 75th anniversary coming next year, Leopold probably would be at least mildly surprised to hear what kind of challenges the iconic landscape is up against. These include:

•Tensions between restoration science and the cultivation of ornamental gardens such as Longenecker.

•Increasing public use for activities such as jogging and biking, which were never really envisioned at the Arboretum's founding and threaten the already fragile ecology.

•Surging stormwater from encroaching urban areas that is eroding away the restored prairies Leopold so loved. Dealing with it requires the construction of stormwater infrastructure that is hardly part of the natural landscape originally envisioned.

•Invasive species bullying aside native plants and destroying the diversity of plant life so important on native prairies.

All of these issues are now facing the governing Arboretum Committee and decisions to be made in the coming months are likely to set a course for the much-loved institution for years to come. Whether that direction will closely follow the founding principles or stake out a different future is yet to be seen.

"It's absolutely a critical time,'' said Don Waller, a UW-Madison professor of botany who has served in the past on the Arboretum Committee and stays abreast of issues. "We face a turning point.''

The dark, green recesses of the Arboretum — that big absence of buildings and, at night, light, adjacent to the busy Beltline — have become as much a symbol of Madison as its lakes. Curt Meine, Aldo Leopold's biographer and a writer and conservation biologist, remembered first coming to Madison years ago and stumbling across the Arboretum.

"I remember thinking, 'Wow, what are all these trees doing in the middle of the city?' '' Meine said.

But this is much more than an empty spot on the map. This is the site of the first restored native prairie in the world, the place where scientists such as Leopold and famed botanist John Curtis first dreamed about what seemed impossible, bringing back something that we humans had nearly destroyed, the native prairie. With the realization of their vision, the Arboretum became the birthplace of an entire discipline — restoration ecology. And the prairies they planted all those years ago still grow; smoke rises from them each spring when they are burned.

Kevin McSweeney, the Arboretum's director, said the idea of the Arboretum as an important and historic landscape is found in quarters far beyond Madison.

"That notion really extends globally,'' McSweeney said. "This place is special because of the Leopold connection and because it is the birthplace of restoration ecology.''

Leopold laid out the foundation for the Arboretum's work in his 1934 dedication speech. And the difficulties faced today by those who are setting the Arboretum's course stem as much from trying to figure out how to follow that original vision as they do from the press of the encroaching urban environment.

This is what Leopold said: "Our idea, in a nutshell, is to reconstruct, primarily for the use of the University, a sample of original Wisconsin — a sample of what Dane County looked like when our ancestors arrived here during the 1840s.''

From that speech and from the wisdom of many others who helped establish the Arboretum came a straightforward mission statement,

"Our mission is to conserve and restore Arboretum lands, advance restoration ecology, and foster the land ethic.''

But Joy Zedler, a UW-Madison professor of botany who holds the Aldo Leopold chair in restoration ecology and who oversees much of the research at the Arboretum, worries that some recent decisions reflect a move away from the original emphasis on research and education and a nod to increasing public use.

Zedler was the only member of the Arboretum Committee to vote against a plan to study the construction of structures such as gazebos in the Arboretum's gardens. One idea was to use such structures for fundraising by making them available for the purchase of naming rights.

"What is our vision?'' Zedler asked. "Are we a visitor center? Or are we a research and science facility? Or are we for public recreation?''

Do such plans, made more necessary by tight budgets, portend a different direction for the Arboretum?

McSweeney said that's not the case, that restoration and research remain the bedrock reasons for the Arboretum's existence. And he said some recent decisions by the Arboretum Committee — such as not allowing extensive signage on the property — show a sensitivity to that original vision of a natural landscape that harkens to a distant and more pastoral time.

McSweeney acknowledged the difficulty of balancing public use and the restoration and science agenda. And he's aware that in his dedication speech, Leopold said that the Arboretum's work "will be done for research rather than for amusement, and for use by the University, rather than for use by the town.''

But that has changed, McSweeney said.

"My personal perspective is that people have been coming here for a long time and they are not going to go away," he said. "And in the tradition of the Wisconsin idea, it is our obligation to provide a diverse array of outreach programs, from gardening classes to nature camps for kids. It's a way we can convey to people why we do what we do and that values of the natural world.''

Carrying out that deceptively simple mission has become frustratingly complicated on a number of fronts, according to McSweeney. It is also difficult to focus on restoring landscapes such as prairies and wetlands when those places are being destroyed by erosion and invasive species.

That challenge has been picked up by Zedler. Working with her students, Zedler has tried to maintain Leopold's vision of a restored landscape while at the same time coming up with ways to study and understand and hopefully overcome the more modern threats. Perhaps, she said, a better grasp of the diverse number of plants on a restored prairie might provide tools in the fight against invasives.

"You would hope,'' Zedler said, "that by creating a landscape with a high diversity of plants you could resist invasives.''

Another example is management of stormwater. Of all the modern-day threats, few have been as vexing as the flood of rainwater that inundates the Arboretum after storms. The problem has its origin in areas far outside the Arboretum's boundaries. The Lake Wingra watershed, of which the Arboretum is a part, extends far to the east; stormwater from huge parking lots along Odana Road, for example, eventually finds its way into the Arboretum. That water erodes restored prairies, washes silt into wetlands, pollutes waters with nutrients and sediments, and introduces invasives.

It fell to Dave Liebl, a pollution prevention specialist with UW-Madison's engineering department, to chair a committee that would come up with a stormwater plan that conformed with the Arboretum's history and ideals of restoration and research. How do you, for example, turn a stormwater retention pond into anything resembling a natural feature? It is, in the end, infrastructure and that word never appeared in Leopold's list of lofty goals.

What the stormwater plan does, according to McSweeney, is adapt stormwater management to those principles. It calls for reducing the quantity and quality of stormwater to pre-settlement levels. And it tries to find ways to inject research and restoration principles even into the construction of stormwater structures, such as retention ponds.

Even Leopold, in his dedication speech, laid the foundation for using science to study future problems. The very act of establishing the Arboretum and its research agenda, Leopold said, "is an admission that science does not yet know enough, or is not yet sufficiently listened to, to anticipate and prevent this process of wreckage which attends our supposedly advancing footsteps.''

While finding ways to accommodate change and to fulfill the Arboretum's original mission has not been easy, Zedler remains optimistic. After all, in the face of it all, with a modern city and all of its problems pressing at its borders, the Arboretum remains a special place where wild turkeys and sandhill cranes stalk about, part sanctuary but also part outdoor classroom and laboratory with the capacity to teach us better how to live in a besieged natural world.

Zedler, despite her reservations, believes even Leopold would be able to see, through all of the changes, a place where people are working to make real the dream he put into words in 1934.

"He would probably be proud of the science that has been accomplished,'' Zedler said. "He would be surprised at the range of difficulties that have been encountered. But he would be proud.''