The sylvan city: restoring Central Park.

THE ORIGINAL DESIGN BROUGHT A NATIVE FOREST TO NEW YORK CITY. THE QUESTION NOW: CAN WE BRING IT BACK?

IF THERE IS A "GROUND ZERO" FOR EVALUATING THE TASK OF CREATING A SUSTAINABLE NATIVE FOREST IN AMERICA, it is in New York City's Central Park. Envision it as it is seen today from the air--an island-like green rectangle in the middle of Manhattan, one of the most densely populated islands in the world, which is, in turn, within another urban "island"--the tri-state metropolitan region.

Central Park's 843 acres are profoundly affected by the larger urban ecosystem: emissions from commuter traffic; chemicals added to the city's water supply-the source of the park's irrigation, drinking water, and manmade streams and lakes; air pollutants; and use by millions of people all add stress to the park's ecosystem. If a native forest can happen here, it can happen anywhere.

THE PARK'S FOREST LEGACY

Central Park represents a fragment of the deciduous forest that covered the entire Northeast coast at one time. Although plant records are not explicit until the 1800s, we do know that much of the original oak-hickory forest on Manhattan Island was cut to provide ship masts, building lumber, and firewood, first for the Dutch, then English traders and settlers. The city's tax records show that as many as 5,000 people lived within Central Park's original boundaries--59th to 106th Streets--in the 1850s. Land was being cleared for anything from piggeries, shanties, and garbage dumps to upscale residences; churches and cemeteries; taverns; farms with pastures, cropland, and orchards; and even several small bustling villages.

Although Clarence Cook, a well-known journalist, described the pre-park site as barren rock-strewn land with pestiferous swamps and occupied by squatters, goats, and a bone-boiling works, an 1857 pre-construction survey of the vegetation tells a different story. Charles Rowolle and Ignatz Pilat recorded more than 280 plant species, most of them native to the region. For land described as barren, the estimated numbers of traditional forest trees were impressive: 12,000 American hornbeam (ironwood), 9,000 red maple, 8,000 oaks of nine different species, 6,000 sweet gum, 3,000 black locust, 1,500 hickories, 1,200 willow, 1,000 birch, 500 American chestnut, and 300 flowering dogwood, to name a few.

CENTRAL PARK'S DESIGN AND CONSTRUCTION

The artistic style chosen for the park by its designers, Frederick Law Olmsted and Calvert Vaux, was imported from Europe. The romantic style created by landscape artists such as Humphrey Repton and Joseph Paxton had swept through England and the continent during the late 1700s, turning estates and public gardens formerly constructed in straight lines and geometrical compositions into naturally composed scenery. The pastoral landscape consisted of broad expanses of gently rolling meadows and placid lakes.

In direct contrast, the picturesque landscape was composed to mimic the beauty and unbridled wilderness of the Adirondack and Appalachian Mountains. Existing tree stands were supplemented to form continuous forest canopy; vines were trained to grow over cliffs and tree trunks; mosses and ferns were encouraged to grow in boulder crevices; imported soil was mounded up and planted with evergreens to create the illusion of miniature mountains; streams were dammed or rerouted to create tumbling cascades.

To construct Central Park, many thousands of cartloads of top soil were imported from New Jersey and Long Island, hundreds of pounds of gun powder were used to blast the Manhattan schist bedrock for the sunken transverse roads, miles of clay pipe were laid to drain the landscape, and the land was regraded and paved to form a complex system of paths and drives.

A CENTURY OF LIFE AS A PARK

Like most urban parks, Central Park has had its ups and downs of care and neglect. The most severe decline occurred during the 1960s and '70s when New York budget cuts coincided with the rediscovery of the park as a vital recreational and cultural component of public life.

But while use was increasing--spurred by new concern for physical fitness and an appetite for large outdoor events--the financial investment needed to maintain the park was decreasing. This deadly combination was soon manifested in the landscape: a loss of groundcover, diseased trees, severe soil erosion and compaction, the breakdown of the underground stormwater drainage system, floods, and eutrophic water bodies. The park was literally "going down the drain."

In 1980, the cycle of deterioration halted with the creation of a unique public-private partnership to manage and restore the park. The Central Park Conservancy--a not-for-profit organization that raises private funds to supplement the city's operations and capital budgets for the Park-was the brainchild of Central Park Administrator Elizabeth Barlow Rogers, an urban planner and transplanted Texan.

"I knew the city could never provide the level of funding necessary to support a world-class park. The park should be treated as a cultural institution on equal standing with institutions such as the Metropolitan Museum of Art or Carnegie Hall. Fortunately, thousands of others have agreed with me," says Rogers, who is also president of the Conservancy. "I also realized that it would be impossible to raise a dime without knowing the park's vital statistics and how to revive the health of the patient."

Thus one of the fledgling Conservancy's first projects was to initiate a plan to rebuild and maintain the entire 843-acre park. To prepare the plan, the area was first examined from top to bottom by teams of hydrologists, engineers, soil scientists, foresters, sociologists, preservationists, historians, and landscape architects. Their mission was to inventory each resource and report on its state of health.

"Before the tree survey was completed, we didn't even know how many trees were in the park--let alone what condition they were in," says Neil Calvanese, deputy chief of operations for horticulture. "Only then could we put together a maintenance plan to care for our trees and know what species to plant for the next century."

As the planning team analyzed the data, it became clear that the landscape should be divided into three distinct categories based on their physical attributes and management needs. The first two, meadow and parkland (turf and trees), were simpler landscapes that had to be intensively managed since they received the most intensive use. The third category included the park's 130 acres of woodlands--Olmsted's original picturesque landscapes.

In 1989 the Consenancy raised funds to hire a woodlands manager and initiate further studies. One of the most important surveyed users, park managers, and scientists, subsequently focusing attention and resources on five major problems in the woodlands: off-path trampling of the forest floor, off-path biking and vehicles, a breakdown of the stormwater drainage system, the spread of invasive plants--all introduced when the Park was constructed, and perceived and real safety.

A WOODLANDS RESTORATION PHILOSOPHY

Over the past five years, a unique management philosophy has guided work in the woodlands. To reduce the disruption and stress of a major construction project, much of the restoration work has been incorporated into the day-to-day management of the landscapes. To protect the existing forest skeleton--the overstory tree canopy and the precious soil profile developed over the past century--woodlands restoration is a slow and incremental process that takes decades rather than months to complete.

Central Park's woodlands are being used as a laboratory to discover both how urban forests really work and whether a native forest can be sustained in extreme urban conditions. Doctors Mark McDonnell, director of the Bartlett Arboretum, University of Connecticut; Richard Pouyat, forest ecologist with the USDA Forest Service; and Margaret Carriero, microbial ecologist with Fordam University's Calder Center, and other scientists have already established a gradient of research information that compares urban, suburban, and rural forest conditions. Central Park is "ground zero" for all studies, and distance along the gradient is measured from it. Only native species are being planted in the woodlands, using Rowolle and Pilat's 1857 plant list and those from forests further upstate along the gradient as guides.

The woodlands team is supplementing information gained from scientific research with more loosely structured monitoring projects. Test plots have been set up to find out if the invasive Japanese knotweed can be controlled solely through mechanical means and if so, how long it takes. These plots will be monitored for at least five years. Other plots have been established to test the effects of certain herbicides. The results can later be compared and management policies developed from the information. Results from monitoring projects such as these will help avoid large-scale missteps and focus attention on solving problems instead of treating symptoms.

In addition to documenting the monitoring projects, the woodlands manager is responsible for keeping records of all management interventions, including new plants introduced and new restoration strategies. Recordkeeping is a critical part of long-term restorations. Nothing will be gained from all the current painstaking work unless future woodlands managers can return to verify the results of a project.

Finally, all those responsible for the woodlands are committed to a public participation and consensus-building process. Consensus-building that began with the woodlands survey has continued through a Woodlands Advisory Board of park managers, scientists, and members of the environmental community, who meet monthly to propose, discuss, and decide the woodlands' future.

A vision for the woodlands of the future has begun. Park managers hope to recreate a self-sustaining native forest in as rich and diverse a palette as possible, given the urban conditions. Already new forest floor species such as foam flower, alum root, heart-leaved aster, bleeding heart, and cardinal flower are thriving. Will they survive to reproduce themselves? Only time will tell.

Nature is also working overtime. In the spring of 1994, hundreds of tiny oak and hickory seedlings sprouted in the park's 90-acre North Woods, all seeded from existing trees planted at the turn of the century. Dennis Burton, the woodlands manager, plotted them all and will monitor their fragile existence. You are welcome to drop by in the year 2010 to see what happened.

RELATED ARTICLE: WOODLAND MANAGEMENT & RESTORATION CHALLENGES

In constructing Central Park, Olmsted and Vaux were creating an ideal naturalistic landscape--natural in its visual composition but not in its species. Non-native plants imported from England and France augmented what native species could be found in the American nurseries. Some plants were placed in unsuitable environments simply because the size or color of the leaf made a dramatic composition. Various combinations of plants were used that would never have co-existed in a traditional forest setting.

Some, such as Japanese knotweed and Norway and sycamore maple, became invasive and supplanted native for-eat-floor plants. The Woodlands Advisory Board decided early on to control and gradually remove these plants in favor of natives.

The woodlands, in addition to being important historically, are the most complex natural system in the park. Just how complex they are was not sufficiently recognized in the initial plan recommendations, particularly in planning "how" to restore them. Major issues still must be resolved before a long-term management plan can be adopted. For instance, should the central portion of the Loch--once sculpted into a long lake but now in its original form as a stream--be dredged to restore the Olmsted and Vaux design or should the existing riparian forest be kept and enhanced?

The issues go beyond the question of historic versus ecological restoration to issues of how much intervention is appropriate. If the Loch is to be managed as a riparian forest, should the existing seed bank (which is mainly various species of ash) determine the future stream-side tree species or should other hydrophyllic species be introduced? This debate will continue in the public forum until these question 15 are answered.

Marianne Cramer is a landscape architect and currently the Central Park planner.