Reconstructing the Ecological Past of Cities

By Timothy Beatley

Landscape ecologist Eric Sanderson explains that he got into thinking about the nature of New York City when he moved there from the West in 1998, a way of reconciling his ecological interests and training with his new urban setting and home. Employed by the Wildlife Conservation Society (formerly the New York Zoological Society), and based at the Bronx Zoo, Sanderson began to look for ways to balance his more traditional conservation research with work in the big city.

The result has been a pioneering effort to understand what the ecology and environment of Manhattan was like when Henry Hudson sailed into New York Harbor on September 12, 1609. In his role as an ecological sleuth, Sanderson's big break was the discovery of a military map prepared by British cartographers in 1782, showing many of the streams, hills, and early ecology that existed in the revolutionary era.

Sanderson's groundbreaking work became the Mannahatta Project (a reference to the native Lenape word for the island), and resulted in the publication in 2009 of Mannahatta: A Natural History of New York City. The place inhabited by the Lenape for centuries, the "island of many hills," contained some 55 different ecosystem types (close to the diversity found in Yellowstone National Park, Sanderson notes, but in a fraction of the size), and was home to more than 1,000 species of plants and animals. 

Using GIS and 3-D modeling, Sanderson's team has produced beautiful, compelling images of what the landscape must have looked like in 1609. They are striking renderings, sharply contrasted with the highly built-up environments of present-day Manhattan. As a follow-up, Sanderson created the Welikia Project (www.welikia.org), which extends this methodology to the outer boroughs of New York City.

Why choose the ecology of 400 years ago? Sanderson is honest in acknowledging the cultural hook of 1609; it is a significant date in New York's history. In the final chapter of Mannahatta he looks forward, speculating about what New York City could look like in 2409. Provocatively, Sanderson lays out a sustainable vision, and wonders what might be possible if the 12 million residents of the present-day metropolitan area all lived at Manhattan densities.

The boldness of the temporal sweep in the Mannahatta idea is breathtaking — looking 400 years into the past, imagining a future 400 years hence, a sweeping 800-year arc of time. It took us a while to get into our resource-consumptive, sprawling development patterns; it may take us an equal period of time to get out.

Build your own Mannahatta

Sanderson's very latest chapter is the unveiling of a new website and online visioning project called Mannahatta2409. Users log in, select a block, a series of blocks, a neighborhood, or another scale in New York, and then use painting tools to indicate what kind of future they'd like to see (and how much of the original nature they want to protect or restore). A physical vision is generated as well as a dashboard that tells you how your vision stacks up on biodiversity, water, carbon, and population. (To construct your own vision, try the beta version at www.Mannahatta2409.org.) Through Mannahatta2409, just unveiled in February, "all of us can share in creating that future," Sanderson says.

The power of Sanderson's work is certainly about challenging the public to take hold of its future, but also, from my perspective, about placing the city's underlying nature at the core of this work. Sanderson's career as a landscape ecologist is dedicated, as he says, "to trying to help people appreciate the features of the forest and build them into the city." Sanderson offers some compelling renderings of what some of these overly built-up urban spaces might look like if some nature is returned to the scene.

This is also important to understanding what has been lost in the process of city-building, and in cultivating a sense of duty to compensate or repair where we can. "It shows when you build buildings that you've changed something . . . you've supplanted the nature that was there. And right now everybody gets a free pass on that," Sanderson said in a recent lecture to my Cities + Nature class at the University of Virginia. In his latest book, Terra Nova, Sanderson refers to this concept of recompense as "gate duties" (such as taxes on the extraction of oil or fees to cover the environmental costs of plastic waste).

Surprisingly, much of the remnant nature of 1609 persists — and these maps help us to understand current conditions and vulnerability. Sanderson's analysis shows that areas that saw major shoreline flooding in Hurricane Sandy are the same areas that were once (watery) wetlands. And a Manhattan Google processing facility that expends huge amounts of energy continuously pumping water from its basement actually is located precisely where a major historical stream once ran. The stream is now underground, of course, although the underlying hydrological conditions seem not to have changed much.

Sanderson tells me that it is architects and designers working on projects in New York City who often find the most value in his work. "Whether or not you believe we should have more nature, or less, in the city, at least you know [it once worked as a functioning ecosystem], and it worked for a long time, and it worked in a complete way that ecosystems do. So it gives you ideas," he says.

Sanderson's striking images of New York's ecological past reach us emotionally in ways other techniques cannot. What he has shown has sometimes been met with tears, he says, as people feel the loss of so much nature to development. It is unrealistic to assume that much of this original wildness could be replicated or replaced in a dense city like New York, but Sanderson's work — and the reactions it causes — tells us surely some of it can be.

Resources

Image: Mannahatta takes us back 400 years, to New York City as it might have been when Henry Hudson arrived. From Mannahatta: A Natural History of New York City.

Timothy Beatley is the Teresa Heinz Professor of Sustainable Communities at the University of Virginia, where he directs the Biophilic Cities Project.