Ecologist Maps Manhattan of 400 Years Ago

On a recent cold, Thursday evening, a friend and I squeezed our way into a filled-to-capacity room at the Arsenal in Central Park to hear Dr. Eric Sanderson speak about the Mannahatta Project-an impressive undertaking sure to gain attention as we approach the quadricentennial of Henry Hudson's famous voyage of 1609. Sanderson, a ruddy-cheeked and ebullient man, began his talk by showing some photos of two dramatically magnificent natural areas: the California Redwood Forests and the Rockies. Then he told us that Landscape of New York City 400 years ago would have rivaled that of Yellowstone or Yosemite today.

Manhattan, or what the Lenape Indians called Mannahatta, was more biologically diverse than either of those two areas, and with its hardwood forests, freshwater, and estuarine environments, Mannahatta's 54 different ecological communities (that is, interacting species living in the same place, bound together by a network of influences) and lush greenery would have dazzled any nature lover. Sanderson has been working on the Mannahatta Project for the last decade. He first became fascinated with his adopted city after he accepted a position here with the Wildlife Conservation Society, and began to study old maps. One map in particular, an 18th-century British Headquarters map, fascinated him. The map, made for British officers defending the island, details the contours of the island's topography, swamp, and river locations. Sanderson has been using this British map, Randel's Farm Maps, and a GPS system to create his own contour map of what Manhattan looked like in 1609, when Henry Hudson and his crew sailed into New York Harbor and the island was inhabited only by the Lenape. He has been able to produce an expansive vision of Mannahatta's ecologic richness through a computer program he created, named "Muir webs," after the famous naturalist John Muir.

Sanderson is using his program to map what would have existed on each city block in Mannahatta 400 years ago. The program works through a process of matching animals to their habitats and vice-versa. By knowing that a certain animal species existed in an area of Manhattan and knowing what that animal ate, Sanderson can predict through the Muir webs program what plants or soils would have been there as well, or conversely can use knowledge of plants and soils to discover what animals would have found a habitat in any specific area.

Sanderson used the geology depicted on the British Headquarters map to come up with his soil map. It took Sanderson five years to get a topography map. He now has a bathymetry map (a map of measurements of oceans, seas, and other waterbodies), too. From that, he can tell where the springs and wetlands used to be, as well as the measurements of slope and wind exposure. He used all of these sources and layered them together to create an amazing uber-map made up of 50,000 different ecosystems.

Sanderson's view of the long-lost island buried under all that concrete is fascinating and filled with revelatory information. At one time, a person could boat from one river to the other. SoHo had Lispenard Meadows and Washington Square had Minetta Brook. Further uptown, there was also Harlem Meer and Creek, a beach on West 125th Street, and a small forest on Murray Hill. New York today is also significantly wider than the original island of Mannahatta, as the borders of the island we now know are largely the result of dumped garbage.

With the help of some graphic design work, Sanderson's mapping has produced some gorgeous 3D renderings of what life used to look like in this erstwhile natural wonderland. Some of the illustrations almost made me weep for what could have been if New York City had been built in concert with its natural abundance, but Anderson is more upbeat.

The Manahatta Project will eventually result in a coffee-table book and exhibit at the American Museum of Natural History. To coincide with the 400th anniversary of Hudson's 1609 voyage, Sanderson also hopes to hold ceremonies that will connect today's urban New Yorkers to the island's original habitat—and one that still exists right under their feet. Some of his ideas include tracing Minneta Brook in blue tile through Washington Square Park, placing images of nature on the video screens in Times Square, observing a moment of silence for the previously existing habitat, creating vistas of what that area used to look like and installing them on sides of buses, and launching a 3-D computer map program that allows users to zoom in on specific areas to see how they used to look.

Sanderson believes his research could be used as an educational tool to bring greater awareness about environmental protection to citizens and visitors to New York City. Sanderson ended the talk with a split image of Mannahatta and Manhattan, and pronounced them both "great in different ways." The project is definitely grand and inspiring and worth a "save the date" for September 2009 in your calendars.

Curious about what Manhattan looked like 400 years ago? Check out out more photos of the
Manahatta Project from the New Yorker.

Tags: Biodiversity | Preservation

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