From the NY Times:
Last summer, the city began replacing the wooden boards on two short stretches of boardwalk with concrete strips as a pilot project for a more extensive overhaul of the structure, which extends for two and a half miles along the Brooklyn shoreline.
The change is part of a move away from the tropical hardwoods like ipe (pronounced EE-pay) that have long been used by the city for benches, piers and walkways. The woods are tough enough to withstand a fleet of garbage trucks, but their sources in the Amazon rain forest are being depleted. Under pressure from environmental groups like Rainforest Relief, the city has since 2008 been trying to stop using them, and concrete has become the material of choice for boardwalks.
Officials at the Department of Parks and Recreation have promised that the section of several blocks of the Coney Island Boardwalk along the historic amusement area will remain hardwood. But everything else is vulnerable to conversion to concrete.
The officials say other solutions have drawbacks. North American hardwoods are not as sturdy or long-lasting. Concrete, already used for at least one mile of the five-mile Rockaway Beach Boardwalk, so far seems the cheapest, most durable alternative. Concrete, parks officials say, costs $95 a square foot, compared with $127 for hardwood.