The flora on the High Line, New York City, New York

Within the confines of New York City lies an overlooked oasis of green, the successional lichens, mosses and vascular plants that occupy the abandoned elevated High Line, a commercial railroad paralleling 10th Avenue between 13th and 34th Streets. The High Line consists of a 7.5 X 2330 m strip traversing 20 city blocks. It is exposed to full sun except in the area of 29th Street, which is partially shaded by tall buildings. Human visitors to the High Line have probably inadvertently transported seeds to the site, a source of new species. Additional environmental variables include shallow soil profile (0.01 to 0.7 m), thus inducing drought stress in dry weather, low fertility of soil, human trampling and cutting vegetation, and the smothering of plants by debris such as tires, bottles and additional trash. The aforementioned environmen