FOREST RESTORATION ON A CLOSED LANDFILL - RAPID ADDITION OF NEW SPECIES BY BIRD DISPERSAL

Urban areas often contain sizeable pockets of degraded land, such as i nactive landfills, that could be reclaimed as wildlife habitat and as connecting links to enhance remnant natural areas. In the northeastern U.S., many such lands fail to undergo natural succession to woodland, instead retaining a weedy, herbaceous cover for many years. We hypoth esize that seed dispersal is a limiting factor, and that a form of sec ondary succession could be stimulated by introducing clusters of trees and shrubs to attract avian seed disperses. As a direct test we censu sed a 1. 5 -ha experimental plantation on the Fresh Kills Landfill (St aten Island, New York) one year after installation in search of eviden ce that the plantation was spreading or increasing in diversity. The 1 7 planted species, many from coastal scrub forests native to this regi on, were surviving well but contributed almost no seedlings to the are a, in part because only 20 % of the installed trees or shrubs were rep roductive. Of the 1079 woody seedlings found, 95 % came from sources o utside the plantation; most (71 % ) were from fleshy-fruited, bird-dis persed plants from nearby woodland fringes Although the restoration pl anting itself bad not begun to produce seedlings, it did function as a site for attracting dispersers, who enriched the young community with 20 new species. One-fourth of all new recruits were from nine additio nal wind-dispersed species. Locations with a high ratio of trees to sh rubs had proportionately more recruits, indicating that plant size con tributed to disperser attraction. The density of new recruits of each species was dependent on distance from the nearest potential seed sour ce. Introducing native species with the capacity to attract avian disp ersers may be the key to success of many restoration programs.