Gr. Robinson et Sn. Handel, FOREST RESTORATION ON A CLOSED LANDFILL - RAPID ADDITION OF NEW SPECIES BY BIRD DISPERSAL, Conservation biology, 7(2), 1993, pp. 271-278
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.