The soil seed bank and its relationship to the aboveground vegetation in deciduous forests in New York City

Abstract

The soil seed bank was studied in two deciduous forests in Bronx (New York City), NY. The purpose of this study was to determine how the biotic andabiotic differences between urban and rural forests arereflected in urban forest seed banks. Soil samples werecollected in two consecutive years and monitored for emergencein the greenhouse over two years. In 1993, the mean number ofemergents ranged from 4636 to 5373 m-2 (excluding ferns), or from 6972 to 9651 m-2 (including ferns). In 1994, the mean number of emergents ranged from 1656 to 2013 m-2 (excluding ferns), or from 5019 to 5992 m-2 (including ferns). Graminoids and fernscombined accounted for approximately 70% of all emergents eachyear. Three taxa, Rubus spp., Betula lenta, and Liriodendron tulipifera, comprised 60–80% of the woody emergents and were theonly woody taxa to exhibit delayed germination. A substantialnumber of forbs, graminoids and ferns (15–50%) exhibiteddelayed germination. The nonnative woody species Ailanthusaltissima, Morus alba, and Celastrus orbiculatus were absentfrom the aboveground vegetation of some forest plots yet werepresent at low densities in the seed bank. A greater meandensity of emergents and the presence of nonnative species arethe main differences between the seed banks of these urbanforests and those reported for similar nonurban forests in thisregion.