Gr. Robinson et al., A CENTURY OF CHANGE IN THE STATEN-ISLAND FLORA - ECOLOGICAL CORRELATES OF SPECIES LOSSES AND INVASIONS, Bulletin of the Torrey Botanical Club, 121(2), 1994, pp. 119-129
We analyzed three consecutive floristic censuses of Staten Island, New
York, to determine (1) the general pattern of vascular plant species
gains and losses over 112 years (1879-1991), (2) the extent of increas
es in non-native species, and (3) ecological features that characteriz
e those species that were lost. Over forty per cent of the original na
tive species (53% of regionally rare and endangered species) are prese
ntly missing. Most of the losses have occurred during an accelerating
period of suburbanization over the last 60 yr. At the same time, the p
roportion of non-native species has increased from 19% to > 33% of the
flora, while average abundances of most native species apparently dec
lined. Species from different habitats were lost in similar proportion
s, indicating that broad-scale habitat alteration has been the main fa
ctor in the flora's decline. Only two ecological features examined wer
e statistically correlated with the missing species: (1) herbaceous sp
ecies were more vulnerable than woody plants; (2) species reported to
be uncommon in a previous census were more likely to be absent in the
next. Unless conservation measures are improved, further degradation o
f this historically rich and varied flora can be anticipated.