species, and so habitat conservation remains key to
the conservation of the native species.
Plants in peril
With all the attention given to animals in these
pages, it is important to note, for the sake of bal-
ance, that the problems also extend to plants.
According to the IUCN 1997 Red List assessment
(Walter and Gillet 1998), the total number of
confirmed plant extinctions globally since AD 1600
is 396, with a similar number of unconfirmed
losses, and perhaps as many as 33 500 threatened
species. Table 11.2 provides a figure of 384 extinc-
tions. The equivalent figures from the 2004 IUCN
Red List (www.redlist.org/;visited March
2006) are 100 extinct, and 8321 threatened, which
amounts to a rather more conservative appraisal.
The variation between these assessments high-
lights the uncertainty associated with such efforts,
and the need for continued efforts to improve the
resolution of conservation assessments (cf.
Whittakeret al. 2005). With plants, given the lack of
adequate species-level fossil data, it is particularly
difficult to assess extinctions from the prehistoric
period on islands: there undoubtedly have been
numerous anthropogenic extinctions that will
remain long undetected (for an example, see
Flenley 1993). Once again, the figures given in
Table 11.8 should thus be taken as of largely indica-
tive value. The table summarizes the 1997 Red List
data on plant extinction and threat in islands or
archipelagoes that have lost more than 5 species.
According to this assessment, anthropogenic
extinctions of plants from the 12 most affected
islands/archipelagos total 120 species (30% of all
the extinct species), whereas 137 more were con-
sidered possibly extinct. In global terms, these fig-
ures indicate a disproportionate rate of loss and
threat concentrated on islands. Geographically, the
pattern of vascular plant species loss is rather sim-
ilar to that of vertebrate animals (Table 11.6), with
fairly high numbers of possible or confirmed
extinctions in Hawaii, the Mascarenes, the
Caribbean, and St Helena.
St Helena provides a classic example of the dam-
age to a remote oceanic island brought about by
incorporation into European trading routes. It is an
isolated island of 122 km^2 , located in the South
Atlantic. Since discovery by the Portuguese in
AD1502, the vegetation has been completely trans-
formed by browsing, grazing, erosion, cutting for316 ANTHROPOGENIC LOSSES AND THREATS TO ISLAND ECOSYSTEMS
Table 11.8Islands and archipelagoes that account for more than five extinct or possibly extinct vascular plant
species since AD1600, attributable to anthropogenic activities. Sources: Walter and Gillet (1998); Primack and Ros
(2002); Groombridge and Jenkins (2002). As noted in the text, the 2004 IUCN assessment is less pessimistic on both
extinctions and threatened species. These figures should therefore be treated with caution
Islands No. of extinct No. of possibly No. of extinct + No. of threatened
species extinct species possibly extinct sp. species
Hawaii 3 99 102 623
Mauritius 38 4 42 256
Cuba 23 0 23 811
Madagascar 0 19 19 306
French Polynesia 12 0 12 157
Rodrigues 9 2 11 51
New Caledonia 5 5 10 481
St Helena 10 0 10 41
Réunion 6 1 7 95
Tasmania 7 0 7 142
New Zealand 7 0 7 236
Fiji 0 7 7 72
Total 120 137 257 3271