240 
correlated to slope or aspect and occurred on both 
the Pentecost Sandstone and the Elgee Siltstone. In 
places it gave way to small groves of Callitris 
intratropica with understoreys dominated by 
Calytrix exstipulata. This community type has 
previously been recorded on the nearby Cockatoo, 
Irvine, Bathurst and Kingfisher Islands (previously 
known as the Wood Islands) some 30 km to the 
east on the same lithologies (Burbidge et al. 1978; 
K.F. Kenneally, unpub). 
Aerial photographs show a very open eucalypt 
woodland along the southern edge of the island 
coincident with the Warton Sandstone (Tyler and 
Griffin 1993). This area was not surveyed due to 
both time and access limitations. Woodlands on 
this substrate type have been described for 
Augustus, Heywood, Champagny, Unwins and 
Saint Andrew Islands of the Bonaparte Archipelago 
lying some 130 km to the north east (Burbidge et al. 
1978) and for an area in the proposed Prince 
Regent National Park (Miles et al. 1975). The 
composition of the woodlands on the Warton 
Sandstone is similar to the Eucalyptus miniata - 
Eucalyptus confertiflora open woodlands described 
above, but commonly also including Eucalyptus 
perfoliata, Plectrachne pungens, and less commonly 
Eucalyptus ferruginea and Acacia stipulosa. 
Large mangrove communities occur in two 
sheltered bays south of the settlement. In addition, 
much of the coastline of the island supports a 
narrow mangrove fringe (Figure 1). Four species of 
mangrove were recorded from the large stand 
immediately south of the settlement: Avicennia 
marina, Camptostemon schultzii, Excoecaria agallocha 
and Rhizophora stylosa. The mangrove communities 
are small and species poor compared to the much 
more extensive mangrove stands on the nearby 
mainland (Kenneally 1982). 
Small patches of vine forest dominated by 
Canarium australianum were found in the steep 
creek lines on the eastern end of the island (Figure 
1). Patch size ranges from just a few trees to several 
hectares in extent. The patches shown in Figure 1 
are those that were visited on the ground and / or 
were discernible on the photo-mosaic. There are 
undoubtedly more smaller patches than could be 
mapped at this scale. Koolan Island is at the south 
western edge of the main area of occurrence of 
rainforest in the Kimberley. The only patches 
further to the south west are those on the northern 
shore of King Sound and the coastal areas of the 
Dampier Peninsula (McKenzie 1991). 
More than 1500 patches of rainforest are 
scattered across the Kimberley. These range in size 
from a few tree crowns to more than 100 ha 
(McKenzie 1991). Kenneally et al. (1991) in a study 
of 99 Kimberley rainforests (largely vine forest) 
recorded 575 species. Only one of these species was 
endemic to the rainforest, with most species 
G.J. Keighery, N. Gibson, K.F. Kenneally, A.A. Mitchell 
occurring widely in a number of habitats across 
northern Australia. The reason for the widespread 
nature of most of these species appears to be both 
their ability to cope with nutrient-poor substrates 
and propagule dispersal by birds and bats 
(McKenzie 1991). Our data are consistent with this 
hypothesis. One hundred and one of the 575 
species recorded from Kimberley rainforest patches 
are found on Koolan Island. 
Koolan Island shares 45.5 and 52.1% of the taxa 
recorded from the two closest rainforest patches 
studied by Kenneally et al. (1991) (02/3 and 25/3 
on Yampi Peninsula, some 50 km to the east south 
east, with 33 and 46 species respectively). These 
data further indicate the widespread nature of the 
Kimberley rainforest flora. 
Twelve small beaches occurred in protected bays 
around Koolan Island. Most of the beaches are 
adjacent to mangrove community but, in addition, 
a distinct community develops on the mobile 
sands. Common components of these beach 
communities include Spinifex longifolius, Commelina 
ensifolia, Ipomoea pes-caprae and Abrus precatorius. 
Two beaches to the south east of the settlement 
and another north of the airfield were frequently 
used by the residents for recreation and were 
serviced by gravel roads. 
Minor vegetation units include the narrow 
fringing vegetation of Melaleuca viridiflora along 
some of the larger creek lines, and the Callitris 
intratropica stands. Species-poor haematite scree 
communities, seen at several locations. These were 
dominated by combinations of trees and / or 
shrubs. Common species included Callitris 
intratropica, Canarium australianum, Pouteria sericea, 
Vitex acuminata and Pavetta kimberleyana. All of 
these units are restricted to a few hectares in 
extent. 
DISCUSSION 
The flora and vegetation of Koolan Island is very 
similar to both the adjacent mainland and nearby 
Cockatoo Island. Tt is a sub-humid tropical 
sandstone flora which is widespread across 
northern Australia. Twelve new naturalised weeds 
for Western Australia were recorded from the 
island ( Allamanda cathartica, Antigon leptopus, 
Cascabela thevetia, Cassia fistula, Delonix regia, 
Gliricidia sepium, Moringa oleifera, Peltophorum 
pterocarpa, Ruellia tuberosa, Senna alata, Tecoma stans, 
Turnera ulmifolia). Antigon leptopus, Delonix regia, 
Tecoma stans, and Turnera ulmifolia are also 
common weeds on Christmas Island. 
One native species was found to be restricted to 
Koolan Island. This was an apparently undescribed 
species of smooth, white barked eucalypt (E. aff. 
cadophora Keighery and Gibson 15 and 95). This 
taxon was found occasionally across the island. 
