Records of the Western Australian Museum 17: 237-248 (1995). 
- 01 ' v :cj v 
Biological inventory of Koolan Island, Western Australia 
1. Flora and vegetation 
G.J. Keighery 1 , Neil Gibson 1 , K.F. Kenneally 2 and A.A. Mitchell 3 
1 Wildlife Research Centre, Department of Conservation and Land Management, PO Box 51, Wanneroo, 
Western Australia 6065 
2 Science Publication Unit, Department of Conservation and Land Management, PO Box 104, Como, 
Western Australia 6152 
3 Department of Agriculture, Baron-Hay Court, South Perth, Western Australia 6151 
Abstract - A total of 282 plant taxa have been recorded from five major 
vegetation units on Koolan Island at the head of the Yampi Peninsula. This 
represents over a quarter of the flora recorded for the Fitzgerald Botanical 
District. A total of 12 new naturalised weeds were recorded from the island. 
The closure of the iron ore mine on Koolan Island and the removal of the 
town will provide opportunities to study both weed invasion and persistence 
and the establishment of a large permanent wetland in a sub-humid tropical 
environment. 
INTRODUCTION 
A biological survey of Koolan Island was 
undertaken over a week during the wet season of 
February 1993. This survey was supplemented by 
herbarium records and previous collections by 
KFK and AAM. This paper describes the flora and 
vegetation of the island, while a subsequent paper 
will describe the island's fauna. This work will 
provide a benchmark against which to measure the 
rehabilitation of the island following closure of the 
major iron ore mine in October 1993 after 29 years 
of operation. Despite a long history of exploration 
and mining on the island its flora and vegetation 
have been little studied, with the earliest 
collections in the Western Australian Herbarium 
(PERTH) dating from the mid 1960s (also see Beard 
1979). 
STUDY AREA 
Koolan Island is located 130 km north of Derby 
at the northern end of the Yampi Peninsula. It is 
separated from the mainland by a channel 1 km 
wide. The island is 13 km long and 5.5 km wide at 
its widest point, with the long axis of the island 
orientated NW - SE (Figure 1). Koolan is one of the 
many islands of the Buccaneer Archipelago. This 
area experiences a monsoonal climate with an 
annual rainfall of about 960 mm with most falling 
between December and March, Mean summer 
temperatures for Derby (some 130 km to the south) 
range from 35 to 37 degrees with high relative 
humidities (Bureau of Meteorology 1975). 
The island is essentially a series of parallel flat- 
topped ridges formed from steeply dipping beds 
of the resistant Warton and Pentecost Sandstones 
and a series of deeply incised creeks through softer 
Elgee Siltstone (Tyler and Griffin 1993). The 
adjacent mainland has essentially similar geology 
and geomorphology. The basal part of the 
Pentecost Sandstone on Koolan Island is composed 
of high grade haematite (iron ore) and was mined 
from 1965 until 1993. 
This ore proved to be of very high grade 
(average 65% iron) with over 50 million tonnes 
having been extracted. A smaller mine operated on 
nearby Cockatoo Island between 1957 and 1986. 
The main pit on Koolan Island is 1.5 km long, 45 m 
wide and was mined at the eastern end to a depth 
of 80 m below sea level. This pit will fill with fresh 
water from a natural aquifer once mining 
operations cease. 
The town associated with this mine was located 
at the eastern end of the island and had a 
population of 850 people. Most of the towns people 
left in October 1992 with complete closure planned 
by October 1993. It is planned that all buildings 
will be removed and all road surfaces removed 
and ripped. Only the airstrip will be left intact. 
METHODS 
During the wet season survey most of the field 
work was concentrated on the eastern two thirds 
of the island along roads and down creek lines. 
The area of Warton Sandstone along the southern 
edge of the island, supporting very open eucalypt 
woodland (Figure 1), was not visited due to time 
