Geoscience Reference
In-Depth Information
The cultivation of islands, therefore, represented a conflict between the wish
of National Parks officials to conserve native island habitats and the desire of
settlers for productive land.
Another infestation of prickly pear was reported in 1951, at Pioneer Point
in the Whitsunday Group, and in 1953 a diesoline flame-thrower was used in
an attempt to control weeds at Long Island, in the Molle Group. In contrast,
other exotic species were introduced deliberately, as at Long Island in 1956, when
reportedly severe sand erosion at the island's beaches prompted the introduction
of marram grass to stabilise the sand . 46 B y 1960, the control of some exotic species
on islands had become a significant problem. At Brampton Island, a helicopter
was used to spray pesticide in an attempt to destroy Lantana , which had heavily
infested the island, as the District Forester at Mackay described: 'The Lantana has
spread right through the bush and presents an impenetrable thicket in places' . 47
In the same year, the Lessees of North Keppel Island were required - as conditions
of Special Lease 10756 - to clear the island of 'noxious weeds, noxious plants,
Lantana and prickly-pear within six months' . 48
The effects of the introduction of exotic vegetation species to some island
ecosystems interacted in various ways with other human activities. For example,
P. H. Anderson, the Lessee of Lady Musgrave Island, complained in 1966 that he
had planted pawpaw and coconut trees on the island and those had flourished
until someone brought goats to the island, which destroyed the plantations . 49
At Goold Island, in 1968, the landscape was altered as a result of interactions
between deforestation and the spread of weed species; the District Forester at
Atherton reported that at Goold Island introduced weeds had been present for
more than 50 years, but they were spreading increasingly rapidly as a result of
forest clearanc e. 50 In one report, A. S. Thorsborne, a naturalist, stated:
Introduced weeds are taking over [at Goold Island] because so many trees
have been and still are being cut down to supply tent poles and firewood. […]
The sun beats down on the cleared spots and the native plants and shrubs
die - in places there is now no vegetation at all and burr and other noxious
weeds infest the vegetated parts . 51
This report indicates that the direct impacts of vegetation clearance were followed
by ecological succession once the pre-existing vegetation had been removed.
Other references to introduced plant species are found in documentary
sources: for example, potatoes and onions planted by campers were found at
Lady Musgrave Island in 1975; rubbervine was growing at Holbourne Island in
1998; several exotic species colonised Hinchinbrook Island; and Lantana and
'sensitive plant' grow at Dunk Island (QNPWS, 1998a, 1999b; QPWS 2000) . 52
Overall, the evidence suggests that some significant changes in island vegetation
have occurred due to the introduction of exotic plant species. However, further
investigation of the vegetation histories of those islands is required if those
changes are to be reconstructed in greater detail.
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