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Pest plant control is an important part of the conservation of the natural vegetation of Whyalla Conservation Park. There is also a requirement under the Animal and Plant Control Act to control certain pest species. There are other species which pose a threat to natural vegetation and which are desirable to control.
Disturbance plays a major role in weed infestation in the Park, in conjunction with the network of tracks which act as vectors.
Considerable Boxthorn control was undertaken a few years ago and Boxthorn is no longer considered to be a significant weed species although vigilance is required to control regrowth and re-infestation. This is also the case for Bathurst burr. The major pest plant species are, in priority order, Horehound, Three-cornered Jack, Saffron thistle, Wards weed and Onion weed. Maltese cockspur is also present in the Park. Control measures have been undertaken for some of these species and are ongoing.
Potential pest plants
Several potential pest plant species have been found in close proximity to the Park or within it. Examples are Carrion flower (Stapelia variegata), Prickly-pear or Indian fig (Opuntia ficus-indica) and Devils rope (Opuntia imbricata). Another potential pest plant species, Gazania (Gazania linearis) is widely planted in Whyalla and is showing signs of naturalising on the northern border of the city.
The long rectangular shape of the Park, results in a boundary of approximately 14 kilometres, enclosing a comparatively small area. These factors enhance the opportunities for pest species to enter the Park. A rabbit proof fence around the Park is not practical due to high costs and problems of vandalism and maintenance.
Pest species such as foxes, rabbits and cats are now quite common. These are priority species.
Rabbit control work has been undertaken in the Park. Most rabbit warrens have been mapped and fumigation carried out on a regular basis. Control measures should be extended into neighbouring land where the landholder approves.
The re-location of the Whyalla refuse dump to a site five kilometres south of the Park may provide a source of pests (particularly cats) which may, in turn, threaten the Park.
The provisions of the Country Fires Act 1989 applies to NPWSA Reserves. As a landholder, the Department is obliged to protect life and property from fire, and to prevent or inhibit the outbreak of fire or its spread. The Whyalla Conservation Park is also within the Whyalla MFS district, as gazetted under the South Australian Metropolitan Fire Service Act 1936-1987. The Whyalla SAMFS will therefore respond to, and will initially be responsible for the control of, any occurrence of fire within the Park.
The Ranger responsible for the Park is based in Port Augusta. NPWSA firefighting equipment is based at Mambray Creek (Mt Remarkable National Park) and Port Augusta. Response to fires in Whyalla Conservation Park are dealt with in the NPWSA North Region Fire Response Plan and the SAMFS Whyalla Response Plan.
The closest fire stations to the Park are Whyalla and Whyalla West Metropolitan Fire Service stations (response time - 15 min). If the MFS requires assistance, a second alarm is declared and assistance from other stations is requested (Carpenter, 1993, pers. comm.). The nearest other SAMFS station is Port Augusta (50 min) and the nearest CFS units are at Stirling North (55 min) and Iron Knob (45 min).
Any fire may be detrimental to the continuation and/or preservation of the Western myall low open woodland association. As in the case of most Acacias, Western myalls are killed easily, particularly if a fire burns to the base of their trunks, or the canopy is 100% scorched, and the average mortality rate in a fire is 80% (Lay, 1990). No fuel reduction burning will be undertaken in the Park for this reason.
One source of ignition of fire in the Park is likely to be from visitor activity. The Park is subject to a district wide ban on open fires from 1st November to 30th April each year. In addition, wood fires and barbecues are banned at other times of the year due to the potential impact on resources, and the risk of fires escaping. Gas barbecues are permitted all year, except on total fire ban days.
The ETSA power lines which traverse the Park are also a potential source of ignition.
Whyalla Conservation Park has a comprehensive network of internal tracks, of which strategic tracks will be maintained for management access. Access to the Park for fire protection and suppression is adequate.