Page 593 - Week 02 - Thursday, 18 February 2016
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Environmental weeds are one of the main threats to biodiversity in this country, with few natural places left that can be said to be totally free of weeds. The strategy in the territory is to use a risk-based approach to ensure priority areas are afforded the protection they need from the harmful effects of weeds. From the beginning of the financial year to 31 December, 5,849 hectares of land has thus far been controlled for weeds: 4,218 hectares of control has been provided by contractors; 1,485 by TAMS employees; and 145 hectares by ParkCare volunteers.
Approximately 57 different species of weeds have been targeted during the reporting period, with serrated tussock, St John’s wort, African lovegrass and broom accounting for nearly 75 per cent of the area controlled. These four species pose the greatest threat to the ongoing viability of our protected areas, and indeed to the viability of agricultural production. Serrated tussock, for example, has the potential to form monocultures, completely excluding native grasses or decimating the productivity of grazing pastures. Given the damage that aggressive weeds can do to our local environment, the ACT government is committed to controlling their spread to ensure they remain out of agricultural land and high-value conservation areas such as our native grasslands.
In considering the work completed to date, we should bear in mind weed control work in any given year is susceptible to prevailing weather conditions. Typically, over any given 12 months most weed control is delivered in the second half of the year where more stable weather patterns in late summer into autumn make for effective weed control during good growing conditions. The weather conditions thus far have provided for a slow weed year, which is a positive thing. However, experience suggests that, coming into the autumn period, weed activity will pick up again.
During the reporting period TAMS dealt with four instances of weed incursions in the territory of weeds which are not yet widespread in the territory but, should they become so, would cause great environmental, social and economic harm. I would like to summarise one such incursion, that of alligator weed, as I believe it demonstrates the critical importance a strong weed control program plays in the biosecurity of the territory and, in this case, the greater Murray-Darling Basin. Alligator weed is a devastating weed that grows in and around waterways. It has the potential to spread very quickly, choking out the natural environments, reducing water quality and sometimes causing localised fish death.
Alligator weed also has the potential to disrupt irrigation agriculture in the Murray-Darling Basin, where it can clog irrigation channels and compete with irrigation crops on a large scale. Many millions of dollars have already been spent on controlling the weed where it has occurred in the basin. Late last year a large infestation of alligator weed was reported at Acacia inlet in Lake Burley Griffin, and a smaller outbreak in Isabella pond in Tuggeranong. TAMS officers worked closely with NCA contractors to address the Acacia inlet outbreak and worked to destroy plants in Isabella pond. In addition, TAMS officers have commenced surveillance of the Molonglo River downstream of Lake Burley Griffin in an attempt to pick up any plants that may have spread.
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