Page 3944 - Week 11 - Tuesday, 15 Sept 2009
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carbon storage levels, above ground—trees—and below ground. We also need to be looking at how much potential there is in fact to sequester carbon in woodlands and grasslands in the ACT. It is not all in trees.
Carbon sequestration relies on an ecosystem to be functional. The bushfires of 2003, which were commented on in the report and by my colleague Mr Rattenbury, not only destroyed a large number of trees and released a large amount of carbon but burnt the landscape generally right down to the humus level, taking away the ability of the former natural microbial processes to enhance the biodegradation of litter into stable soil humates within ACT forests—in other words, deep, rich, productive soils. The fires took away the ability of the landscape to significantly offset urban emissions, and it will be a long time, if ever, I fear, before these natural processes are fully restored.
The drought, of course, does not help. Adding extra nutrient to the soils by adding mulch and other organic matter will. This will help to cool the ecosystems and create a moister microclimate. This is especially important in our water catchment areas, as moist, healthy soils contribute to higher water yields as well as enhanced biodiversity and ecological values. With another hot, dry bushfire season fast approaching, we and the forest need all the help they can get. We should be collecting our organic matter and using it to mulch our newly planted trees and shrubs, not putting it into landfill.
That brings me to another major part of this story: waste. Organic waste is a vital part of the story of carbon sequestration. At present, almost 50 per cent of ACT household waste is made up of food and compostable waste and 25,000 tonnes of organic waste goes to landfill annually just from domestic household collections. In addition, a further 30,000 tonnes comes from the business sector, and we are still waiting for this government to produce a program which allows for organic waste collection.
In landfill, unfortunately all this buried food breaks down to produce methane, which is one of the worst greenhouse gases. It is 23 times as potent as carbon dioxide. Although the ACT landfill system does use a methane gas capture system to convert methane to energy, these systems only capture a fraction of the toxic gases, and methane is only part of the waste and climate change story in any case. In terms of carbon sequestration, we need to start understanding that organic waste is not waste. It is in fact part of the carbon cycle and it needs to be processed into another valuable product, compost.
Re-sequestering this organic matter would reduce landfill emissions and greatly improve the capacity of our soil. Merely increasing by 0.5 per cent the organic carbon in two per cent of Australia’s agricultural land would sequester all of Australia’s greenhouse emissions. Instead, we continue to put these into our landfill.
Recent trials in New South Wales, such as the city-to-soil and the groundswell projects, have demonstrated that, with the right support, residents can separate organic matter from their garbage, with extremely low levels of contamination. Our neighbours in Goulburn and Queanbeyan participated successfully in these trials and now we would like the ACT to do the same.
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