Page 3940 - Week 11 - Tuesday, 15 Sept 2009
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The report looks at the sequestration capacity of the vegetation biomass in the ACT. It covers how much of the 2008 carbon stock is contained in the biomass currently and how that stock will change between now and 2015. The ACT was divided into urban estate and non-urban estate to conduct the study. There were a number of interesting points to emerge. Non-urban estate includes the arboretum, former pine plantations and unplanted parks and reserves in the urban environment. Urban estate includes streetscapes but not residential gardens. Non-urban estate will sequester 108,000 tonnes of carbon between 2008 and 2015. Almost half that total comes from radiata pine plantations—some 51,000 tonnes. Native vegetation sequesters 57,000 tonnes, and urban estate will sequester 98,000 tonnes. Therefore, the non-urban native vegetation will sequester only 28 per cent to 2015 while the urban estate will collect 48 per cent.
It is worth noting that the bushfires had a significant effect on non-urban estate, emitting an estimated 2.833 million tonnes of carbon through combustion and a net increase of 1.613 million tonnes in debris regrowth offset by decaying debris. It is worth noting also that the arboretum is expected to add 2,000 tonnes of carbon over seven years, and raising Cotter Dam will add 18,000 tonnes. There are a number of interesting parts to the work in relation to the Cotter Dam, in particular, and that is, of course, one of the challenges that will be faced. We know that there are mitigation measures; we know that there are offsets in relation to Cotter Dam. The carbon sequestration audit actually states that, assuming all planted trees in a 1,000-hectare area of native species revegetation survive and there is no fire event or other disturbance, modelling indicates it will take approximately 11 years to sequester the volume of carbon emitted by the inundated vegetation. That seems a reasonable approach and that seems a reasonable amount of time, given the importance of this project to the community and given the fact that the Cotter Dam will last for many, many years beyond those 11 years.
This is important and interesting work but, like anything in this debate, it is a single measure that must be taken into consideration with other factors. It will be part of the overall picture as we look at this issue in coming years. The sequestration of carbon will simply be one factor in mitigation of emissions. I commend the paper. I think it has an interesting contribution to make to the debate, and we look forward to seeing further studies that come out both from the ANU and, no doubt, from the ACT government in the future.
MR RATTENBURY (Molonglo) (11.50): I welcome the opportunity to speak about this report, A carbon sequestration audit of vegetation biomass in the Australian Capital Territory. I also welcome the report, and I agree with the minister that it provides a useful contribution to the climate change debate and a useful analysis for the government in the lead-up to their establishment of a climate change target and energy policy for the ACT. These issues are, after all, interconnected, and this report on carbon sequestration should help inform any offsets policy the government establishes on the way to zero net emissions in the ACT.
Trees are an important part of our response to climate change, for building climate resilience, for preventing erosion, for biodiversity, for urban cooling in a climate where our days are getting hotter and drier, and as a carbon store. New evidence from
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