The ABC (Australia’s equivalent of the UK BBC) in its only ever article specifically on Carbon Debt (as based on a Search of the ABC revealing 20 related items) (2008): “The replanting of Gippsland forests is creating carbon sinks that could help stem global warming… Brendan Condon - the director of not-for-profit organisation Climate Positive, which works with businesses and households to measure, reduce and offset carbon emissions - puts it, this area is a perfect carbon sink. "One of the unique things about the Strezlecki's [a mountain range in Gippsland, Victoria, Australia] is it's the highest carbon yield forest type that you can find on the Australian land mass, or pretty much anywhere in the world," Brendan says. "It was once covered by forest giants - these Eucalyptus Regnans trees that grew over 100 metres in height. They hold around 1400 tonnes of carbon dioxide equivalent per hectare. If you look at the core Strezlecki forest area it held around half a billion tonnes of carbon dioxide before a lot of it was cleared. It's a massive opportunity to use eco-systems to sink carbon and give us a hand with the mess we are in with global warming," Brendan says” (Catherine McAloon, “Trees to repay carbon debt”, ABC Gippsland, 30 July 2008: http://www.abc.net.au/local/stories/2008/07/29/2318107.htm ).
[Editor note: Dr David Lindenmayer et al. have identified the SE Australian temperate moist Eucalyptus regnans forests as having the world's highest known total biomass carbon density (living plus dead) of 1,867 tonnes carbon per ha (2009): “From analysis of published global site biomass data (n = 136) from primary forests, we discovered (i) the world's highest known total biomass carbon density (living plus dead) of 1,867 tonnes carbon per ha (average value from 13 sites) occurs in Australian temperate moist Eucalyptus regnans forests, and (ii) average values of the global site biomass data were higher for sampled temperate moist forests (n = 44) than for sampled tropical (n = 36) and boreal (n = 52) forests (n is number of sites per forest biome). Spatially averaged Intergovernmental Panel on Climate Change biome default values are lower than our average site values for temperate moist forests, because the temperate biome contains a diversity of forest ecosystem types that support a range of mature carbon stocks or have a long land-use history with reduced carbon stocks. We describe a framework for identifying forests important for carbon storage based on the factors that account for high biomass carbon densities, including (i) relatively cool temperatures and moderately high precipitation producing rates of fast growth but slow decomposition, and (ii) older forests that are often multiaged and multilayered and have experienced minimal human disturbance. Our results are relevant to negotiations under the United Nations Framework Convention on Climate Change regarding forest conservation, management, and restoration. Conserving forests with large stocks of biomass from deforestation and degradation avoids significant carbon emissions to the atmosphere, irrespective of the source country, and should be among allowable mitigation activities. Similarly, management that allows restoration of a forest's carbon sequestration potential also should be recognized” (Heather Keith, Brendan G. Mackey, and David B. Lindenmayer PNAS July 14, 2009, vol. 106 (28), pages 11635-11640: http://www.pnas.org/content/106/28/11635.short ).
However David Lindenmayer and Chloe Sato have found that this Mountain Ash ( Eucalyptus regnans) system is facing collapse due to fire and logging (2018): “Increasing numbers of ecosystems globally are at risk of collapse. However, most descriptions of terrestrial ecosystem collapse are post hoc with few empirically based examples of ecosystems in the process of collapse. This limits learning about collapse and impedes development of effective early-warning indicators. Based on multidecadal and multifaceted monitoring, we present evidence that the Australian mainland Mountain Ash ecosystem is collapsing. Collapse is indicated by marked changes in ecosystem condition, particularly the rapid decline in populations of keystone ecosystem structures. There also has been significant decline in biodiversity strongly associated with these structures and disruptions of key ecosystem processes. In documenting the decline of the Mountain Ash ecosystem, we uncovered evidence of hidden collapse. This is where an ecosystem superficially appears to be relatively intact, but a prolonged period of decline coupled with long lag times for recovery of dominant ecosystem components mean that collapse is almost inevitable. In ecosystems susceptible to hidden collapse, management interventions will be required decades earlier than currently perceived by policy makers. Responding to hidden collapse is further complicated by our finding that different drivers produce different pathways to collapse, but these drivers can interact in ways that exacerbate and perpetuate collapse. Management must focus not only on reducing the number of critical stressors influencing an ecosystem but also on breaking feedbacks between stressors. We demonstrate the importance of multidecadal monitoring programs in measuring state variables that can inform quantitative predictions of collapse as well as help identify management responses that can avert system-wide collapse” (David Lindenmayer and Chloe Sato, “Hidden collapse is driven by fire and logging in a socioecological forest ecosystem”, PNAS May 15, 2018, 115 (20), 5181-5186: http://www.pnas.org/content/115/20/5181 ).
Without re-afforesting arable land we could presently obtain 1.7 GtC/yr (straw from agriculture) + 4.2 GtC/yr (total grass upgrowth from grasslands upgrowth) + 6 GtC/yr (possible sustainable woodharvest) = 11.9 GtC/yr [43.7 Gt CO2-equivalent/year] as compared to the revised, man-made annual greenhouse gas (GHG) pollution of 64 Gt CO2-equivalent per year (taking land use and the realistic, 20-year time frame CH4 Global Warming Potential into account (Robert Goodland and Jeff Anfang. “Livestock and climate change. What if the key actors in climate change are … cows, pigs and chickens?”, World Watch, November/December 2009: http://www.worldwatch.org/files/pdf/Livestock%20and%20Climate%20Change.pdf ; p224, Progress in Thermochemical Biomass Conversion, volume 1, IAE Bioenergy, ed. A,V, Bridgewater, Blackwell Science: http://books.google.com.au/books?id=rdqGX0LEg7sC&pg=PA224&lpg=PA224&dq=Gt++biomass+%22arable+land%22&source=bl&ots=KfEmoUUg6T&sig=EuLvPTf4uJHK6Wq7jbpQ3WLHcnM&hl=en&ei=UdzISZXlDpmMsQPH3cyMAQ&sa=X&oi=book_result&resnum=1&ct=result#PPP1,M1 ; Gideon Polya, “Forest biomass-derived Biochar can profitably reduce global warming and bushfire risk”, Yarra Valley Climate Action Group: https://sites.google.com/site/yarravalleyclimateactiongroup/forest-biomass-derived-biochar-can-profitably-reduce-global-warming-and-bushfire-risk ).