Tasmania is the only Australian state or territory with net negative carbon emissions. The large annual uptake of carbon by native forests regrowing after earlier logging or wildfires more than offsets emissions from energy generation, transport, and other sources. Despite the beneficial contributions from both public and private native forests managed for wood production and other forest values, anti-forestry lobbyists regularly use the media to claim that harvesting of Tasmania’s native forests leads to large net emissions of carbon. Such claims are demonstrably untrue and reflect a poor understanding of the flows of carbon in harvested forests and the wood products produced from them.
Firstly, it is important to note that 60% of Tasmanian native forests are in conservation tenures and thus excluded from wood production. Where harvesting does occur in available and suitable public and private forests, it is now mostly in regrowth forests, unlike in the past, when older and higher-carbon-density forests were being harvested. The sustainable harvesting of Tasmania’s native forests is underpinned by a world-class forest practices system that includes a legislated Code of Forest Practice and an independent Forest Practices Authority that monitors compliance with that Code.
Accounting for the effects of timber harvesting on carbon emissions is complicated by the diversity of forest types involved, the different timber harvesting systems used, and the relic effects of past logging and wildfire. Despite the claims of anti-logging advocates, clear-felling and burning is used only in certain forest types, and selective harvesting is now the most common harvesting system employed.
Publicly available data from ABARES shows that in 2022-23, 935,000 cubic metres of log was produced from the State’s native forests. Of this, about 200,000 m3 came from privately-owned native forests, while 735,000 m3 was from the available and suitable portion of the public native forest estate. This level of annual log production from Tasmania’s native forests has been steady for the last 12 years.
We know from detailed research that each cubic metre of harvested wood contains approximately 1 tonne of carbon dioxide equivalent (CO2-e). We also know from extensive field measurements across many forest harvesting operations, that approximately 70% of felled biomass is removed off-site in harvested logs (which is considerably more than the 40% claimed by anti-logging advocates); while the remaining 30% is left in the forest to be either burnt or to decay over time.
Using the information in the previous paragraph, the total carbon in the felled trees in public forests that produced about 735,000 m3 of logs annually is estimated to be 1.05 Mt CO2e. Even if we assumed that all that carbon was emitted (which it is clearly not as discussed below) it would represent only 30% of that emitted annually from Tasmania’s highest emitting sector (Energy) (+ 3.5 Mt CO2-e).
Part of the carbon in harvested wood enters long-term storage either whilst in service or in landfill. Wood is also used in construction to substitute for high-emission alternative materials (steel, concrete, and aluminium) and to create wood products that might otherwise be sourced from overseas, where production emissions are much higher than in Australia. When these factors are properly assessed in a lifecycle analysis, it has been shown that sustainable harvesting does not cause net carbon emissions and that harvesting leads to greater mitigation of carbon emissions than an alternative no-harvesting forest management option.
Claims by anti-forestry activists that harvesting of native forests is the largest contributor to carbon emissions in Tasmania are wrong.
The Australian government uses IPCC-approved methods to produce the National Inventory Report on changes in forest carbon. This includes changes in forest carbon stocks as well as change in the carbon pool in harvested wood products. The substitution benefits of using wood are not credited to the forest sector but are still beneficial to Australia’s overall net carbon balance.
The Tasmanian government (2024) has summarised and interpreted data from the National Inventory Report showing that Tasmania overall was carbon negative by 4.34 Mt CO2-e in 2022. This is largely because both harvested private native forests (minus 6.06 Mt CO2-e) and harvested multiple use State forests (minus 5.54 Mt CO2-e) are acting as major carbon sinks. This is largely due to the carbon being stored in regrowth generated by past wildfires and harvesting events.
Sequestration of carbon has been relatively steady in the private forest estate for the last decade, and relatively steady in multiple use State forests since 1990 despite very large reductions in wood harvests during that period. Clearly, sustainable harvesting of native forests is not depleting forest carbon stocks in Tasmania.
The Tasmanian public deserves better than to be repeatedly deceived by false claims that native forest timber harvesting is a major source of carbon emissions.
