Our tall wet eucalypt forests are some of the most carbon-dense native forests in the world. The logging industry and it’s lobbyists often argue that wood products in buildings and furniture become long-term storage for carbon.
However, these claims are misleading. Most native trees cut down in Tasmania become woodchips, pulp and pallets, which have short lifespans before going to landfill. In landfill, the wood breaks down and releases carbon back into the atmosphere.
On the other hand, our evolving carbon market means Australia’s native forests are extremely valuable as long-term carbon stores. It’s time to recognise logging for short-lived wood products is a poor use of native forests.
The problem with logging native forests
Tasmania has carbon rich eucalyptus regnan and eucalyptus obliqua forests that have evolved over millennia and hold vast carbon stores not only in the trunks of the trees, but also in the carbon rich soils which are significant carbon sinks in themselves.
These forests can store up to 1,140 tonnes of carbon per hectare for centuries when left to their natural cycles, and when left intact these tall wet forests have proven to hold moisture in the landscape acting as fire buffers when bushfires, and escaped logging fires, move through.
Myth one: storing carbon in wood products
The first myth we want to address is logging native forests is beneficial because the carbon is stored in wood products. This argument depends on the proportion of forest biomass ending up in wood products, and how long they last before ending up in landfill.
On average, logs suitable to be sawn into timber make up only an average 35% of total logs cut from native forests.
Of this 35%, sawmills convert less than 40% into sawn timber for building and furniture. Offcuts are woodchipped and pulped for paper manufacturing, along with sawdust increasingly being touted as a feedstock to make wood pellets for biomass heaters.
Sawn timber equates to an average 14% of log volume cut from native forest. The remaining 84% of logs cut are used in short-lived and often disposable products like copy paper and pallets.
The lifespan of paper products is approximately three years. Although around 75% of paper and cardboard is recovered, recycling is growing more uncertain and untransparent, with recovered paper being sent to landfill.
The maximum lifespan of a timber pallet, which are predominantly made from native forest eucalypt, is seven years. At the end of their service, timber pallets are sent to landfill, chipped for particleboard, reused for landscape mulch or burnt for energy generation, again emitting more carbon.
Longer-lived wood products, such as the small proportion of native timber used in building and furniture, have a lifespan of around 90 years. These wood products are used to justify logging native forests. The majority of timber used in construction consists of plantation softwood, not native forest hardwood.
But at the end of their service life, the majority of these wood products also end up in landfill, or burnt when a building is demolished or renovated.
Myth two: the need to log South East Asian rainforests
A second myth is using logs from our native forests will prevent logging and degradation of rainforests across South East Asia, particularly for paper production.
This is patently absurd. The wood from Tasmania’s, or any of the Australian states, plantation sectors – which are timber farms, rather than trees growing “wild” in native forests – could replace native forest logs used for paper manufacturing several times over.
In fact, in 2016-17 89% of logs used to make wood pulp (pulplogs) for paper production in Victoria came from plantation trees, with the majority of hardwood logs exported.
And Australia is a net exporter by volume of lower-value unprocessed logs and woodchips.
Processing pulplogs from well managed plantations instead of exporting them would give a much needed jobs boost for local economies.
With most of these plantations established on previously cleared farmland, they offer one of the most robust ways for the land use sector to off-set greenhouse gas emissions.
The time is right for Australian governments to develop a long-term carbon storage plan that includes intact native forests.
Logging results in at least 94% of a forest’s stored carbon ending up in the atmosphere. A maximum of 6% of its carbon remains in sawn timber, for up to 90 years (but typically much shorter). This is patently counterproductive from a carbon-storage point of view.
Nothing can compete with longevity of storage in a living forest particularly when you consider the small proportion of a logged forest that ends up in a medium or ‘long lived’ wood products. The recovery rate of sawn timber from a sawlog is less than 30 per cent and the percentage of sawlogs in a forest can be as low as 10 per cent… which is why markets for ‘waste’ or pulp logs are so critical for economic viability .