Logging Coupe Burns and Greenhouse Gas Emissions

Usually in autumn the forestry department (currently DELWP –Department of Environment, Land, Water & Planning) carry out asset protection burns across Victoria. At the same time the vegetation left in logging coupes – by now bulldozed into windrows and partially dried – is also burned. These burns contribute a large amount of greenhouse gas to the atmosphere and from experience I know that these burns can be intense, like big bonfires. One recent twitter account (above) noted that as well as the ‘asset protection’ burns in the Yarra Ranges there were also 37 logging coupe burns which the Melbourne Age had conveniently omitted from an article on the smoke pollution aspect of the burning on winemaking. It prompted me to do some very rough, back of the envelope, calculations on how much greenhouse gas was produced by these burns.

Starting with 1900 tons of carbon calculated as stored in mature mountain ash forest I proceeded as follows. I assumed that logging of other species (messmate) and less mature forests reduced this figure to 60% giving an average of carbon per hectare of the coupes logged at 1140 tons. I also assumed that 50% of this carbon was removed as logs leaving 570 tons per ha in the form of heads, leaves, stumps, roots and non-targeted species lying in the coupes in windrows.

This was then multiplied by an estimated average size of the coupe of 24 hectares, by the number of burns carried out (37) and by converting the carbon to carbon dioxide by a multiple of 3 – the weight of gas following the combustion process where each atom of carbon combines with 2 slightly heavier atoms of oxygen. The result is astounding. These Yarra Ranges coupe burns produced as much CO2 – more than 1,500,000 tones – as 60,000 Australian citizens produce in a year.  Alternatively each hectare of coupe burn produces 1690 tons of CO2 – a rule of thumb that can be applied across the State, especially to Gippsland and the Alps.

This calculation does not account for other greenhouse gases produced in this process, mainly methane and nitrous oxides. Further there is the total of greenhouse gases from those ‘asset protection’ burns designed specifically to protect the timber resource for future logging (I hope to look into this soon by examining the current DELWP fire protection plans and the Phoenix fire model). Nor is there any accounting of the CO2 produced in the felling, transporting and processing of the logs. How much CO2 then is produced per timber and forestry worker?  At a nominal value or cost of $30 per ton of CO2 the logging industry, and the employment it provides, can be classified as heavily subsidised indeed.