The Trees of Bairnsdale

Plane Tree Avenue and Eucalypt remnant on Mitchell River

Bairnsdale is a tree friendly town. It has a treed median strip along the Princes Highway and Main Street from the western edge of town almost to the river with natives to the west of the hospital and exotics in the garden in the main part of town. Along the Mitchell River the Bairnsdale Urban Landcare Group (BULG) are gradually restoring the native vegetation and on the south-west side from the old port there is a wonderful avenue of plane trees.

I have written frequently of the importance of trees as a ‘carbon store’. See here and here. It is an often repeated slogan that trees are the only form of ‘carbon capture and storage’ that actually works. I have made a few calculations of the carbon stored in some of the town’s trees. The avenue of 14 well established plane trees – a deciduous hardwood – are of indeterminate age. Each stores about 32 tons of carbon or 100 tons of CO2 equivalent. The remnant eucalypts (see image above) along the river of which there remains a small number store upwards of 90 tons of carbon each. As a carbon store the hardwoods almost double the softwoods and this difference increases with age. In another example seven attractive Eucalypts (spotted gum?) found at the north end of Pyke Street store about 5 tons of carbon each.

The plane trees as well as being a carbon store provide both shade and have a cooling effect via transpiration. The leaf area of a mature plane tree is many times the size of that of a eucalypt of comparable age or size. On a very hot days being under the plane trees by the river is the coolest spot in town. The expansion of the flying fox population from their main roosting site near the junction of McCulloch and Riverine Streets may be a threat to these magnificent trees. This expansion which has occurred the previous three summers (but so far not this year) may possibly be influenced by climate change but more probably is directly related to the food supply. Each time the plane trees suffered substantial leaf loss but have since recovered.

Trees such as the plane tree offer a double effect in terms of climate with mitigation via temperature moderation and with the removal of the most potent greenhouse gas – carbon dioxide – from the atmosphere. This is commonly known as carbon drawdown. Whilst the various local governments and volunteer organisations like BULG have done an admirable job there is plenty of ‘room for improvement’. The number of trees in the urban area could easily be doubled with an emphasis on shade trees near bitumen and built up surfaces combined with a mixture of natives where space is available.