Why are old trees so important?

Many animals use trees for habitat in Australia, with animals from all major fauna groups solely depending on them for shelter, refuge and food. Possums eat Eucalyptus leaves while birds, flying foxes and small tree-dwelling mammals feed off flower nectar of many different tree species. Trees provide shelter via hollows, which are an essential habitat feature for birds, arboreal mammals, frogs and some tree dwelling snake species. Some hollows even naturally store water which has been shown to be important drinking sources for Feather-tailed Gliders and tree frogs. Some tree species found locally around Sydney, such as the Smooth-barked Apple (Angophora costata) and the Blackbutt (Eucalyptus pilularis) are able to produce large hollows which are essential nest habitat for the Powerful Owls (Ninox strenua).

 

Australian Owlet Nightjar (Aegotheles cristatus): A bird which is entirely dependent on tree hollows for shelter | Copyright Chad Beranek 2016

Australian Owlet Nightjar (Aegotheles cristatus): A bird which is entirely dependent on tree hollows for shelter | Copyright Chad Beranek 2016

 

So where does tree age come into the picture? Tree age is important as for hollows to form a tree must be very mature. The age at which hollows to naturally form varies among tree species. For example, Blackbutt hollows start forming around 100 years old. At 140 years of age, the average Blackbutt will have numerous smaller sized hollows which are usable for small mammals and birds. For larger hollows to develop to accommodate larger animals, a Blackbutt will need to reach an age of around 210 years of age.

 

Sugar Glider (Petaurus breviceps): Require old growth trees for shelter | Copyright Chad Beranek 2015

Sugar Glider (Petaurus breviceps): Require old growth trees for shelter | Copyright Chad Beranek 2015

 

The process that occurs for hollows to form is one of natures many fascinating processes. Firstly a tree must receive some kind of damage, which occurs naturally from twigs or branches breaking off. This unprotected scar then becomes infected by fungus which proceeds to rot the wood. This fungal infection enables easy access for termites which then make a nest in the rotting wood and feast on the fungus and the lignin in the wood. Once termites have established a nest, loose bits of the wood and termite nest will dislodge and thus form a hollow. Once again it must be remembered that this process cannot happen over night and requires decades to create viable habitat hollows.

 

 

Now given all these facts, it really puts perspective on current law practices which involve trees. Given how vitally important old growth hollow bearing trees are to a huge amount of different species, including many threatened species, why does the law make it so easy for trees to be cut down? While some trees may be a hazard for property, many of these laws are being abused just so a property owner can get better water views in attempt to get better property value.

 

A stand of Blackbutt (Eucalyptus pilularis) coexisting fine in suburbia | Copyright Chad Beranek 2015

A stand of Blackbutt (Eucalyptus pilularis) coexisting fine in suburbia | Copyright Chad Beranek 2015

 

In conclusion, we must pay respect to trees and pay even more respect to elderly trees! Instead of cutting older trees down to mitigate potential property damage, first seek other potential options, such as pruning more hazardous branches, leaving the tree to stand. Also be on the lookout for illegal tree lopping which is becoming a bigger occurrence these days with our out of control property market.

At the moment, there are hundreds of trees threatened to be cut down in Centennial Park. Heritage listed figs which line the streets are at risk of the new light rail that is proprosed. To find out how you can make a difference please visit Saving Sydneys Trees, and attend the protest on the 1st of May!