Tree age testing
This project is an initiative led by Logan City Council that began in 2019 to better understand the age, ecological value and long-term habitat contributions of large, old trees across the city.
Large, old trees, often referred to as “veteran trees,” require many decades to develop the hollows that provide shelter for wildlife such as:
- birds
- gliders
- owls
- microbats
- insects.
These hollows usually form only after branches break and slowly decay over long periods. As a result, the oldest trees tend to offer the greatest variety of wildlife habitat and play a vital role in the local ecosystem.
How tree age is estimated
To estimate the age of selected trees, we engage an arborist who uses a specialist tool called a resistograph. This tool inserts a fine drill bit into the trunk of the tree and records variations in wood density. This data is analysed to determine the number of growth rings, allowing the arborist to estimate the tree's age.
Curious about how this technology reveals a tree’s age without harming the tree? To learn more about how resistograph testing, visit Land for Wildlife.
Logans Oldest Trees
Testing that is carried out as part of the Tree Age Testing Project has identified several significant old trees across Logan.
The table below details some of Logan’s oldest trees identified to date.
| Location |
Species |
Trunk Diameter (cm) |
Age (2026) |
| Greenbank |
Eucalyptus tereticornis |
206 |
419 |
| North Maclean |
Eucalyptus tereticornis |
238.5 |
385 |
| Cedar Grove |
Eucalyptus tereticornis |
208 |
323 |
| Greenbank |
Eucalyptus microcorys |
189 |
326 |
| Glenlogan |
Eucalyptus tereticornis |
211 |
363 |
Why tree age matters
Understanding the age of veteran trees helps us:
- Recognise and protect veteran habitat trees. Age testing demonstrates just how long these trees have taken to reach their current stage, highlighting their conservation importance.
- Support long-term conservation planning. Age estimates assist in identifying areas of ecological significance, supporting Council planning and environmental decision-making.
- Educate and engage the community. Sharing the age and ecological value of large trees can help residents build stronger connections with nature and encourage participation in Council’s conservation programs such as Environmental Conservation Partnerships.
Get involved
If you know of a native tree that could be of significant age, whether it’s on your property or on Council land, please let Council know by emailing environment@logan.qld.gov.au.
If you would like to learn more about the trees and other native species on your property, refer to our Environmental Conservation Partnerships program.