Treenet 2013

TreeNet is a not for profit group that has been looking at the performance of trees in the urban landscape. Based in Adelaide and utilising the resources of the Adelaide University and the Waite Arboretum, TreeNet has been looking at the management of trees in urban landscapes consistently for the last 15 years.

Speciality Trees was very keen to arrive in Adelaide early to meet with Dr Kate Delaporte who has been working on the hybridisation of Eucalypts and is responsible for Nullarbor Rose and Nullarbor Lime that we have been trialling.

Kate demonstrated the process of crossing the male and female parents and how to ensure that there is no self-pollination.  Her work has been mainly with cut flower and garden varieties however the principals are the same for the development of better landscape and street varieties. Some interesting facts are that nearly all Eucalypts will cross successfully. They will also cross with Corymbia and Angophora quite happily.

SpecialityTrees is particularly looking for more compact forms with good branch attachment, low rubbish and uniformity. We already have a number of selections including leucoxylon, sideroxylon, melliodora, Angophora, maculata, citriodora, Lophostemon etc. to start our breeding program.

The TreeNet Symposium is held at the National Wine Centre which is adjacent to the Botanic Gardens. These botanic gardens are a wonderful asset and well worth walking about particularly looking at trees that will survive in slightly harsher conditions than Melbourne. There are unusual specimens here including Ficus platypoda and Podocarpus.
 

The flower of Eucalyptus macrocarpa 'Nullabour Lime'

Dr Greg Moore (former principal at Burnley) is the chair of TreeNet and he opened the Symposium with a call to arms around the performance, importance and the protection of trees in urban environments. He feels that despite the benefits of trees there is a predisposition to remove rather than working with them, seeing the problem rather than the benefit.

The theme of the Symposium this year was about the effect that plants have on the health of other ecologies and societies.

A very interesting paper by Prof Phil Weinstein dealt with the effect of the removal of trees in Southern Australia and the relationship to the spread of Ross River Fever. The mosquitoes that carry the disease live in brackish water, due to the removal of trees and the rise of the water table and salt levels there is now salty water in areas of inland southern Australia where the mosquitoes can breed. So this disease is becoming a much bigger problem. The point being made was the knock on effect of our actions in seemingly unrelated environs.

The effect on the health and well-being of people are directly influenced by their environment and the importance of trees and urban green space is vital to ensure quality of life. Dr Suzanne O’Keefe from La Trobe University spoke about the aging and the importance of gardens as a satisfying activity as well as the importance for mental health and exercise.

Peter Levett spoke about the work of using stormwater to water trees with the use of inlet points and inground drainage and absorption pits. This is increasing the value of trees, using them to reduce pollution, control water runoff and flood mitigation whilst increasing the amenity value of urban green space.

Michael Leers (honours student at Burnley now in Perth) spoke about the effects of orientation of the tree when planting. In the Draft National Tree Standard there is a requirement to mark north on the tree so that the planting team can correctly orientate the tree to the way that is has been growing in the nursery. Michael discovered that there was no difference when this was or wasn’t done. His discussion, while not overaly convincing may have dispelled one of the myths that surround trees. He also did some work on the effects of sun scald and the effect that different surfaces; bitumen, concrete, gravel and mulch had on this phenomenon. The results were inconclusive and so more work needs to be done here. The images he had and the temperatures reached though were amazing.

Dave Williams, a Forester and Arborist here in Melbourne presented a paper applying forester principals to the urban forest. He was looking at the longevity of trees and the correlation between species, age and performance. Really interesting work that may affect the varieties that we grow and how different species are managed in the urban environment.

Greg Moore gave the last paper of the day on the vascular connection between the root and the crown. He has obviously been very involved with the damage that has been inflicted on old trees in the Melbourne Botanic Gardens over the last few years and how to get recovery if possible. He painted an amazing story of what can be achieved when acting quickly and decisively. The upshot was to put as much bark back as possible and hope. A mature large Eucalypt with good levels of carbohydrates can live up to 10 years before succumbing to the injury. He also indicated that Bridge Grafting is an option and should be considered, but cost and how it looks is an issue.

On the third day there were a number of practical sessions and training on various topics from pest and disease program through to the management of old trees. We also had the opportunity of a guided walk around the Waite Arboretum where they plant trees and maintain them for only two years and then let them go. With the development and acceleration of climate change, the trees that will be planted in Melbourne will more than likely have to deal with a climate similar to Adelaide’s. This makes the Waite Arboretum a very important observation point for Melbourne species going forward.

For more information about any of these speakers or on the Treenet organisation, please visit their website here.