The Ecocity World Summit may have ended on July 14, but there was still one last task to be finished. On the chilly morning of July 26, a group of hardy volunteers from the Friends of the Maribrynong Valley, Parks Victoria, National Australia Bank and The University of Melbourne gathered for a planting day on a wide bend of the Maribyrnong River in Avondale Heights.

For approximately 40,000 years, the Maribrynong River has been the home of the Wurundjeri people of the Kulin nation. In the early 1800’s however European settlement stripped the banks of the Maribyrnong River of its native eucalypts and casaurinas and sewage and noxious waste from nearby industries poured into the river. By the time the environmental, cultural and recreational importance of the river was recognised, the river’s ecological system was severely degraded and the western river sections such as Avondale Heights were dubbed as ‘Worst Smelbourne’ due to the insipid smell.

The 400 trees planted in Avondale Heights (provided under the Greening the West Program through Port Phillip and Western Port Catchment Management Authority) was the second stage of the Ecocity planting project. Stage one of the project was completed on June 28 at Newell’s Paddock with 600 ground covers and shrubs planted by staff of The University of Melbourne, presenters of the Ecocity World Summit, volunteers from the Friends of Newell’s Paddock group and 50 year students from Footscray City College. This second stage enabled the planting of top and middle storey native acacias, casaurinas and melicytus trees. These were chosen by the Friends of the Maribyrnong Valley for their ability to withstand the brackish water found in this tidal section of the river. 

For over thirty years, the volunteers from the Friends of the Maribrynong Valley group have worked with the city council and other government bodies to regenerate this section of the river with the first plantings now fully grown. These provided us the opportunity to ‘glimpse into the crystal ball’ and see how our 400 tube stock trees would look in years to come. It will just take time.

Estimating the carbon sequestration that this project would achieve over time proved tricky. Estimates suggest that the planting at Newell’s Paddock will contribute to the storage of approximately 400t CO2e over a 30 year period while the 400 trees at Avondale Heights will capture approximately 57t CO2e over a 30 year period.  These estimates are conservative owing to the scarcity of modelling tools and research generally on the role that wetlands play in carbon sequestration. We do know two things however: that recent findings suggest that inland wetlands may contain an estimated 33% of the soil carbon pool despite only occupying 6-8% of the earth’s surface (Carnell et al. 2016) and; that carbon sequestration aside, the benefits to the community will be immense.

The planting of these trees brought the total number of plantings to 1000, symbolic of roughly the number of delegates that attended the Summit. While the Melbourne Organising Committee foresees a wave of new collaborations and findings arising as a result of the three day event, this project is the first tangible outcome that can be directly linked to the Ecocity World Summit and a good sign of things to come.

Citation

Carnell P, Windecker S, Brenker M, Yukate B, Johnson K and Macreadie P. 2016. Carbon sequestration by Victorian inland wetlands. Blue Carbon Lab, Deakin University, Victoria, Australia.