In a frightening statistic, more than 90% of trees planted by Perth councils in an attempt to cool hot suburbs will die before maturing. The three main causes of death include:

  1. Defective root systems, due to gradual changes in nursery technologies over the past 50 years
  2. The practice of ‘hydrozoning’, a watering technique used in parks and reserves which prioritises turf and recreational areas over trees
  3. Increasing infill and resulting ‘hardscaping’ which has led to a decrease in soil quality

Recognising the seriousness of this mortality rate, Perth councils are pouring cash into greening, and slight adjustments have been made which will hopefully achieve big results.

Standards Australia has this year released a new Australian Standard aiming to improve the quality of root health in trees. Hydrozoning plans must also be adapted to better care for trees, and lastly soil health must be improved with planning for trees occurring at the same time as planning for infrastructure, allowing for the required volume and quality of soil (mindful of Perth’s already sandy soil).

Arbor Centre Principal, Rob Bodenstaff, said, “You need to engineer in a tree, not expect it to tolerate everything else we do. We do have solutions to all this stuff. It’s not high-level science … you can drought-proof trees and suburbs. Within the same budget we could get far better outcomes. If nothing happens, we’ll have constant celebration of trees being planted and the constant disappointment of realising they have failed.”[1]

Learn more about innovative tree solutions for urban forests here.

[1] http://www.watoday.com.au/wa-news/nine-in-10-trees-planted-by-perth-councils-will-never-mature-expert-20151201-glcnjm.html