A tree planting program on land controlled by the National Capital Authority will aim to boost canopy cover, increase the number of young trees and improve the diversity of species, with research showing that 70 per cent of the population will need to be replaced in the next 40 years.
The NCA has finalised its Tree Management Policy after community consultation but it has already planted 425 trees across the areas it manages, including more drought-tolerant and resilient species, and trialled new species in the Lindsay Pryor National Arboretum.
It will also replace the ageing poplars outside the National Library of Australia with a species that complements the heritage and structure of the building and is not listed as a noxious weed for the ACT. The authority will also aim to revitalise the treescapes on Commonwealth and Kings Avenues.
The NCA has committed to boosting tree canopy from 33 per cent to 40 per cent by 2030, ensuring that no one species represents more than 10 per cent of the population.
Ninety-three per cent of its 18,000 trees have a useful life expectancy over 20 years but the NCA policy says the data indicates more young trees are needed and it will ensure that least 10 per cent of the population are juvenile, up from the current 8 per cent.
The policy says NCA trees are relatively healthy, well managed and cared for, but they are under pressure from a number of directions.
“Climate change, urban development and the need for open space to be multi-functional all place various stresses on our trees and in some cases could cause an increase in the number of trees that decline and die,” the policy states.
It notes a range of climate adapted species suitable for NCA landscapes will be developed and updated every five years, and new non-invasive tree species will be trialled within the Lindsay Pryor National Arboretum and other areas.
A central tree database will also be maintained to include records of maintenance history, annual condition assessments, required works and heritage and ecological values.
Measures to enhance and protect tree health will be deployed including improving the soil, leading practice urban tree management, irrigation regimes and developing management plans for old trees.
The policy says all management options will be explored before a tree is removed and if it is, at least one must be planted to offset it.
There are already community concerns about the 95-year-old cedars planted by Charles Weston on the Commonwealth Avenue median strip that may have to make way for light rail to Woden.
The policy says the most common species is Eucalyptus mannifera at 12 per cent, followed by Eucalyptus bicostata at 11.5 per cent, representing almost a quarter of the NCA’s tree population.
The policy will be reviewed and updated every 10 years and can be found on the NCA website.