City Services has conceded meeting its tree planting quota will be a challenge, with the urban canopy goal requiring a step up from a 10,000 tree target to 18,000 this year.
Planting fell short last year with 9888 trees in the ground, with about 5 per cent expected to perish.
Additional contractors are being procured to almost double planting right across Canberra for the 2022-2023 season, with a focus on sparsely covered suburbs in order to reach the goal of 54,000 new trees by 2024.
City Services manager Daniel Iglesias said there were a number of reasons why trees may not be successful and as that knowledge increased it would inform planting to increase success rates.
"We are focusing on areas which have low canopy cover, where we can get the best bang for our buck," Mr Iglesias told a recent Senate estimates hearing.
While the ACT's ambitious 30 per cent urban tree canopy cover by 2045 plan has been broadly welcomed, conservationists have warned poorly planned planting can also do damage.
Friends of Grasslands president Jamie Pittock said the right trees in the right places have many benefits, including sequestering carbon and conserving biodiversity.
The ANU Fenner School academic said much of Canberra was once native grassland and grassy woodland and additional work was needed to restore these endangered ecosystems.
"Poorly planned tree planting could damage endangered native grasslands," he said.
"It is also important to plant trees that are not weed species."
Professor Pittock said tree planting must include other components of ecosystem restoration, including planting herbaceous and shrub species and using elements such as timber and rocks to increase benefits for wildlife conservation.
"There have been some instances of trees being planted in places that could negatively impact indigenous biodiversity," he said.
"The choice of species planted, spacing of plantings and the diversity of species planted could be enhanced."
Prof Pittock said while City Services had responded to concerns about the potential impact on Indigenous biodiversity, more checks were needed to ensure trees were planted in the best places.
He said Friends of Grasslands were surprised counting only included actively planted trees, rather than the regeneration of trees as a result of better management of grassy woodlands in the urban area, such as from reduced mowing.
"The target could usefully be broadened beyond trees to embrace further conservation of native grassland and grassy woodlands in our city," Prof Pittock said.
"This would involve better conservation of remnant habitats outside the formal ACT park system and more emphasis on restoration of ecosystems that expand and link remnant habitats."
ANU professor of natural history and palaeoecology Simon Haberle said simply setting targets was not enough.
There needed to be consideration of the type of species and diversity across the urban landscape, he said.
"We know that increased diversity of tree planting can help reduce the impact of airborne allergies from tree pollen. Shifting the species selected to be more in favour of non-allergenic trees will also be important in the long term planting plan for the ACT," Prof Haberle said.
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