Tiny forests planted in Sydney to restore urban tree canopy

Tiny forests are starting to spring up in small land plots in Sydney's suburbs as locals look to replace the city's disappearing tree canopy and stave off urban heat.

Taking advantage of underutilised green spaces in council reserves and school grounds, the trees are planted in enriched soil to quickly grow forests in 200-square-metre plots.

One project in West Pymble in Sydney's north has created a patch of endangered Sydney turpentine ironbark forest shading a previously flat grass reserve near a petrol station.

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Shannon Antsee from Earthwatch, an NGO that plants small forests, said the West Pymble forest had shot up as high as 7 metres.

"We find that we get really rapid growth of our tiny forests," Ms Antsee said.

"Sometimes council have underused, underutilised parks and we can use those spaces to turn them back into green sanctuaries."

Ku-ring-gai Council Mayor Christine Kay said the tiny forest helped solve the problem of forming tree canopy in a constrained urban site.

"Tree plantings on our streets and in our parks are usually very slow to form a canopy," Cr Kay said.

"The initiative provides a scalable blueprint for other councils seeking measurable outcomes from small urban sites."

A Macquarie University assessment of the forest at West Pymble Village Green found the plants were 87 per cent bigger than plants in a nearby control plot.

A tiny forest was recently planted in Campbelltown, becoming the second Earthwatch had planted in the Sydney area.

Ms Antsee says the forests grow quickly because they use what's known as the Miyawaki method, developed by Japanese botanist Akira Miyawaki in the 1970s.

The method involves densely planting a variety of plants in nutrient-rich soil. The resulting competition between plants forces them to grow upwards quickly.

"Within 200 square metres we aim for at least two to five different species and we also add nutrients into the soil," Ms Antsee said.

Land clearing spurs more forest projects

Groundswell Collective is another NGO that plants tiny forests, mostly in the Hunter and Lake Macquarie regions of NSW.

Founder Anna Noon said she got into building tiny forests in response to land clearing for housing in the Lake Macquarie area.

She says Groundswell has since planted 21 tiny forests in mostly regional schools and one in the Cook Islands, covering about 5,480 square metres.

"For us, it was really about taking practical community action," Ms Noon said.

"Reducing urban heat and kind of counteracting some of those impacts that we saw from development and from climate change."

A Macquarie University study from 2020 found vegetation could lower surface temperatures by up to 6 degrees Celsius during the day.

A solution to Sydney's unequal tree canopy

Tiny forests are a possible solution for areas that have been missing out on attempts by governments to regrow Sydney's tree canopy.

Most of Sydney's council areas have less than 20 per cent tree canopy coverage, particularly in Western Sydney which fuels the urban heat island effect.

A recent study by The University of Sydney found the tree canopy was coming back, but some parts of Sydney were missing out on being able to replant their missing trees.

Associate Professor Nader Naderpajouh said it was hard to put more canopy into inner city areas with leafy reputations like Ku-ring-gai because of the existing built environments.

"It's very built and there is not much room,"

Dr Naderpajouh said.

The analysis found neighbourhoods in the Fairfield, Liverpool, Bayside and Ku-ring-gai were among the council areas with the least opportunities for tree regrowth.

Dr Naderpajouh said solutions such as tiny forests might help restore the canopy in areas where there was not a lot of room to grow new trees.

"Projects with dense focus can improve the capacity of certain areas," Dr Naderpajouh said.

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