Sydney turns over a new leaf and says goodbye to much-maligned plane trees
The use of plane trees along the streets of Sydney will be gradually eliminated, according to the City of Sydney.
In some parts of the City of Sydney, plane trees make up nearly 10% of the trees found on the streets and in parks. However, they have faced criticism from various sources throughout the years.
Tim Flannery previously referred to them as “exotic plants…with the same value to our native animals as cement poles.”
In 2005, a choice was made to plant a row of them on William Street in the eastern part of the city. This decision was criticized as “disastrous,” and community advocates have been urging Sydney to follow Melbourne’s example and gradually remove them.
Asthma and hay fever sufferers are the primary critics of the issue. During the spring season, plane trees release small, spiky fibers known as trichomes that can cause irritation in the eyes, nose, and throat. However, there is limited research that proves a direct connection between trichomes and asthma, as their release coincides with an increase in pollen from other sources.
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However, in 2019, Prof Robyn O’Hehir, the director of respiratory medicine, allergy, and clinical immunology research at Monash University, informed Guardian Australia that the fine particles emitted by plane trees could potentially lead to throat irritation and laryngospasm in individuals who are not typically susceptible to allergies. This statement was made in the context of Melbourne’s proposed ban on plane trees.
However, the City of Sydney’s choice was influenced by another factor: the evolving climate.
According to Karen Sweeney, the urban forest manager for the council, Sydney’s climate is expected to resemble Grafton’s current climate by 2050.
The city is facing the challenge of maintaining its tree coverage in a changing climate, with hotter temperatures and longer droughts. To address this, the city is considering altering the tree species mix and shifting away from using plane trees.
She stated that due to the slow growth of trees, waiting until 2050 is not an option. We must begin taking action now to prepare our forests for the changing climate.
“It is crucial to manage urban heat by ensuring that there is not a significant decrease in the amount of tree canopy due to their inability to flourish at that particular time.”
The council has approved new plans for urban forestry and street trees that have the goal of expanding the city’s canopy coverage in order to provide shade and maintain cooler communities.
Specialists carefully assessed each block and street to identify the most suitable species for a future climate that is expected to be warmer, more humid, and experience longer droughts by 2050.
In Sydney, trees are only removed as a last resort. This means that types of trees that may not thrive in the changing climate will be slowly replaced as they reach the end of their lifespan.
The current trees will be substituted with a combination of indigenous varieties, such as bloodwoods, tulipwoods, and ivory curls, as well as non-native deciduous species that will still allow sunlight to pass through during winter, while also being able to withstand high temperatures and dry conditions.
According to Sweeney, approximately 98% of areas will have plane trees replaced. However, they will still be planted in certain locations with significant cultural importance or where the environment can sustain their growth under different climate conditions. An example of this would be a well-watered park with suitable soil.
Sweeney stated that the change will be gradual instead of sudden.
“We have already eliminated certain plane trees in certain areas, but it will become more noticeable to people in the years to come.”
John Siemon, the individual in charge of horticulture and maintaining the living plant collections at the Royal Botanic Gardens Sydney, oversees a vast area of land spanning 730 hectares and containing approximately 50,000 trees.
He stated the significance of recalling the reason for planting a large quantity of plane trees initially.
According to Siemon, plane trees are an incredibly hardy type of tree. They are able to flourish even in places covered in concrete or designed landscapes, and they also create beautiful shaded pathways.
Several options were attempted previously, such as using native species, but according to him, not all of them were successful.
“As the climate continues to change, it is necessary to reconsider previous actions.”
Additionally, there are advantages to diversifying the quantity and variety of species utilized.
“Utilizing a variety of plant species is a beneficial approach in promoting biodiversity and reducing the impact of pests and diseases.”
He suggested that natives should be our primary source.
There are several reasons why one might choose to go with non-native plants, even though many native species are well-suited and able to thrive in our climate.
Only a small number of Australian species are deciduous. While there are some, they may not fulfill the necessary environmental role.
Instead of using plane trees, Siemon proposed using native trees like the Illawarra flame tree (Brachyiton acerifolius), Waterhousia (Waterhousia floribunda), Queensland brush box (Lophostemon confertus), or Water gum (Tristaniopsis laurina), or a well-liked non-native species such as the jacaranda (Jacaranda mimosifolia), which is currently flowering.
The Moreton Bay fig, also known as Ficus macrophylla, was planted in the Domain in 1847 and is one of the earliest street tree plantings. It has proven to be very successful and is known for its large shade canopies that are appreciated by the public.