EXCURSION - TREE CONVERSATIONS
urban forest strategy, melbourne.
Making a City Greener. 2012-2032
Author: City of Melbourne
FROM MELBOURNE'S ELMS WITH LOVE
“… today I was struck, not by a branch, but by your radiant beauty. You must get messages like this all the time. You're such an attractive tree,” reads the letter to a green leaf elm, one of Melbourne’s 70,000 trees. Each was given an ID number and email address on “Urban Forest Visual”, the city council’s online database for problems related to vandalism or hazards. But citizens didn’t use the information in this manner, and instead, they started writing personal messages to the trees, thousands of them. This converted the digital platform into an important communication and citizen engagement tool in the City of Melbourne’s Urban Forest Strategy, launched in 2012.
MELBOURNE IS GETTING BIGGER AND HOTTER
Melbourne was named ‘most liveable city’ for many consecutive years. Most historic gardens, such as the Botanical Gardens and Carlton Gardens, were established in the 19th century. During the gold rush, ‘Marvellous Melbourne’ was one of the world’s wealthiest and fastest growing cities, and it continues to grow to this day. With an average growth rate of almost four percent over the last seven years, its population is projected to increase from 4.5 million in 2017 to eight million in the next 20 years. By then, the city will also nearly double its current number of 150,000 residents who live within the central municipal area, covering 37.7 square kilometres. Urban growth is bound to make the low-density city much more compact, which may intensify the impact of climate change.
Melbourne is getting hotter. In the future, the surrounding region is likely to experience higher average temperatures, extreme weather events such as heat waves, storms or floods, and a decrease in average annual rainfall. The city suffered an extreme heat event in 2009 following a 13-year drought. Tree foliage and trunks were literally scorched, and the tree population’s health declined due to heat stress, intensified by urban heat island effects and water restrictions.
AGEING TREES
One major challenge for managing the City of Melbourne’s urban forest is an ageing tree population and a lack of diversity. The forest contains more than 388 different species. Three of them play a dominant role: elms, planes and river red gums. In some central areas, roughly 75 percent of the urban forest is made up of plane trees. The elm plantings along avenues and within parks are unique as they represent some of the few remaining mature elm avenues in the world that weren’t affected by the Dutch Elm Disease. Nevertheless, the lack of species diversity poses a risk and contributes to vulnerability to disease, ageing, or heat waves.
These problems made it necessary to research the current status of the urban forest. This was assessed based on tree health, species composition, canopy cover and useful life expectancy (ULE) using an extensive mapping process. The results provided vital input for the development of a future strategy and its targets. They also highlighted the urgent need for quick action, specifically regarding the heritage gardens. Twenty-three percent of trees are expected to reach the end of their useful life within ten years and 39 percent within 20 years.
A HOLISTIC AND INCLUSIVE STRATEGY
This is where the Urban Forest Strategy comes into play. It lays out a management and adaptation plan with the ambitious goal of increasing public realm canopy cover from 22 percent to 40 percent by 2040. The Strategy includes all types of green infrastructure on public and private land as well as green walls and roofs. It is linked to other government policies and shows a commitment to green governance. The City of Melbourne considers the strategy a vital tool for climate change mitigation and adaptation, reducing storm water flows, nutrient loads and air pollution, and improving community health and wellbeing. Economic benefits are also significant, as the urban forest is supposed to help reduce energy and health services costs, increase property values, and avoid infrastructure damage. Although it is difficult to quantify the urban forest’s monetary value, the municipality estimates an asset value of around 700 million Australian dollars.
Ian Shears, Practice Lead Urban Forest and Green Infrastructure at the City of Melbourne, points out the Urban Forest Strategy’s uniqueness: its holistic and multi-disciplinary approach goes beyond jurisdictional thinking and involves all relevant stakeholders. It was co-designed with the community throughout all stages, leading to a transformative and inclusive outcome.
PERFORMANCE-BASED OUTCOMES
Covering different scales, the objectives and targets were translated into each of the municipality’s individual Urban Forest Precinct Plans. The Plans’ targets focus on performance-based outcomes rather than specific instructions for tree planting. They focus less on quantification, but rather on finding the right tree for the right site and conditions. This can lead to conflicts with heritage regulations and legislation on indigenous planting and biodiversity, and mediation may become necessary. Other targets relate to the diversification of tree species, the improvement of vegetation health, soil moisture and water quality, as well as urban ecology and biodiversity. These objectives clearly go beyond new tree plantings and replacements. Engineering solutions will have to be implemented, including the creation of porous surfaces, rain gardens and large-scale underground rainwater retention, in order to keep water consumption low.
THE MOST IMPORTANT ELEMENTS IN THE FOREST ARE THE PEOPLE
Community engagement is another key to achieving a long-term legacy, outlined in the Strategy’s education and empowerment components. “Citizen foresters” are trained to take on advocacy and monitoring tasks. There is a noticeable shift in the dialogue concerning the public landscape of the future. Advancing the conversation includes learning from the indigenous community, as many of the landscapes hold great significance in Aboriginal culture.
A significant portion of the City of Melbourne’s urban forest is located on private land. The 'Urban Forest Fund' was initiated in order to build partnerships with the private sector for residential or urban agriculture projects. New private development needs to achieve specific targets, including 40 percent canopy cover and 30 percent permeability. Regulations are also in the planning stages for green roofs and walls. According to the City of Melbourne, the implementation of their Strategy is progressing well. Roughly 3,000 to 3,500 new tree plantings take place per year. Some of the projects realised to date include underground water tanks in Birrarung Marr, Fitzroy Gardens and Lincoln Square. Plans for flood risk reduction through green infrastructure in the Elizabeth Street catchment are on the way. One of the more visible initiatives is ‘Green Your Laneway’, which features pilot projects for creating green along the streets and walls of four laneways. Thus far, the City of Melbourne’s Urban Forest Strategy has generated plenty of media buzz. By assuming the role of advocates, the team behind the strategy aims to ensure that their message is not only heard within the community, but on a regional and an international level as well.
And when Melbourne’s citizens write letters to their trees, the trees sometimes even respond. Chinese Elm Tree ID 1030595’s answer is: “I really enjoy stretching my stomata and giving my chloroplasts a good workout. I spent the weekend well hydrated and preparing for the upcoming summer months. And you?”
This article first appeared in Topos Magazine, Edition 103 Trees, 2018, under the title 'From Melb's Elms with Love'.
All images © City of Melbourne