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Western Sydney University study links urban tree canopy to temperature

Tree canopy - Sydney

Urban streets with lots of trees must be cooler than those without, right? Recent research from Western Sydney University proves just that, revealing how the presence or absence of trees impacts temperatures at the ground level in urban environments. The study led by Dr Sebastian Pfautsch, a senior research fellow at the university, analysed temperatures at various locations in Parramatta, Cumberland and Campbelltown last summer.

Two streets in Parramatta – located just a kilometre apart – showed a clear difference in temperature during a heatwave. Daking Street was the hottest street in the City of Parramatta’s municipality with residents experiencing a sweltering 13 days of 40°C or higher temperatures. Galloway Street, on the other hand, had a relatively milder microclimate with the area having just five days of temperatures above 40 degrees.

What was the difference? The study found it was the streets’ tree canopies. With just 10% tree coverage and more exposed bitumen, Daking Street was unsurprisingly hotter. Galloway Street had 30% tree canopy cover, reducing the heat from the sun hitting the ground.
Pfautsch’s research once again underlines the importance of tree canopies in urban ecosystems and how they can impact the microclimate of each area; greater tree coverage, for instance, can create 10-degree temperature differences, increasing comfort levels even during extreme summer heatwaves. Without a tree canopy, the heat from the sun directly hits the ground and gets trapped, before being released into the atmosphere and increasing the temperature.

Pfautsch has called for legislation that would require every house to plant two trees to mitigate heat. The research also blames construction for the increasing urban temperatures. City of Parramatta Council Lord Mayor Bob Dwyer reiterated their commitment to NSW Government’s plans to plant five million trees across Sydney by 2030, a move that’s expected to take the city’s tree canopy from the current 16.8% to 40%. No doubt the residents on sweltering Daking Street, and many other hot urban streets, hope it happens.

Combining Christmas spirit and urban trees in San Francisco

San Fran

‘Tis the season to be jolly and for some forward-thinking San Francisco residents, it’s also an opportunity to grow the urban forest with an innovative Christmas tree program. While they may not look like the traditional Christmas trees we’re used to, this Friends of the Urban Forest (a San Francisco nonprofit) program lets residents have a tree in their house for the holidays that then gets planted in January, benefiting the whole community.

Karla Nagy, a Program Director at Friends of the Urban Forest, said, “Many people don’t want to invest in a tree that is just going to ultimately add to the waste stream, and they’re excited about the possibility of a live tree that they know is going to be planted. You can buy a live Christmas tree at Home Depot—it’s not something new—but where are you going to plant that tree? In San Francisco, most people have tiny backyards, and they don’t have a place to plant a pine tree that’s going to get quite large—and may not even survive in San Francisco at all.”

The benefits of urban trees are well established: improving air quality, reducing diseases like asthma, fighting climate change, making people feel happier and younger, and reducing the urban heat island effect. But for these to work, cities need a tree canopy that covers at least 40% of the city. In San Francisco, coverage is currently a measly 13.7% – far less than many other major cities in the USA.

Given its rapid rate of development, planting trees in San Francisco makes sense but initiatives to increase green canopy – with a goal to plant 50,000 trees over the next 20 years – are failing. Last year, only one more tree was planted than the number removed.

Friends of the Urban Forest chooses trees from areas with similar climates that can survive long periods of drought. Nagy said, “Often, many of the trees that we lend out are like Charlie Brown Christmas trees. They’re a little gawky, they might have just a few branches, and most of them look nothing like a Christmas tree. So, we’re targeting people who can think outside the box of what a holiday tree looks like. I think it’s a great way to introduce people to urban forestry and the importance of street trees. It’s a way to connect with people on a different level than planting trees in front of their house.”

Source: https://www.fastcompany.com/90434618/these-nontraditional-living-christmas-trees-get-replanted-on-city-streets-after-the-holidays

Urban forests increase the health and wealth of cities

health & wealth

According to climate scientists who calculated the value of urban forests, town planners can almost double their money by simply planting 20% more trees. Urban trees are proven to increase property values and bring a range of benefits to communities. Of these benefits, the ability to mitigate the urban heat island effect is one of the biggest.

In 2018, researchers valued the contribution of urban forests at $500 million for the average megacity. That is, a city that has a population of at least 10 million people. In their study, researchers considered pollution absorbed, temperatures lowered, and moisture taken up by urban trees.

Tree canopies already cover 20% of the area of the study’s sample of 10 megacities across five continents. However, according to the research, the same cities could find room for 20% more forest. “By cultivating the trees within the city, residents and visitors get direct benefits,” said Theodore Endreny – professor of environmental resources engineering at the State University of New York.

“They’re getting an immediate cleansing of the air that’s around them. They’re getting that direct cooling from the trees, and even food and other products. There’s potential to increase the coverage of urban forests in our megacities, and that would make them more sustainable, better places to live.”

“While nature provides a bounty of essential goods and services, such as food, flood protection and many more, it also has rich social, cultural, spiritual and religious significance.”

Megacities are most afflicted by the urban heat island effect – and climate scientists have repeatedly warned that extreme temperatures could rise to potentially lethal levels.

The study is part of a wider shift to work with nature to confront climate change – and to use nature’s contributions to inform policies and decisions, particularly in the developing world where forests and land are being destroyed.

In the journal Science, a second group of researchers argued “a better understanding of the way nature – in the form of forests, wetlands, savannahs and all the creatures that depend on the natural world – underwrites human wellbeing should inform political and economic decisions.”

This, in many cases, would involve tapping into the wisdom of local communities and indigenous people who depend more directly on nature’s riches.

“Nature’s contributions to people are of critical importance to rich and poor in developed and developing countries alike. Nature underpins every person’s wellbeing and ambitions – from health and happiness to prosperity and security”, said Sir Robert Watson, chair of the Intergovernmental Platform on Biodiversity and Ecosystem Services.

“People need to better understand the full value of nature to ensure its protection and sustainable use.”

“This new inclusive framework demonstrates that while nature provides a bounty of essential goods and services, such as food, flood protection and many more, it also has rich social, cultural, spiritual and religious significance – which needs to be valued in policymaking as well.”

Darwin’s 4,000 Tree Planting Project is underway

Darwin

In October 2019, Stage 1 of City of Darwin’s 4,000 Tree Planting Project started in the suburb of Anula. Lord Mayor Kon Vatskalis planted the first tree of the four-stage project, which is expected to be completed by mid-2020.

The project focuses on planting trees in suburban areas of Darwin. This includes 903 new trees in parks and greenbelts across Anula, Malak and Wulagi – three suburbs hit particularly hard by Cyclone Marcus

“Our focus is on replacing the thousands of trees lost during Cyclone Marcus to create a city that is cool, green and liveable,” said Lord Mayor Kon Vatskalis. “A lot of work has been completed in the city centre and we are now shifting our attention to the suburbs.”

“We are committed to achieving a more robust and resilient urban forest across Darwin – and the $5.8M allocated to beautification and tree planting in the 2019/20 budget will see us achieve this,” he said.

Since January 2019, a significant number of trees has already been planted. The number is expected to grow to 8,000 by the end of December. “This is a wonderful achievement by our team – and, more importantly, a terrific outcome for our community,” said Lord Mayor Vatskalis.

In terms of the type of trees planted, Jamie Lewis, Senior Coordinator Parks and Reserves, said Darwin had learnt many lessons from Cyclone Marcus. “Thousands of trees were lost during Cyclone Marcus and it is important that we promote diversity,” he said.

“We will be planting trees of varying age, characteristics and size, with a mix of Australian and Northern Territory natives and tropical exotic species, to create a robust urban forest.”

“A major focus is putting the right tree in the right place with the right soil and the right watering system,” Jamie added.

The 4,000 Tree Planting Project is part of the City of Darwin’s $53M commitment to completing major landscaping and greening projects in 2019/20. Stage 1 includes 8885m of irrigation and 1806 drip emitters. Stages 2, 3 and 4 commence in January 2020, with planting across all Darwin suburbs.

Philippines tree planting goals for school graduates

Philippines

In recognition of the many gifts that trees offer to communities – such as shade, cooling, air filtration and beauty – legislators in the Philippines have proposed an ambitious new graduation requirement. Under the new bill, which has been passed by the House of Representatives, every student in the nation must plant 10 trees before leaving elementary school, high school and college.

While the bill has no counterpart in the Senate, making its future uncertain, that hasn’t stopped it from making headlines around the world. If formally passed into law, the “Graduation Legacy for the Environment Act” would make the Philippines government responsible for everything from producing seedlings to monitoring tree growth. Students would do the actual planting.

To ensure the bill has the desired effect of increasing natural tree canopy and protective native plant species, the bill is accompanied by some rules. First, it prioritises planting of indigenous tree species over imported varieties as a key step in preserving local biodiversity. Species such as Pterocarpus indicus or narra, the rose-scented national tree of the Philippines, has become extinct in some regions, making it a high priority for preservation. The bill also specifies where students can plant their graduation trees, with a focus on government-owned land, from rainforests to oceanside mangroves to city streets.

Co-author of the bill, Rep. Gary Alejano, said that every student planting 10 trees would result in 175 million new trees in the Philippines each year—or 525 billion “in the course of one generation.” However, this assumes that all the trees planted will survive, which is not a realistic scenario – particularly in urban areas.

For context, an analysis of street trees in the United States revealed an average lifespan of 19 to 28 years, which translates to an annual mortality rate of 3.5 to 5.1 percent. According to these calculations, only half of every 100 street trees planted would make it to their own high school graduation. However, these statistics shouldn’t discourage planting. In fact, they should encourage cities to plant more trees in a systematic fashion.

Despite the popularity of conservation projects, like the Million Tree Initiative, urban canopies are declining in many American cities. More research is required to determine why some trees thrive in certain environments, while others die. At any rate, one thing is clear – just planting trees isn’t enough.

In urban areas, where humans and nature co-exist, trees need to be actively managed. They require pruning, soil aeration and protection against invasive species. So, while the Philippines bill faces many obstacles – both political and natural – it’s a good reminder that anyone, anywhere can make a difference by planting a tree or 10.

Should Sydney be managed as an urban forest?

Sydney

 

According to planning experts, Sydney needs a tree-planting program in suburban areas to boost wellbeing within the community and provide habitats for wildlife. These changes should be part of a shift to manage cities as “urban forests”.

Under the urban forest model, urban planners would consider tree canopy at a city-wide level and recognise trees as valuable assets with broad economic benefits.

“Land managers are looking at a tree as a liability, they’ve got to prune it, they’ve got to maintain it,” said Peter Davies, Associate Professor in Environmental Science at Macquarie University. “If we went to the other side of the ledger to value the benefits, we’d see that tree or that avenue of trees in a whole new light.”

Research has proven that city trees improve reduce urban heat, improve air quality, entice people to exercise outdoors, and reduce stress. Urban trees are also important for biodiversity, which a United Nations report recently identified as a global crisis.

The Australian Institute of Landscape Architects recently called for a “national living infrastructure strategy” to help boost tree canopy across Australia.

Daniel Bennet, the Chairman of the Institute’s national advocacy committee, said street trees were most needed in the Sydney’s western suburbs. Canopy cover in Western Sydney is currently under 20 per cent in most places – well below the suggested target of 30 per cent.

In south eastern suburbs such as Botany Bay, Rockdale, Randwick, canopy cover is as low as 12 per cent. Western suburbs such as Fairfield, Auburn and Holroyd have marginally higher cover at 15-17 per cent. However, the difference in the western suburbs is that there are more soft, grassy surfaces where tree could be planted. This is opposed to the inner city which, according to the Benchmarking Australia’s Urban Tree Canopy report from 2014, is dominated by hard surfaces.

Mr Bennet said people visited large parks with leafy trees across Sydney, but lived in “harsh, polluted” suburbs with no little or no trees.
“I don’t think people realise what impact [more trees would] have on their lives,” Mr Bennet said. “Trees are more than things that create oxygen, they also improve our mental health, our anxiety levels and our general health.”

Dr Keane said “trees do something important that bushes and shrubs and open green grass can’t do” by regulating the climate. With predictions that western Sydney could have up to 52 days a year above 35 degrees by 2090 if emissions aren’t reduced (up from an historical average of 10.6 day), climate control is only set to become more critical.

Dr Keane called on Rob Stokes, Sydney’s Planning and Public Spaces Minister, to increase trees in the built environment.

Dr Stokes said tree canopy was a “big part” of both parts of his portfolio. “There are public open spaces and there are also open spaces that are private and the network of the two is important for sunlight and air and climate and biodiversity – critters don’t see the land boundaries,” he said.

Despite the Berejiklian government’s plan to plant five million trees in Sydney by 2030, the surge of construction in the city has come at the cost of trees. The construction of the light rail in the eastern suburbs involved the controversial decision to fell dozens of trees including several century-old Moreton Bay fig trees. More recent examples include 1900-2650 trees to be removed for the Parramatta Light Rail, and the proposal to clear more than 800 mature trees to build 3500 dwellings on the Ivanhoe Estate in the north-western suburb of Macquarie Park.

Seattle’s big trees: Advocates call for more protection

Seattle
A new charge to protect Seattle’s treasured city’s trees is under way, after stalled efforts to update tree regulations last year.

A new tree ordinance was proposed by the Seattle City Council in 2018, but advocates said that it weakened protections for the city’s “exceptional” trees – the large trees that help most with cooling, carbon emissions and stormwater. Last year’s ordinance didn’t pass, but City Council is expected to pass new legislation that will help retain these treasured trees, particularly in environmentally stressed areas.

Environmental group, Plant Amnesty, believes there are around 6,000 “exceptional” trees left in Seattle, which are 30 inches wide or more – basically the width of a front door. Dominic Barrera, Plant Amnesty’s Executive Director, said that trees provide an important buffer from warehouses and Boeing Field.

“Looking at that juxtaposition of the industrial district and then a few trees that protect us from it just really shows how important these trees are for everybody,” he said. “Especially those of us living in those environmentally tarnished areas.”

In Northeast Seattle, the century-old Douglas Firs around the Seattle Audubon office is just one example of an iconic tree that characterises the city, while combatting noise and air pollution.

Joshua Morris, the urban conservation manager with Seattle Audubon who also serves on the Seattle’s Urban Forestry Commission, said he supports more tracking and protections for existing trees.

“We’ll never see the size of these trees again. They’re treasures, and hopefully we can convince Seattleites of that, and write something into the tree protection ordinance.”

He also said the new regulations must strike the right balance so property owners will comply. “There’s difficulty ensuring compliance, getting private property owners to actually comply with a tree ordinance, not making it onerous or too high a permit fee.”

Developers will be watching closely to see whether new tree regulations restrict building projects or create additional costs.

While there’s currently no requirement for developers to plant larger or more mature trees, this strategy could help Seattle increase its tree canopy. So could the introduction of permits for tree removal, which has helped the suburb of Lake Forest Park increase tree canopy in recent years from 46 percent to nearly 50 percent.

Lake Forest Park City Council member John Resha said, “Our regulations are focused on the end state of maintaining and growing canopy rather than restricting removal.” But he said, “There is one place where we say no.” That’s the removal of trees that qualify as ‘exceptional.’ “These quiet giants are part of the fabric of our city,” Resha said. He said they’ve successfully grown their canopy by creating a city code “that resonates with its community.”

Plan to link and protect Melbourne’s urban forests

Melbourne

Melbourne has launched a bold new plan to improve the connectivity and extent of its urban forests. The plan, entitled, Living Melbourne: our metropolitan urban forest was developed by The Nature Conservancy and Resilient Melbourne and aims to “create a profound shift in the way we think about, value and grow Melbourne into the future”.

As part of the plan, trees in the city will be mapped to understand what species exist, why they exist, and what can be done to protect and expand urban forests. It’s the first time that such a vast area of Australia has been mapped.

City of Melbourne Lord Mayor Sally Capp said the Living Melbourne strategy unites local governments and land authorities around the protection and enhancement of urban forests.

“Melbourne is renowned for its parks and gardens. A healthy urban forest is crucial to maintaining our status as one of the world’s most liveable cities, and enhancing the wellbeing of our residents and visitors,” she said.

“The Living Melbourne strategy has mapped all the trees, shrubs and vegetation across public and private land in the greater Melbourne metropolitan area, highlighting the areas that have abundant greening and those that have very little”.

“Nature doesn’t care about municipal boundaries, which is why it was so important for us to collaborate with Melbourne’s 32 councils, the Victorian Government and other authorities to ensure a consistent approach to protecting and growing our urban forests.”

During mapping conducted during the strategy development, Greater Melbourne was found to have a total of 15 per cent tree canopy cover. The eastern region has the highest cover (25 per cent), followed by the inner south-east region (22 per cent) and, finally, the western region (4 per cent).

Land surface temperatures were also studied to determine where the urban heat island effect had the biggest impact. Findings indicated that, on average, temperature hot spots occur in areas that have less than 3 per cent vegetation cover and no tall trees.

Cathy Oke, Chair of the City of Melbourne Environment Portfolio Councillor, said the Living Melbourne strategy would help address the impacts of climate change on the environment and population.

“Within the City of Melbourne, our vast urban forest of 70,000 trees is under threat from the effects of climate change, such as extreme heat,” Cr Oke said.

“While we are already taking action to boost greening, including planting 3,000 climate resilient trees every year, there is so much we can learn from our neighbours while sharing our experiences as well.”

“Living Melbourne’s six recommendations for healthy people and nature align closely with our own commitments and strategic framework to take urgent action on climate change.”

The Living Melbourne plan is the culmination of over three years of collaboration between The Nature Conservancy and Resilient Melbourne. It has been formally endorsed by 41 organisations, including the City of Melbourne.

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