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.”

Philippines tree planting goals for school graduates


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?



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

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 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.

How urban trees save the U.S. up to $12 billion each year

How trees save U.S money

It’s well known that urban trees provide a huge range of environmental, economic and health benefits. However, a new study has highlighted the extent of these benefits by showing how the urban tree cover saves the U.S. up to $12 billion annually. This includes reduced deaths, injuries and electricity usage for air-conditioning.

In the hot U.S. summer, high air temperatures and heat waves pose significant risks for people with existing health conditions. Those with cardiovascular, renal and pulmonary conditions are particularly susceptible. To combat the extreme heat, air-conditioner usage spikes, putting increasing loads on the electrical grid during the day.

A great way to reduce heat-related injury and death, while also smoothing out electricity usage, is to increase urban tree cover. Trees provide much-needed shade in urban areas. They also cool down the air around them through evapotranspiration – a process trees use to move water through their branches.

In the recent study, researchers from the Nature Conservancy, NASA and Stanford University surveyed urban tree cover in 97 U.S. cities. They applied their findings across the country’s entire urban population. The study is one of the most comprehensive on the impact of heat in urban cities, especially since it quantifies the connection to human health and electrical demand across a large and diverse data set.

In previous decades, before air-conditioning became popular in U.S. households, urban tree cover prevented more heat-related mortality. However, as air-conditioning has become more common, electricity costs have increased. The study aimed to determine the costs saved by urban tree cover from reduced electricity consumption, as well as mortality and morbidity from heat-related health problems.

The study found that, in the 97 cities, each person saved between $21 to $49 each year from the presence of tree cover. When these findings were applied across the entire U.S. urban population, the total amount saved in “heat-reduction services” is estimated to be between $5.3 to $12.1 billion each year.

Shade from urban trees alone can reduce the temperature of buildings and pavement by 10 to 20 degrees Celsius on a summer day. Air temperature changes are more modest at 0.5 to 2.0 degrees Celsius, but even this minor reduction significantly reduces impacts on health and the electrical grid.

While urban trees benefit everyone, it’s worth noting that urban tree cover is thicker in cities with a higher socioeconomic status. Populations in poorer areas where there are fewer urban trees are suffering more from heat waves. When implemented with other changes, increasing urban tree cover in these areas could save more lives and prevent expensive hospital visits for people who can’t afford them.

Source: https://www.forbes.com/sites/linhanhcat/2019/05/09/urban-tree-cover-saves-12-billion-annually

Four ways trees enrich U.S. life, now and throughout history

The 4 ways

Across the U.S., trees are branching out to signal the start of summer. While the beauty of trees is always appreciated, we often take the benefits for granted. However, research shows that trees add significant value to U.S culture – now and throughout history. Here are four expert views on how trees enrich our lives.

  1. Greening and cooling city streets

Urban trees haven’t always been part of U.S. landscapes. The first major U.S. tree-planting campaign launched in New York City in the 1870s, led by physician Stephen Smith, who believed that trees could save lives by providing shade during heat waves.

While it took several decades to win legislative support, other New Yorkers joined the cause. In 1897, they started forming committees to plant trees in front of homes, schools and tenement blocks.

“For these early activists planting trees was a way to cool streets and buildings in the summer and beautify the city’s gritty urban landscape,” says Harvard University landscape architecture professor Sonja Dümpelmann.

“Only later would scientists come to realise the enormous potential that urban trees besides entire forests held in mitigating the effects of climate change.”

  1. Holding down the Great Plains

During the 1930s, planting trees was so crucial to the mission of the Civilian Conservation Corps (CCC) that the agency was nicknamed “Roosevelt’s Tree Army”.

The CCC was invented to put young men to work on practical tasks during the Great Depression. Soil conservation was one such task, to combat dust storms ravaging the Great Plains.

CCC members planted an incredible 3 billion trees in national forests throughout the U.S. as well as a “shelter belt” that stretched from North Dakota south to Texas, holding vulnerable soil in place. They also reseeded U.S. national forests across the country.

Benjamin Alexander, a historian at the City University of New York, sees the CCC as a predecessor of the modern conservation movement:

“Although it is hard to picture a CCC-style initiative winning political support today, some of its ideas still resonate. Notably, the Obama administration’s economic stimulus plan and some proposals for upgrading U.S. infrastructure present federal spending on projects that benefit society as a legitimate way to stimulate economic growth. The CCC combined that strategy with the idea that America’s natural resources should be protected so that everyone could enjoy them.”

  1. Improving urban air and water quality

Trees are regarded as a valuable investment by many city planners today. Theodore Endreny, a professor of engineering at the State University of New York’s College of Environmental Science and Forestry, put a dollar figure on that value by calculating it with his research team.

“Trees clean the air and water, reduce stormwater floods, improve building energy use and mitigate climate change, among other things,” Endreny says. “For every dollar invested in planting, cities see an average US$2.25 return on their investment each year.”

Endreny’s research group went further to developed a free software package called i-Tree Tools that estimates how trees will help to mitigate flooding, air pollution, building energy use and carbon dioxide emissions in a specific community. They found the benefits of trees were particularly great in huge global cities like Beijing, Cairo and Mexico City. They also found that all these cities, even the greenest and leafiest, had potential to add more trees.

  1. Making streets safer

On most U.S. city streets, trees are planted in pits on the sidewalk, primarily for aesthetics and shade. However, Anne Lusk, a research scientist at the Harvard T.H. Chan School of Public Health, says trees can add even more value when planted as part of smartly designed transportation networks with separate paths for cars and bikes.

In a survey of Boston pedestrians and cyclists, Lusk’s team found that people strongly preferred streets where rows of trees or bushes separated sidewalks and cycle tracks from the street. Respondents said this formation would make them feel safer, cooler and less exposed to pollution from cars.

Lusk believes these designs should also be maximised to keep urban trees healthy and people happy, saying trees should be an integral part of reimagining urban transport.

“It is time to put equal effort into designing green streets for bicyclists, pedestrians, bus riders and residents who live on transit routes, as well as for drivers,” she says.

Source: https://theconversation.com/the-value-of-trees-4-essential-reads-116047

The vital role of trees in urban landscape design

How trees add value to landscape architecture

Trees are beautiful to look at – the lush greenery, the sound of leaves, the way the connect the Earth to the sky. However, as William ‘Chip’ Winslow – a landscape architecture professor at Texas A&M University – explains, trees bring more than aesthetic value to urban landscape design.

“The biggest things that trees provide for us are ecosystem services, which helps the entire environment,” Winslow says. “Many people don’t realize that not only do they give off oxygen, essential to our survival, but trees can help absorb water through their root systems.”

Trees soak up water and help minimise the damages caused by heavy rainfall and flooding. They also decrease stormwater runoff when planted as part of a wetlands system. “If it’s the right tree in the right place,” says Winslow.

“The services that trees bring, such as shade, add value to an area. When you get rid of a tree, you don’t get those anymore, so that value drops.”

Trees are clearly valuable, yet they still aren’t being incorporated into every architectural or landscape design. This is partly because businesses don’t understand (or prioritise) the benefits.

“People want their signs and storefronts to be seen and don’t want to deal with fallen leaves and branches, plus there is always ongoing maintenance to be done to keep a tree healthy,” Winslow says.

It can also be difficult to build around a tree or insert one into a specific place. Tree root systems are vast, and the health of a tree’s roots can determine whether a tree lives or dies. As such, the right systems and care are required to preserve or add a tree to a landscape.

To add a tree, contractors must ensure the tree and its roots have adequate space to expand and grow. Without the required space, the tree’s root system may be suffocated, eventually killing the tree.

Once planted, trees need to be regularly assessed for health. A landscape design that incorporates a tree into its look will be significantly diminished if that tree dies. That’s why careful consideration is needed to choose the most suitable species before construction begins.

A final thing to consider when designing a green urban space is the history of the area or the tree you are building around. Many cities have rules that forbid removal of heritage trees, or trees over a certain size.

“These are the kinds of trees that are part of and belong to the community, not just the landowner,” said Winslow.

A stunning example is Texas A&M’s famous Century Tree. As well as being a large, attractive live oak, the Century Tree is part of the tradition and culture of the university.

“Heritage trees like this one are part of the history of an area and certainly must be planned around,” Winslow said.

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