Slow Aging by Planting more Trees


Does Planting Trees Slow Aging?


Green park trees

In an increasingly urbanized world, where more than half of the global population resides in cities, the importance of urban green spaces cannot be understated. Parks, green roofs, and community gardens offer not only aesthetic appeal but also critical ecosystem services. A recent study in ScienceAdvances has documented the potential benefits of urban greenness for healthy aging, including improved cardiovascular health and reduced mortality rates. While physical activity and social interactions have been suggested as potential pathways linking greenness to health outcomes, the underlying molecular biological mechanisms remain unclear.

Epigenetic modifications, such as DNA methylation levels, have emerged as a promising avenue for understanding the link between environmental exposures, health conditions, and aging. Accumulated exposure to environmental factors can lead to DNA hyper- or hypomethylation, ultimately influencing human health. Epigenome-wide association studies have identified regions of DNA methylation that are associated with residential greenness and are implicated in physical activity, mental health, metabolic diseases, and neoplasms. DNA methylation-based biological age, known as epigenetic age, has been proposed as a predictive marker for age-related health outcomes.

Previous studies have established associations between epigenetic age and cardiovascular disease, cancer, and mortality, as well as various lifestyle and exposure factors. However, the relationship between greenness exposure and epigenetic age has been understudied, with only one cross-sectional study conducted thus far. Furthermore, no studies have examined the role of race and sex in the association between greenness and epigenetic age, which is crucial for understanding and reducing disparities in greenness exposure and its associated benefits.

To address these gaps, the findings explore the associations between long-term greenness exposure and epigenetic age, considering race, sex, and neighborhood deprivation as effect modifiers.



Characteristics of Study Participants

Over 900 participants were included, with a mean age of 45.3 years. The cohort consisted of 376 Black participants and 548 white participants, with 453 men and 471 women. Approximately 54.5% of participants had parks within a 5-km radius of their residential address. The mean Normalized Difference Vegetation Index (NDVI) value within the 5-km buffer radius 1 year before the Year 20 visit was 0.38 . Participants with parks within 5 km had slightly lower NDVI values  compared to those without parks . Moderate correlations were observed for epigenetic age acceleration.

Association between Greenness and Epigenetic Aging

Their analysis revealed a significant association between 20-year exposure to greenness, and epigenetic aging. Greater greenness was associated with slower epigenetic aging, suggesting a potential protective effect of urban green spaces on the aging process. However, when considering racial disparities, we found that Black participants had less surrounding greenness compared to white participants.

This disparity in greenness exposure led to an attenuated association between greenness and epigenetic aging in Black participants, compared to white participants. This highlights the need to address and reduce disparities in greenness exposure among different racial groups.

Furthermore, the association between greenness and epigenetic aging was influenced by neighborhood socioeconomic status. Participants living in disadvantaged neighborhoods showed a stronger association between greenness and epigenetic aging, with compared to less disadvantaged neighborhoods. These findings underscore the importance of considering neighborhood characteristics and socioeconomic factors in understanding the relationship between greenness and epigenetic aging.



The results of the study provide valuable insights into the associations between urban greenness and epigenetic aging. The observed relationship between greater greenness and slower epigenetic aging suggests that urban green spaces have the potential to promote healthy aging and mitigate the effects of biological aging processes. This aligns with previous research highlighting the benefits of green spaces for cardiovascular health, mental well-being, and overall mortality reduction.

However, it is crucial to acknowledge and address the existing inequalities in greenness exposure. The findings also highlighted the greenness gap between racial groups, with Black participants experiencing lower levels of greenness compared to their white counterparts. This highlights the need for equitable distribution of green spaces and environmental resources to ensure that all communities can access the health benefits they provide.

Neighborhood deprivation, characterized by lower socioeconomic status and limited resources, may exacerbate the impact of environmental exposures on health outcomes. Recently at our event 'Where the Shade hits the Pavement' Dr. Kim Loo spoke about the link between lack of environmental exposure and the health effects of at risk people and why efforts should be directed toward promoting green infrastructure and urban planning strategies that prioritize the creation and maintenance of green spaces in disadvantaged areas.

Overall, the study contributes to the growing body of evidence supporting the role of urban greenness in healthy aging. By understanding the complex interplay between greenness, epigenetic aging, and social determinants of health, we can inform policies and interventions aimed at creating more equitable and sustainable urban environments that promote the well-being of all individuals.

Read the full report.


Key Takeaways

Inequalities in Urban Greenness and Epigenetic Aging:

  • The study examines the association between 20-year exposure to greenness and epigenetic aging in a large, biracial (Black/white), U.S. urban cohort.
  • Greater greenness is associated with slower epigenetic aging.
  • Black participants have less surrounding greenness and a weaker association between greenness and epigenetic aging compared to white participants.
  • Participants in disadvantaged neighborhoods show a stronger association between greenness and epigenetic aging compared to those in less disadvantaged neighborhoods.
  • Urban green space provides critical ecosystem services and potential benefits to healthy aging, including better cardiovascular health and lower mortality.
  • Long-term exposure to greenness has a relationship with slower epigenetic aging, with different associations observed based on race and neighborhood socioeconomic status.

The study suggests that greenness exposure in urban areas is associated with slower epigenetic aging, but the relationship varies by race and neighborhood socioeconomic status. Black participants and those in disadvantaged neighborhoods experience lower levels of surrounding greenness and have attenuated associations between greenness and epigenetic aging. Understanding these inequalities and their implications can help inform efforts to reduce disparities in greenness exposure and promote equitable access to the health benefits of urban green spaces.

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

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.


Six international cities with outstanding green infrastructure

Six international cities with outstanding green infrastructure

Green infrastructure and urban sustainability are becoming increasingly high priorities for cities all around the world, however some are already streets ahead. Here are six of the top cities who are leading the pack.


  1. Singapore

Now known as one of Asia’s greenest cities, Singapore’s water supplies were once so scarce that they had to import water from Malaysia. However, Singapore has since turned things around, making two-thirds of the city’s hard surfaces rainwater catchments, which deposit water to 18 reservoirs.

Other sustainability systems include advanced water purification and recycling processes, a driverless metro and environmentally-friendly meeting venues.


  1. Stockholm

Stockholm in Sweden became the first European Green Capital in 2010, thanks to an administrative system that makes sustainability a priority. In Stockholm, eco-taxis get preferred placement at the front of taxi ranks, while more than 700 kilometers of bike lanes and a community bicycle rental program encourage people to cycle rather than drive.

Stockholm even has an official ‘eco-district’, located in Hammarby Sjöstad. Its goal is to halve the carbon footprint of a typical city, by providing residents with gas and electricity from renewable sources, as well as houses made from raw materials.


  1. Virginia Beach, VA

Virginia Beach is ranked second on the Environmental Protection Agency’s list of mid-sized cities with the most buildings that also received the ENERGY STAR rating for energy efficiency.

The city has a strong focus on school-related sustainability, with the Virginia Beach public school system being the only K-12 division to receive a Governor’s Award for Environmental Excellence, which recognises continual efforts made toward conservation.


  1. Portland, OR

When Portland residents voted in the 2018 midterm elections, they favoured a ballot initiative that imposed a one percent tax for large corporations. The revenue generated by this initiative will go toward supporting change minimisation strategies in the city.

Earlier in 2018, Portland also made single-family home owners responsible for disclosing their home’s energy efficiency rating (measured by a professional assessment) before putting their home on the market. This allows potential buyers to make more informed purchasing decisions, while also encouraging sellers to make their homes more sustainable.


  1. Boston, MA

Boston’s goal is to be carbon-neutral by 2050, and the city is also working towards a zero-waste goal. The climate change plan involves planting trees to help absorb floodwaters that could result from worsening storms, plus looking at ways to reduce greenhouse gas emissions by giving residents sustainable transportation options.

In Boston, there are nearly 200 bicycle rental stations. The city is also considering how to accommodate more electric vehicles by installing more convenient charging points.


  1. Vancouver, British Columbia

Vancouver is the third most sustainable North American city, according to data published in 2017. Notable green initiatives include the Tap Map app, which helps people find places to refill their reusable water bottles. In 2015, Vancouver also banned organic materials from landfills, encouraging people to recycle their food scraps.

In terms of urban buildings, Vancouver has a particularly eco-friendly landscape and scores a higher-than-average rating for walkability. That means fewer vehicles, less pollution and a smaller carbon footprint.


Swinburne trials world-first urban forest management project

Swinburne trials world-first urban forest management project

A new pilot program led by Swinburne is using water-sensor technology to better manage urban forests in Melbourne.

Dr Scott Rayburg, Swinburne Water Resources Engineering senior lecturer, and his team have joined forces with ICT International and RMIT University to install $31,000 worth of tree water sensors at CERES Community Environment Park – a not-for-profit sustainability centre located in the inner-city suburb of East Brunswick.

The sensors are designed to create stronger, healthier urban forests. They also enable park managers and members of the community to track the progress of trees via online platforms that provide real-time data on water use and water stress.

During the pilot, data will be collected via sensors attached to the trees. It will be used to determine the most suitable species for current and future climates. It will also allow forest managers to determine how much water to apply to their trees, and when.

Dr. Rayburg says, “The project is transformational. Instead of trees dying at 80 years of age because they are spending their whole lives in water stress, they’ll live to be two or three or maybe even four hundred years old. That matters because when we lose a tree in an urban landscape we lose habitat, we lose cooling, we lose a part of ourselves, and people have a really visceral connection to trees.”

He also notes that this project is the first of its kind in the world, saying “These sensors have previously been used in agriculture and plant biology, but never before in an urban forest management setting.”

The sensors are the first stage in this pioneering project, which plans to go one step further with an app that allows the trees to ‘talk’.

“The City of Melbourne has a platform called Urban Forest Visual that allows people to send an email to a tree and then somebody from the City of Melbourne responds to the email,” Dr Rayburg says. “This has been really popular, which demonstrates the desire people have to interact with nature, even in cities.”

“We want to take this to the next level; instead of a person responding, we want the tree to respond.”

The proposed app will allow members of the community to contact a tree and ask how it’s going. Using the real time watering data, the tree will send back an instant response which might confirm its feeling healthy, or even ask for some water.

The hope is that the app will get more people engaged with Melbourne’s urban forest and tree health, taking some pressure off local councils.

Main image: The sensors in the instrumented trees (as pictured) at CERES provide constant, real-time watering data.


U.S. non-profit generates private funding for urban trees

Despite evidence that urban trees offer a diverse range of benefits – from improving air and water quality to reducing energy costs, improving human health, and even storing carbon – they are disappearing at an alarming rate from cities across the U.S.

A recent paper by two Forest Service scientists reports that 36 millions trees are lost each year in U.S. metropolitan areas. The reasons are largely financial, with many municipalities unable to find enough money to finance green projects. It’s been reported there’s a growing recognition of the inequity of tree-canopy distribution in U.S cities, with vast cover in wealthy areas and far fewer trees in disadvantaged neighbourhoods. Add to this the difficulties posed by drought and increased temperatures due to climate change, and it’s clear to see why urban trees are suffering.

However, good news is on the horizon. To help find more funding for urban trees, some local governments, including Austin, Texas, and King County, Washington are running pilot projects with a non-profit organisation called City Forest Credits (CFC) in Seattle. The projects are generating funding for city tree canopies from private companies and individuals who wish to offset their carbon emissions. These companies and individuals buy credits for tree planting or preservation, contributing to greener urban environments.

The credits generated from these projects “are specifically catered to the urban environment and the unique challenges and possibilities there, so they differ from traditional carbon credits,” said Ian Leahy, a member of the CFC protocol board, and Director of Urban Forestry Programs at American Forests – a non-profit conservation group.

Zach Baumer, Climate Program Manager for the City of Austin, and fellow member of the CFC board, said, “I think the work is innovative and potentially game-changing. To harness the market to create environmental benefits in cities is a great thing.”

To be eligible for new carbon credits, city tree projects must follow official procedures for urban forests. These include rules covering specific factors like the location and duration of a project, and how the carbon will be quantified.


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