Hong Kong Polytechnic University launches new project to monitor urban tree stability

urban tree stability - Hong Kong

Urban trees need structural stability to survive strong winds and weather events. But how do we assess the stability of tree roots and therefore the tree itself? Hong Kong Polytechnic University (PolyU) recently kicked off the Jockey Smart City Tree Management Project. This large-scale project will tailor-make and install sensors on the lower trunks of selected urban trees to monitor their tilting angle in a 3-dimensional manner. Leveraging smart sensing technology (SST) and Geographic Information Systems (GIS), the project will monitor urban tree stability to enhance timely mitigation measures to increase urban tree longevity.

Dr Miranda Lou, Executive Vice President of PolyU, said, “Committed to the pursuit for application-oriented research, PolyU researchers will apply smart sensing technology and Geographic Information Systems for monitoring tree stability. Our vision of establishing this system is to facilitate green management in the city for longer tree lives, so as to further improve our air quality for enhancing the living environment for the local community.”

Ir Hon Chi-keung, JP, Permanent Secretary for Development (Works) of HKSAR Development Bureau, said, “This project is a good opportunity to showcase Hong Kong’s positive attitude towards innovative technologies and technology applications. Through the close co-operation between the tree management departments and the project teams, an effective tree monitoring system will be established to enhance the tree management works in all aspects, enabling the continual development of Hong Kong into a safe and liveable city.”

Data collected will be used for a quantifiable analysis of the trees’ root plate movement and then a threshold developed based on numerous environmental factors. When the tilting angle of a tree exceeds the threshold, the project team will be alerted to conduct a visit to verify the data for the purpose of calibrating the system. When considered necessary, it will also inform the relevant tree management team to undertake actions in a timely manner.

Commencing in February 2018, approximately 8000 urban trees across the territory will be monitored over a 3-year period. Through early notification and response, the project aims to increase longevity of invaluable urban trees in Hong Kong.

Source: https://www.opengovasia.com/articles/hong-kongs-polyu-to-apply-smart-sensing-technology-in-urban-tree-management

Study finds London’s trees may absorb as much carbon as tropical rainforests

green park london

In dense urban cities like London, city parks are beloved for the green space and respite they provide. They also help to keep the heat island effect in check by absorbing carbon dioxide. In fact, a study published in Carbon Balance and Management found that urban forests in London may be storing as much carbon as tropical rainforests.

One of the researchers of the study, Mathias Disney, said, “Urban trees are particularly effective at absorbing carbon dioxide because they are located so close to sources such as fossil fuel-burning transport and industrial activity.”

To determine just how good the trees in Camden are at absorbing carbon dioxide, Disney and his fellow researchers at University College London (UCL) set out to measure the trees in the London borough of Camden. Using airborne LIDAR (Light Detection and Ranging) scans of trees combined with LIDAR scans conducted on the ground, the researchers not only estimated the biomass of the 85,000 trees in Camden but also created a formula to predict the differences in size-to-mass ratios between urban and non-urban trees. In areas such as Hampstead Heath, researchers found trees store up to 178 tonnes of carbon per hectare (t/ha) in comparison to the median value for tropical rainforests of 190 tonnes t/ha. Camden is also a particularly carbon-heavy borough.

So, there’s a lot of carbon to soak up and trees are just the organisms to do it – making them hugely valuable. According to a UCL press statement about the study, Treenomics estimates that the environmental value of Greater London’s trees is around £133 million a year ($176 million), with their carbon storage capacity worth around £4.8 million a year.

Disney said, “This may equate to less than £20 a year per tree, but the real value may be much higher, given how hard it is to quantify the wider benefits of trees and how long they live. The cost of replacing a large, mature tree is many tens of thousands of pounds, and replacing it with one or more small saplings means you won’t see the equivalent net benefit for many decades after.”

All the more reason to give urban trees the best possible start with enough uncompacted soil and room to grow, ensuring their longevity for years to come.

Source: https://www.mnn.com/earth-matters/wilderness-resources/stories/london-urban-forest-carbon-storage-match-rainforests   

Water sensitive urban design could stem future flooding in Hobart

water sensitive urban design - Singleton

Australia’s island state, Hobart, is well known for its history of catastrophic fires, including the disastrous wildfires of 1897-98 and 1967. As the second-driest city in Australia, it’s easy to forget though that Hobart is also vulnerable to serious flooding. Until earlier this month that is, when a record 236.2mm of rain fell on Mount Wellington and 129.2mm fell in Hobart. The deluge flooded the city, with the Hobart Rivulet breaking its banks and flooding other lower lying areas in Sandy Bay, South Hobart, New Town, Lenah Valley and Kingston. In Hobart, cars were swept away in Collins St and Syme St and McRobies Rd in South Hobart.

Hobart’s closeness to nature and surrounding hilly terrain makes the city especially prone to wildfire and flash-flooding. But, the May 2018 flooding is also partly attributable to the city’s postwar planning. Like the rest of Australia, city planning in Hobart was dominated by, “a disconnection from nature. Creeks and streams were filled in, built over or walled off (taming nature), creating risks of catastrophic failure in unexpected conditions. This approach also overlooked the important ecological functions of watercourses.”

Unfortunately, the problem is only getting worst as Hobart expands, with houses, roads and buildings increasing the hardscaped area and decreasing green cover, which acts like a sponge. Planners now must apply water-sensitive urban design principles, including protecting floodplains from development, limiting the development of very steep land, and restricting land uses on flood-prone sites. Separately, thought must be given to the development of the urban forest – planting urban trees and carefully incorporating water sensitive urban design to better manage stormwater runoff. Good planning can help prevent future disasters and keep Hobart’s residents out of harm’s way.

Source: https://theconversation.com/lessons-in-resilience-what-city-planners-can-learn-from-hobarts-floods-96529

New “Sydney Modern” gallery plans updated to prioritise green space

Sydney green space

Modifications will be made to the Art Gallery of NSW’s new “Sydney Modern” wing after two thirds of public submissions to Planning NSW criticised the design. The most notable criticism of the planned $344 million development was the lack of trees and open green space.

The modern wing – a series of pavilions to be built on the hill to the north east of the existing gallery opposite the Botanical Gardens – will now also feature natural stone cladding to complement the Sydney sandstone of the existing 1909 Walter Liberty Vernon gallery building and make the new wing less conspicuous.

Concerns raised by nearly 200 people and organisations attacked the loss of open green space in the city as something that could not be reversed. In a submission, the Eastwood Evening Garden Club said a meeting of its 100 members had decided to oppose the expansion because of the destruction of trees and open space. At a time of global warming, green areas needed to be protected without “adding to our increasing ‘cement city’,” it said.

The gallery’s revised proposal will covert parking spaces into open space, create more green roof space and feature a central public lawn in a proposed Art Garden. The gallery also promised to remove only 124 trees (versus 141) and plant 273 new trees, including more mature specimens.

Source: https://www.smh.com.au/national/nsw/art-gallery-s-sydney-modern-adds-trees-open-space-and-softens-look-to-address-critics-20180424-p4zben.html

How Understanding Soils and Watering Can Prevent Street Tree Failure

A new video released by Citygreen demonstrates the importance of understanding soils and watering to prevent street tree failure. Citygreen Consultant, Nathaniel Hardy, visits a stressed street tree located in the dry climate of the ACT. Despite being irrigated with a suitably large volume of water, the tree is lacking outer foliage with bare, dead branches clearly visible. So, why is the tree failing to thrive despite receiving the required volume of water?

Nathaniel draws attention to the finely-textured, clay-filled soil in the rectangular garden bed surrounding the tree. A circular mulch ring around the tree is simply not big enough to cope with the volume of water being provided, so much of the water is escaping into the larger garden bed and then onto the surrounding pavement. Because the pavement is only slightly elevated, water does not have a sufficient opportunity to penetrate the fine soil and irrigate the roots below. Instead, we see a dry, caked soil surface which has become largely impervious to water.

As the video demonstrates, simply providing the required volume of water is not enough. Understanding the character of your soil and the runoff behaviour of water provided is integral to providing an environment in which street trees can thrive.

To find out more about Citygreen’s innovative water sensitive urban landscape solutions, visit www.citygreen.com. To speak to Citygreen about this video, email info@citygreen.com.

Shepparton Urban Forest Strategy aims to reduce tree vandalism

tree vandalism

Greater Shepparton City Council is planning to plant 1500 trees each year as part of its urban forest strategy. Frustratingly, each year 60 to 80 trees in Shepparton are vandalised – about 5% of all new tree plantings. These senseless acts of destruction are costing the council between $15000 and $20000 a year.

Heath Chasemore, council’s Park, Sport and Recreation Manager, said street trees cost $250 to replace – including maintenance to establish the trees. In CBD locations, costs are even more with more advanced tree stock required, services and other infrastructure to work around.

Disappointingly, a second wilga tree was recently damaged along Vaughan St, Shepparton – the second incident of damage to trees in this shopping precinct.

Chasemore said, “We do lose a small percentage of trees to vandalism each year — roughly five per cent. This behaviour by a limited number of individuals shows little or no regard for our community and is extremely disappointing.

“Wilga trees are hard to propagate and slow growing, however we have had great success with this species in our Vaughan St precinct, where they have prospered and provide great aesthetic appeal to the streetscape as part of our urban forest strategy. The cost of replacing trees and dealing with senseless vandalism ultimately is borne by the ratepayers.’’

It is hoped the urban forest strategy will increase awareness of the benefits of urban trees and reduce the rate of vandalism.

Source: http://www.sheppnews.com.au/2018/01/10/126850/leave-street-trees-alone

World’s first vertical forest for low-income housing coming to the Netherlands

Stefano Boeri Architetti Eindhoven Trudo Tower facade
© Stefano Boeri Architetti

Stefano Boeri is famous for his vertical forests around the globe, but his latest project will be the first forest tower funded by a social housing project to provide low-income housing. The Trudo Vertical Forest, located in Eindhoven, will showcase how good architecture can tackle both climate change and urban housing issues.

The tower will consist of 19 stories with 125 units – all covered in a luscious vertical forest featuring 125 trees and 5200 plants. The 246-foot tower will be covered in a rich, biodiverse environment to help control urban pollution and provide homes for a variety of animals and insects.

Boeri said, “The high-rise building of Eindhoven confirms that it is possible to combine the great challenges of climate change with those of housing shortages. Urban forestry is not only necessary to improve the environment of the world’s cities but also an opportunity to improve the living conditions of less fortunate city dwellers.”

Francesca Cesa Bianchi, Project Director of Stefano Boeri Architetti, said, “The Trudo Vertical Forest sets new living standards. Each apartment will have a surface area of under 50 square meters and the exclusive benefit of 1 tree, 20 shrubs and over 4 square meters of terrace. Thanks to the use of prefabrication, the rationalization of technical solutions for the facade, and the consequent optimization of resources, this will be the first Vertical Forest prototype destined for social housing.”

Source: https://inhabitat.com/the-worlds-first-vertical-forest-for-low-income-housing-is-coming-to-the-netherlands/

Forget the beach – go somewhere green for ultimate relaxation

Cornmeal Parade

In the land Down Under, we’re currently in the thick of a long, hot summer. Most of us spend our spare time during this season at the beach. But, what if there was another destination that offered even greater relaxation? Somewhere less busy, searing, and sandy? Somewhere green, of course. In Australia, we’re lucky to have more than 500 national parks – wild, rejuvenating, and free for all.

Lord knows we need a little relaxation. According to an Australian Bureau of Statistics survey completed in 2007, one in five Australians experiences a mental disorder each year. Most common are anxiety disorders, like obsessive-compulsive disorder, social anxiety, or panic disorder.

Thankfully, there is a relatively simple salve with more than 40 years of research showing that exposure to nature increases calm, decreases agitation, and improves concentration and creative thought. Writer and I Quit Sugar dynamo, Sarah Wilson, is renowned for her solo hikes – jumping on a train to a national park somewhere out of town and disappearing into the wild for days at a time. She says she returns settled, sated, and full of creative ideas.

Of course, when we’re not on holidays, it’s not always possible to plant ourselves in a national park. In this sense, urban greenery is more important than ever before.

Zoe Myers, an Urban Design Specialist at the University of Western Australia, says research shows that city dwellers have a 20% higher chance of suffering anxiety and an almost 40% higher chance of developing depression. Fortunately, research also shows that people in urban areas who live closest to the greatest green space are much less likely to suffer poor mental health.

The benefits of urban greening are endless – cooler cities in summer, warmer cities in winter, slower stormwater runoff, filtering of air pollution, habitat for animals, happier people, and more prosperous local economies. If you can, take a trip to a national park and soak in the natural goodness. But, when you’re back at work, don’t forget to take lunch in the park – toes in the grass, breeze in your hair, eyes on the branches above.

Source: http://www.smh.com.au/comment/keep-calm-reasons-to-head-for-the-park-not-the-beach-20171223-h09pzg.html

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