Posted by Ben Gooden on Tue, Mar 22, 2022 @ 9:38 AM

Why don’t trees grow well in cities?

In every city, around the world, you see trees that are not meeting their full potential within the urban environment. To the human eye, these trees can appear twisted or have damaged branches, making them unhealthy and deformed.

In serve cases, the trees will gradually decline and end up being removed, with just an open space in the pavement remaining.

Sadly, cutting down dying trees from city landscapes has become all too familiar, and is something we want to explore in this article.

Designing a Tree Planting Method

One of the first reasons for unsuccessful tree growth, in many cases, lies in the failure to fully design a tree planting method. The implementation of any successful method, must first ask questions surrounding the location of the site: what is the soil profile that the tree is being planted into; will there be enough air-filled porosity or oxygen at the depth of planting; does the location have the necessary space to provide for the tree’s root system?

These questions must then be answered by adopting appropriate solutions, such as: applying nutrients to amend the soil profile where necessary; choosing the best-sized tree to fit the location, avoiding having to repair tree root damage to pavements; utilising road-based material that is conducive to tree growth; installing adequate draining mechanisms, so that the tree does not become waterlogged in wet seasons.

Typically, the cities with a healthy and thriving urban forest today, have adopted a comprehensively designed tree planting method to overcome the problem of frequent tree deaths within city landscapes. However, if a tree planting method, like the one discussed above, cannot be fully funded, then tree growing failures in cities will continue to occur.

Tree Planting Budget

To allow trees to reach full maturity, and ideally become self-sufficient, a suitable budget must be allocated. Without a sufficient budget, cities will experience the premature deaths of trees, which will need replacement within 3-5 years of planting.

A well-funded tree planting program would avoid the cost of continual tree removal and replacements, and alternatively appreciate the future value of trees as an asset within any urban environment.

Human Behaviors

Another reason for trees not growing well in cities is human behavior.

This can be broken up into a number of areas, but one is vandalism. Unfortunately, it is not uncommon, to see trees vandalized, especially young trees. Once trees are beyond a certain stage of life, they tend to be less susceptible to vandalism, but while they’re young, they are very vulnerable to being damaged by vandals: debarking trunks; snapping branches; or scratching graffiti onto limbs

Traffic impact is another human behavior that negatively affects tree growth. This frequently occurs with curb plantings, whereby trees are planted close to the roadside. If crown lifting is not performed, and the trees develop a low canopy, then low-lying branches can be smashed and damaged by passing traffic. This is especially the case, where you see a camber on the road that causes tall vehicles to intersect with the tree’s canopy, causing limbs and branches to tear off, allowing infection to set in.

Low-speed vehicular impact in parking lots can similarly impact tree growth. This frequently happens in parking lots, where trees have been planted with the best intentions, but wheel stops have been either omitted or placed in the wrong positions.

For example, at home improvement centers, frequented by trade vehicles with overhanging tray bodies; reverse parking can lead to vehicles, unintentionally smashing into the young trees.  This can be overcome by studying the trees surrounding, to allow for better tree placement and tree protection.

An Altered Environment

The urban climate in which trees are planted can also lead to poor growth performance. Cities have their own microclimate, which is a very different environment to the natural forest. It is well documented that some tree species will actually grow a lot faster in a city than they will in their natural open forest environment, because of the urban heat island effect, leading to warmer temperatures and thus more growth.

However, in a lot of cases, the urban environment does not necessarily result in successful tree growth.  For example, wind velocities in city landscapes are very different to the natural forest environment.

In the forest, trees are protected by one another against environmental forces of nature, but in urban planting, trees are typically planted on their own, and therefore become more exposed.

Adding to this exposure is the fact that the trees are often planted in close proximity to tall buildings, where the street forms a canyon. Winds can then blast up this ‘canyon’ with extremely high velocity, blowing the trees around, causing damage to the root systems.

Oftentimes, the wind will cause a young tree’s root system to be weakened, which may only be noticeable when the tree becomes much larger, unfortunately resulting in limbs breakages, or a whole tree collapses, which can be catastrophic.

Solutions

Fortunately, there are solutions to all of these issues. Citygreen has decades of experience in successfully establishing urban forests to prevent premature tree death. A system that Citygreen has patented and used throughout the world with success is the Stratavault™ system.

 

Case Studies – Stratavault™ system

Downtown Ennis, located south of Dallas, in the United States, is known for its 19th-century historic architecture and iconic brick streets. With its current population of over 20,000, the city was looking to cultivate residential growth.

With this goal in mind, Citygreen’s Stratavault™ system was chosen the make the area more attractive, accessible and beneficial to downtown residents and tourists alike.

Adopting a ‘Green Streets’ approach, the areas impermeable curb and gutter section was replaced with a suspended paving system – that is, Citygreen’s Stratavault™ system, to allow trees to grow and thrive into maturity.

Capable of supporting heavy duty vehicular loading, permeable pavers were installed on top of soil cells which provided a medium for trees to grow in, whilst also capturing stormwater on-site to irrigate the trees.

Citygreen’s Stratavault™ was also utilised to enhance the redevelopment of Barangaroo South, in Sydney, Australia.

Designed to encourage both passive and active outdoor activities, the redevelopment of Barangaroo South’s landscape, initially faced significant difficulties. The density of paved areas and streets, was not able to provide a conducive environment for trees to thrive in.

To overcome this problem, Citygreen’s Stratavault™ was utilised. With its open matrix design, the system ensures that there is enough uncompacted soil space to facilitate strong root growth without damaging the surrounding paved surfaces.

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As shown above, Citygreen is an expert in every phase of design, and implementation of streetscape upgrades, incorporating healthy, sustainable green infrastructure – reach out to Citygreen for a Design Workshop today.

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Posted by Ben Gooden on Tue, Sep 21, 2021 @ 5:48 AM

The critical role of ‘everyday nature’ for the future of cities

A growing population puts increasing pressure on biodiversity when residential areas encroach on natural systems. The Built environment report describes Australia’s urban footprint, and the implications for air quality, water quality and the natural environment.

As Australia’s population grows, additional urban land is required, or existing land is used more intensely. In Australia, population growth tends to be most concentrated in outer suburbs, in inner cities, in urban infill areas and along the coast. Our big cities continue to expand into natural areas on the city fringes, despite the well-recognised problems associated with higher infrastructure costs, lack of amenity, car dependency, poor job access, and diminished agriculture and open space (Newton 2012). In Melbourne, 50 per cent of the approximately 40,000 new dwellings built each year are in new greenfield sites (Buxton 2014). Targets for infill housing established in recent metropolitan strategic plans are not being achieved (Newton 2012).

The threatened Grassy Eucalypt Woodland of the Victorian Volcanic Plain is encroached on by Melbourne’s peri-urban zone, with woodland remnants cleared to allow increasing urban development. Additional growth centres are planned. In response, the Victorian Government is establishing conservation areas in and outside the growth corridors to protect threatened species and ecological communities of national and state significance, and to manage the impacts of urban development in urban growth corridors. Similarly, encroachment of urban development on the Cumberland Plain Woodland in the Sydney Basin has reduced the community to small fragments scattered across the western suburbs of Sydney, and it is now listed as critically endangered.

Urban development is a major driver of environmental change. Urban areas contain threats to, and opportunities for, biodiversity. The conversion or degradation of natural ecosystems in urban areas has the most obvious and immediate impacts on biodiversity. In addition, human settlements and development are often the entry point for introduced species, which are a major pressure on biodiversity. For example, non-native invasive garden plants, introduced to Australia by and for the urban population, make up an estimated 72 per cent of environmental weeds that affect biodiversity (Groves et al. 2005).

In contrast, the urban environment can prove an attractive habitat for a wide range of taxa because of abundant food and shelter. Urban areas may also provide more stable resources for some native species as a result of planting selection and supplemental watering. Some urban habitats, such as railway lines, abandoned industrial lands and urban wetlands, can be rich in native species and can play an important role in maintaining the biodiversity of a city.

Although the presence of wildlife in urban areas can enhance human quality of life (see Box BIO3), some urban animal populations can prove problematic because of their impacts on amenity or their role as vectors of disease. For example, roosting by flying foxes in urban and peri-urban areas can result in contact and conflict with humans. Human concerns include noise, odour and faeces from flying fox camps, particularly when they occur near residences. Transmission of disease, particularly Hendra virus and Australian bat lyssavirus, is also a key concern and has received much attention during the past few years. Although smaller camps are often tolerated, larger camps become a focus of community disquiet. The spectacled flying fox (P. conspicillatus) and grey-headed flying fox (Pteropus poliocephalus) are both listed as vulnerable under the EPBC Act. They have both shown marked changes in the distribution of their abundance during the past 15 years, in the form of increases in the number of urban camps and in the proportion of their populations found in urban contexts (Tait et al. 2014, Westcott et al. 2015). It is unclear whether these changes represent responses to the development of appropriate conditions in urban areas, the deterioration of conditions elsewhere or the cessation of exclusion from urban areas. Regardless, the shift represents a major management dilemma, given the conflict it produces and the conservation status of the 2 species.

Cities are often located in areas with high biodiversity, and the process of urbanisation itself is likely to have led to many species that formerly occurred in these places now being threatened. In 2015, Ives et al. (2016) analysed the extent to which the distribution of 1643 species of national environmental significance under the EPBC Act overlapped with 99 Australian cities of more than 10,000 residents (Figure BIO5). They found that 25 per cent of listed plants and 46 per cent of listed animals had distributions that intersected with cities. The distributions of 8 threatened species (all plants) entirely overlapped with cities, whereas 51 (10 per cent) of the 503 threatened species found in cities had more than 30 per cent of their distribution in urban areas. The research showed that cities contain substantially more threatened species per unit area than non-urban areas.

 

Note: Urban areas are outlined in black. Cities shown in greater detail in boxes are (a) Perth, (b) Brisbane and (c) Melbourne. Source: Dr Pia Lentini, University of Melbourne, used under CC BY NC using data supplied by the Australian Government Department of the Environment and Energy

Urban growth has been shown to cause overall reductions in the distributions of birds in Brisbane; however, spatially constrained, compact development substantially slows these reductions, resulting in fewer local extinctions. Averted local extinctions under compact development are most pronounced for urban-sensitive species that are dependent on large intact remnants of natural habitat or open space within a city (Sushinsky et al. 2013). Other research has shown that large native trees in urban areas provide crucial habitat for wildlife. In Canberra, the presence of large native trees in urban parks increases bird diversity and abundance (Stagoll et al. 2012).

Citizen-science initiatives focused on urban areas, such as BirdLife Australia’s Birds in Backyards and School of Ants Australia, are helping to improve knowledge about urban biodiversity and management.

Nature in cities delivers a remarkable range of benefits to human health and wellbeing. Individuals are more likely to live longer (Donovan et al. 2013), and have better general health and wellbeing (Dallimer et al. 2012) in a city with more trees.

Urban greening can substantially improve the resilience of cities to climate change, potentially cooling cities by up to 8 °C in summer, alleviating the impacts of flooding and providing shelter from extreme weather events. Vegetation in cities can also play a significant role in mitigating climate change impacts by sequestering greenhouse gases, and reducing energy consumption for cooling and heating.

Cities host numerous threatened plant and animal species. In Australian cities, more than 3 times as many threatened species are found per unit area than in rural areas (Ives et al. 2016). Some species are found only in cities, whereas others rely on cities for key food and habitat resources. The future of many threatened species will depend on actions to accommodate their needs within city boundaries.

Creating opportunities in cities for everyday interactions with nature provides an unparalleled opportunity to reconnect people with biodiversity, and expose urban residents to the myriad health and wellbeing benefits provided by nature. Furthermore, urban renaturing has the potential to connect urban residents with Indigenous history and culture, and create an avenue for preserving traditional knowledge and engaging urban Indigenous people in city planning processes.

The reasons for embracing nature in cities are compelling, but the pathways to achieve this vision are not always straightforward. An important first step is to reframe the way nature is considered in the planning process. Rather than considering nature as a constraint—a ‘problem’ to be dealt with—nature can be seen as an opportunity and a valued resource to be preserved and maximised at all stages of planning and design. It also requires a different conceptualisation of nature, where novelty is the norm and apparently scrappy bits of urban nature can have as much value as pristine nature reserves. The future of our cities may well depend on a new conceptualisation of urban landscapes, where nature can thrive and people can enjoy—every day—the remarkable range of benefits that nature can deliver (Figure BIO6).

Source: © Sarah Bekessy, GE Garrard & LM Mata, RMIT University, Melbourne; and RG Hobbs, University of Western Australia; all rights reserved

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Posted by Sally Cameron on Sun, Dec 13, 2015 @ 10:29 PM

AILA champions Green Infrastructure in Australia

AILA champions Green Infrastructure in Australia:

The health of Australians is continuing to decline, with 80% of Australians predicted to be overweight or obese by 2025. This week, the Australian Institute of Landscape Architects (AILA) has taken action, urging the Federal Government to take a global leadership position on Green Infrastructure and acknowledge Australia’s urban landscape as a key driver for improved health, environmental, and social outcomes.

In a submission made to Infrastructure Australia’s 15 Year Infrastructure Plan for Australia, the AILA made four recommendations:

  1. A National Green Infrastructure Strategy from the Federal Government to provide guidance on how infrastructure projects can be a catalyst for enhanced landscape outcomes through green infrastructure investment;
  2. Minimum ‘SITES’ Ratings for Federally Funded Projects to encourage a global standard of integration of natural and physical infrastructure;
  3. A National Green Infrastructure Training Program for built environment practitioners, including engineers, planners and senior level policy makers involved in the planning, design and development of infrastructure across a diversity of asset classes; and
  4. A Project Briefing Guide for Integrating Landscape through Infrastructure Development to become the key national resource used to influence project briefing processes on federally funded projects.

According to AILA CEO, Shahana McKenzie, the Government has an opportunity to reprioritise outdoor spaces such as parks, streetscapes, and public precincts, enabling the Australian population to be more active and in turn reducing escalating healthcare costs. The AILA strongly believes that an increased investment in Green Infrastructure would be a minor cost resulting in significant medium and long-term benefits to the liveability of Australia’s urban areas.

For more information on the Australian Infrastructure Audit, visit this page.

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Posted by Christina Greene on Tue, Mar 03, 2015 @ 10:13 PM

Advanced Tree Pit Design Enhances Urban Forestry

With increasing urbanization, and more highly concentrated populations within cities, strengthening the green infrastructure is becoming increasingly important. One of the largest opportunities for impact is maintaining and enhancing the urban canopy. This is addressed most readily by advanced tree pit design, which refers to the subterranean structures put in place during planting.

In Minneapolis, the local government conducted research that revealed well-planted trees provide a strong financial incentive in addition to the ecosystem benefits. The research found a $2 million savings between a storm water conveyance system, or subterranean cell systems.

Peter MacDonagh, a landscape architect, said in an ASLA interview, “larger, older trees are far more valuable than younger ones, so work needs to be done to preserve these and use new techniques to enable younger trees to stay in place longer.”

As trees were planted in the past, the soil they were placed in was compacted, causing a lack of nutrients, storm water management, and root establishment. As a result, the trees struggle to thrive and provide their benefits to the local environment and infrastructure. Often, these struggling trees will either die, stop growing, or begin to push through and ruin sidewalks and roads.

“The Center for Urban Forest Research calculates that large-canopy trees …outperform small trees…and they do not start adding significant environmental performance until they reach 30 feet,” states Matthew Gordy, a landscape and urban design professional.

By utilizing cell systems, the strain put on the trees’ growth is almost completely eliminated, resulting in lower costs, and increased shade, stormwater management, and overall well being of the populaces and local infrastructure.

Get more information on advanced soil cell systems here.

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Posted by Kristyn Maslog-Levis on Tue, Jun 03, 2014 @ 8:28 PM

Green tech needed as CO2 emissions increase

 

Carbon dioxide levels in the northern hemisphere hit 400 parts per million for the first time in human history, according to an article by the Sydney Morning Herald.

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Posted by Kristyn Maslog-Levis on Wed, May 07, 2014 @ 7:21 PM

The Future of Cityscapes Depend on Green Infrastructures

An investigation by a research group called The Resilience of Cityscapes, published in the international Biotope City journal, showed that green roofs, living walls, and greened permeable pavements has a multitude of positive effects.

“The impact of green infrastructure on an urban fabric has been visualised by computer modeling tools. The computer model results showed that all tested green technologies provide benefits to the urban microclimate and water storage capacity,” the report said.

It showed that green infrastructure is the solution to the resilience of cityscapes worldwide. The report said there is a huge trend in urbanisation with more than 50 percent of the world’s population now living in cities.

“Two effects of this influx can be observed: the occupied city area grows and
density increases. At the same time citizens request more infrastructure from cities such as public transport, recreation and sewage systems. City planners are challenged to combine the pressure of growth and integration of satisfactory infrastructure.”

The research monitored 14 green roofs, five living walls and nine surface consolidation methods in the city of Vienna to see their microclimatic effects.

Compared to surfaces like plaster or brick, plants convert sun energy into oxygen and air humidity.

“It is assumed that plants ameliorate the urban microclimate (by adding humidity and reducing radiation and wind speed) while regular surfaces
reduce the thermal comfort of cities. Aside from the positive microclimatic effects plants are also able to store water.”

Plants also improve the predicted mean vote (PMV), which describes the human thermal wellbeing. The research tested an urban area in Vienna under different types of “scenarios”. These include the climate scenario, greening scenario, the minimum greening scenario, and the maximum greening scenario.

The tests found that green infrastructure can act as a buffer for climatic extremes.

“By means of computer simulation, the measurements at test sites have been transferred to representative urban typologies of the City of Vienna. To find out, which microclimatic effect could be achieved by green infrastructure, two greening scenarios have been applied on urban typologies and subjected to today’s and future climatic framework conditions. The simulations make clear, that the urban microclimate can be ameliorated by integration of green infrastructure.”

It emphasised that green infrastructure is the “one appealing solution to improve the resilience of cities against climate change”.

“Apart from the microclimatic effects and the positive influence on thermal comfort, green infrastructure provides a broad range of added values: water retention, health promotion and psychological effects (stress reduction), habitat and habitat connection for fauna and flora, biodiversity and urban farming.”

The report also realised the hindrances to the implementation of green infrastructures such as different types of value on facades where some are often protected. There are also things like different regulations in different cities or the fact that most buildings are privately owned and therefore needs incentives for their properties to be developed into green infrastructure.

These are things that need to be overcome as the report also said that just a single green infrastructure would not be effective in the bigger scheme of things. In order to have the full effect of the benefits of green infrastructures in cityscapes, “a combination of different types of green infrastructure and a network of green infrastructure throughout the city is necessary”. CTA_Full Treepit Library

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Posted by Kristyn Maslog-Levis on Wed, Apr 30, 2014 @ 7:14 PM

Benefits of Green Roofs, Walls and Facades

Image from Fytogreen. This is Fytogreen’s vertical garden project in 1 Blight St, Sydney.

Winter is coming to Australia and with the cold weather comes heating costs. However, heating costs may soon be a thing of the past with an alternative greener concept.

Victoria’s Growing Green Guide, a project by The University of Melbourne, The Inner Melbourne Action Plan and several industry experts, is pushing for green roofs as a more cost-effective alternative to answer heating needs.

The guide provides technical advice on how to design, build and manage green roofs, walls and facades so they can provide multiple benefits over a long period of time.

According to the guide, green roofs, walls and facades provide several benefits to the community and its residents. Here are some excerpts from the report:

  • Building owners and developers are increasingly installing green roofs, walls or facades to add a point of difference, increase commercial returns, provide visual appeal and turn a building into a local landmark. It increases property value as well as other benefits for building owners. Green roofs can lengthen the lifespan of a traditional roof surface. They protect a roof’s waterproof membrane from solar radiation and add insulating materials to reduce severe temperature fluctuations on the roof surface. The report says early design discussions will help ensure that the roof, wall, or façade can be planned and incorporated in other building aspects such as drainage, irrigation, lighting and weight loading.
  • Green roofs absorb and retain rainwater and can be used to manage stormwater run-off in urban environments. They can also filter particulates and pollutants. Stormwater run-off can be reduced or slowed because it is stored in the substrate. Additional water storage capacity in green roof systems can be provided through incorporation of a water retentive layer or drainage layer at the base of the green roof.
  • It reduces building heating and cooling requirements. Green walls and facades can reduce heat gain in summer by directly shading the building surface. Green roofs reduce heat transfer through the roof and ambient temperatures on the roof surface, improving the performance of heating, ventilation and air conditioning (HVAC) systems.
  • Green walls, roofs and facades reduce the urban heat island effect. Temperatures can be reduced by covering a roof or wall with a layer of vegetation that shades building materials, which would otherwise absorb heat. Evapotranspiration provides cooling effects, as water is evaporated from the soil and plants transpire by taking water in through roots and releasing it through leaves. The report suggests a city-wide strategy to implement green roofs, walls and facades to help mitigate some of the negative consequences of the UHI effect.
  • Green roofs can contribute to and enhance biodiversity by providing new urban habitats and specific habitats for rare or important species of plants or animals. It can also provide a link or corridor across urban ecological deserts and assist in migration of invertebrates and birds.
  • These green infrastructures can increase amenity and provide opportunities for food production, recreation, relaxation or commercial ventures. Green roofs, walls and facades can be used for multi-level greenery designs that connect with ground level green spaces.
  • Finally, they also contribute to the removal of gaseous pollutants from the air. Plants with a high foliage density or with textured leaf surfaces that trap small particles also assist in removing particulate pollution, through dry deposition on the foliage or through rain wash.

The good news is that most building surfaces have the potential for greening. It’s just a matter of knowing how to do it properly to get the most benefits out of it. A copy of the guide is free to view for those interested.

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Posted by Christina Greene on Tue, Apr 29, 2014 @ 7:01 PM

Controlling Stormwater Runoff with Trees

Controlling Stormwater Runoff with Trees

by Rick Magill
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“Our experience, in working with a Citygreen Design Studio was second to none. We found responses from the design studio to be very timely, and technically thorough. We went backwards and forwards a number of times, looking at different iterations of the design and, nothing was too much trouble to examine and explore different possibilities. I would highly recommend the Citygreen Design Studio to any future client considering using your services.”

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“We are big on compliance on all projects, and the fact that their SmartCertify cloud platform covers all bases, and supports their 20 year warranties, is critical – especially that these pits are being installed under roadways and footpaths.”

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"I reviewed all the previous projects that we have installed in the past couple years using your product and I can happily report back that we have 0% mortality in the soil cells, which is incredible!"

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