How Landscape Architects Plant Trees in Cities

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Landscape architects are experts in designing and creating beautiful, sustainable landscapes. One of the essential components of their work is planting trees in urban environments. Trees provide numerous benefits to the urban environment, including enhancing air quality, reducing stormwater runoff, and providing shade and habitat for wildlife. In this section, we will explore how landscape architects plant trees and the techniques they use to ensure their success.

Key Takeaways:

  • Landscape architects play a crucial role in planting trees to create sustainable and healthy environments.
  • Proper selection of tree species, planting techniques, and maintenance are essential for the long-term health of trees.
  • Landscape architects navigate unique challenges when planting trees in urban environments.
  • By following best practices in tree planting, we can contribute to a greener and healthier future.

The Importance of Tree Planting for Urban Landscapes

Tree planting is an essential component of creating sustainable and healthy environments, especially in urban areas. Landscape architects follow best practices to ensure the successful establishment and growth of trees, including sustainable tree planting and urban tree planting.

One of the critical tree planting best practices is selecting appropriate tree species. Landscape architects carefully choose the tree species that are well-suited to the local climate and site conditions. They prefer native tree species as they provide numerous benefits, such as supporting local wildlife and improving biodiversity.

Soil and tree root preparation is crucial for sustainable tree planting. Landscape architects use innovative techniques like soil cells, such as Stratavault or soil vault systems, to ensure adequate space for root growth and improve soil quality. This is especially important in urban areas where soil compaction and pollution can be a significant challenge.

Tree roots are opportunistic, seeking out favorable growing conditions. Moisture trapped beneath impermeable pavements, oxygenated sand layers, moist conditions in service trenches, cracks in road pavements and curbs- these are some areas that tree roots will explore to satisfy the life needs of the tree which leads to pavement and infrastructure damage.

Landscape architects also employ various tree planting techniques to ensure proper tree planting. This includes preparing the hole properly, handling the root ball, and planting the tree at the correct depth. These techniques promote healthy root development and establish strong trees.

Proper maintenance is crucial for the long-term health of planted trees. Landscape architects monitor the trees for signs of stress, pests, or diseases. They provide necessary pruning, fertilization, and irrigation to ensure optimal growth and resilience. Moreover, they also consider factors like site conditions and tree spacing to optimize the tree’s health and longevity.

Overall, landscape architects prioritize sustainability in tree planting projects to ensure that the planted trees contribute to a resilient and environmentally friendly landscape. By following their best practices, we can contribute to a greener and healthier future.

Selecting Tree Species for your Landscape

When it comes to planting trees, landscape architects carefully consider which tree species to select. Native tree species are often preferred, as they are better adapted to the local climate and conditions and can provide numerous benefits. In fact, selecting the right species can make all the difference in the success of a tree planting project.

Native trees also support local wildlife and improve biodiversity. They are often hardier than non-native species, able to withstand harsh weather conditions and local pests and diseases. Additionally, native species are more likely to support the specific ecology of the area, including pollinators like bees and butterflies.

Related: Best Species for Reducing Air Pollution

However, it’s not just about selecting native species. Landscape architects also take into account factors such as tree growth rate, size, and appearance to ensure the right tree is selected for the right location. They also consider the soil conditions and water availability, as well as any potential hazards that may impact the growth of the tree.

By carefully selecting the appropriate tree species, landscape architects can create healthier and more resilient urban forests. Not only do these trees provide environmental benefits, but they also contribute to the beauty of our urban landscapes.

Tree Planting Techniques

Proper tree planting techniques are essential for successful tree growth and development. Landscape architects utilize various methods to ensure optimal tree health.

One crucial technique is proper hole preparation. The hole should be dug to the appropriate depth and width, allowing enough space for the roots to spread out. The root ball should be handled carefully to prevent damage. The edge of the root ball should be lightly hand brushed to bring all the fine roots out and larger structural roots at the edge of the root ball should be pruned if their roots are facing inward to avoid root swirl. We do this to ensure once the tree is planted in it’s new surroundings new growth is focused on growing outwards into new soil.

Correct planting depth is also important. The topmost root of the tree should sit slightly above the soil level to prevent it from suffocating. After planting, the soil should be carefully compacted to eliminate air pockets and provide support for the young tree.

Overall, landscape architects should follow specific tree planting methods that ensure the long-term success of the planted trees.

Soil Preparation and Soil Cells

Landscape architects understand the critical role of soil preparation in ensuring successful tree planting. They use innovative techniques like soil cells to improve soil quality and provide adequate space for root growth, promoting healthy trees.

Related: How much Soil do Street Trees Need?

Soil cells are a specially designed system that provides structural support for pavements and surfaces while simultaneously providing ample space for root growth and water drainage. Stratavault and soil vault systems are examples of these systems that feature an interlocking matrix design that creates ideal conditions for soil moisture and movement.

Advantages of Soil CellsDisadvantages of Soil Cells
* Improved soil structure and quality
* Prolonged tree lifespan
* Enhanced stormwater infiltration and drainage
* Reduced soil compaction and increased porosity
* Prevents root damage from construction or digging
* Lower lifetime maintenance cost of surrounding infrastructure
* High initial installation cost

By using soil vault systems such as those created by Citygreen, landscape architects can promote healthy tree growth and create sustainable landscapes that benefit both the environment and the community.

Tree Planting Best Practices

Related: Ultimate Guide on How to Plant Trees in Urban Areas

Planting a tree is more than just digging a hole and dropping in the sapling. It requires careful consideration and attention to detail to ensure the tree has the best chance of thriving for years to come. Here are some best practices for tree planting:

  • Proper Mulching: Adding a layer of organic mulch around the base of the tree can help retain moisture and suppress weeds. However, make sure to keep the mulch away from the trunk to prevent rot.
  • Adequate Watering: Newly planted trees require regular watering to establish their root system. Depending on the climate and soil conditions, this may mean watering daily or a few times per week.
  • Regular Maintenance: Trees require ongoing care, such as pruning and fertilization, to maintain their health and shape. Regular inspection for pests and diseases is also critical to prevent issues from becoming more severe.
  • Site Conditions: Consider the specific site conditions, such as sun exposure and soil type, when selecting and planting trees. This will help ensure the tree is well-suited to its environment and has the best chance of thriving.
  • Tree Spacing: Proper tree spacing is crucial to avoid overcrowding and competition for resources. Landscape architects consider factors such as mature tree size, growth rate, and root system when determining appropriate spacing.

By following these best practices, you can help ensure the long-term health and success of your newly planted trees.

Maintaining Tree Health

Proper maintenance is essential for ensuring the long-term health and vitality of planted trees. Landscape architects follow specific best practices when it comes to tree planting, and these practices extend to tree maintenance as well.

One of the most critical aspects of tree maintenance is monitoring the trees for signs of stress, pests, or diseases. Early detection and treatment are essential to prevent further damage and maintain optimal tree health. Landscape architects also provide necessary pruning, fertilization, and irrigation to promote healthy growth and resilience.

When it comes to pruning, it’s important to follow industry best practices. Incorrect pruning techniques can lead to damage and even death of the tree. Landscape architects use specialized tools and techniques to remove dead or diseased branches, promote proper growth, and maintain the tree’s overall health.

Fertilization is another critical aspect of tree maintenance. Landscape architects apply appropriate fertilizer to provide essential nutrients to the tree’s roots, promoting vigorous growth and a healthy canopy. Proper watering is also crucial, with landscape architects recommending deep and infrequent watering to promote root growth and water efficiency.

In addition to these best practices, landscape architects also consider factors like site conditions and tree spacing when it comes to tree maintenance. They take steps to prevent damage caused by lawn equipment or other external factors and ensure that the tree has adequate space to grow without competing with nearby trees or infrastructure.

In summary, proper maintenance is essential for the long-term health and vitality of planted trees. Landscape architects follow specific best practices when it comes to pruning, fertilization, and watering, and monitor trees for signs of stress, pests, and disease. By following these practices, they ensure that planted trees thrive and contribute to the overall beauty and sustainability of our landscapes.

Ensuring Sustainability

Landscape architects understand the importance of planting trees with sustainability in mind. They consider factors such as water efficiency, carbon sequestration, and the overall ecological impact when designing a planting project.

By selecting appropriate tree species and employing proper planting techniques, landscape architects create healthy ecosystems that provide numerous benefits to the environment and local communities.

But sustainability doesn’t end with the planting phase. Proper maintenance, such as regular pruning and fertilization, helps promote long-term growth and ensures the trees continue to provide environmental benefits for years to come.

By prioritizing sustainable tree planting, landscape architects contribute to a healthier and more resilient future for our planet.

Urban Tree Planting Challenges

Planting trees in urban areas can be challenging due to various factors. Landscape architects face obstacles such as limited space, soil compaction, and pollution that can affect the growth and health of trees. Despite these challenges, there are innovative techniques that can help overcome these issues.

One of the main challenges of urban tree planting is limited space. In urban environments, space is at a premium, and finding adequate space to plant trees can be a challenge. Landscape architects use techniques such as vertical planting, tree pits, and raised planter beds to create more space for tree growth.

Soil compaction is another issue that landscape architects face when planting trees in urban areas. Compacted soil can limit root growth and the ability of trees to absorb water and nutrients. Landscape architects use techniques such as soil aeration and the installation of soil cells, like Stratavault or soil vault systems, to provide more space for root growth and improve soil quality to ensure trees have the best possible conditions to thrive in urban environments.

Pollution is also a major concern when planting trees in urban environments. Air pollution can damage leaves and limit growth, while soil pollution can affect the health of tree roots. Landscape architects choose tree species that are resistant to pollution and use air and soil filtration systems to improve air and water quality.

Despite these challenges, landscape architects are committed to creating green urban environments through sustainable tree planting practices. By utilizing innovative techniques and selecting the right tree species, they can build thriving urban forests that make our cities healthier, more resilient, and more beautiful.

Conclusion

In conclusion, landscape architects are an essential part of creating sustainable and healthy environments by planting trees. By following their best practices and techniques, they ensure the successful establishment and growth of urban green spaces. From selecting appropriate tree species to employing proper planting techniques, landscape architects play a critical role in establishing thriving urban forests. Their expertise in maintaining tree health and ensuring sustainability contributes to a greener and healthier future for us all. Through their dedication and hard work, landscape architects demonstrate how planting trees can positively impact our communities and the environment. So, if you want to learn how landscape architects plant trees and help create a greener future, keep exploring and discovering!

FAQ

How do landscape architects plant trees?

Landscape architects plant trees using various techniques, such as proper hole preparation, handling root balls, and ensuring the correct planting depth. These techniques promote healthy root development and establish strong trees.

Why is tree planting important?

Tree planting is important because it contributes to creating sustainable and healthy environments. Landscape architects follow best practices to ensure successful tree establishment and growth in urban areas, considering factors such as soil conditions, water availability, and selecting appropriate tree species.

How do landscape architects select tree species for planting?

Landscape architects carefully choose tree species that are well-suited to the local climate and conditions. Native tree species are often preferred as they are adapted to the environment and provide numerous benefits, such as supporting local wildlife and improving biodiversity.

What techniques do landscape architects use for tree planting?

Landscape architects employ various techniques for tree planting, including proper hole preparation, root ball handling, and ensuring the correct planting depth. These techniques help promote healthy root development and establish strong trees.

What is soil preparation and how does it relate to tree planting?

Soil preparation is an essential step in successful tree planting. Landscape architects may use innovative techniques like soil cells, such as Stratavault or soil vault systems, to provide adequate space for root growth and improved soil quality.

What are some tree planting best practices?

Landscape architects follow specific best practices when planting trees, including proper mulching, adequate watering, and regular maintenance. They also consider site conditions and tree spacing to optimize tree health and longevity.

How do landscape architects maintain tree health?

Landscape architects monitor planted trees for signs of stress, pests, or diseases and provide necessary pruning, fertilization, and irrigation to ensure optimal growth and resilience.

How does tree planting contribute to sustainability?

Landscape architects prioritize sustainability in tree planting projects, considering factors like water efficiency, carbon sequestration, and overall ecological impact. This ensures that planted trees contribute to a resilient and environmentally friendly landscape.

What are the challenges of urban tree planting?

Urban environments pose unique challenges for tree planting, such as limited space, soil compaction, and pollution. Landscape architects employ innovative techniques to overcome these challenges and create thriving urban forests.

How do landscape architects contribute to creating sustainable landscapes?

Landscape architects play a critical role in planting trees and creating sustainable landscapes. Their expertise in selecting tree species, employing proper planting techniques, and ensuring long-term tree health results in beautiful and thriving urban green spaces.

How to Manage Stormwater Sustainably

An article published online by editor and writer Melissa Denchak highlighted some shocking stormwater statistics coming out of America. Denchak stated that ‘an estimated 10 trillion gallons of untreated stormwater runoff, containing everything from raw sewage to trash to toxins, enters U.S waterways from city sewer systems every year, polluting the environment and drinking supplies… [with] runoff causes significant flooding as well.’ (Denchak 2022). 

Denchak described the ‘U.S Environmental Protection Agency (EPA) estimates that upgrading the stormwater and other public water systems will require at least $150 billion in investment over the next two decades. 

This problem is not unique to the U.S, it is a problem all over the globe. The question is, how do we address the issues caused by stormwater runoff?

In this article, Citygreen will argue that green infrastructure offers a cost-effective solution to handling flooding and stormwater pollution. 

To start, let’s break down the basics. 

Why is Green Infrastructure Important for Managing Stormwater? 

Green infrastructure sets out to replicate the circular economy of the natural environment. Attempting to mirror the efficient and self-renewing processes found in nature.

In urban settings, green infrastructure encompasses a variety of water management practices, such as treepits, planted verges, bioretention pits, swales and other measures that capture, filter, and reuse stormwater. Essentially, green infrastructure replicates natural hydrological processes using soil and plants to slow down, recycle and clean stormwater runoff.

Green WSUD stormwater mangement

What is Stormwater Runoff?

Stormwater runoff is the product of a rain event causing water to flow across the land into sewers and waterways. With the expansion of our bustling cities and the widening sprawl of our urban areas, there are more impermeable surfaces than ever, increasing the intensity of stormwater runoff.

According to Denchak, ‘the average city block can generate more than five times as much runoff as a forested area of equal size’ (Denchak 2022). 

circular economy of water

What is an Example of a Successful Green Infrastructure Project? 

Denchak proposed that New York’s Staten Island Bluebelt was the ‘first and largest green infrastructure project in the U.S.’ A rapid increase in population size saw the Island struggling to deal with sanitary waste and stormwater runoff.

The Bluebelt project ‘helped solve these issues by preserving streams, wetland areas, and other drainage corridors (Bluebelts) that use natural mechanisms to capture, store, and filter stormwater’ (Denchak 2022). Nowadays, the Bluebelt comprises more than 14,000 acres and can temporarily hold and filter as much as 350,000 gallons of rainfall. 

WSUD water drain feeding water into the tree soil vault

How does Citygreen Implement and Manage Stormwater Projects?

Over the past three decades, Citygreen has made significant investments in stormwater infrastructure projects. We learnt early on that mimicking natural systems to manage rainfall, is the most cost-effectively way to deal with stormwater runoff.

An example of a green infrastructure design that Citygreen has developed is the Strataflow™ system.  Instead of a traditional bioretention basin, Citygreen’s Strataflow™ uses an underground structural soil vault system, which delivers a high standard of stormwater treatment with a completely natural look. To any passer-by, what you see is a healthy, flourishing tree surrounded by a grassy verge, but beneath the ground is an advanced WSUD(water sensitive urban design). 

sustainable stormwater management soil cell

This design starts with a traditional drain or catch basin or the Strataflow Kerb Inlet; this device sits in the road kerb alignment, retaining the inherent structure of the concrete kerb. The inlet has a grate (acting as a screen) to stop larger-sized pollutants from entering the system, which inhibits healthy tree growth. 

The inlet lets water from the road carriageway flow through the front grate of the drain at a capacity of up to 18 litres/ 5 gallons per second. This allows the inlet to minimise pollutants entering waterways and reduce flood risks by controlling the stormwater flow entering our city’s underground drains. 

strataflow kerb inlet sitting in the kern

When the water flows through the street, it enters through the inlet and flows underground. From there, the stormwater reaches the advanced structural soil cell system, where the stormwater is stored, filtered and distributed effectively for the benefit of urban trees and proper stormwater management.

The inlet ensures the water drains down at the correct optimal depth beneath the pavement height. From there, the stormwater reaches the structural soil cell system and the tree’s root system, where the stormwater is stored, cleaned and distributed effectively to increase urban tree growth and proper stormwater management principles.

animation of how strataflow works to benefits stormwater usage

Essentially, Strataflow™ utilises readily available stormwater rather than potable water to irrigate street trees, which improves the vitality of trees and reduces the impact of stormwater and stormwater contaminants on the local environment, all while maintaining a high natural presentation. 

Stormwater Management Case Study

Pemberton is a small mountain town located 20 minutes North of world-renowned ski resort Whistler in Beautiful British Columbia, Canada.

In 2019 the town of Pemberton was awarded a government grant to upgrade ageing infrastructure and give their tourist town a facelift. Pemberton had some issues with flooding which they were keen to fix and at the same time wanted to create an inviting and enjoyable experience for the visitors and residents of the town.

One of the solutions was the Stratavault system, this system was placed underneath all sidewalks for two reasons. The first was to collect the mass of snow run off and rainfall that would typically flood the town, slow this water down and clean it with the soil held in the Stratavault system then push excess water into a nearby pond where it could be used for irrigation purposes throughout the town. The second was to hold enough soil so the trees that were planted in urban environments could have access to nutrient-rich soil for many years to come.

Book a Citygreen Consultant

Looking for a cost-effective and sustainable stormwater solution? Contact our friendly Citygreen Team today.

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

blog 1 1 plant trees Citygreen

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, is there enough soil for the tree to actually thrive once it reaches maturity?

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.

blog 7 plant trees Citygreen

Tree Planting Budget

To allow trees to reach full maturity, and ideally become self-sufficient, a suitable budget and management plan must be allocated. Without a sufficient budget, cities will experience the premature deaths of city 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 increase the future value of trees as an asset within any urban environment.

blog 2 plant trees Citygreen

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 or powerlines. 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.

20211108 082645 plant trees Citygreen

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.

P1010594 plant trees Citygreen

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.

Ennis case study images 1024x536 1 plant trees Citygreen Ennis new3 1024x536 1 plant trees Citygreen

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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.

How to Improve ‘Everyday Nature’ for the Betterment of your Community

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. 2014Westcott 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.

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 nature interactions 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).

soe2016 bio fig6 future of liveable cities depends on nature plant trees Citygreen

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

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.

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.

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.

(more…)

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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