Resources: Articles
Lara A Roman, 2014-Jun 26, Scenario Journal
How Many Trees are Enough? Tree Death and the Urban Canopy
This essay discusses street tree mortality in terms of demographic concepts and advocates for the application of these approaches in urban forest planning. Based on an old article, it is said that the lifespan of an urban tree is 32 years and a more recent study shows that it is 13 years. Further calculations on current trends show that it would be around 7 years eventually. It is necessary to monitor the mortality rates of trees in the urban context. The added costs of replanting are high and if tree mortalities are taken care of, these finances can be used for other benefits of the city. The study also monitors the population of these tree clusters across US cities and their changing trends. More studies to support the cause are required to improve the tools available for urban forest managers to plan ahead, embedding their planting campaigns within the population dynamics of cultivated city landscapes. Read more...
Tags: Tree mortality
L. R. Costello, J. D. MacDonald, K. A. Jacobs, 1991
USDA Forest Service Gen. Tech. Rep. PSW-126.
Soil Aeration and Tree Health: Correlating Soil Oxygen Measurements With the Decline of Established Oaks
This paper studies how environmental stress on urban trees can be reduced by understanding the soil aeration required for the growth of healthy trees. As a part of the experiment methodology the researchers, measure the soil aeration status at different field locations. It measures the oxygen levels to compare the health of these trees. The results of the study show that the oxygen diffusion rate of the soil and moisture content in it are interdependent and promote healthier growth of the tree. Read more...
Tags: aeration management practices, soil aeration
Lara A Roman, John J Battles, Joe R McBride, 2016-03-01,
United States Dept of Agriculture
Urban tree mortality: a primer on demographic approaches
This report is a primer on demographic concepts applied to urban trees, with terms and analytical methods adapted to the cultivated urban landscape. It includes an overview of the uses of urban tree mortality rate data for research and management, a summary of lessons learned from ecological monitoring in other systems, and a discussion of opportunities for long-term urban forest monitoring by researchers and practitioners. Urban tree demography is essential to understanding temporal changes in urban forest systems, just as tree demography is used to analyze changes in natural forest systems. Read more...
Tags: Urban tree mortality
Sean McMinn, 2019-09-05,
NPR
Trees Are Key To Fighting Urban Heat — But Cities Keep Losing Them
Studies carried out in the US show that the income of a neighbourhood is related to the tree cover there. The neighbourhoods with cooler temperatures were the ones with maximum tree cover and high incomes. The article also mentions the health benefits of trees like longer life spans, lower levels of stress, better air quality and lower rates of cardiac disease. Taking the case of Louisville, where the studies were carried out initially, the researchers also discuss the maintenance and care of these trees, and the funds required for that. Oftentimes it is difficult to raise funds for the aftercare of trees planted. The government bodies still encourage people to plant more trees and also look after them for the betterment of their own neighbourhoods. Read more...
Tags: Tree cover, heat island effect, climate crisis, income, finances
University of Wisconsin-Madison, 2019-03-25,
ScienceDaily
Trees are crucial to the future of our cities
Studies show that the right amount of tree cover can help reduce the temperature by 10 degrees Fahrenheit. Monica Turner, a University of Wisconsin-Madison professor in the department of Integrative Biology and a co-author of the study, says that cities are generally warmer than the countryside. Climate change is forcing city planners to prepare to make cities more comfortable.
Roads absorb heat throughout the day and release heat during the night. On the other hand, trees help reduce the same effect through their canopy cover and shade, as well as transpiration.
Carly Ziter, the lead author of the paper, mentions that studies like these have tended to focus on what is known as the "urban heat island" effect. Those studies often use satellites to take ground surface temperature readings or measure air temperature within and outside the city. Studies have shown that developed, less vegetated cityscapes are much warmer than the rural lands around them.
The data shows that forty per cent canopy cover is the threshold required to trigger the large cooling effects that trees have to offer. The author adds that we should be more outspoken since the trees we plant now and their mortality will determine the temperatures of our cities in the future. Read more...
Tags: Ecosystem services, urban trees, benefits
Elise Stolte, 2016-08-01
Edmonton Journal
New soil cell technology aims to grow big trees in Edmonton's tight spaces
The article describes the trees in Edmonton, Alberta, which are grown in small pits between sidewalks and a heavily-compacted road. The mortality of these trees is high and about three years after planting there is only 40% of the canopy remaining.
They are now trying to adapt to new technology where small plastic tables stacked underground and filled with rich, un-compacted soil can give the trees the space they need, even under sidewalks or parking spaces. These alternative technologies can cost up to $16,000. Budget dollars are directed to drainage and transportation needs instead of trees. However, well-planted trees and mature canopies provide many unexpected benefits.
Edmonton has experimented with new soil cell technologies along several streets, including Stony Plain Road, 112 Avenue in the Highlands and 96 Street downtown. New soil cells shaped like plastic tables provide a compacted parking surface or sidewalk while protecting the uncompacted soil beneath. It creates long soil vaults between trees or soil bridges underneath sidewalks to allow roots to reach front yards. Read more...
Tags: technology, case study, tree mortality, ecosystem services
Erik Anderson, 2020-02-26
The Conversation
Thousands of city trees have been lost to development, when we need them more than ever
The urban heat island effect is a global concern. The article is based on research carried out in the city of Melbourne, Australia. Mapping the development of urban infrastructure and trees in this context, it was found that the number of trees being removed was higher than the number of trees being planted. The rate of tree removal was higher in areas of major development. The girth of the trees cut down was mostly around 30cm and a few larger trees of 60cm girth. There's always an added cost for tree removal, replacement and its ecological value. Read more...
Tags: Climate change, heat island, canopy cover, tree mortality
Hannah Kost, 2020-08-25
CBC
Federal government announces $2M in funding for Calgary's willow tree plantation farm
Willow trees help in carbon emissions and the government of Calgary is set to invest 2 million dollars on the project. The project uses treated wastewater to water the plantations and reduced the use of chemical fertilizers. The plan is to make Canada net zero emission by 2050.
Tags: Finance, tree plantation
M. Leff, 2016
Food and Agriculture Organization of the United Nations
The Sustainable Urban Forest - A Step-by-Step Approach
The document touches on various ways trees contribute to the city's sustainable development. The ecosystem services provided by trees are for all living beings from humans, birds and all of the animal kingdom. Trees help improve air quality, carbon sequestration and in energy saving. Additionally, “Green infrastructure” utilizes vegetation to provide some of the functions of conventional grey infrastructure, such as water treatment plants and stormwater management systems, but with additional environmental, economic, and social benefits. The study also describes the tree cover in urban areas. The canopy cover helps determine the area under the urban forest that helps the city towards achieving its green goals. Using various geographical mapping tools, the study provides a method to analyse data regarding urban tree cover. The further chapters give detailed processes on the management of this urban forest, species diversity, planning and implementation of such projects.
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Tags: Sustainable urban forest
Andrew Tarantola, 2020-10-26
Engadget
Dendra System's seed-spitting drones rebuild forests from the air
Forest covers across the world are decreasing and action needs to be taken to improve the cover that's the world environment's breathing lungs. Dendra's system is a drone-based forest restoration company working across the globe to restore forests using AI and technology-based solutions. The drones carry up to 50 different species of seeds and can plant several hundreds of hectares in a day. With the help of GIS data, they can monitor and track the progress of the forest restoration project. Hovering from about 2m above the ground, the speed of the drone drops about 150 seed pods per second into the ground depending on the soil type and conditions. In a concluding note, the author speaks of carbon sequestration and how technology can be developed to be used for trapping carbon.
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Tags: seed spitting, urban forests, loss of forest cover,
Peg Staeheli, 2018-02-05
Deeproot
Tree Pits Are the “Pits” But We Can Make Them Better
Tree pit designs play an important role in the growth and health of a tree. Many urban planners allot 4'x4' dimension pits for the trees planted along sidewalks, pavements, curbs, etc. But that isn't always sufficient depending on the tree and how deep the roots grow. For the growth of a healthy tree, the roots need space to aerate. With the smaller pit sizes, the trees typically don't live more than 15 years. The article suggests that the space between the trees and adjacent pedestrian spaces be increased to at least 6', with 8-10' even more optimal as this permits more water and air to enter the substrate feeding the tree roots. For surface treatment they suggest wood chips or gravel/ stone to allow water to seep in and keep the moisture intact.
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Tags: tree planting, benefits, tree pit designs, retrofitting
Leda Marritz, 2014-07-09
Deeproot
Is Average Tree Lifespan a Meaningful Number?
The article is based on a study carried out by Lara Roman, a Research Ecologist with the USDA Forest Service. It talks about the life expectancy of urban trees and how it can be further improved.
The field data on urban tree mortality suggest that as the number of trees originally planted die over time, community foresters must keep replacing trees, year after year, to have any chance of increasing population counts and canopy cover. Predictions about half-life could then be used as guidelines for managing planting and replacement cycles. As explained in the article, the half-life is “the time by which half of the planted trees can be expected to die". The concept of half-life may be a more meaningful measure of urban forest longevity. In conclusion, Roman urges that in urban forestry the emphasis must shift from the count of trees planted to the records of trees that survived.
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Tags: life expectancy of trees
Bjorn Embren, 2019-09-30
Fachverband Pflanzenkohle (Association for Biochar)
Porosity With Stone Biochar and Compost
Talks about the soil composition in urban areas and research being carried out in the domain. Soils of about 40% porosity. The most important aspect is the porosity for gas exchange which would help the trees to grow better. The Stockholm solution is an engineered nature-based solution that uses biochar. The structural soil is composed to take the pedestrian traffics as well. The technology has been derived in such a way that the pits leave room for the drainage lines to go across and both systems coexist.
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Tags: Stockholm, urban trees, urban soils
Bjorn Embren, 2020-07-03
Arboricultural Association
Talking Trees and Biochar with Bjorn Embren
Björn Embren discusses his experiences of planting trees over a couple of years. Soil is a substrate that supports life- microorganisms, trees and smaller insects. Urban soils contain a lot of debris from the construction industry as well, which makes the nature of these soils poor. While exploring nature-based solutions to promote the better growth of these urban trees, they introduced the use of biochar. Biochar is charcoal made from recycled material through the process of pyrolysis. It helped fight climate change and contributed to a circular economy. Aeration of the ground is very important since it allows the tree roots to breathe and other living beings to survive within the soil ecosystem. Biochar promotes aeration due to the gaps in the pieces.
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Tags: Stockholm, urban trees, urban soils
Vittoria Traverso,2020-May 4
BBC Future Planet
The best trees to reduce air pollution
Cities come at the price of their green space' adding to the opening statement of the article, the vegetation provides habitat for wildlife and people as well as clean air for all. Plants are often called the lungs of the ecosystem as they purify the air. In most cities, the plan is to increase the urban forests or tree cover to improve the quality of air in the city. Researchers also say that it depends on the different types of trees. Trees with denser canopies and wider leaves are better at absorbing pollutants than smaller ones.
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Tags: Air pollution, climate mitigation
Sar Williams, 2021-Apr 8
Saskatoon StarPhoenix
Gardening: A step-by-step guide to getting a tree in the ground
The article describes the process of planting a tree in the garden. Planting a new tree from seed ensures healthier growth of the tree, and the tree is able to provide and thrive better as opposed to transplanting a full-grown tree. To ensure that a transplanted tree will survive, the article describes step by step method to do so. It is of utmost importance that the rootball remains intact and is placed in the hole dug in the ground. Creating a berm or dike, that will act like a catchment around the tree, will ensure that the water is well-drained in the soil. Staking the tree slows its growth. Not staking the tree may prove more beneficial. Mulching the ground is a crucial step as it ensures that the moisture is retained in the soil and keeps the nutrients intact.
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Tags: urban trees, gardening,
Univ. of Gothenburg, Sweden, 2021-Dec 15
The Faculty of Science
Trees are important for cleaner air in cities
In the project’s first study, the researchers measured pollutants in the air and compared them with pollutants on the leaves of deciduous (broadleaf) trees.
The trees’ leaves absorb the pollutants. The results are clear: the pollutants in the leaves increased over time and the researchers could show a clear correlation between the level of air pollutants and the concentration of pollutants in the leaves. "These types of extensive measurements of pollutants in both vegetation and the air are unusual, and the study confirms that trees play a role in improving air quality in cities,” says Håkan Pleijel, professor of environmental sciences at the University of Gothenburg University.
Conifers are important for cleansing the air in the winter. The researchers also measured pollutants in the needles of black pine (Pinus nigra) conifers in urban settings and in the Botanical Garden’s arboretum.
Air pollution levels were vastly variable in different places in Gothenburg. The figure shows a total of 32 PAHs in the air at seven urban sites in Gothenburg and in the Botanical Garden’s arboretum.
The research project “Clean the air with plants – can PAH exposure be reduced with urban vegetation?” is led by Professor Håkan Pleijel at the University of Gothenburg and is a collaboration among the University of Gothenburg, Gothenburg Botanical Garden, and Lund University. The researchers measured pollutants in two tree species in Gothenburg and compared these with pollutants in the air.
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Tags: Environmental impacts of trees, Statistics
Ivana González, Erica Smith Fichman, Kurt Shickman, Sophia Schmidt, 2022-Aug-29
WHYY & Radio times podcast
Heat islands, urban trees and other cooling solutions for hot cities
The podcast talks about how the heat island effect changes in every neighbourhood depending on their canopy cover, asphalt roads etc, and how environmental justice plays a role in such cases. Less canopy cover and higher concrete surfaces radiate the heat. Data regarding heat islands and air pollution in Philly is being gathered to further analyse how it impacts the economy and improves the quality of living in such neighbourhoods. The data support that growing more trees proves beneficial for communities. Poor air quality, people's health, etc were also studied in these neighbourhoods so that the community contributes to the proposed tree plans. Studies say that the tree cover across the cities isn't always equitable across various parts of the city. Planting trees can prove beneficial in more than just mitigating heat island issues. It has economic benefits too as it can have a psychological impact on the consumers. It helps with the stormwater, shade, and streetscapes as well. Street trees, parks, and gardens create a corridor/ network throughout the city adding to the list of benefits.
The speakers discuss planting the right tree at the right spot depending on the conditions of the area. Trees planted along streets need to be more resilient than others since they face more dirt, pollution, etc. Taking care of trees and their maintenance is equally important as growing them. Further in the podcast, the benefits of trees in terms of well-being, mental health, and trust building within the community are also discussed.
Alternately, apart from trees, reducing the use of asphalt and black shingles and dark reflective surfaces for construction materials also contributes to reducing the heat island. Permeable materials for pavements are a part of the solution to the heat island effect.
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Tags: Heat island effect, cooling cities
John-Rob Pool, David Gibbs, Sadof Alexander and Nancy Harris
2022-Aug-1
The City Fix
5 Reasons Cities Should Include Trees in Climate Action
Most cities are concerned about their greenhouse gas emissions and focus on industries like transportation, housing, energy and waste. Even though trees and urban forests play a crucial role in carbon sequestration, they are often overlooked. Jakarta, Mexico City, Mumbai, Salvador and multiple U.S. communities piloted projects to increase their tree cover. The article highlights the key factors for trees and urban forests to be considered while making strategies for GHC emissions. Trees and forests, emit carbon as well as sequester it. Cities have smaller forest areas, but conserving them can still prove beneficial as they are habitats to larger biodiversity. Tree root systems help with stormwater management by helping with infiltration and reducing the speed of surface runoff. Studies have shown that tree cover can also impact the economy of a neighbourhood, its people's wellbeing and mental health.
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Tags: Climate change, trees, GHG,
Stephanie Dubois 2022-Jul-12
CBC
How much should a tree be worth? Experts say cities should consider climate-related benefits
Some of the benefits of trees are often unaccounted for, particularly in urban centres, including the cooling effect of trees and potential energy savings, their ability to capture carbon and their role in maintaining biodiversity. These aspects need to be assessed to determine a tree's true value, experts say, to encourage the preservation of the current tree population — and to better protect the next generation of growth.
The benefits of single tree or an urban forest, including reducing carbon dioxide and air pollution and helping with stormwater runoff, are important consideration for organizations and city leaders. According to its website, almost 8,000 Canadian organizations and municipalities have used i-Tree, a tool to measure and help understand the benefits of trees for public health, biodiversity, and other factors which are hard to quantify.
Experts say ongoing monitoring of trees and long-term planning around our urban forests will be critical. As a result, keeping the trees alive is more important than planting them. The average urban tree doesn't often get older than 30, or 40 years. If the trees' existing lifespan can be doubled, trees can provide better ecosystem services, they added.
In urban settings, citizens need to be good stewards of the existing tree population and protect them as best they can. Ziter said researchers are currently looking at how the environmental value of trees may evolve over the years, as that, too, will be crucial for both current and future urban trees.
For example, if we think about the benefits of a tree in terms of temperature regulation or flooding today, those trees may be even more important in a future that is hotter or that floods more often, she said. Or maybe those trees will no longer be enough to provide that benefit in the future. How we value our trees can't be a static approach, these assessments should account for the changes we expect to see when it comes to climate.
Trees take a long time to grow. In terms of practical applications, the trees we plant now are the trees that we will benefit from 10, 50, or 100 years from now.
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Tags: Ecosystem services, Environmental impacts of trees, Statistics, Finances
Nina Bassuk, Jason Grabosky, Peter Trowbridge
2005
Urban Horticulture Institute, Cornell University
Using CU-Structural Soil™ in the Urban Environment
Studies show that highly compacted soils, restrict the growth of larger trees. Preparing a better environment for the root systems can help the vegetation along streets flourish and facilitate tree health. The research develops a new composition for structural soil that would allow the roots to penetrate through the pores and isn't highly compacted
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Tags: soil, streetscape, planning, urban trees
Isabelle Gerretsen 2022-Jun-12
BBC Future Planet
How to turn your garden into a carbon sink
The article emphasizes how gardens can be designed to function as a way to sequester carbon. The author explains how lesser lawns, wild species of shrubs and grasses help the garden function like a natural habitat than a designed one. Using no pesticides on crops makes the garden more efficient and effective in its function. Refusing leaf litter, and living mulches and decomposing the biodegradable waste helps complete the cycle within such gardens. Planting a variety of species that facilitate the growth of all plants in the guild promotes maximum carbon drawdown, while creating an excellent microhabitat for organisms.
Tags: Home gardens, trapping carbon, carbon footprint
Alison Munson, Anaïs Paré,
2022-May-26
The Conversation
Large trees are essential for healthy cities
Trees provide many benefits and ecosystem services to urban environments. The quality and quantity produced by the trees depend on the size of these trees. Larger trees provide more benefits as compared to smaller ones. Studies show that large trees provide 44% more benefits than medium trees and 92% more than small trees. Planting these trees in an appropriate way is crucial such that the tree roots system has enough space to grow and aerate. The article suggests strategies to allow enhance tree growth such as less pruning, policies for tree conservation and making apt planting choices based on the characteristics of the tree and the climate of the region.
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Tags: Ecosystem services, trees, benefits
Shefali Rai, Abhilash Verma
2022-Jun-29
World economic forum
The roots of sustainability: 5 reasons why cities need trees
The article elaborates on the five key ways trees contribute to healthy cities. The shared understanding in these cities with a healthy, growing tree cover spans environmental, health, social, biodiversity and economic benefits.
The environmental impact talks about the heat island effect and the role of trees as carbon dioxide vacuums and supporting urban biodiversity. The article also touches base on the effect trees have on human life in cities - improving quality of life, social equality and inclusion for all and economic boost for low-income groups.
Trees reduce energy consumption and heat island effects in the built environment by acting as natural coolers. Physical infrastructure absorbs ambient heat, exuding it back slowly into the environment, further raising ambient temperatures and creating an “urban heat island effect.”
Trees are carbon dioxide vacuums. One tree can store between one to 22 tonnes of CO2 over the course of its life, depending on its type and age. The World Health Organisation (WHO) states that: “The global population (99%) breathe air that exceeds WHO guideline limits and contains high levels of pollutants.” It is expected that 6-9 million people will die prematurely from air pollution by 2060. In addition to mitigating air pollution, urban trees scale down noise and water pollution.
Through tree equity, the many benefits of trees - health, environmental, and socioeconomic development - are available to low-income groups in cities, thereby improving quality of life, social equality, and inclusion.
A good tree cover promotes urban biodiversity by protecting all those who live around and in them, and enhancing urban biodiversity. A diverse tree cover protects overall biodiversity – animals, insects, and natural vegetation – further supporting urban tree health.
Urban trees help achieve 15 of the 17 SDGs. The future of sustainable and inclusive cities necessarily depends on how we tend to and protect our urban trees.
Tags: Environmental impacts of trees, Statistics
Michelle Ghoussoub
2022-Jun-24
CBC
Expanding green canopy can cool neighbourhoods as heat wave danger grows, say experts
Studies carried out in Vancouver, BC, state that preserving the urban green canopy helps cool the neighbourhoods during summers. Evapotranspiration and shade add moisture to the air and help cool it. Urban planners encourage everyone from single family homeowners to communal spaces to increase the tree cover in the neighbourhoods, as there are so many added benefits like wellbeing and climate mitigation.
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Tags: Green canopy, temperature,
Julia Kane
2022-May-27
Grist
Yes, you can save lives by planting trees, a new study says
Studies show that planting trees can improve mortality rates in neighbourhoods. According to a study carried out in US cities, the mortality rate was monitored along with the green covers in the neighbours using satellite images. Trees save lives as they filter harmful pollutants out of the air, dampen stress-inducing noise pollution, encourage outdoor physical activity, boost social interaction and cohesion, improve mental health, and decrease violent crime.
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Tags: Urban greenery, urban planning, mortality
Angela Dewan
2022-Aug-04
CNN
These cities are better at enduring extreme heat. Here’s what they’re doing different
The article highlights the heat wave events that occurred in early 2022, across the European continent. Air conditioners, excess private transportations, glass buildings, and fewer street trees extra amplify this and add to the rising temperatures. Cities like Medellín (Colombia), Vienna, Abu Dhabi (UAE), Miami, Athens, Los Angeles and Paris are deriving strategies to cool their surroundings. The strategies include planting street trees, urban forests, mist trees, architectural elements and repurposing existing elements. Urban forests and street trees proved beneficial in more than just one ways than reducing the heat.
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Tags: Climate crisis, Heat island, strategies
eLife
2022-Sep-27
Newswise
More naturally occurring trees and less clustering could benefit urban forests
The article talks about the benefits of city trees on human health, animals, and plants and their role in thriving an ecosystem and climate change mitigation. Based on data collected during the research, it was found that introduced trees which were clustered were more prone to diseases as opposed to naturally growing individual trees that supported a rich local ecosystem. Studies also suggested that the trees had an impact on the socio-economic growth of a neighbourhood as well.
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Tags: City trees, Health and well-being, benefits
E. Stobbe, J. Sundermann, L. Ascone & S. Kühn
2022-Oct 13
Scientific Reports
Birdsongs alleviate anxiety and paranoia in healthy participants
The environment around us always has influences on the psychological well-being of people. The study demonstrates a comparison of urban traffic soundscapes and birdsong soundscapes and their impact on people's moods. Through various experimental analyses, it infers that listening to birdsongs regardless of diversity improves anxiety, while traffic noise, also regardless of diversity, is related to higher depressiveness.
Based on the study, it is implied that birds need to be provided with suitable habitats for them to thrive in urban areas. Trees with dense canopies provide excellent habitats for avian species- shelter, nesting, roosting and food
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Tags: Soundscapes, birds, environment and psychology, habitat
Eric Sturman
2022-Oct 13
The Fifth State
Creating resilient trees is essential for urban greening
WaterUps, a company based out of Sydney, reinvented age old concept of water wicking beds. The company is carrying out research and developemnt along with field trials to optimise its suitability for commercial, civic and other applications. The article describes the process of how the wicking beds work in addition to the management phase, statistics about water usage, environmental and financial savings provided by opting for wicking bed concept.
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Tags: Statistics, Watering techniques, maintainance,
Andrea Timpano
2022-Oct-17
Architect Magazine
TreesAI Shows Communities How to Maintain and Grow Their Urban Forests
This article throws light on the non-profit Dark Matter Labs based out of Amsterdam. Dark Matter Labs brings together resources to explore and create a new civic society where agency is not owned by a select few but is spread equitably amongst all peoples, entities and the natural world.
Trees AI (Trees as infrastructure), a software developed by the lab, helps cities plan, expand, execute and manage urban foliage projects better. The software platform helps map climate risks and monitor impact in terms of finances. The team is set to do a pilot project with the city of Glasgow. The model involves investors and project developers; investors fund the project for urban green infrastructure and project developers use the funds to grow forests. While investors benefit financially from the outcomes, the model also benefits the environment as well as organisations and community members.
Link to paper: https://drive.google.com/file/d/127XlBUlQ-9_llwJawalifxWoqbBxG8ha/view
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Tags: AI, Green technology, infrastructure
Barcelona Institute for Global Health (ISGlobal)
2022-Nov-17
Science Daily
Planting trees can save lives, study shows
The article is a summary of a larger study on the mortality of street trees based in Portland, Oregon. The results show that in neighbourhoods with more trees planted, mortality rates (deaths per 100,000 persons) were lower. This negative association was significant for cardiovascular and non-accidental mortality (that is, all causes excluding accidents), particularly for males and people over the age of 65. Furthermore, the association got stronger as trees aged and grew: the reduction in mortality rate associated with trees planted 11-15 years before (30%) was double that observed with trees planted in the preceding 1-5 years (15%). This means that older trees are associated with larger mortality decreases, and preserving existing mature trees may be particularly important for public health.
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Tags: planting trees, mortality rate