Urban forest



As we all know that Karachi is famous for being a buzzing sea port and a commercial hub, which provides economic opportunities for a diverse and ever growing populace. This commercial and industrial activity has made Karachi a concrete jungle devoid of any plantations. We all had experienced tough time in the city regarding high pollution levels and thousands of citizens losing their life due to heat waves.

Yesterday I have read a news regarding the urban forest that the Karachi Metropolitan Corporation has cancelled the adoption agreement of a three-acre park for the development of an urban forest in the megapolis. A private company Urban Forest had adopted the park in May 2017 for five years.

Shahzad Qureshi is the owner of Urban Forest, and he told that the KMC has cancelled the five-year adoption agreement without any reason. He said this is not the first time that the KMC has cancelled the agreement.

He said the urban forest contained a lake, 15,000 plants of different types and an organic garden producing different vegetables, which were given to the locals “free of cost”. There was also a treatment plant which was being installed for recycling sewerage water in order to use it for plantation.

The owner have spent nearly Rs9 million during the one-and-a-half year on this urban forest and the cancellation of the agreement is to discourage positive approach.

This news was really disappointing, because the city needs tress and plants to lessen the effect of the rising temperature.

Talking more about the lack of plantation or the cancellation of this advantageous project of urban forest, first of all we should know what urban forests are and what are their benefits;

Urban Forest is the collection of trees and shrubs on all public and private land in and around urban areas. This includes bushland, parkland, gardens and street trees. It is measured as a canopy cover percentage of the total area. Urban Forests are recognised as a primary component of the urban ecosystem.

Trees and vegetation are most useful as a mitigation strategy when planted in strategic locations around buildings or to shade pavement in parking lots and on streets.

As temperatures rise globally, and urbanisation pushes people into concretised spaces, cities are struggling to deal with the negative health impacts. These include not just increased discomfort and exhaustion but respiratory problems, headaches, heat stroke, and even heat-related mortality. The last is a fresh memory for the residents of Karachi, Pakistan’s largest city, due to the heatwave of 2015 which killed over 1,200 people.
The vanished trees and vegetation have decreased evapotranspiration or the natural cooling effects of shading and evaporation of water from soil and leaves. However, Evapotranspiration, alone or in combination with shading, can help reduce peak summer temperatures by 1–5°C.


Rapid Deforestation has caused a havoc around the world. Humans which are only one of the millions of species that inhabit the earth are the cause of the destruction of our habitat.

Cleaner, Cooler Air:
In exchange for giving oxygen, trees absorb carbon dioxide produced from the combustion of various fuels. Trees remove or trap lung-damaging dust, ash, pollen and smoke from the air, in addition to providing shade for people and conserving energy.

Air quality is improved by trees. Trees provide numerous benefits to the urban forest, especially with mitigating air pollution in urban areas and providing a positive impact on human health.
In respect to air pollution reduction, trees provide shade which reduces temperatures and helps keep pollutants already in the air from becoming even more volatile, while also intercepting many of the solid particulates that are airborne.

Cleaner Water:
Trees also act as natural water filters and help significantly slow the movement of storm water, which lowers total runoff volume, soil erosion and flooding. From an economic viewpoint, communities that utilise this important function of trees and canopy cover may spend less money developing additional stormwater management infrastructure.
During a heavy rain, a healthy forest can absorb as much as 20,000 a large volume of water in an hour.

Recent research reveals that many business owners regard the urban forest as an “External extension of business’.

Increased profession price:
Trees enhance community economic stability by attracting businesses and tourists.
Customers are willing to pay as much as 10 percent more for certain goods and services if businesses are located on tree-lined streets.

Office and industrial areas within green, wooded settings are in high demand by employers because employee life enhancement studies show that shady areas to eat and walk during lunch and breaks translates into more stress-free, productive employees. Workers without a view of nature from their desks reported 23% more instances of illnesses than those with a view of greenery.

Increased domestic price:
The presence of trees has a positive effect on occupancy rates and residential home sales. Neighbourhood green-spaces or greenways typically increase the value of properties located nearby.
Healthy trees can add up to 15 percent to residential property value.
Strategically placed trees around a home can reduce summer cooling costs by as much as 30%, while winter heating costs can be reduced by a similar percentage by the use of trees as windbreaks.

Decreased health care costs:
Trees remove or trap lung-damaging dust, ash, pollen and smoke from the air. Green-space and shaded sidewalks encourage outdoor activity.

Lower infrastructure costs:
The presence of trees in a community affect the cost of municipal services such as stormwater control, transportation and air quality. For instance, trees act as natural water filters and help significantly slow the movement of stormwater, which lowers total runoff volume, soil erosion and flooding.
Streets with little or no shade need to be repaved twice as often as those with tree cover.



Studies have found a correlation between community forests and the average amount of physical activity exerted by neighbourhood residents. People are more inclined to get outdoors and exercise when their surroundings are greener. Logically, greater physical activity leads to fewer cases of obesity, which in turn may help reduce other health problems such as heart disease , diabetes and obesity.

Children who spend more time outside pay better attention inside. Attention-deficit/hyperactivity disorder (ADHD) children, in particular, are better able to concentrate, complete tasks, and follow directions after playing in natural settings.

Trees filter airborne pollutants and can reduce the conditions that cause asthma; asthma incidents increase in urban communities where trees are eliminated in favour of new roads, homes or commercial developments.
Post-operative hospital stays are shortened when patients have a view of trees and open spaces.


Studies have identified a direct correlation between the amount of trees and grass in community common spaces and the use of those common spaces by residents, which leads to more opportunities for informal social interaction and greater relationships between neighbours.

Trees can be associated with specific places, such as memories of past events or times, or a favourite tree climbed as a youth.
Trees provide opportunity for physical fitness. Urban forests, parks, and open spaces have become increasingly popular as places to walk, run, bike, and hike.


Trees can contribute to the increase of local food and nutrition security, providing food such as fruits, nuts and leaves for both human consumption and fodder. Their wood, in turn, can be used for cooking and heating.
Trees play an important role in increasing urban biodiversity, providing plants and animals with a favourable habitat, food and protection.
A mature tree can absorb up to 150 kg of CO2 per year. As a result, trees play an important role in climate change mitigation. Especially in cities with high levels of pollution, trees can improve air quality, making cities healthier places to live in.
Strategic placement of trees in cities can help to cool the air between 2 and 8 degrees Celsius, and helping urban communities to adapt to the effects of climate change.
Large trees are excellent filters for urban pollutants and fine particulates. They absorb pollutant gases (such as carbon monoxide, nitrogen oxides, ozone and sulphur oxides) and filter fine particulates such as dust, dirt or smoke out of the air by trapping them on leaves and bark.

Research shows that living in close proximity of urban green spaces and having access to them, can improve physical and mental health, for example by decreasing high blood pressure and stress. This, in turn, contributes to the well-being of urban communities.
Mature trees regulate water flow and play a key role in preventing floods and reducing the risk of natural disasters. A mature evergreen tree, for instance, can intercept more than 15 000 litres of water per year.
Trees also help to reduce carbon emissions by helping to conserve energy.
Planning urban landscapes with trees can increase property value, by up to 20 percent, and attract tourism and business.
A city with well-planned and well-managed green infrastructure becomes more resilient, sustainable and equitable in terms of nutrition and food security, poverty alleviation, livelihood improvement, climate change mitigation and adaptation, disaster risk reduction and ecosystems conservation. Throughout their lifetime, trees can thus provide a benefit package worth two to three times more than the investment made in planting and caring for them.
Cities have their own unique microclimates, caused by a multitude of factors, many of which can be affected by the presence of trees.

From drastic and more expensive steps like coating roads with a light grey seal, to greening rooftops or putting up solar panels or painting the existing roofs white, city governments are coming up with a raft of policy decisions to bring down the temperature. But a simpler step might be simply to revive the forests and KMC must give permission to built urban forest for improving the situation in the city.

Pakistan’s first urban forest, which is going to be built up by government’s permission will employ the Japanese botanist Akira Miyawaki’s method of planting trees. Within this method, different types of trees are planted close together in a small pit, which allows them to grow ten times faster than usual

Miyawaki’s technique makes the trees grow ten times faster than in nature, creating a self-sustaining forest within two to three years.
A forest typically takes a hundred years to mature, but by this technique it grows 10 times faster, is 30 times as dense and 100 times more biodiverse.

Even if Karachi is able to grow 25 urban forests, it would be able to get rid of terrible urban heat island (UHI) effect – an urban area that is significantly hotter than surrounding rural areas due to human activity.
Due to human interventions within an urban landscape, the landscape absorbs more and reflects less heat during the sunshine hours and then at night, releases the additional heat back into the environment . As a consequence, the urban area feels warmer than its surroundings both during the day and at night.

Even air quality can exacerbate the UHI effect, an increase in greenhouse gases raises the temperature by radiative forcing. Radiative forcing means that the energy that is normally reflected back to space stays trapped within the atmosphere by the accumulation of air pollution and greenhouse cases and causes the temperature to go up.

To reduce the impact, cities can plan “green zones” by increasing the number of parks and trees.
The other way is to have urban air corridors that help channel the flow of air through the city, bringing in fresh air from outside, and removing polluted air from within city centres.
An air corridor means a continuous flow of air by means of green zones through the city.

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