Bangladesh – Urban forestry & prevention of air pollution
Urban biodiversity and Dhaka dwellers
Cities are growing rapidly, in 50 years more than 80% of the world’s population will live in an urban environment. Urban green areas e.g. parks and gardens, woodlands and forests with socio-cultural values are important for urban life. Moving in search of a better life, people across the globe have abandoned traditional socio-economic systems, broken ecological bonds with nature, and flocked to urban centers. While this process started in the “northern” or “developed” world, less developed countries have quickly caught up.
Sustainable urban development requires providing a healthy and sustainable living environment with basic services for all. A healthy and multifunctional urban green structure is one of the basic services to provide. Urban and peri-urban forestry (UPF), focusing on the tree-dominated part of urban and periurban green space, is a strategic, integrative, interdisciplinary, and participatory approach. Its goal is to sustainably develop the multiple benefits of forests and trees in urban environments.
Ongoing urbanization has brought about a wide range of challenges across the globe, and not only in terms of population growth. In the United States, for example, metropolitan areas tripled in size between 1950 and 1990. More land is needed for urban areas to provide inputs and outputs of resources and energy, with a detrimental effect on forests and other green areas. During the early 1990s, more than a quarter of green spaces in Asia were expected to be lost within two decades due to continued urbanization and suburbanization.
Continuing urbanization in the developing world has led to major problems in terms of hunger, poverty, inadequate shelter, social segregation, unemployment, pollution of water, soil, and atmosphere; and so onward.
Experiences and research during recent years have shown that urban green structures are more than just “icing on the cake.”
The thought of urban forestry is new in Dhaka. As a developing country, city authorities are busy most of the time to give service facilities to the people rather than think about green resources. Most of the time different green institutions in the city and government deal with big urban greening programme by tree plantation activities. There are no exact areas wise statistics for the percentage of trees in the city and also no area wise planning for tree plantation. In 2002 Dhaka City Corporation (DCC) were able to plant only 29 thousand trees out of the targeted 45 thousand because of lack of empty space. In 2003, DCC has planned to plant six thousand trees to replace those that have been uprooted, and a further ten thousand in whatever empty space is available in Uttara and Mirpur area of Dhaka. But adequate open spaces are needed for the sustainable development of a city.
Let’s discuss why we really need urban biodiversity in term of social, economic and environmental context.
Nursery activity is an important entrepreneurial outlet for the poor people. 78% of nursery owners indicated that the management of their nursery is their only employment. The average daily sales of the nurseries surveyed exceeded USD 130, the biggest and most successful one third of nurseries, however, have average daily sales in excess of USD 190.
Considering among data it can be assume that most of the beneficiary of this industry are low income groups of the urban area.
In Dhaka studies shown that suspended particulate matter (SPM) and ambient sulphur dioxide levels of air pollution are about 4 times and 5 times higher than the levels prescribed in Bangladesh Air Quality Standard. An ADB report shown that 3,850 premature deaths could be avoided had there been a reduction of SPM concentrations in Dhaka to the level of Bangladesh Air Quality Standard.
Economic cost, because of such deaths and illnesses in Bangladesh, may reach US $800 Million a year. One of the most effective ways to control air pollution is creating more woodland around the city and increasing the number of trees in the parks and street in Dhaka. The SPM can be captured by the leaves of evergreen tree species .Several research in US revealed that trees can remove pollution by intercepting airborne particles. In 1994, trees in New York City removed an estimated 1,821 metric tons of air pollution at an estimated value to society of $ 9.5 million. Another study found that woodland in Nottingham was estimated to reduce concentrations of sulphur dioxide and nitrogen oxides in the air by 4-5%.It is also well known that all vegetation absorb carbon dioxide and release oxygen, do purifying the air.
It found that in Dhaka 33% inhabitants experience hearing problems from noise pollution. But increasing trees and other vegetation can play an important role in attenuating noise through and absorbing sound energy. In US one research estimate suggested that 7db noise reduction was achieved for every 33m of forest while other reported field tests show apparent loudness reduced by 50% by wide belts of trees and soft ground.
According to Dhaka city structure plan 1995-2015 policy 10 &11 demands the augmenting of city open space and securing the future open space although there have no specific policy which can support sustainable livelihood.
Well-planned and well managed green areas are essential for environmental and high quality of life for Dhaka city dwellers. So it is very much for RAJUK and Dhaka City Corporation to rethink about these issues and necessary actions need to be taken.