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Preserving green spaces in Dhaka city

Mahfujur Rahman
***Most areas, old or new, of Dhaka city are unplanned and have little scope for creating any green space or enhancing the existing ones, if any still worthy to be called so. But the importance and necessity of green space is simply great and you cannot do without it in too crowded a city like Dhaka.***
VEGETATION in a city is sometimes synonymous to presence of nature in the predominantly man made environment. Urban vegetation is an important point for sustainable development, environmental conservation and urban planning process of a city (Tunay et al, 2007).
The urban environment is characterized by an intense use of the available space, where the preservation of open green spaces is of special ecological importance (Roessner, 2001).
In urban areas various processes are responsible for destruction of vegetation such as construction and infrastructure development. And. green areas are dwindling at unprecedented rate in Dhaka city. However, still there are various types of green areas or vegetation cover in the city. Major types are botanical gardens, homestead gardens, public parks, vegetation around government offices, graveyard and playgrounds. These need to be religiously preserved and. if possible, enhanced.
Urbanization and land use: The urban area is a sharp manifestation of transformation where the land is acquired and put under concrete at a very fast rate. Usually vegetated area decreases. In one stage of urbanization people start to migrate to urban area for jobs and better life standard. The demand for land, a basic requirement for any development, is high and its scarcity acute. Then the pressure on the land becomes intense and unused green patches are lost to residential-
commercial complexes. Against high demand for land people are willing to pay huge amount of money for buying land .In such a situation it becomes economically less attractive to conserve the homestead garden.
Environmental importance: Exclusive vegetation cover is a good indicator of environmental health in the urban areas. Vegetation or living biomass is natural store of carbon and source of oxygen. Presence of vegetation in significant amount in urban area is also reported as a means of reducing sound and air pollution since leaves of trees make a huge surface area for settling down of dust particles and absorption of noise.
Vegetation abundance influences environmental conditions and energy fluxes by selective reflection and absorption of solar radiation, by modulation of evapotranspiration and by sequestration of pollutants. Vegetation in urban locality is the niche of urban ecosystem Ecosystem services such as fresh air generation, maintenance of local hydrogeology for perpetuation of fresh water supply and balancing the temperature for the dwellers depend on the amount and quality of green spaces.
Vulnerability of green spaces in Dhaka: The pres ence of vegetation in Dhaka is diminishing fast. In many cases, the parks and playgrounds are encroached upon illegally by powerful people. On the other hand the poor rootless people occupy many parks. Many parks are infested with slums and unhygienic condition is created there by these people. The open space or area in the city is also decreasing at an alarming
rate. Once open spaces found around the government quarters in Azimpur, Sobhanbag and Mirpur are occupied by new buildings erected to make room for more government officials.
While greening the urban area, whatever small effort is made as such, there is no consideration for indigenous species of plants. Many alien species are planted to the detriment of exiting ecology pattern. A notable problem for the vegetation of the city is air pollution. Various toxic gases such as NOX, SOX have adverse effect on the vegetation. The particulate matters in thick layer of dust on the leaves beside the road reduce the sunlight incidence on the leaves, hence hinder photosynthesis.
Green spaces of Dhaka: An overview: Vegetation zones of Dhaka City are - Agargaon, Dhanmondi, Khilgaon,
Kamrangir Char, Banani and Ramna. Various green spaces are - - Panthokunjo park, Shahidbagh park, Bahadur Shah park, Chaudhuripara Shishu park, Taltala High School, Vegetation around Dhanmondi lake, Vegetation around Gulshan lake, Osmani Uddyan, Zia Uddyan, Ramna Uddyan, Suhrawardi Uddyan. By now extinct or almost extinct parks are Kamlapur park, Karwan Bazar park, Shamibaghpark, English Road park.
Playgrounds: Playgrounds can be considered as vegetation or green space because at least for certain part of the year these lands remain covered by grasses and plantation of some common tree species such as raintree and Mahogany occur surrounding these. Many playgrounds are encroached upon in the city and used for different pur poses such as slum or market.
Graveyards: In the city environment graveyards also have very important ecological role as green space. The land occupied by the graveyards is not negligible and the amount is on an increase. Graveyards support very sound and undisturbed ecosystem. Most prominent and large graveyards are Azimpur Graveyard, Mirpur Graveyard, Banani Graveyard and Iraqi Graveyard.
Government and public offices: Vegetation around the government offices are sometimes almost in natural condition. The vegetation in western part of the Sangsad Bhaban and some vegetation in the park near Bangabhaban are examples. Such prime sites, are: Prime Minister's Office, Prime Minister's Residence, Saangsad Bhaban, Bangabhaban, Old airport, Bangladesh Betar, Meteorological Department.
Reserved area: The reserved areas are examples of some conserved areas in the city .In Dhaka reserved areas are mainly the Bangladesh Rifles Headquarters. Rajarbagh Police Line and Dhaka Cantonment. These areas are out of anthropogenic activities .The land cover changes is not significant in these three areas .These areas contain comparatively more open spaces covered by green vegetation.
Educational institutes: Dhaka University, Eden University College, Bangladesh University of Engineering and Technology (BUET). Jagannath University and Sher-e-Bangla Agriculture University - these public educational i n s t i t u-tion s have appreciable green areas in tlieir respective big and small campuses.
Pressure on the parks and open spaces: The existence of
public parks in the city is greatly threatened by various agents. It is a matter of great regret that many parks are first converted into playgrounds and then occupied by encroachers. Most of the paries are occupied by floating people. Due to their presence the condition of many parks is not good enough to be visited by the city dwellers. In some cases they even turn parks into slums.
Movement for conservation: Various environmental pressure groups are raising their voice for conservation of parks and playgrounds in the city. Bangladesh Paribesh Andolon (BAPA) and Bangladesh Engineers' Institution (BED vowed to clear the grabbed lands of parks and playground (Prothom Alo. 2 December 2007). Citizens are also becoming more conscious about green areas in the city. The mayor of Dhaka city held a meeting with BAPA. Nagorick Sanghoti and Nagorick Committee seeking way-out to save the Osmani Uddan from illegal grabbing (Dainik Samokal 4th January 2008). But nothing has appreciably worked or is working.
Ecological importance: Preventing destruction of natural ecosystems and restoring the denuded ecosystems are basic objectives of any conservation programme in an urban area. Ecosystem comprises the physical environment and the biotic components. The physical components and the biotic community cannot be separated in the real environment. When we separate themit is simply environmental disniption. In an ecosystem the producers are the basic and primary element which exist as biotic
components. Vegetation creates the basis for the ecosystem in the urban area providing various environmental services often called 'Ecosystem Services' such as fresh air generation, water shed management, waste assimilation and waste water purification. In the urban area fresh air generation and water shed management are two most important services provided by vegetation.
Conclusion: Presence of vegetation in the city is presence of nature. In Dhaka, like other cities, all the existing vegetation is man-made or altered by man to a great extent. There is almost no natural vegetation. In the city these green cover contain the remnant biotic diversity of this part of erstwhile green and vast landscape of Modhupur tract. Most of the vegetated areas of the city are publicly owned. These vegetations occur in or around such organizations that are important to people for various purposes. So the importance is enhanced.
Most areas, old or new, of Dhaka city are unplanned and have little scope for creating any green space or enhancing the existing ones, if any still worthy to be called so. But the importance and necessity of green space is simply great and you cannot do without it in too crowded a city like Dhaka. So the authorities concerned as well as the respective area dwellers must be consciously eager to preserve whatever green spaces the city still have and call all others to join effort.