Urban green space and landscapes: key to clean and healthy environment
By: R.K. Roy, R. Rastogi, S. Singh and R. Prasad*
Urbanization is a global phenomenon. The migration of people from rural areas to towns and cities is a common trend for better livelihood and opportunities. In developed countries, the rate of urbanization is comparatively slow than the developing countries. In the last decade, this kind of human migration has increased many folds. Urbanization, the spatial concentration of people and economic activity is arguably the most important social transformation in the history of modern civilization. The timing and speed of urbanization have variations in different countries. The process of urbanization has taken place everywhere in an unstoppable manner.
According to a report by United Nation, 61% of the population will live in urban areas by 2025 especially in the developing countries. This uncontrolled urbanization has many fundamental, social and environmental consequences. In India, an estimated 340 million people (30% of the total population) live in urban areas. As per estimation, 590 million people (40% of the total population) will reach new towns and cities by 2030. If it is continued unabated, we will have to look for long term sustainability and future environmental consequences.
Landscapes and urban green space refer planning, development and plantation of trees and other greeneries for achieving specific purposes. The plantation pattern, selection of plant species and designing of green spaces vary according to the situation. Landscapes and urban green space plays a critical role in keeping our cities clean and healthy.
Importance of Landscape and Urban Green Space
The consequences of rapid urbanization are quite prominent and have several adverse effects on environment. Development of urban green space and landscapes are one of the effective ways for improving air quality, aesthetics and environment. There are international norms for urban green space as a mandatory rule. In developed countries, the standard of green space is 20 sq.m. area per capita which helps maintaining a balance between CO2 and O2 for human wellbeing. As per WHO, the need for green open space is a minimum availability of 9 sq.m per capita. There is wide variation both in coverage and per capita availability of green space globally. However, well planned cities have urban green space 20-40% of the total geographical area. Indian cities are far behind the standard recommended and adapted internationally. New Delhi, the capital city, has green cover about 20% of the geographical area which comes to about 20-22 sq.m. green space per capita. The value of green open spaces within cities for ameliorating local climatic conditions is widely appreciated. These were not only established for recreational needs but for ecological requirement as well. They perform many functions for improving quality of life in the urban areas. Nevertheless, green spaces provide linkage between people and nature.
Efficacy and Environmental Benefits
Urban green space development as Greenbelt serves as an effective means of mitigating industrial and urban pollution. Studies have revealed that a green area having 500 sq. m width surrounding a factory is capable of reducing SO2
concentration by 70%.
Woodland over a hectare absorbs 3.7 tonnes of CO2 from atmosphere and supplies 2.5 tonnes of oxygen.
Reduction of dust particles (27%) in London (Hyde Park) by a green area of 2.5 eq. km. was also reported.
Trees also provide support to wild creatures, birds and biodiversity as a whole.
Social Benefits of urban green space
Urban landscapes provide safe play space for children and contribute to physical, mental and social development.
Plays an important role in the basic education of school children with regard to the environment nature.
Landscape and urban green space provide a refreshing atmosphere with appropriate greenery in contrast to the structures of buildings.
Provides healthy environment by improving quality of air, water and soil.
Provides space for social activities, celebration and other performances.
Provides a perfect outing place for elderly people and family as a whole.
Reduces temperature effect and consequently reduces demand of air conditioning. The annual saving, thus made by a tree is estimated to be Rs. 10,000-12,000.
The cost benefit ratio, a resident may receive back, is estimated to be around Rs. 1000 against annual investment of Rs. 500. Therefore, urban greeneries contribute significantly to reduction in cost of environmental maintenance.
An urban forest is a collection of trees that grow within a city, town or a suburb. In other words, it refers growing of any kind of woody trees in and around human settlements. Urban forests play an important role in ecology of human habitats in many ways viz. filtering air, water, sunlight, provide shelter to animals and above all, recreational area for urban people. They moderate local climate, act as wind break and provide shade. Moreover, they are critical in cooling the urban heat island effect. Urban trees, shrubs and wildlife help people maintain their connection with nature.
Parks occupy a unique position in our social life and are a common facility to the community for pleasure and utility. Development of parks is the most common way of using urban open space. Usually parks contain all groups of plants. Besides, they are the good source of recreation, aesthetic and amelioration of environment. A park over an area of 1-2 hectare creates a cooling effect by 2°C than the surrounding area. Proper planning of parks by selecting perennial ornamentals having pollution tolerant capacity will further accelerate amelioration of environment. In old cities, there may be less availability of space for developing new parks. However, the available open space may be converted into green space. In case of new cities, making provision for development of parks is now mandatory.
Clean and healthy environment is a primary requirement for the urban people. The incessant increase of population pressure on cities and towns has made the environment more polluted. Proper planning of urban green spaces and landscaping with tolerant trees and other plants is an effective way for improving quality of urban life and environment.
*Botanic Garden, Floriculture and Landscaping Division, CSIR- National Botanical Research Institute, Lucknow, India.