The cities are considered to be the most complex non-natural ecosystems. Their viability and their sustainability depend clearly on nature, both around and inside urban structure. The importance of urban green area for human life and welfare can be followed up and analyzed in various aspects: biological, ecological, social, technical, structural and psychological.
This paper highlights the importance of green areas for sustainable urban development. The general notion of sustainable development represents a paradigm in urban planning because a large proportion of world production, consumption and waste generation, is concentrated in cities. The interest for "greening" cities appeared together with this notion and it develops as people feel more and more negative effects of restricting green spaces, with repercussions on quality of life and human health.
"Europe is the most urbanized continent on the planet with about 75% of the population living in the urban area" says the European Environment Agency in 2006 report Urban sprawl in Europe.
In Romania areas occupied by green spaces have a fluctuating trend from year to year and they can not ensure the necessary green area per capita. Moreover, the phenomenon of accelerated degradation of green spaces is felt, together with the declining of its surface, these hovering below the requirements and provisions of regulations.
It is necessary people to understand the effort in urban green infrastructure conservation is not just an expense but an investment that will generate a series of important, unexpectedly economic benefits in the future.
Therefore, the authors wanted to bring arguments supporting the idea mentioned before, in order to convince the reader of the importance of preserving green area in cities and planning new ones where the minimum requirement for green space per capita is not reached. The absence of green spaces can affect our future life and certainly we can not talk about sustainable development anymore.
2. BENEFITS OFFERED BY GREEN SPACES
Under Article 3 of Law 24/2007 on the regulation and management of green spaces in buildable urban, republished in 2009, green areas consist of the following types of land within built up-area:
a) public green spaces with unlimited access: parks, gardens, squares, planted strips;
b) public green spaces with specialized use:
1. botanical and zoological gardens, outdoor museums, exhibition park, environmental and recreational areas for animals trained in circus performance;
2. those related with public facilities: nurseries, kindergartens, schools, hospitals or social protection institutions, buildings of worship, cemeteries
3. bases or sports parks for practicing performance sports.
c) green spaces for recreation: recreation basis, centers of recreation and sports complexes;
d) green spaces to protect lakes and rivers ways;
e) protection passages for the technical infrastructure;
f) recreational forests.
This law does not include a clear definition of the green space term. So it leaves place for interpretations and the possibility of using vacant land for construction.
We considered appropriate to present the following classification of the many benefits green spaces are bringing in urban environment: ecological, social and economic benefits (Chiriac et al. 2009).
From an ecological perspective, green spaces contribute to:
* a chemical treatment of the atmosphere by consuming carbon dioxide in the process of photosynthesis;
* a natural cleansing of the atmosphere by retaining dust;
* a bacteriological purification of the atmosphere, destroying much of microorganisms through the releasing of oxygen and ozone;
* moderating urban climate through shade effect and humidity;
* noise mitigation;
* preservation and perpetuation of indigenous natural vegetation. …