The planning process of an urban landscape system's ecological networks (case study: The city of the Tehran)

Introduction:
To improve the ecological condition of the landscape and prevent its destruction in the process of urban development, it is essential to optimizing its ecological-sociological functions, we utilizing ecological services of the landscape as well as providing our socio-economic needs. For this reason, we should use the principles of landscape ecology for examining and analyzing the structure of the urban landscape and process changing of it and then use the obtained information in development plans and move to sustaining ecological networks and development of the environment.

Materials & Methods:
Conceptual framework:
The human scale landscape is generally well adapted to geographic units such as watersheds and urban areas as well as the spatial domain of human consciousness. Many ecologists consider the landscape as a multi-dimensional and hierarchical concept that means a landscape is a spatial heterogeneous area that its size depends on the subject of the study and the research questions. In this research, the scale of study is 22 municipality zones of Tehran.
For examining the ecological-sociological function we need to study the horizontal and vertical aspects of the landscape and its elements, therefore, we examine the content composition and spatial configuration pattern of landscape's elements.
Measuring the urban landscape of Tehran's ecological-sociological function (ecological networks sustainability)
- Studying the quality of urban landscape of Tehran's elements content composition
Each element of the urban landscape has a different level of ecological-sociological function that depends on several factors. One of the determinants is landscape content (land cover). The ecological function of these structures from up to down is: vegetative, aquatic, open (uncovered) and building.

-Studying the urban landscape of Tehran's elements spatial configuration pattern
Landscape ecology planners considered structural features and patterns related to the ecological function of landscape and ecological network stability, these features including spatial heterogeneity of landscape, ecological and structural connectivity (opposite of fragmentation) between the same type of elements, and the ecological and structural connectivity between all elements of the landscape. Connectivity between all elements is relative because the increase in connectivity would be useful for one function also it would be detrimental to one another.
-Required Metrics for the study of landscape:
To examining the current situation and the process changing of mentioned features (heterogeneity, connectivity, and isolation) in recent years, we use the landscape ecology metrics.
Heterogeneity: CA, PLAND, PR
Connectivity between same type patches: AREA-MN, PN, and PROX
Connection between all elements: CONTAG, IJI
Methode:
To achieve objectives of the project, we followed below steps:
1-Studying of the ecological elements process changing (including the green patch, open patch, blue patch, building patch, building corridor) by software.
2- Dividing the region into two parts to reduce the amount of the large-scale error, or accumulation of valuable ecological elements in one area and study the process of change as well as determining the location of changes make more accurate (after the initial study of the landscape, because of natural and important ecological elements accumulate in the northern half, the landscape was divided into two parts, north and south alongside the Enghelab Street.
3-Studying of the ecological elements process changing (including the green patch, open patch, blue patch, building patch and building corridor) in each of the northern and southern halves by software.
4- A more qualitative studying of the ecological elements process changing{including different types of green patch, types of the open patch, natural corridors (river-valleys)} by reviewing the latest detailed and comprehensive plans, the Atlas of Tehran metropolis and prepared maps of the Tehran by the municipality and relevant projects.
Discussion of Results:
the process changing of metrics for study and planning within the scope of the study does not appropriate. The inappropriate process changing of the metrics (the quality of the landscape elements, the spatial heterogeneity of the landscape, the connectivity of the same type patches and the connection- isolation of all landscape elements), causing to reduce the ecological function of the landscape, imbalance ecological-sociological landscape function and the reduction of ecological networks sustainability. This trend is more important in the northern half because of important ecological elements and the newer development accumulate there. Some of these ecological functions include hydrological, meteorological and biological functions, which we explain a brief analysis about their process changing.
Hydrological function: Due to the expansion of impermeable surfaces, reduction connectivity of green patches (especially natural green patches) and change of the bed and around stream from natural to man-made materials, water is transferred to the urban landscape more rapidly, that caused increased soil erosion at the end of the flow path. Moreover, a large amount of organic and non-organic pollutants enter into these flows, which reduces the water quality and human health. In addition, the drainage of underground aquifers is one of the effects of these structural changes that would lead to catastrophic consequences such as the soil and earth settlement. These factors all reduce the aquatic function of the landscape, therefore, it does not require for aquatic needs of humans and human beings must pay more for their needs and add more ecological footprints effects to the regional landscape.
Meteorological function: Due to the rising population and vehicles in the city, building patch, reduced permeable surfaces, especially green patches, lack of concentration and ecological design of different land use patterns, smoothing the city's natural highlands and destroying important elements in air filtering (such as the river-valleys), Lead us to face the production of pollutants and the expansion of the city's thermal islands, simultaneously, the ecological capacity of the land surface has diminished to absorb and reduce these meteorological abnormalities. All of these factors contribute to the spread and distribution of air pollution and affecting human health. By increasing the height of building to the width of the streets ratio, also the non-ecological design of the building patches, we are facing the blocked air corridors, which eliminates the movement of pollutants and mixes the city's thermal islands.
Biological Function: By reducing the habitat patches and replacing them with building patches, the capacity of the landscape to control and sustain different species is reduced. This problem intensifies by reducing the habitat patch connectivity (non-building patches) as well as imbalance connection-isolation with building elements and human effects. In addition, the elimination of natural green patches and replacing natural green patches with low-quality green patches are effective in this function because structural variation reduced.
for confronting to the destruction of the high-quality ecological elements and the reduction of the landscape ecological functions, we must use this information for landscape ecological planning and ecological networks planning in order to optimize ecological-sociological function and stabling the ecological networks.

Conclusions:
landscape ecology can help landscape planners and managers to reduce landscape destruction and achieve sustainable urban development. One of the ecological tools is the ecological networks. In order to balance urban landscape structure and function, we must consider ecological planning beside to economic and social planning. Based on the principles of the landscape, for the urban landscape ecological planning, we must study the current situation and process changing of the elements and their functions which in turn, lead us to do protective, developmental and corrective planning. The function of landscape and ecological networks depends on the content composition and configuration pattern of landscape elements. Accordingly, a conceptual framework consist of content composition and configuration pattern elements was established for studying the ecological networks of Tehran's landscape, and the metrics were evaluated at different times (1984, 2000 and 2016). The process changing of the urban landscape structure and function is not desirable and did not respond to the ecological needs of urban sustainable development. To solve this issue, plans should be moving toward increasing the ecological quality of the elements, increasing the urban landscape heterogeneity, increasing the connectivity of the same type elements and balancing the connection-isolation between all elements.