Ecological structure assessment of urban green space using the landscape approach(case study: Tehran’s 22nd district)

Urban green space, as an important part of the urban complex ecosystem, offers many ecological, social, and economic services that contribute to the quality of life in cities. Today, the rapid growth of urbanization, along with a lot of changes in land cover and land use, has caused many environmental impacts associated with a reduction in green spaces and, as a result, have negative environmental impacts. Accordingly, the purpose of this study was to investigate the trend of changes in the extent and structure of green spaces in the 22nd district of Tehran from 1996 to 2018 with the landscape ecology approach.

One of the principles of the ecology of the land is to examine the changes in land use and land cover over time. Accordingly, in the present study, using LANDSAT satellite imagery from 1996 and 2018, landslide maps of Tehran’s District 22 were first developed in four classes including man-made, green spaces, open spaces, and water patches. In the following, the selection of landscape metrics at the level of the landscape including normalized entropy, relative richness, edge density, patch area, patch compactness and class-level metrics including the number of patches, edge density at the class level, mean patch size, and mean shape index were analyzed for landscape analysis.

The findings revealed that green areas of zone 22 of Tehran have been structurally changed from 1996 to 2018 from the aspect of cohesion, and doesn't have a desirable situation because the structure of urban green spaces has been diminished. Namely, two type of basic changes have been occurred in ecological landscape, including developing new polygons and segmentation of polygons.

The findings of the research indicated that green patches in the district 22 of Tehran, in comparison with previous years, in terms of number, area, size and shape have undergone major changes and is not in a desirable condition, because the structure of urban green spaces have been fragmented. Accordingly, suitable spots for the development and improvement of the continuity of urban green patches were presented.