Analysis of evolution process of landscape ecology in the City of Qom based on Alberti Model

Landscape as a whole is the reflection of the structure and function and their interaction. Although, metrics of landscape ecology provide an appropriate tool to analysis the structure and function of landscape, but deep understanding need to enquiry the generality and evolution of the landscape as a whole. This is especially important to urban landscape interpretation. In particular, when urban development is the result of spatial development which mainly influenced by socio-economic processes. As results, the environmental context is less considering. Disturbance in the natural and ecological structures is the consequences of such process that lead to the ecological rupture of the landscape. Accordingly, structural changes affect the functioning of the city's natural ecosystems that making cities more and more unsustainable. Hence, it seems that the first step in improving the current situation is to explain the pattern of landscape changes appropriately and provide a truthful understanding of the effects of urban development patterns of the ecosystem.Accordingly, the purpose of this study is to evaluate the overall landscape changes of Qom over 30 years. Therefore, an attempt has been made to: first, compute the structural and functional changes of the landscape by using landscape metrics. Therefore, the natural and artificial structures that make up the city's landscape were extracted from the US Geological Survey (USGS) using satellite images. Images were taken in 1989 from the Landsat Satellite 5 (TM), in 1999 and 2009 from the Landsat .7 (ETM), and the 2019 from Landsat 8 (OLI). Then, it was classified by Supervised Classification method and Maximum Likelihood using the ENVI software. The natural and artificial structure was classified into four categories: vegetation, building, communication and bare lands. Then, ten appropriate metrics was calculated to quantify the changes in these four aforementioned categories. The essential calculations have been done by the Fragstats software.The results of the study show the uninvited and accelerated changes in the ecosystem of the Qom bese on application of landscape metrics. Qom has experienced serious structural and functional changes over thirty years. The man-made landscape is developing at the expense of devastating natural structures. Natural patches are disappearing. While, the introduced patches are increasing progressively. Of course, introduced patches has not a significant effect on the overall trend of landscape change. Examining the trend of LPI, AREA-MN, SHAPE-AM, SHAPE-MN indicators provides information about changes in the visual form of the landscape. The increase in artificial patches, along with the lessening of the largest desert patches to one-third, indicates the emerging of the progressive fragmentation in the desert landscape of Qom. Meanwhile, the shape of the city is changing into the simple geometric pattern, which means the loss of natural ecosystems. The status of the indicators during different years expresses the simplification of the urban landscape. The result is multiple effects on the urban environment, such as changes in microclimate and its consequences on the fragile desert ecosystem. Therefore, it is necessary to revise the development model and consider serious attention to natural oriented approaches while responding to human needs in such areas. It seems that the present a model of ecological planning along with strategic proposals is obligatory to practice the ecological-based projects for future developments to enhance the quality of Qom ecological landscape.