تحلیل تغییرات کاربری اراضی و سیمای سرزمین در مناطق شهری و پیرامون آن ها، مطالعه موردی: شهر شاهرود (مقاله علمی وزارت علوم)
درجه علمی: نشریه علمی (وزارت علوم)
آرشیو
چکیده
هدف این پژوهش بررسی تغییرات کاربری اراضی و سیمای سرزمین در شهر شاهرود در بازه زمانی 1379 تا 1400 و پیش بینی آن برای سال 1410 است. تحقیق حاضر از نظر ماهیت، توصیفی - تحلیلی می باشد. داده های موردنیاز از تصاویر ماهواره لندست (تصاویر سنجنده +ETM برای سال 1379 و 1389 و سنجنده OLI برای سال 1400) استخراج شد. طبقه بندی تصاویر در نرم افزارENVI 5.3 با بهره گیری از الگوریتم حداکثر احتمال انجام شد و سپس به منظور سنجش متریک های اکولوژی سرزمین وارد نرم افزار FRAGSTATS 4.2 گردید. نتایج تحقیق نشان داد که در دوره مدنظر (1379 تا 1400)، مساحت زمین های مرتعی تقریباً ثبات نسبی داشته، کاربری محیط ساخته شده 48/2 درصد و کشاورزی و باغی 32/1 درصد در سال افزایش مساحت داشته، درحالی که مساحت اراضی بایر، سالانه 03/1 درصد کاهش داشته است که نشان می دهد بخش زیادی از این اراضی بایر به نفع اراضی ساخته شده (محیط شهری و روستایی)، زراعی و باغی تغییر کاربری یافته اند. هر چند در دوره موردبررسی، متریک های میانگین مساحت لکه ها (MPS) و بزرگ ترین لکه (LPI) برای کاربری مرتع، محیط ساخته شده و زمین های زراعی و باغی بهبودیافته اما تغییرات شاخص مجاورت و پراکندگی (IJI) نشان از گرایش به پراکندگی این کاربری ها در طول زمان دارد. در مقیاس کل سیمای سرزمین، کاهش متریک پیوستگی (CONTAG) و مساحت بزرگ ترین لکه، افزایش تعداد لکه ها (NP) و شاخص تنوع شانون (SHDI) بیانگر آن است که سیمای منطقه موردمطالعه در جهت ازهم گسیختگی و پراکندگی تغییریافته است. گسترش فیزیکی شهر شاهرود که بیشتر با الگوی پراکنده رخ داده از عوامل اصلی شکل گیری چنین وضعیتی در سیمای سرزمین منطقه بوده است.Analysis of Land Use and Landscape Changes in Urban and Peripheral Regions ,Case Study: Shahroud City
This research aims to investigate the changes in land use and landscape of Shahroud city from 2000 to 2021 and its forecast for 2031. A descriptive-analytical approach characterizes the present research. The data was obtained through Landsat satellite images - images of ETM+ for 2000 and 2010 and OLI for 2021-. After corrections and pre-processing operations, these images were classified in ENVI 5.3 software using the maximum likelihood algorithm. Then, the produced maps were entered into the FRAGSTATS 4.2 software to measure landscape ecology metrics. The results of the research showed that in the period (2000 to 2031), the total area of rangelands was relatively stable; the area of the built environment increased by 2.48%, and croplands and orchards increased by 1.32% per year. At the same time, the area of vacant lands has decreased by 1.03% annually, which shows that a large part of these vacant lands has been changed in favor of built (urban and rural) croplands and orchards. Although, in the studied period, the metrics of Means Patch Size (MPS) and Largest Patch Index (LPI) for the rangelands, built environment croplands, and orchard lands have improved, the changes in the Interspersion Juxtaposition Index (IJI) show a tendency to interspersion of these land uses during the time. On the scale of the general landscape, the decrease in the metric of CONTAG and LPI and the increase in NP and SHDI indicate that the landscape of Shahroud has become more disintegrated and dispersed. The physical expansion of Shahroud city, which has happened mainly in a sprawl pattern, was one of the main factors in forming such a situation in the landscape.
Extended Abstract
Introduction
This research aims to investigate the changes in land use and landscape of Shahroud city from 2000 to 2021 and its forecast for 2031. Shahroud city, as the second population and economic center of Semnan province, has grown significantly in recent decades. The changes in the population of Shahroud city between 1956 and 2016 have shown this city's significant population and spatial growth in these 60 years. The physical expansion of the city has been accompanied by the dispersion of built-up elements such as roads, facilities, infrastructures, and buildings and the increase of distances between different places and the merge of nearby villages to the city boundaries and all of these processes change the land cover/use and landscape, which ultimately challenges the sustainable development of the region and the city. Therefore, this paper examines the past and future trends of land use and landscape changes in Shahroud using ecological metrics of landscape.
In this research, it is intended to answer the following questions:
- What has changed the land use pattern in Shahroud city based on the ecological metrics of landscape from 2000 to 2021?
- How has the landscape of the studied area changed between 2000 and 2021?
- How will be the pattern of land use and landscape of the studied area in 2031?
Methodology
A descriptive-analytical approach characterizes the present research. The data was obtained through Landsat satellite images - images of ETM+ for 2000 and 2010 and OLI for 2021-. After corrections and pre-processing operations, these images were classified in ENVI5.3 software using the maximum likelihood algorithm. Then, the produced maps were entered into the FRAHSTATS 4.2 software to measure landscape ecology metrics. The metrics used in this research are Number of Patches(NP), Class Area(CA), Percentage of landscape(PLAND), Means of Patch Size (MPS), Largest patch index (LPI), Shannon's Diversity Index(SHDI) and Interspersion Juxtaposition Index (IJI).
Results and discussion
The results of the research showed that in the period (2000 to 2031), the total area of rangelands was relatively stable; the area of the built environment increased by 2.48%, and croplands and orchards increased by 1.32% per year. The area of vacant lands has decreased by 1.03% annually, which shows that a large part of these vacant lands has been changed in favor of built (urban and rural) croplands and orchards. According to the PLAND index, which represents the share of each land use in the entire landscape, the largest area belongs to vacant lands. Although the share of this class has decreased from 66.5% in 2000 year to 55.49% in 2021, it is still the dominant land use in the landscape of Shahroud. At the beginning of the period, the share of the built environment was 13.04% of the total area, which reached 20.14% at the end of the period, and its rank was upgraded from third to second. The PLAND index of rangelands did not change significantly in this period, and its share in 2021 was about 6.68% of the total area. Even though the share of cropland and orchard class increased from 14.96 to 19.69 percent, its rank has degraded from second to third. Although, in the studied period, the metrics of Means Patch Size (MPS) and Largest Patch Index (LPI) for the rangeland, built environment, and agricultural and orchard lands have improved, the changes in the Interspersion Juxtaposition Index (IJI) show a tendency to interspersion of these land uses during the time. The highest amount of IJI belongs to vacant lands, followed by built-up lands; rangelands have the lowest amount. On the scale of the general landscape, the decrease in the metric of CONTAG and LPI and the increase in NP and SHDI indicate that the landscape of Shahroud has become more disintegrated and dispersed.
Conclusion
The most important points that can be obtained from the study of land use changes and the landscape of Shahroud city and its surroundings consist of the following:
1- The physical expansion of Shahroud city has mainly occurred in a sprawl pattern. It has led to the increasing dominance of built environments in the landscape, which has played an important role in the disintegration of the landscape.
2-Maintaining the area and share of rangelands is a positive point. However, this class's decreased integrity and increased fragmentation are considered negative points due to their effect on ecological unsustainability.
3- The area of orchards and croplands increased, and consequently, its share in the landscape has increased. A positive assessment can be made about the non-decrease of the area of this land use despite the city's physical growth. However, whether the increase in its area has negative ecological consequences depends on factors such as water and soil resources management, preservation of natural vegetation and rangeland, etc., which are not discussed in this research.
4- The vacant lands have been faced with a decrease in area and an increase in fragmentation due to the change of this land use to other uses, especially the built environment.
Finally, if land use changes continue until 2031, the region's landscape will be more fragmented and dispersed. Therefore, it is necessary to control urban sprawl by applying strategies such as infill development and focusing on the management and protection of rangelands and agricultural lands so that this process changes the direction of ecological sustainability.
Funding
This article is extracted from a research project that was financially supported by Bozormehr University of Qaenat.
Authors’ Contribution
All of the authors approved the content of the manuscript and agreed on all aspects of the work.
Conflict of Interest
Authors declared no conflict of interest.
Acknowledgments
The authors would like to acknowledge the financial support of Bozorgmehr University of Qaenat for this research.
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