Evaluation and Analysis of the Degree of Ecological Security in the Integrated Spatial Framework of the Caspian Plain with an Emphasis on Urban Areas

Document Type : Research Paper

Authors

1 Department of Environment, Kish International Campus, University of Tehran, Kish, Iran.

2 Department of Environmental Planning, Management and HSE, Faculty of Environment, University of Tehran, Tehran, Iran.

3 Department of Disaster Engineering, Environmental Education and Systems, Faculty of Environment, University of Tehran, Tehran, Iran.

4 Department of Environmental Hazards, Marine Science Research Institute, University of Tehran, Tehran. Iran.

Abstract

Ecological security—defined as maintaining the health, stability, and integrity of ecosystems—plays a critical role in achieving sustainable development. In the Caspian Plain, one of Iran’s key biodiversity hotspots, climate change and intensified human activities have increasingly threatened ecological stability. This study examined changes in ecological security across the Sari–Qaem Shahr–Babol–Amol urban corridor from 2001 to 2023. To assess these changes, several environmental indicators were derived from Landsat imagery, including impervious surface area (ISA), biotope area ratio (BAR), city density index (CDI), urban expansion intensity (UEI), proportion of vegetation (PV), normalized difference moisture index (NDMI), urban thermal field variance index (UTFVI), modified soil‑adjusted vegetation index (MSAVI), normalized difference bare soil index (NDBSI), and road density. Principal component analysis (PCA) was then applied to calculate the eigenvalue contribution of each parameter and formulate the ecological security index for the study area. The results indicate that 72.7% of the region exhibited high ecological security, 15.9% moderate security, and 11.4% low security. Over the study period, 4% of areas with high ecological security declined, while areas with medium and low ecological security increased by 2.1% and 1.9%, respectively. Vegetation loss and rising urban density were identified as the primary drivers of reduced ecological security. These findings highlight the urgent need for comprehensive land‑use planning and environmental management in the region. Priority should be given to protecting and enhancing areas with high ecological security—particularly natural vegetation cover—while regulating the expansion of built‑up areas to prevent further ecological degradation.
 
Extended Abstract
1-Introduction
Ecological security refers to maintaining the sustainability, stability, and health of ecosystem components, and it plays a crucial role in environmental planning and the pursuit of sustainable development. Yet, in many regions around the world, ecosystems are increasingly affected by both human‑induced and natural pressures, leading to the degradation of their health, integrity, and long‑term viability. The Caspian Plain, recognized as one of the most fertile regions of Iran, has experienced significant ecological stress. Climate change, along with human activities such as land‑use change, urban sprawl, tourism expansion, and industrial development, has diminished the ecological services of this valuable region and threatened its ecological security. Given the high ecological sensitivity and strategic importance of this ecosystem, establishing a robust framework for evaluating ecological security is essential for guiding sustainable development efforts. The present study aims to assess and analyze the degree of ecological security in the Caspian Plain as an integrated spatial planning unit, with particular emphasis on urban areas. This evaluation provides a clearer understanding of the extent and nature of ecological degradation that has occurred, and how these changes have contributed to the decline in ecological security across the region.
 
2-Materials and Methods
This study was conducted to examine changes in ecological security across the Sari–Qaemshahr–Babol–Amol urban chain from 2001 to 2023. To achieve this, land‑cover maps were generated from Landsat imagery using the Support Vector Machine (SVM) classification algorithm. A series of environmental indicators—including impervious surface area (ISA), biotope area ratio (BAR), city density index (CDI), urban expansion intensity (UEI), proportion of vegetation (PV), normalized difference moisture index (NDMI), urban thermal field variance index (UTFVI), modified soil‑adjusted vegetation index (MSAVI), normalized difference built‑up and soil index (NDBSI), and road density—were then derived from the satellite data. Principal Component Analysis (PCA) was applied to determine the eigenvalue contribution of each parameter, and these values were subsequently used to formulate the ecological security index for the study area.
 
3- Results and Discussion
The results indicate that agricultural lands, forests, and barren areas declined over the study period, while urban land cover expanded by approximately 117 km² between 2001 and 2023. Amol City experienced the greatest increase in urban area, with an expansion of 9 km². It also recorded the highest rise in impervious surface percentage, increasing from 36% to 43%. If this value reaches 60%, the ecological risk in the region will approach a critical threshold. Babol City exhibited the highest biotope area ratio (BAR), although it also showed the largest decrease, declining from 64% to 56%. The Urban Expansion Intensity (UEI) results revealed that most of the built‑up land growth in the Caspian Plain was associated with rural expansion. Only in Babol and Amol did the urban fabric itself grow substantially—by 1.9% and 1.2%, respectively—indicating relatively high UEI values. Landscape ecological metrics for built‑up areas over the 23‑year period showed irregular urban growth and increasing fragmentation of ecological patches. The ecological security modeling demonstrated that 72.7% of the study area had high ecological security, 15.9% had medium security, and 11.4% had low security, the latter primarily associated with compact built‑up zones in city centers. Over the study period, areas with high ecological security decreased by 4%, while medium‑ and low‑security areas increased by 2.1% and 1.9%, respectively.
 
4- Conclusion
The results of this study indicate a substantial increase in built‑up areas (over 3%) and a significant decline in forest cover (nearly 10%) across the Caspian Plain between 2001 and 2023. These trends highlight urban expansion and vegetation loss as the primary drivers of natural environmental degradation in the region. The findings also reveal that ecological security has deteriorated more severely in urban areas than in rural areas. Among the evaluated parameters, greenness and urban building density exerted the strongest influence on ecological security levels. Overall, the outcomes of this research provide a valuable theoretical foundation for comprehensive ecological security management in the urban regions of the Caspian Plain. By addressing multiple dimensions of ecological degradation, the study offers insights that can guide future planning and policy‑making aimed at safeguarding the region’s environmental stability.

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Main Subjects

References

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