Quantifying Landscape Degradation Following Construction of a Highway Using Landscape Metrics in Southern Iran

Alireza Mohammadi,Faezeh Fatemizadeh

doi:10.3389/fevo.2021.721313

Alireza Mohammadi, Faezeh Fatemizadeh

Open Access

https://doi.org/10.3389/fevo.2021.721313

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Abstract

Rapid expansion of roads is among the strongest drivers of the loss and degradation of natural habitats. The goal of the present study is to quantify landscape fragmentation and degradation before and after the construction of the Isfahan-Shiraz highway in southern Iran. To this end, the ecological impacts of the highway on forests, rangelands, and protected areas were evaluated. Impacts of the construction of the highway were studied within a 1,000-m buffer around the road, which was then overlaid on maps of forests, rangelands, and protected areas. Class area, number of patches, largest patch index, edge density, landscape shape index, mean patch size, and patch cohesion index were used to gauge changes in the spatial configuration of the landscape; the ecological impacts of the highway were quantified using effective mesh size (MESH), division index, and splitting index. The results indicated that after the construction of the highway, 6,406.9 ha of forest habitat, 16,647.1 ha of rangeland habitat, and 912 of the Tang-e Bostanak Protected Area will be lost. The effective MESH metric showed that after the construction of the highway, the area of forest, rangeland habitats and protected area will decrease by 20,537, 49,149, and 71,822 ha, respectively. Our findings revealed drastic habitat loss and landscape fragmentation associated with construction of the highway, serving as references for conservation planning and development.

Highlights

Over the last few decades, anthropogenic activities have substantially altered landscape structure, pattern and dynamics in response to spatial and temporal changes in land utilization (Singh et al, 2017; Kumar et al, 2018)
The results showed that under natural conditions, the cohesion of the forest landscape in our study area is 98%, which will decrease to 97% after the construction of the highway, indicating lowered cohesion of the forest landscape and hampered physical connection between forest patches (Table 2)
Our aim was to study the impacts of the road network on its surrounding environment and nearby protected areas at the landscape level in southern Iran

Summary

Introduction

Over the last few decades, anthropogenic activities have substantially altered landscape structure, pattern and dynamics in response to spatial and temporal changes in land utilization (Singh et al, 2017; Kumar et al, 2018). Landscape fragmentation is to a large extent caused by infrastructural development, mining activities, reduction in forest cover, population growth, conversion of land due to agricultural expansion, etc. The rapid growth of the global human population coupled with accelerating economic development has led to increasing construction of road infrastructures, raising the alarm over possible impacts on the environment and habitats Roads are essential to economic growth and improved quality of human life; these man-made features can negatively impact wildlife by partitioning habitats and increasing wildlife mortality due to collisions with vehicles (Ali et al, 2015; Carter et al, 2020; Ascensão et al, 2021)

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