Assessing the landscape ecological risk of road construction: The case of the Phnom Penh-Sihanoukville Expressway in Cambodia

Extensive development of expressway infrastructure alters the layout of terrain resulting and results in major ecological concerns. Therefore, it has become necessary to investigate how to assess the effects of land use changes on the landscape pattern and explore pertinent environmental concerns related to road construction. This study develops a numerical mothed to assess the ecological risk of road construction in terms of landscape pattern by combining the landscape disturbance index and the vulnerability index. The model is used to assess the landscape ecological risk of a particular portion of the Phnom Penh-Sihanoukville Expressway in Cambodia. The empirical study found that the rise in the amount of construction land was transferred from the area of grassland to cultivated land. It is identified through calculating the landscape pattern index that the integrity of the landscape decreases due to the expressway construction; ecological landscape tends to be complicated and fragmented; and the gravity center of the land use landscape pattern transitions in the same direction as the expressway construction. The ecological risk was assessed and it was found that the expressway construction led to a transition to poorer ecological quality along the road as a whole, and that areas of high ecological risk and higher ecological risk were gradually concentrated from the two ends to the central area. The study develops the landscape ecological risk assessment model and extends the landscape ecological risk assessment index to the ecological assessment of expressway construction. It can also effectively guide the ecological risk assessment of major international road projects.