Assessing highway's impacts on landscape patterns and ecosystem services: A case study in Puli Township, Taiwan

• Highway construction results in isolation and fragmentation of land uses.
• The road-effect zone is highly asymmetric along either side of the highway. Spatial policies result in land-use changes along major roads.
• Maintaining forest lands improves habitat quality.
• An integrated approach is needed to assess highway-induced changes.

Highway construction facilitates urban growth in Taiwan. However, the long-term effects of transportation infrastructure are not well understood; these include land-use changes, changes in landscape patterns, and the alteration of ecosystem services. To assess the effects of different land-use scenarios under various agricultural and environmental conservation policy regimes, this study applies an integrated approach to analyze the effects of Highway 6 construction on Puli Township. Interviews with neighborhood leaders of Puli Township, along with remote sensing analysis, reveal that both biophysical and socioeconomic factors are the major forces driving land-use change. The effects of these land-use changes are varied. An example is the road-effect zone, which for Puli Township extends 400 m perpendicular to the length of the highway; however, due to differing spatial patterns it is highly asymmetric; indirect effects include the spatial restructuring of certain landscapes, which can drastically influence habitat dynamics. Land-use simulation results indicate that agricultural and environmental conservation policies have significant effects on projected land-use patterns in the southern part of Puli's downtown area and in areas along major roads. Specifically, highway construction and subsequent urbanization under various land-use policies result in varying degrees of isolation and fragmentation in the overall landscape pattern. A habitat quality assessment using the InVEST model indicates that the conservation of agricultural and forested lands improves habitat quality and preserves rare habitats. In summary, appropriate environmental policies will mediate both the direct and indirect impacts of Highway 6 on landscape patterns and ecosystem services in Puli Township.