Transportation infrastructure and biodiversity: Evaluating the ecological cost of transport networks

Much attention has been paid to the environmental consequences of transportation, yet causal evidence regarding its ecological costs remains unclear. Using prefecture-level panel data from 2013 to 2023 in China, this paper evaluates the marginal ecological costs of linear transportation networks, including roads and railways. Intercity transport networks in China have expanded at the expense of biodiversity loss. I show that transportation infrastructure causes systematic ecological losses. Quantitatively, an increase of 1 meter per square kilometer in network density leads to a 0.115 increase in biodiversity loss, as measured by a decline in species occurrences. The empirical results are robust to a rich set of tests including instrumental variables regressions and Poisson regressions. When the network density exceeds approximately 450 meters per square kilometer, the costs rise substantially. The underlying mechanisms are further examined: forest loss and fragmentation are identified as non-negligible contributing factors. Significant spatial heterogeneity in the costs is demonstrated by geographically weighted regressions, calling for tailored regional policies.