The Ecological Co-benefits of Population Urbanization: Causal Evidence from China's New-type Urbanization Policy

While existing research generally views urbanization as a threat to biodiversity, this study presents contrary findings based on China’s quasi-natural experiment in new-type urbanization. Utilizing county-level panel data and bird observation records from China between 2012 and 2022, we employ a staggered difference-in-differences approach for causal identification. The results indicate that the new-type urbanization policy has increased the average number of bird species in pilot areas by 4.691. This effect is attributed to overall improvements in habitat quality, specifically through enhanced regional ecological environmental conditions, expanded green infrastructure, and optimized industrial spatial layouts. The impact of the policy is most significant in regions with lower baseline biodiversity, in the northwestern segment of the Hu Huanyong Line with smaller population density, and in municipal districts. Further analysis reveals that while bird diversity exhibits spatial dependence across counties, the effects of the policy are largely confined to the pilot areas, without significant spatial spillover. This study substantiates the ecologica2 benefits of people-centered urbanization and provides empirical evidence and policy 43 insights from China for biodiversity conservation in the context of global 44 urbanization.