Modeling the effects of urban park 3D environmental features on bird diversity with interpretable machine learning: A case study of Harbin, northeastern China

Urban parks are essential habitats for birds in densely built environments. However, most studies focus only on horizontal features, overlooking the role of integrated vertical structures. Using bird records from the China Bird Report (CBR) collected between 2020 and 2024, this study focused on major urban parks in Harbin, a cold high-latitude city in Northeast China. Using interpretable machine learning models, we assessed the impact of three-dimensional (3D) park features on bird species richness and identified key variables along with their nonlinear relationships. Subsequently, we grouped bird species by ecological traits and applied ordination analysis to assess their differential abundance responses to the 3D environmental characteristics of urban parks. Results showed that: (1) urban park 3D environmental features had a certain influence on bird richness, among which disturbance from built-up land and the coverage of commercial buildings were the most important factors; (2) different bird groups responded differently to the urban park 3D environmental features. Specifically, waterbirds and generalist birds preferred mixed habitats dominated by water, wetlands, and tall vegetation, and exhibited significant edge effects caused by built-up land disturbance. In contrast, forest birds were mainly affected by greenspace configuration. Although they showed tolerance to human disturbance, this trend may increase the risk of biotic homogenization. The study used a 3D environmental framework integrating horizontal and vertical dimensions to explore how bird diversity is shaped, providing detailed recommendations for biodiversity-sensitive park planning in Harbin.