Shuifei Chen

1 INTRODUCTION Urban tree diversity is critical for sustaining multiple ecosystem services and benefits (Davies et al., 2017; Duinker et al., 2015). Trees in cities comprise diverse species with different origins, functional traits, and environmental adaptations (Esperon-Rodriguez et al., 2020). Higher urban tree diversity enhances ecosystem functions, including carbon sequestration, temperature regulation, stormwater mitigation, pollution removal, and wildlife habitat (O'Sullivan et al., 2017).

Abstract : Nitrogen (N) and phosphorus (P) are key elements essential for plant growth and development. Due to fertilizer application, rapid urbanization, and fossil fuel combustion, nitrogen deposition has reached relatively high levels in China. However, there is still uncertainty regarding the response of N:P stoichiometry in plants and soil to N deposition across different ecosystems.