County-scale assessment of Spartina alterniflora spread risk in Hebei’s coastal areas using the MaxEnt model

• County-scale risk mapping supports targeted local control and management policies. • Multisource remote sensing images identified Spartina alterniflora current distribution. • Temperature-related variables are key drivers of S. alterniflora invasion risk. • Cross-county invasion risk emphasizes the need for joint regional control strategies. Spartina alterniflora spread and invasion risks have been extensively studied at global and national scales in recent years, there remains a lack of targeted guidance for control policies and measures at the county level, where practical implementation typically occurs. This study identified the current distribution of Spartina alterniflora using multi-source data from various remote sensing images and predicted its spread and invasion risks across the coastal counties of Hebei Province using the Maxent model. The results showed that: (1) Huanghua and Fengnan counties are the core distribution areas of Spartina alterniflora in Hebei Province. Specially, Huanghua County contains 7% high-risk and 32% medium-risk areas, while Fengnan County includes 29% and 37%, respectively; (2) The most important variables in this study as follows in order: average diurnal temperature range in June, exchangeable sodium salt of the top sediment, average diurnal ground temperature range in June, accumulated temperature from March to June, elevation; (3) Huanghua and Fengnan counties should be prioritized for Spartina alterniflora control, while continuous monitoring remain essential in the middle intertidal zone of other counties, and micro-topographic modification is advocated in high- and medium-risk areas to change its environmental suitability. Finally, this study highlights the importance of incorporating tidal level and hydrodynamic conditions in future research.