Road transportation is a major contributor to global greenhouse gas emissions, yet roadside vegetation along expressways can serve as an effective carbon sink. However, systematic assessments of the carbon sequestration potential of roadside plants in central China remain limited. This study evaluated the carbon sequestration capacity of vegetation along a 158 km section of the G4 Expressway in Hubei Province. Field measurements of net photosynthetic rate and leaf area index were conducted for 3