This study has improved the traditional evaluation model of ecosystem services value (ESV) by introducing a regional modification coefficient, an environmental cost coefficient, and by assessing the spatial distribution and temporal trends of the ESV which is driven by land use changes. As an empirical application, this improved assessment model was applied to a case study of a typical ecological transect at 38 degrees N of the Hebei Province, Northern China. This area consists of the Taihang Mountain area, the piedmont plain, the low plain and the coastal plain from the west to the east. It was found that in the Taihang Mountain area, the ESV per unit area in the western part of the region was higher than in the eastern part of the region; forest and grassland were dominant contributors to the total ESV in the region. In the piedmont plain and the low plain areas, the ESV per unit area was very low and had a homogeneous distribution pattern; the highest total ESV contribution in these two regions came from farmland. In the coastal plain, wetlands, water bodies, and farmlands contributed the majority of the total ESV in the region; the ESV per unit area in the eastern part of this region was significantly higher than that found in the center and western ends of the region; the spatial difference here was more significant compared to the other three ecological zones. The total ESV of the whole study area had a lower growth rate (0.92%) from 1990 to 2000 compared to the rate (6.57%) from 2000 to 2008. The ESV of gas regulation, climate regulation, recreation and culture, water regulation, and biodiversity protection increased from 1990 to 2008 while the ESV of food production showed a decreasing trend due to the reduction of farmland areas. Therefore, in order to maintain a healthy and stable ecosystem, it is proposed that provincial governments should implement ecological construction projects continuously to promote positive ecosystem services and oppose negative ecosystem services.
