Linking Vegetation Diversity and Soils on Highway Slopes: A Case Study of the Zhengzhou–Xinxiang Section of the Beijing–Hong Kong–Macau Highway

The rapid development of highways has caused a series of ecological problems, the restoration of which is an important part of highway construction. However, most related studies have focused only on the early stages of slope restoration. The present study investigated the Zhengzhou–Xinxiang section of the Beijing–Hong Kong–Macau Highway, which has been restored over more than 20 years, examining nine representative vegetation communities within this section and investigating their species diversity and soil physicochemical properties. Redundancy analysis and the grey correlation degree model were used to determine the relationship and coupling mechanism between vegetation diversity and soil physiochemical properties. The results showed some differences in the diversity of different vegetation communities and soil physicochemical properties; vegetation diversity was mainly influenced by organic material, total and available nitrogen, total and available phosphorus, slope, available potassium, and soil bulk density. Overall, environmental factors had a strong correlation with the Simpson dominance index and a weak correlation with the species richness index. The degree of coordination between vegetation community diversity and the soil coupling of the road slope remained on low and medium levels. Artificial vegetation restoration can regulate water and fertilizer resources and promote the restoration of highway slope vegetation.