The Relationship between Soil Moisture and LAI in Different Types of Soil in Central Eastern China

As important parameters in the land atmosphere system, both soil moisture (SM) and vegetation play a significant role in land atmosphere interactions. Using observational data from clay and sand stations over central eastern China, the relationship between leaf area index (LAI) and SM (LAI SM) in different types of soil was investigated. The results show that the LAI SM correlation is significantly positive in clay but not significant in sand. The physical causes for the discrepant LAI SM correlations in different types of soil were explored from the perspectives of evapotranspiration (ET) and soil water retention. In clay stations, increasing LAI is associated with greater soil-water-retention capacity. Although the increasing LAI corresponds to increasing ET, the impact of ET on SM is weak because of the small particle size of soil. Consequently, the LAI SM relationship in clay is significantly positive. In sand stations, ET is negatively correlated with SM owing to the large soil particle size, resulting in a negative LAI SM correlation in sand. However, soil water retention is weakened by the increased LAI, which may be an important factor causing the insignificant LAI SM correlation in sand.