Precipitation-vegetation coupling and its influence on erosion on the Loess Plateau, China

The relationships between precipitation, vegetation and erosion are important and are unsolved issues in the field of earth surface processes. Based on data from the Loess Plateau of China, some non-linear relationships between forest cover (Cf), mean annual rainfall erosivity (Re) and annual precipitation (Pm) have been found. A threshold has been identified at Pm = 450 mm, that is, when Pm is < 450 mm, Cf is low and basically does not vary with Pm; when Pm exceeds 450 mm, Cf increases rapidly. Furthermore, two thresholds are identified in the relationship between rainfall erosivity and annual precipitation. When Pm is < 300 mm, Re is low and basically does not vary with Pm. When Pm exceeds 300 mm, Re increases rapidly; when Pm becomes > 530 mm, the rate at which Re increases with Pm becomes higher. Based on these relationships, the non-linear relationship between erosion intensity and annual precipitation (i.e., the erosion intensity increases with annual precipitation to a peak and then declines) is explained. The implication of these thresholds for erosion control on the Loess Plateau is discussed.