Fig. 1
From: Rare earth element geochemistry in soils along arid and semiarid grasslands in northern China
Map of sampling localities on a continental scale. Across northern China from west to east, the sampling sites are labeled S01–S21 in order. Based on the aridity index (AI), the sites are divided into three climate subtypes: arid areas (0 ≤ AI < 0.2, represented by light blue circles), semi-arid areas (0.2 < AI ≤ 0.5, represented by blue circles), and dry sub-humid areas (AI ≥ 0.5), represented by dark blue circles)