Figure 1 in Distribution of earthworm growth stages along a naturally occurring soil salinity gradient

Figure 1. (A) Field sampling location for earthworm and soil collections in southeast North Dakota, USA. (B) Five plots were established along a salinity gradient based on an electrical conductivity (EC1:1) survey. (C) Within each plot, five sub-plot locations were sampled. (D) Intact soil cores (20 cm in diameter, 15 cm deep) were hand-sorted for earthworms, which were counted and classified based on growth stage. Soils from each core were analyzed for physical and chemical soil properties.