The study looked at how different factors like slope, land use, and soil depth affect the levels of carbon, nitrogen, and phosphorus in soil in a karst valley area undergoing ecological restoration. They collected soil samples from different areas and depths and found that soil on the east-facing slope had more carbon and nitrogen, while phosphorus was higher on the west-facing slope. Phosphorus levels were highest in plantation forests. Carbon and nitrogen decreased with soil depth, but phosphorus did not change much. Overall, the slope aspect had a bigger impact on soil nutrients than land use or soil depth in this area.