The study looked at how different types of plants affect water runoff in a small area in the mountains of Beijing. They found that areas with vegetation had more water in the soil, and the depth of the plant litter layer affected how much water it could hold. Areas with plants had less water runoff compared to bare land. Black locust and Rhus typhina plants were good at catching rainwater. During moderate and heavy rains, areas with plants had less water runoff compared to areas without plants.