The study looked at how new trees grow in man-made forests of a specific type of pine tree in China. They found that the number of young trees increased when there were more trees in the forest, but only up to a certain point. The direction the slope faced also affected how many young trees grew. Trees grew best in the middle of the slope, and fewer grew as you went up the slope. The study suggests that having a medium number of trees on a shady slope is best for the new trees to grow naturally.