The study looked at plants in Jiuding Mountain and how their diversity changes with altitude. Trees in the upper part of the mountain affect the growth of shrubs and grasses below. In areas with more trees, there are fewer shrubs and grasses. But in higher areas with fewer trees, there are more shrubs and grasses. The diversity of plants decreases as you go from trees to grasses to shrubs, especially at altitudes above 3,500 meters. At these high altitudes, grasses have the highest diversity, followed by shrubs, with trees being rare.