Many factors determine what types of plants will grow in an area. Elevation, latitude, soil, terrain and climate are all significant, but the most important factor is water.

Water from spring rains and snowmelt is critical to plant growth and survival. Wind Cave National Park receives about 17 inches of precipitation a year so it is extremely important for plants and animals to use it efficiently. Because the needles of conifers, such as pine, juniper, and spruce, have less surface area than leaves of most deciduous trees, they are more efficient water users. Therefore, conifers can survive in areas where aspens or cottonwoods would die of thirst.