Some Trees Need Full Sunlight
Some trees, depending on the species, can suffer from too much shade. Simply put, many conifers and hardwood trees have to be in full sunlight most of the day to survive. These trees are what foresters and botanists call "shade intolerant". Trees that is can take shade are shade tolerant.
Tree species that cannot tolerate shade well are pine, many oaks, poplar, hickory, black cherry, cottonwood, willow and Douglas fir. Trees that can take shade are hemlock, spruce, most birch and elm, beech, basswood and dogwood.
This pine, planted under mimosa, black cherry and hackberry, will be continually stressed and eventually die (see photo). The loblolly will never be able to overcome these low lighting conditions near the canopy floor.