Many different organisms can satisfy their needs within the habitats provided in a tree. Trees provide shelter from climate and predators. Tree bark acts as a substrate for small plants and a habitat for many insects. Some animals eat the fruits, seeds, leaves, and woody parts of living trees. These animals are in turn eaten by other animals.
Some organisms depend on the decaying litter from a tree for food.
A tree may be one part of a larger habitat. Trees serve as a major food source for large animals. The productivity of a population of trees can be an indicator of the health of other organisms. Restoring a healthy population of trees can enhance the habitat for other organisms.