Biodiversity is the key to health.
The strength of a forest – or any other ecosystem – is measured by its biodiversity. The variety of tree species and ages in a forest determines everything from the types of wildlife it can support to the threats it can withstand.
Many species of wildlife depend on narrow slides of the ecosystem for food or camouflage, so those small areas must contain every type of flora or fauna the species needs. Some species can also depend on microclimates created in part by trees of a particular age or type. In addition to supporting life, a forest with the right combination of trees can recover from wildfires, repel insect infestations, and even thwart diseases. The balance is such that the loss of just one species, or a single generation of trees, could change the forest’s ability to support certain forms of wildlife, or to protect itself from danger. As the naturalist John Muir said, “When we try to pick out anything by itself, we find it hitched to everything else in the universe.”
Natural forests are dynamic – they sprout, grow, mature, die, and re-seed to start the process again. At each stage of this succession cycle, the forest hosts a different mix of trees and understory plants. When something threatens this natural process, such as wildfire or logging, the face of the forest can change. American Forests’ Global ReLeaf program encourages the planting of diverse native species, which maintain and restore the symbiotic relationships that constitute an ecosystem.