A key goal of forest management planning is to provide enough of each forest structure to fulfill the needs of the various species in the ecosystem. A forest plan that pushes for an inordinate amount of old growth will ultimately shortchange the future of some crucial component of the ecosystem and will inevitably reduce the system's biodiversity. Different animals benefit from different species of trees. Pileated woodpeckers, on the other hand, favor larger sizes of western larch and ponderosa pine.
Many animals use two or three forest structure types.
Grouse find food in the youngest forest stages but winter in mature forests. Owls, eagles, and ravens nest in mature forest but feed in open patches. Large mammals such as elk and lynx range over a wide area and utilize several forest structures. Lynx, for example, use mature stands of large trees for cover but prey on the rabbits who primarily live in shrubby areas. Forest health problems require treatment.