Climate, soil and dominant plant species determine which layers develop. Wildlife species are not always confined to any one layer. In fact, some wildlife need several forest layers. For example, wild turkeys forage on the forest floor but roost in tall trees. Forests provide food, cover, nesting sites and safe migratory routes for insects, amphibians, reptiles, birds, mammals and other wildlife.
Forests also help fish.
By intercepting and capturing rain, forests regulate the flow of stormwater and filter out nutrients and sediment. The roots of riparian vegetation stabilize the soil, reducing erosion into waterways. Trees and other overhanging vegetation shade waterways, helping to keep water temperatures cool. Through these functions, riparian forests help to maintain water quality for fish and other aquatic species. Riparian forests are essential to the life stages of aquatic life and more than one half of terrestrial life.