Beavers adapt to their biome by engineering the landscape to meet their needs. They do this by constructing dams in streams and rivers, building lodges out of branches and mud, and felling trees for construction material and food.
For the beavers themselves, the dams raise the water level in an area, protecting their lodges from predators. The mud the lodges are made of dries into rock-hard material, which prevents predators such as wolverines and wolves from getting inside and also keeps the lodge warm in severe winter weather. Beavers create the lodge entrances underwater, making it impossible for other animals to enter. The lodges typically have two chambers, one in which to dry off and another to live in. Beavers do not usually build new lodges every season but instead return to the same ones, repairing them year after year.
According the Alaska Department of Fish and Game, beavers are so vital to an ecosystem that when they are taken away, the ecosystem loses its integrity. Their tree felling and dam construction not only provides them with protection and food, but it also benefits other inhabitants of the ecosystem. The ponds provide wetland habitation for animals such as other mammals, fish, birds, amphibians and insects. The dams limit the effects of erosion and sedimentation and provide filtration that cleanses rivers and streams.