Beavers, large members of the rodent family in North America, are often referred to as "ecosystem/keystone engineers" by wildlife managers. Ecosystem engineers are described as animals that create, alter, or destroy a habitat. Beavers contribute to river ecosystems by bringing down old and dead trees along riverbanks. They use these trees to make their dams. Although these dams are primarily used for protection and food storage, scientists report that these dams change the surrounding environment in different ways. Given this information, in three to five sentences, describe a potential benefit that beavers contribute to the ecosystem as keystone engineers and describe a plausible impact that the removal of beavers could have on the surrounding ecosystem. (4 points)