The beaver works as an ecosystem engineer and keystone species as its activities can have a great impact on the landscape and biodiversity of an area. Aside from humans, no other extant animal appears to do more to shape its environment. When building dams and lodges, beavers alter the paths of streams and rivers allowing for the creation of extensive wetland habitats. In one study, beavers were associated with large increases in open-water areas. When beavers returned to an area, 160% more open-water was available during droughts than in previous years when they were absent. Beaver dams have a tendency to raise the water table, both in mineral soil environments and in wetlands such as peatlands. In peatlands particularly, their dams can stabilize the often fluctuating water table, which controls the levels of both carbon and water.