Building Dams and Creating Wetlands
Beavers naturally restore wetlands by using logs, rocks and mud to build dams in various rivers.
Wetlands are low-lying areas of land that are covered by water for long periods and are important to biodiversity because they support aquatic plants and wildlife. They are also important carbon sinks because they absorb carbon dioxide and act as a buffer against the impacts of floods, drought, hurricanes, and tsunamis. Unfortunately, wetlands are at risk of disappearing due to agricultural and urban developments and climate change.
Ecologists and biologists are calling for a new paradigm of management and restoration of lands and wetlands which involves the help of beavers. They call these animals “ecosystem engineers” because they can reshape entire habitats to suit their needs.
Beavers built dams to sleep, raise their babies, and protect them from predators. These dams are made out of trees and branches, mud, rocks and grass. The logs are cut using their strong front teeth. The beavers chew tree trunks until they fall and use the remaining logs and branches as building materials. The stones are placed at the base, and the mud is used to seal the dam’s upstream wall.
The beavers build their dams on waterways which slows down the flow of water and keeps it on the landscape longer, creating ponds and wetlands. These areas eventually become living and breeding spaces for a wide range of other species. Additionally, these dams reduce soil erosion and retain sediment. These dams will absorb and filter pollutants such as heavy metals, pesticides and fertilizers. The benefit of this is that it improves the quality of water downstream used by humans and other species.
For the past 50 years, beavers have been continuously reintroduced to areas in the US and Canada to help restore wetland ecosystems. Studies have found that ponds engineered by beavers contained nearly twice as many mammal species compared to other ponds. Studies have also found that in response to mega-fire events, the areas built by beavers were able to stay preserved. These areas weren’t burnt and remained well-watered following these events.
Studies have also shown that the wetlands created by the beavers store a lot of water, so plants in these areas are not affected during periods of drought. There have been over 100 reintroduction projects in North America and northern Europe in which beaver dams have protected areas from drought.
The beaver wetlands will eventually become peatlands as the dead vegetation accumulates underwater. Like wetlands, peatlands are important for carbon sequestration.
It is possible for humans to construct wetlands. These specially designed wetlands can receive, remove, or filter various contaminants found in surface water, groundwater or runoff. However, these constructed, manmade wetlands can be very expensive. They could cost upwards of $10 000 to $100 000 per acre to build. They also take between 1-2 years to be constructed. What’s more, they require large areas of land to build. Beavers will help build these wetlands on existing water and do it for free.
Beavers can play an important role in restoring ecosystems. If we let them do their jobs, wetlands will be restored, and the effects of climate change can be minimized.