Mr. and Mrs. Beaver rescued and guided the Pevensies through the terrains of Narnia, ensuring they reached their destination in order to fulfil their prophecies. But the role of beavers does not end there, for in the reality we occupy, they are the keystone species in their ecosystems. Part of the rodent family, beavers are commonly found in North America, parts of Europe and selected regions of Asia. As ecosystem engineers, they build dams and thereby construct wetlands, a system which supports a great diversity of species.
So why are beavers so important for biodiversity?
The famous dams built by beavers are made of aspen tree trunks. Beginning their construction endeavours right from felling the tree, beavers chop down trees and drag them to their spot of choice. The felled branches and trunks are placed ingeniously across flowing waters, slowing the rate of flow and redirecting it toward a new path. The dam acts as a semipermeable membrane in some sense, allowing beavers to commute from under the structure, while ensuring that water predators cannot get through to them.
This is not all, for the reduced speeds of water facilitate sedimentation of minerals, creating a mineral-rich reservoir behind the dam, one that subsequently supports a multitude of lifeforms long after the beavers leave too. These mineral pools are also capable of acting as natural filters, absorbing chemicals from fertilisers and manures. The water that flows on from these pools is thus of higher quality, making it more feasible for use by other species, including humans.
Terrestrial species also benefit!
The remnants of the cut trees give rise to shoots that are consumed by elk and moose populations, attracting them toward the beaver habitats. The story does not end there. Once the taller aspen trees are removed, smaller trees that were previously in their shadows are able to gain the upper hand in acquiring nutrients, boosting their growth. Wetlands are known to be a diverse, thriving ecosystem. Certain species are specially adapted to exist in such systems.
A cascading effect of the dams built, wetlands are formed, and a variety of species dependent on the said system, thrive. Right from insects and amphibians, to water birds, these systems teem with life. Starting from the lowest rung on the trophic ladder, wetlands create a habitat for several producers, such as algae, submerged plants, etc. The presence of these attracts invertebrates and amphibians such as crustaceans, insect larvae, toads or mollusks. In turn, beings higher up on the food pyramid , such as deers, otters, muskrats, osprey, etc., too migrate toward this pulsing system. Piecing it all together, one can already see how the ecosystem has begun to shift and move toward increasing diversity post the beaver-interference.
Beavers also provide a plethora of ecosystem Services
Having given a boost to diversity in flora and fauna and improving water quality, beaver dams do not end the list yet. The formation of wetlands gives rise to several ecosystem services, including mitigating floods and droughts. Yes, it is ironic that one entity is able to work with the extremes of water availability. Bears dig into the mud present under water surfaces, decelerating the evaporation rates. Post this activity, they build their dams which pushes water sideways.
The dams acts as barricades to high-speed flowing waters, protecting other habitats downstream from impending floods. It is this very slow and seeping flow of water that aids in times of drought as well. Drying of water bodies would lead to the eventual death of species heavily dependent on the water body for basic survival, such as the aquatic flora and fauna. However, water flowing at a steady rate, and being fed through a reservoir upstream, is seen aiding in the survival of these species, mitigating the effects of a drought.
The Eurasian Beaver became extinct in the Wild!
Knowing all of the ecosystem services that cascade as an after-effect of beavers presence in that habitat, the species themselves were seen declining in their home ranges. Eurasian beavers hit extinction in the wild, nearly 400 years ago. This was an aftermath of continued persecution of the species. North American beavers too showed drastically declining populations, largely caused due to habitat destruction and degradation that follows urbanising activities.
Why were beavers being persecuted? Their dam building activities would often come in conflict with the human populations, for the boundary between the wild and the domestic was getting blur by the minute. Ornamental and agricultural plants would be felled and destroyed, while reservoir building would lead to flooding of agricultural lands and roads around the area. The most common response to such conflicts, as is seen with most other animals, was for beavers to land on the receiving end of impending death.
Rewilding Beavers is the Way to go!
The impact was evident, for the terrain began to dry-up and show little diversity in the flora and fauna found. As a result, humans rushed to protect and re-wild the areas with beavers. The UK granted the Eurasian beavers legal protection in the hopes of breathing back life into the drying wetlands. Under this law, beavers are now protected from being captured, killed, injured or even disturbed. In North America, the steps taken are slightly less drastic, with more focus on mitigating the conflicts, educating and generating awareness on the importance of beavers amongst the people as well as introducing non-lethal control measures to avoid said conflicts.
Perhaps such measures will allow for the mutual benefit and coexistence of humans and beavers, and as an extension, the wetland ecosystem. Reintroudincg wolves also has shown to increase beaver populations in Yellowstone National Park.
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Written by: Samanvitha Santusht