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Ecosystem Engineers

Beavers are known for their hard work and iconic architecture, including dams. Learn how these ingenious designs transform ecosystems.

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Aside from humans, it has been said beavers modify environments more than any other species, so let’s examine a landscape without and with beavers.

This is a 3-part illustration showing what happens when beavers impact a dry valley landscape. The three stages show the progression of water spreading across the land as vegetation grows expansively.

The presence of beavers can transform a landscape from a simple creek area with relatively low vegetation to a flourishing valley scattered with water, a variety of plants and animals.

In the illustration above, the left panel depicts a landscape before the arrival of beavers. The sides of the narrow river are tidy and lacking in vegetation. Few animals call the area home, as there isn’t enough diversity of food and habitat. And though it appears calm, the area sees periods of intense flooding, drought, and even wildfires. 

 

But introduce the creation of dams, and something new begins. Plants start to pop up along the water’s edge, offering more food for nearby wildlife. The water starts to spread across the landscape. This second panel– it’s getting messier, in a good way.

 

By the time beavers have lived there for a while, the same pocket of land now featured in the third panel buzzes and blooms with life. Insects hum near the stream’s surface, and determined turtles find the perfect spot for sunbathing. Downy woodpeckers sing their cheery tune while the whole story of the landscape changes.

This is an illustration of an open book with watercolor style drawings featuring 1) a pond with water lillies, 2) a downy woodpecker flying in the wind, and 3) a turtle sunning itself on a log.

What transformations can happen when beavers move into an area?

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  • Beavers are relatively slow on land so they build lodges and dams – multi-leveled safehouses surrounded by water for safety.

  • Their instinct to construct forces the water to slow. This allows sediment and pollution to sink and be stored at the bottom of the beaver pond. Over time, small streams spread from the river’s main source, moving into the surrounding area and connecting in a complex web across the landscape.

  • As floodplains receive this influx of water, they become healthy wetland environments.

 

“Degraded streams are simplified from multiple stream channels to one or none, but beavers have the power to maintain water – fueling the engine of living productivity. In many places the absence of beaver has created a landscape devoid of water.” 

- Jefferson Jacobs, Riparian Restoration Manager for the Oregon Natural Desert Association

This is an illustration of a beaver dam on a water system. This overhead view shows how beaver dams spreads out a concentrated water source into multiple streams that support a riparian landscape.

Illustration of a stream branching into multiple directions thanks to the presence of beavers. When they build dams across a water source, they slow its course and divert the flow, creating multiple streams and raising the water table.

Apart from dams, the diet of beavers affects landscapes, too. Beavers are vegetarian rodents with a strong preference for crispy alder. When they chew around wooded areas, ground once covered by impenetrable shade becomes interspersed with light allowing smaller vegetation to thrive.

The driving force behind beaver excellence may be practical day-to-day necessities, but that doesn’t make it any less remarkable. Learn how beavers create critical habitat for countless other species.

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