Beavers as ecosystem builders

» Posted by on Oct 28, 2014 in Environmental | Comments Off on Beavers as ecosystem builders

Beavers as ecosystem builders

Either until recently or perhaps even now, beavers are routinely trapped and shot. The their homes (dams) have been destroyed by dynamite. However, it is being realized and proven that they can help reclaim and rebuild a hydrologic cycle that used to be the norm across much of North America.  This rebuilt hydrologic cycle can now assist in the defense against warmer and drier climate.

In North America beavers used to number in the millions and were an integral part of the hydrological system. Some valleys were filled with continuous dams creating numerous wetlands.

The population plummeted, largely because of fur trapping, and by the 1930s there were no more than 100,000 beavers, almost entirely in Canada.  Lately the numbers have rebounded to an estimated six million.

Beavers are ecosystem engineers. The pooled water leads to a cascade of ecological changes. The pond nourishes young willows, aspens and other trees — prime beaver food — and provides a haven for fish that like slow-flowing water. The growth of grass and shrubs alongside the pond improves habitat for songbirds, deer and elk. Dams also raise the groundwater levels.

Although it may not seem that beavers are beneficial to fish populations, they do help protect fish from rising water temperatures in rivers. The deep pools formed by beaver dams ensure there is cooler water at the bottom.

However, an overabundance of beavers can they can do serious damage if they are left unchecked.  A device that simulates the noise of flowing water can help direct beavers and their activities to areas more desirable to humans.  Is there a downside to beaver dams, well yes, new dams and non-flowing water can be perfect for various non-native fish species such as carp which then displace some native species.

There are still many unknowns of what the return of beavers means for arid ecosystems. Will it be always good in all situations? It is likely going to take 10 – 20 years to find out.

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