The Beaver - An Ecosystem Engineer

Today’s post is going to be talking about one of the world’s best ecosystem engineers, the beaver. The term ecosystem engineer is defined as an organism which is capable of modifying, creating or destroying habitat and directly or indirectly modulates the availability of resources to other species, causing physical state changes in biotic or abiotic materials.

For beavers this engineering generally takes the form of dams and the lodges they create to live in. however beavers also create extensive networks of canals which they dig out to help transport the wood they fell to areas where it is required. The largest known beaver dam is in Buffalo National Park (Canada) and was created in 1975 measuring 850m, which is a number which keeps growing as beavers add extensions to it. 

The effects of beaver dams have both a positive and negative effect as they create vast flooded areas above them, this dra

matically changes the ecosystem in that area. These changes allow some organisms to prosper while others terrestrial organisms suffer, it depends on the area as to which group of organisms are affected. Dams also affect nutrient flows down the river, just
like artificial dams and so have long reaching effects on ecosystems than just the immediate surroundings of the dam. A study in 2006 showed that dams effected groundwater flow in the Rockies, forcing it to flow towards the sides of valleys. This in turn leads to the rise in the water table which helps to sustain plants and animals during dry summer seasons.

As for the beaver it’s self it is extremely well suited for its engineering lifestyle. Like all rodents beavers have extended incisors which grow continually throughout their lives. These teeth are used for the felling of trees and bushes to help build their dams and lodges as well as providing food. These teeth are also adapted to be self-sharpening due to their composition. The front of a beavers tooth is made of hard enamel while the back portion is softer dentin; this means the rear of the tooth is worn away fast and resulting in the creation of a sharp edge. Also their webbed feet allow them to effectively move mud around when they are either digging canals or patching up holes in the dam.

Beavers live in family groups within lodges, which again are a master piece of engineering. From the outside lodges usually look like a pile of sticks however inside are several chambers which are used to eat and sleep in. To increase protection the only entrances to a beaver dam are located underwater and so provide an easy escape route if a predator attempts to break through into the lodge. These underwater entrances also allow access to food stores during the winter while the lake is frozen over.

There are currently two species of beavers in existence today (the Eurasian and North American beaver) and one species which has become extinct.  Beavers have also undergone local extinctions due to the influences of man for instance in the UK and parts of America they were hunted for their pelts which were considered valuable. However reintroduction programs are being considered within Scotland for the Eurasian beaver and trial programs have been underway since 2009 which was more than 400 years since beavers were last seen in Scotland. These trials were closely monitored to see the effects of the reintroduction (the 2015 report can be seen below) and a decision is yet to be made as to whether beavers should be reintroduced into Scotland. What do you think should happen?

Thanks for reading!

Check out this link

http://www.snh.gov.uk/protecting-scotlands-nature/beavers/beaver-trial-monitoring-reports/

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