Saturday, 22 August 2009

Sedge Rafts and Scent Mounds

This is a photograph, taken last summer, of a beaver swimming in the Big Pond at Bamff. Behind it is a raft of sedge (mainly). Sometimes the beavers swim under the sedge and make themselves a hole in the middle, rather as seals make breathing holes for themselves in the Arctic ice, and spend time grazing the vegetation there.

Usually people think of beavers as having an effect on the composition of woodland by turning the broadleaved trees that can tolerate coppicing into shrubs and leaving the conifers, which will shade out the broadleaves eventually.

This may be true sometimes, but when conifers cast a dense shade near the water's edge beavers may well bark the trees, or at any rate some of them and the barked trees will die eventually. This will allow light demanding trees to flourish

The other thing that is important, particularly where a coniferous woodland borders on a stream inhabited by beavers, is that the building of dams will raise the water table of the nearby ground and this may drown the root systems of the conifers. Once again willows and other species of tree that tolerate wet ground will survive.

The next photograph shows a scent mound at a feeding station. A few days ago I posted a photograph of a small heap of vegetation and wrote that I thought it was a scent mound, but that I hadn't taken the trouble to get down on my knees and smell it. Well, I did just that in this case because there was an old plastic tree tube to hand on which to kneel. I did so and was rewarded with the strong musky, sweet smell of beaver.

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