Lots of birch trees are the death of the moor?
Birch trees need somewhere with a lot of moisture. They extract water from the moor and quickly overgrow large areas. It takes lots of time and effort to maintain the expanses of the Great Moor and to keep them free of birch trees.
Grazing by moorland sheep (Fig. 2) hampers the growth of birch trees by the sheep eating the fresh birch leaves. However, the birch trees hit out again.
Fire clearance (Figs. 5 and 6) achieves the same purpose. The birch trees are weakened. They spout much less the following year.