The shrub layer of a woodland contains mostly woody plants that grow from roughly knee to head height. This includes plants such as nettle, bramble and bracken.
The shrub layer can provide dense cover for larger animals such as deer to hide in and find safety.
In some woodlands the herb and shrub layers may be a lot less dense or almost absent. This can be a sign of overgrazing from too many deer or from the presence of grazing domestic farm animals.
However, in woods dominated by beech or conifer trees these plant layers are reduced as the leaves/ needles densely cover the ground preventing plants below from growing.