Coppice bowls need protecting, Deer are very fond of the new shoots that start to grow in the spring, it can take three times longer for the coppice to re-grow if these bowls are not protected. I like to make a stick ring from all the top branches and twigs, by the time they break down and rot they will have given the new shoots a long enough protection for them to survive the deer (hopefully!) Normally this "top" would be just burnt, so I believe that it makes a much better and more environmentally sound use.
Incidentally we also decided to leave one tree on each bowl, this will allow a light window for the new Ash saplings when it is cut down in few years time.