This is a wild cherry, Prunus mahaleb, which was collected in Germany (yes indeed they grow wild in Germany now!).The first two images are as of April 2009. Now it looked like the tree has already grown strong new roots. so I dared to style the crown already. It looks quite pathetic and hopeless at the moment. In five to ten years this will be an impressive cherry tree. It will never look like a bonsai, but like a very old tree it will look.