During weekend repotting session I was working with this ash. As vigorous as it is, it could have stayed in pot for at least one season. Even if after taking out from pot it is clearly visible pot was fully packed with fine fiber roots ( just remainder it is sitting in anorganic mix of Zeoilte and Teramol since it was collected, if there are people out there not believing in using modern substrates. I hope we do not have to prove it works fantastic anymore tough). Reason I was taking it out was removal of larger roots. This tree was potted initially into plastic bowl after collecting. Than it was repotted several years ago into this chinese pot. Being careful I was removing minimum amount of roots when fitting it into this pot. This obviously led to larger roots reaching very edge of the pot. Larger roots are problematic from several reasons. One is obviously aesthetical, it is generally better from design point of view, to have several smaller roots than one fat big root. Second reason is related to size of the pot, and effective volume of the roots. In small pot if you substitute one bigger roots by cutting it by mass of fiber roots it is much better for the tree.
So, if you look on initial picture you see one of those large roots ending just on periphery of the pot. This root was shortened significantly, as was two others on other side of the root ball. Edges of the roots were covered with moss to keep them wet, this will hopefully help in development of the new fiber roots at cuts.
Now tree is sitting in same pot, new one for this tree is in production phase already. Since removed roots was forcing tree into certain position, now it was possible to rotate the tree to achieve better front. Top of the crown will be edited, when tree start to show its vigor after few weeks from now.