wehn you cut that "ash" into staves
since your unsure exactly what it is
it might be best to leave the staves a bit larger
that way you will have enough wifth in the stave to make sure you can over build or even under build a couple
to see what the wood can handle
it would be a shame to make a bunch of small sized staves and then find out you needed a more for it to handle a hunting weight bow
just a little foor for thought