Looks like willow to me.
Is it good nebari though? I would say not, at the moment, as it is too early in this trees journey for the nebari to have developed. What you have is radial roots, the nebari will fill in as the tree develops and thickens.
Pruning these thick roots to about an inch from the trunk, and burying the trunk base an inch or more when re-potting will assist in the development of the nebari by causing new roots to form near the base of the trunk. Willows grow roots very easily, but protect the tree from wind and hot sun after such treatment when re-potting for about 4-6 weeks after buds shoot. Pruning branches back to one or two buds when re-potting will assist in the trees recovery.
These new roots will fuse over time with teh roots you have now and form your nebari.
If you leave the tree as it is now, the current roots will simply thicken and may not fuse nicely to form a good nebari, but one with large gaps.
Sorry, but I have no pictures of willow nebari, nor any other species, so that you may judge my experience and suitability in answering your question. You will simply have to take my advice with a pinch of salt.
Regards
Paul