Sorry to say that, but that doesn't look like alder to me at all. Way too much colour, and I have yet to see alder with rippling or curling. The alder that I have (and I know it's alder, because I took it straight from the site where the tree was felled) is very bland, almost white, and has very little colour in it (apart from some bluish streaks).
I like the bowls, though. Very nice! This one looks like you did some off-centre turning with it?