User blog comment:Plexioth- xD/Monster Hunter 3 Ultimate/@comment-4800630-20120320175954/@comment-1006487-20120321175254

The game itself actually talks about it as element. Since the Status Up skill also doesn't influence it, I would count it as element. I don't know if Element Up increases the slime activation rate, but it is just a very uncommon skill so it wouldn't even be used as that I guess.