If define biodiversity just by sheer number of sp, yes.

That's why biodiversity has so many definitions and the one used here is the most basic one which can lead to bad conclusions. I recall a study in an area affected by deforestation where plant "biodiversity" actually increased—but this was a natural, expected effect, driven by colonizing species that require more light to germinate from their seeds. The stable equilibrium one would expect, however, involves lower biodiversity.