JuicieJ
SHOW ME YA MOVES!
I see no reason the TP forest temple is the OoT forest temple. They don't look at all the same, the location doesn't look at all the same (aside from being in a forest, which is not much), and I can't think of any other clues that suggested it might be the same (if there are, please don't hold out).
Well, there are no real similarities, but just look at all the other references to Ocarina of Time. We've got Death Mountain & the Hero's Bow, the Sacred Grove (Temple of Time), (most likely) the Hero's Shade, the clothing Link wears, which belonged to the Hero before him... The list goes on, but there are many parallels between them. That being so, naming the dungeon the Forest Temple seems like a clear indication that it was supposed to be the same one. And, for all we know, it could have just fallen apart over time, just like the Temple of Time (although that one is hinted at by Aonuma to have been Ganondorf). Anyway, Occam's Razor would point toward it being the same Forest Temple as that of OoT. But, even if that's not the case, there's no way it's the Great Deku Tree, as, again, a sprout would have taken its place right in front of it, and the other would have decayed (again, with the new one in front of it.)