A manipulated landscape is still a landscape... a manipulated portrait is still a portrait... a manipulated macro is still a macro, etc... but it would only be nice and fair to state that there were manipulations in the image (so that the viewers don't get mislead)...
Only when the manipulation becomes the actual main subject of the image, then I feel it could or should go into the Manipulation category.
Without getting into the discussion about what manipulation is... it's a thin line sometimes... ;o)

We do not see things as they are. ǝɹɐ ǝʍ sɐ sƃuıɥʇ ǝǝs ǝʍ