Dyir
First Post
How does that preclude the creature from benefiting from its construct abilities? It gets to keep anything not expressly removed by the change.
Look, take a half-dragon/human for example. As soon as you place the half-dragon template on the human, you change it to a [Dragon] type. Does it lose it's human benefits or abilities? No. It still gets the extra feat and the extra skill points.
How does that preclude the creature from benefiting from its construct abilities? It gets to keep anything not expressly removed by the change.
Technically, the example abilities that you mention are "racial traits" and not "type traits." Therefore the half-dragon/human has the Dragon type but all of the racial abilities of both human and half-dragon (since the template doesn't remove the human racial traits).
A better example would be a draco-lich. I don't have my books with me, but I assume that a dragon that becomes such a creature has its type changed to "undead." I believe that it probably looses all of the "Dragon type" traits and gains all of the "Undead type" traits. However, it retains all of the racial traits it had while alive except those that the template specifically takes away.
By the rules a creature can have only one type, but I've only seen in one place where a creature with one type has abilities from a different type: the Abominations in the Epic-Level Handbook. I suppose it makes sense for an animated tree to follow suit and have traits from both types, but it would be the other other example I could think of.