In reply to:

I still hold, that european explorers defined areas a jungles, because they wanted to be able to claim them...and it would have been harder for them to justify their land grabs if they called them forests.

I don't think I've ever seen any references to the seemingly unending forests of pre-Euro confiscation of North America as jungle. I've never heard it refered to as anything but forests, yet that didn't stop the colonization and confiscation of these lands.