Well after colors of the wind when he learns how important nature is.

None of them? I have no clue.

or Phillip :)

Im sure he cares for it more after being with Pocahontas.

none of them care about the environment the only prince i saw that does is sora(kingdom hearts) even though he is not a prince he kind of is because he and Kiari practically are married

I don't think John Smith cares the most, though he certainly does care, at least after Colours of the Wind. But I don't think you can abandon years of a single way of thinking, and he thought that nature was his to conquer before meeting Pocahontas. And where did Prince Ferdinard caring about Nature come from? That's funny in a way.
But I think Eric would care about nature, at least the nature of the sea, beaches, you get my drift. Because he is a sailor and he seems passionate about sailing and the sea. I think he'd care if the beaches or ocean was ever majorly threatened. Plus, Ariel would only strengthen his love of the sea in my opinion, so I think he'd certainly care, at least in a certain area of nature.

Prince Phillip is the only one who hangs out in the wilderness. He even apparently likes to bathe out in nature.

Prince Phillip,or Eric, but if your an animal at some point then you would certainly know more about nature than a human. Naveen had the actual experience. He even got married in a bayou!!!!

@hajirah4: That's an interesting point I hadn't really thought about...

...but I guess I would ultimately disagree. Naveen was forced into his animal situation, and I don't really think he made any connection beyond the ones he had for Ray and Louis. Ray had his head in the stars, while Louis dreamt of life in the human world.

Phillip and Eric hung out in nature for fun, although in Eric's case it was on a fishing boat.

wtf, this is stupid

He always had some appreciation of the beauty of the land, although he originally believed that it was there for humans to make the most of. But after he met Pocahontas, I think he became more aware and appreciating of nature than any of the other princes. My second choice would be Eric.

I agree ^
I can't see anyone else being sensitive for the enviroemnt.
what makes you think that Eric or anyone else would be?

@milky-way: John Smith was explicitly anti-environmental before he was influenced by Pocahontas.

John Smith sings about his desire to conquer new lands, and he tells Pocahontas that they're going to turn Virginia's land into big cities like back home. When she protests, he says that it's only because she's an ignorant savage who doesn't know any better.

In other words, he's the complete opposite of "environmental". Not only does he not have an appreciation for nature, he considers replacing it with pollution filled industrial cities (like London of the time) to be an improvement. Furthermore, he has no respect whatsoever for those who disagree.