Victoria’s Secret model Miranda Kerr has gone nude for the first time in her career. The dimpled-cheeked model is baring all — chained to a tree — on the cover of Australian Rolling Stone Magazine, in the name of saving koala bears in the outback.

It’s all part of Miranda’s new gig as celebrity spokesmodel for the Australian Koala Foundation’s “No Tree, No Me” campaign.

“It’s a sad thing – there are only about 100,000 koalas left in Australia,” Miranda — who is reportedly engaged to boyfriend Orlando Bloom — says of the cuddly koalas plight.

“Something like 80 percent of the koalas’ habitat has been destroyed since Europeans arrived in Australia,” she explains. “I believe every effort we make now has a reaction – if we’re making positive changes, if we’re all doing the simple, small things we can do to help the environment, it makes a big difference.”

“The great thing about having people recognize you is you can try to make a positive difference – that’s what I’m trying to do, especially for young women.”