There are a number of Ardens.

Arden proper, is the great forest of Amber.

"Deep Arden" is a very real an independent shadow of power some distance from Amber.

"Greater Arden" is both of them and several thousand shadows, or parts of shadows, between the two and spreading out from them.

Amber's Arden is a nearly idealized forest in an Arthurian or Ariostoesque sense.

Deep Arden is older, stronger and much weirder.

Unicorns and The Unicorn frequent the various aspects of Arden.

While most of the princes and princesses of Amber have some love for Arden, Julian loves it best and knows if far better than any of the others.

One of the distinctive species of Arden is the Erltiger. Erltigers are green where normal tigers are red or gold, they're stronger, have far greater stamina and are sapient and capable of speech. Successful ones might live a century or more. They don't have much in the way of organization, so treaties are impossible, but the erltigers near Amber have an understanding with Julian and his Rangers; they leave humans alone and the Rangers don't relentlessly hunt them down with stormhounds. Fractious erltigers are usually killed or beaten into wisdom by wiser ones.