A serene settlement native to Pokemon White that's home to many rare Pokemon from beyond Unova.
In a direct parallel to Black City, White Forest is an exclusive area to Pokemon White . Like Black City, the number of residents--and thus features--depends on the player's actions.
More precisely, the number of residents varies according to the frequency of your visits to White Forest and your interaction with the residents. Then, depending on the number of residents, the landscape of White Forest will change to match.
Whereas Black City offered exciting Pokemon battles, the purpose of White Forest is catching Pokemon from previous Pokemon titles. The type of Pokemon you find is tied to the presence of certain residents. If you speak to certain residents, they will tell you what Pokemon can be found in the grass or water.
In a similar manner to Black City, if you don't visit White Forest regularly or don't speak to the residents enough, they may scarper for greener pastures. Or if you took your good time getting to White Forest, you may find a barren forest when you get there...
To fix this problem, you will need to seek a Pokemon Black player and use Entralink to access their Black City . Once there, you can invite residents (or a copy of them, rather) to your White Forest.