Ecological migration refers to migration in order to protect the special ecology or restore the ecology of a certain area.

[Resolution] The villagers' migration in item A is due to the fossilization of the land and the deterioration of the natural environment, which meets the definition. The migration of items B, C and D is not due to the harsh natural environment, nor for the purpose of ecological protection.

The key to this definition is the purpose of overall migration: to protect the special ecology of a certain area or restore the ecology of a certain area, or because of the harsh natural environment, there is no condition for poverty alleviation on the spot.