Is a pampa an example of ecological succession?

I’m not very sure if a pampa is an example of an ecological succession.

The reason of my doubt is due I’ve remember hearing that a Pampa is formed when a Valley which has had a river on it, no longer has it due the river changed its course and left the place without water.

But is it okay for this reason to imply that the Pampa (biome) is the result of an ecological succession?. The wikipedia entry doesn’t give much details.

But it constrains the term for only the lands located in Brazil and Uruguay. It does not give any indication why some other places such as in Bolivia and Peru also use the term. Given these, could it be confused with a Mediterranean forest or with a Chaparral?.

Are those of the same origin?. Can someone help me here?. I’m confused about these.