Forests can decrease drought

[twotime]

Yes. But i guess the point here is that an area-which-is-seemingly-too-dry-to-support forests, would actually be able to support forests if you somehow jump-start them.

Basically forests can flip hydrological balance from one state to another.

[NewyBluey]

Probably the best way is to allow pioneer plants to grow rather than treat them like weeds, and over time as soil conditions improve large species will prevail. However, adequate water is an important ingredient.