1 They are classified with flooded savannas as the flooded grasslands and savannas biome, which occurs mostly in the tropics and subtropics. 2  Montane savannas are high-altitude savannas, located in a few spots around the world's high mountain regions, part of the montane grasslands and shrublands biome. savanna or savannah is a grassland ecosystem characterised by the trees being sufficiently widely spaced so that the canopy does not close.