Llanos
People raised so many cows on the Llanos that the grasslands changed.  Human beings set fire to the grasslands to kill trees and shrubs and grow better grass for the cows.  Human beings brought new grasses from other parts of the Earth because they thought they would be better for the cows to eat.  For example, they brought the African grass Melinis minutiflora.  Now, large parts of the Llanos are govered in African grass.