After the Amazon, the Cerrado is the largest biome in Brazil. These savannas are formed by a variety of habitats such as grasslands, wooded savannas, dry forests and gallery forests. In these habitats natural fires are a very important part of the system, creating conditions that result in the great variety of plants, birds and mammals. Despite the general dry appearance of the vegetation, the Cerrado areas are a very important water source for many of the rivers in Brazil, such as the ones that flow into the Pantanal. It once covered most of Central Brazil, but due to deforestation (mainly for cattle ranching and crops plantation) it now stands as one of the most threatened ecosystems in South America. Towards Northeast Brazil the Cerrado gives place to the Caatinga, a dryer habitat comprised mostly of stunted, thorny vegetation that also holds a big diversity of animals and plants, many of which endemic and threatened of extinction.