flora is divided into three regions: Amazon rainforest (Floresta tropical amazônica): composed of dense and humid forest typical of the lower Branco River, extending through the southwest region. General fields of the Branco River (Campos Gerais do Rio Branco): with approximately , also known as the lavrado region. Lavrado is also known as savannah. Formed by grass-plot, but along the watercourses, called igarapés, there are large palm trees known as buritizeiros. In the lavrado there are also, in great quantity, bushes, paricaranas and muricizeiros. Mountainous region (Região Serrana): with typical mountainous vegetation, thinner trees and valleys rich in humus with good-quality grass for livestock. In any of the regions, there are three different types of vegetation cover taking into account the river banks. These are: Mainland forests (Matas de terra firme): comprising forests located in lands never affected by river floods. Floodplain forests (Matas de várzeas): these are the forests that cover the lands affected by the floods of rivers. Riparian forests (Matas ciliares): these are preserved by law and are also flooded every year by river floods. Demography According to the population estimate of 2020 carried out by the Brazilian Institute of Geography and Statistics (IBGE), Roraima had a population of 631,181 inhabitants, which makes the state the least populous federative unit in Brazil. The capital, Boa Vista, concentrates 66.4% of the state's population. The population of Roraima has almost doubled in twenty years. In 1991, the state had only 217,583 inhabitants, a significant increase of 95.51% in population growth. The municipalities that showed the highest population growth were Boa Vista, the capital, and Rorainópolis. As for the annual population growth in Roraima, the state ranks among the fastest-growing in Brazil, with a rate of 4.6%, much higher than the national average of 1.6% growth. In this regard, it is second only to Amapá, which registers more than 5% annual growth. However, this high population growth has been declining in recent years. An example of this is the rate presented in 2000 when Roraima showed 49.09% of population growth with 1991. In the last census, in 2010, that number dropped to 31.13%. Of the total population of the state in 2010, 229,343 inhabitants are men and 221,884 inhabitants are women. In recent years, the growth of the urban population has intensified significantly, exceeding the total rural population. According to the 2000 estimate, 80.3% of the inhabitants lived in cities.