This expansion of rainforest has occurred over the last three millennia. Climate change could reverse this expansion of tropical rainforest. A drier climate could lead to an increase in fire frequency, allowing for an ecological shift of rainforest to dry forest. Should this happen there is a possibility some rainforest species could become extirpated from the region. The Huanchaca Plateau within the park is 600–900 m above sea level and is composed of pre-Cambrian sandstone and quartzite of the Brazilian Shield. There are patches of evergreen forest on the soils that are deep and nutrient rich in the Plateau. Deep fertile soils support forest, while heavily weathered sandstone rocks with a thin layer of soil sustain open savannah. The adjacent low land plain to the west is blanketed by Cenozoic alluvial sediments and dominated by wet rain forests which transition into dry forests at the southern border of the park. It is estimated that the park is home to approximately 4,000 species of vascular plants, including bromeliads, passion flowers, heliconias, aroids, and palms. Trees include the mahogany. The area encompasses five major ecosystems ranging from Amazonian rain forest, gallery forest and semi-deciduous tropical forest to flooded savanna and dry cerrado. So far, 2705 different species of plants have been identified. Because there is such a wide range of different habitats that exist in the park, this number is split into different sections of the park. 1500 of the 2705 plants exist in moist forest, 800 in cerrado, 700 in dry forest, 500 in savanna wetlands, and another 500 in aquatic and disturbed habitats, and rock outcrops. In addition to the 2705 plants that have already been identified, there are still 6000 being evaluated (RAP 1998). The most diverse family out of all the taxa in the national park is the family Leguminosae. This family occurs in all ecosystems and in virtually all life forms except as epiphytes. Certain families of species thrive in all the park's habitats, such as the "Rubiaceae", "Melastomataceae", "Bignoniaceae", and the "Apocynaceae". Other species do better in specific habitats such as the cerrado ("Gramineae, Cyperaceae, Labiatae, and Compositae") or in savanna wetlands ("Lythraceae, Stercurliaceae, Onagraceae, Eriocaulaceae, and Xyridaceae").