Florística e aspectos fitogeográficos dos "campos" do Parque Estadual do Jaraguá, São Paulo, Brasil

Abstract

The savannic and grassland formations in the Domain of the Atlantic Forest in the city of São Paulo are still poorly studied. The highest areas of the State Park of Jaraguá (PEJ), between 905 to 1125 m above sea level, harbor a grassland formation that is vulnerable to human disturbance. The first floristic inventory carried out in PEJ in 2009 registered 55 species of shrubs and trees occurring in campo formation (grassland). The recent rediscovery of a rare species, Baccharis trineura Soria & Zardini, in the open areas of PEJ stimulated this floristic study of the vascular plants found there. The floristic list was then compared to other inventories from mountaintop grasslands and cerrados nearby, all within the Atlantic Forest Domain. This study also aimed to investigate whether the PEJ campos have an anthropic or autochthonous origin. Fieldwork was carried out twice a month throughout a year, along the 37 hectares of enclaves of open formations found in PEJ. This inventory produced a list of 242 native species belonging to 50 vascular plant families; 112 species are cerrado species, while 34 are ruderal. These comparison of these data to the floristic lists of other cerrados from mountaintops nearby revealed that the PEJ enclaves share 51 species with the cerrados of State Park of Juquery, 20 with the campos of Núcleo Curucutu of the State Park of Serra do Mar, 28 with the cerrado from Estação Ecológica de Santa Bárbara, 16 with the cerrados from Reserva Biológica de Moji Guaçu and 11 with the cerrado of State Park of Furnas do Bom Jesus. The high number of native species compared to the low presence of ruderals and exotic elements, as well as the presence of vulnerable species, indicates an autochtonous origin for the campos at PEJ. The high number of typical species of the cerrado flora and the high similarity with other cerrado vegetations found nearby, as well as the expressive number of pyrophytes indicate that the PEJ campos probably constitute disjunct patches of cerrado, a fire-driven open vegetation. A brief discussion of a likely relictual nature of this grassland formation is presented.