Some centuries ago, the Cerrado type woodland occupied a continuous area on the Central Plateau, from where it extended in the form of peninsulas or isolated outcrops – some of them still persist. This is the case of the enclaves found in the Atlantic Rain Forest and in the Paraíba Valley, between São Paulo and Rio de Janeiro. Like other São Paulo woodland stands of Cerrado, those of the valley are strongly threatened, even in state-owned areas, according to a survey carried out by Giselda Durigan and Geraldo Franco, of the Forestry Institute of São Paulo, and Marinez Ferreira de Siqueira, from the Reference Center for Environmental Information (Cria), of Campinas.
They tracked across five areas of Cerrado in the municipalities of São José dos Campos, Caçapava and Taubaté, as part of a project of the Biota – FAPESP program, and carried out a diagnosis of eighty six small areas, on which predominates the rural form of this type of vegetation: spoiled land (campo sujo), fields, and cerradostricto sensu . They identified one hundred and twenty two species of which fifteen are typical of the local flora, such as Acosmium subelegans (perobinha-do-campo in Portuguese), Aegiphila lhotzkyana (tamanqueira in Portuguese), Byrsonima coccolobifolia (murici in Portuguese), Tabebuia ochracea (yellow tecoma), Cybistax antisyphilitica (green tecoma), Schefflera macrocarpa (mandiocão in Portuguese) and Erythroxylum suberosum (mercúrio-do-campo).
The flora of the Cerrado of the Paraíba Valley, in a general manner, is relatively poor, due to the expansion of the towns and to the highway network, atmospheric pollution or even to natural factors linked to isolation and the local environmental conditions. There is an average of sixty species in each woodland stand, but seventeen of them are not found in any other region of the state, such as the Alibertia elliptica, Tabernaemontana laeta, Leucochloron incuriale, Periandra mediterranea, Miconia ferruginata and Sorocea jureiana. Some of them are much more common in the state of Minas Gerais and others in areas of transition from the Atlantic Rain Forest to the Cerrado. Actually, the Cerrado of the valley is more similar to that of the state of Minas Gerais than to the west of the State of São Paulo.
Since these areas are distant from others that would allow for the entry of new species, the tendency is that the vegetation becomes poorer and poorer. However, for the researchers, the elevated number of unique occurrences and the peculiarity of the environmental conditions, turn these areas into high priorities for the conservation of the Cerrado in the state and for the understanding of the ecological processes that determine the existence of this type of vegetation.
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