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Mata Atlântica: CPD Site SA14
CABO FRIO REGION
The Cabo Frio region is in the State of Rio de Janeiro, c. 120 km directly east of the city of Rio de Janeiro. This cape region covers c. 1500 km² from sea-level up to c. 500 m, with less than 10% above 100 m. The region is bordered on the east and south by the Atlantic Ocean, on the west by the local Serra do Mato Grosso, and on the north by the upper limits of the watershed of the Araruama Lagoon and the lower reaches of the Una and São João rivers.
Three distinct physiographic units are in this region (Map 50): (1) sandy coastal plains (beach ridges, dunes) and lowlands (tidal areas, lagoons, alluvial deposits); (2) low hills of the Búzios and Cabo Frio peninsulas and coastal islands; and (3) inland hills to c. 500 m.
The regional geology consists of a Precambrian crystalline basement of granitic-gneiss rocks, with local alkaline intrusions. The evolution of the coastal plain has been greatly affected by relative sea-level changes. The outer dune system was formed some 2000 years ago under colder and drier conditions (FEEMA 1988).
Inland and coastal climatic types prevail within the region (Barbiére 1984). From Cabo Frio Island northward to the Búzios Peninsula, the climate is greatly influenced by cold oceanic upwelling from the Falkland Current off the coast (Martin, Flexor and Valentin 1989), which causes reduced precipitation and moderated temperatures. The mean annual rainfall is c. 800 mm and the mean annual temperature 25°C, with minimum 12°C and maximum 36°C. The soil's water balance is in deficit throughout the year, in marked contrast to most of south-eastern coastal Brazil. However, relative humidity averages over 80% due to the moisture-laden winds from the ocean.
The vegetation varies according to its physiographic location and distance from the ocean (Ule 1901; Lacerda, Araújo and Maciel 1993).
The sea-land interface, which occupies a very small portion of the region, is covered by floristically poor low mangrove forests (Avicennia, Rhizophora, Laguncularia) and saltwater marshes (Salicornia, Sesuvium, Triglochin). Strand vegetation has many species common along tropical coasts.
Low areas between the beach ridges and dune slacks support characteristic marshy vegetation. Beach ridges are occupied by diverse vegetation types that vary from sparse open communities to dense evergreen forest. The remnant forest (15-20 m high) contains at least 110 tree species, according to a preliminary survey of c. 4 ha (Sá et al. 1992), and is dominated by Leguminosae (Pterocarpus rohrii, Pseudopiptadenia contorta, Albizia polycephala) and Myrtaceae (Eugenia, Myrciaria, Marlierea). Most of the sandy coastal plain is covered by open scrub vegetation probably caused by human activities; the Leguminosae and Myrtaceae are still prominent, together with Bromeliaceae and Euphorbiaceae.
The low xeromorphic forest on hillsides facing the ocean from Cabo Frio Island to the Búzios Peninsula is unique along this east coast. Columnar cacti give a characteristic appearance to the low thickets. Many endemic species occur. Present climatic conditions may have maintained this enclave as a holdover from vegetation that existed during the drier and colder glacial periods of the Pleistocene (Ab'Sáber 1974).
Farther from the ocean, the low mountains (to c. 500 m) support forests similar to the Atlantic Coast rain forest, but with fewer epiphytes. Little is known on the floristic composition of these forests, but many Atlantic forest and coastal plain species occur.
The flora of the region is poorly known, except on the sandy coastal plains ("restingas"). Of the 740 species listed for the region, c. 80% are from the coastal plain (Araújo and Henriques 1984). The total number of species will most certainly reach 1500-2200 when complete inventories are made.
Based on a comparison with other areas of restinga from the Rio de Janeiro coast, Cabo Frio is much richer in species, having 57% of the species represented in 12% of the total area. The Cabo Frio region also contains the most endemic coastal plain species: 26 of the 36 endemics listed for the restingas of Rio de Janeiro (Lacerda, Araújo and Maciel 1993). Eleven endemic species have been identified from the hillside thickets. Endemic trees of the region include Chrysophyllum januariensis, Duguetia rhizantha, Erythroxylum glazioui, Marlierea schottii, Rollinia parviflora and Swartzia glazioviana. Several disjunct species have their southern limit in the Cabo Frio region, e.g. Bonnetia stricta, Connarus ovatifolius, Cathedra bahiensis and Stephanopodium blanchetianum.
Individual trees of the now rare Brazil-wood (Caesalpinia echinata) are found in the Cabo Frio region. Once an important dyewood and still used for violin bows, this species was intimately connected with the history and colonization of Brazil (Cunha and Lima 1992). Local fishermen use many plants, not only in their work but also as a source of medicinals.
Social and environmental values
The restinga vegetation of the Cabo Frio region is very important for three restricted-range bird species (Stattersfield et al., 1997), which are threatened by the continuing destruction of this habitat. They are the golden-tailed parrotlet (Touit surda), restinga antwren (Formicivora littoralis) and black-backed tanager (Tangara peruviana). The antwren has a particularly small range, being endemic to the restinga of the State of Rio de Janeiro, so the Cabo Frio region comprises much of its range.
The dune vegetation is of great importance for maintaining environmental stability. The local climatic conditions promote formation of active dune systems, which in areas where the vegetation has been destroyed block roads and invade buildings.
The scenic beauty of the region combining white sands, verdant vegetation and the azure blue waters of the ocean has long been an attraction for tourism.
There are many archaeological sites in the region that contain important remains, both prehistoric (Kneip and Pallestrini 1984; Schmitz 1990) and historic (Cunha and Lima 1992). The region is also an important locale for the study of global climate change (Martin and Suguio 1989).
Cattle-raising and agriculture (e.g. growing sugarcane) are carried out in the Cabo Frio region. The ecosystems are seriously threatened by expanding land-development and increasing pressure from tourism. Lack of regional planning strategy and environmental controls allows occupation of the sandy coastal plains by housing projects (for vacation homes) with inadequate infrastructure and by sanitary landfill operations. Salt- producing flats on the edge of the Araruama Lagoon, when abandoned, have been built up instead of being returned to the lagoon to improve the fishery. Remnants of the forest also are being cleared for summer homes for tourists. The lack of infrastructure and enforcement additionally threatens the few conservation units.
There are two ecological reserves in the Cabo Frio region, the Reserva Ecológica de Jacarepiá (12.5 km²) and the Reserva Ecológica de Massambaba (13.7 km²), and two environmental protection zones, the Area de Proteção Ambiental de Massambaba (111 km²) which includes the two ecological reserves and the APA de Sapiatiba (60 km²). The dunes are protected by decree from the Fundação Estadual de Engenharia do Meio Ambiente (FEEMA). However, these units are administered by the State of Rio de Janeiro with very limited funds. As a result, the boundaries have not been fenced, there are no rangers in the units and no local headquarters, etc.
Some hope for preservation of natural wealth of the Cabo Frio region lies in assistance from the locally active non- governmental organizations, whose members are attentive to infractions of the law and notify the appropriate State authorities.
Map 50. Cabo Frio Region, South-eastern Brazil (CPD Site SA14)
Ab'Sáber, A.N. (1974). O domínio morfoclimático semi-árido das caatingas brasileiras. Geomorfologia (São Paulo) 43: 1-39.
Araújo, D.S. Dunn de and Henriques, R.P.B. (1984). Análise florística das restingas do estado do Rio de Janeiro. In Lacerda, L.D. de, Araújo, D.S. Dunn de, Cerqueira, R. and Turcq, B. (eds), Restingas: origem, estrutura, processos. Centro Educacional Universidade Federal Fluminense (CEUFF), Niterói. Pp. 159-193.
Barbiére, E.B. (1984). Cabo Frio e Iguaba Grande, dois microclimas distintos a um curto intervalo espacial. In Lacerda, L.D. de, Araújo, D.S. Dunn de, Cerqueira, R. and Turcq, B. (eds), Restingas: origem, estrutura, processos. CEUFF, Niterói. Pp. 3-13.
Cunha, M.W. da and Lima, H.C. de (1992). Travels to the land of Brazilwood. Ag. Bras. Cultura, Rio de Janeiro. 64 pp.
FEEMA (1988). A importância da biota de Cabo Frio. Fundação Estadual de Engenharia do Meio Ambiente (FEEMA), Rio de Janeiro. 50 pp.
Kneip, L.M. and Pallestrini, L. (1984). Restingas do estado do Rio de Janeiro (Niterói a Cabo Frio): 8 mil anos de ocupação humana. In Lacerda, L.D. de, Araújo, D.S. Dunn de, Cerqueira, R. and Turcq, B. (eds), Restingas: origem, estrutura, processos. CEUFF, Niterói. Pp. 139-146.
Lacerda, L.D. de, Araújo, D.S. Dunn de and Maciel, N.C. (1993). Dry coastal ecosystems of the tropical Brazilian coast. In van der Maarel, E. (ed.), Dry coastal ecosystems: Africa, America, Asia and Oceania. Ecosystems of the World 2B. Elsevier, Amsterdam. Pp. 477-493.
Martin, L. and Suguio, K. (1989). Excursion route along the Brazilian coast between Santos (State of São Paulo) and Campos (north of State of Rio de Janeiro). International Symposium on Global Changes in South America during the Quaternary. Special Publ. No. 2. Associação Brasileira de Estudos do Quaternário, São Paulo. Pp. 1-136.
Martin, L., Flexor, J.-M. and Valentin, J.L. (1989). The influence of the "El Niño" phenomenon on the enhancement or annihilation of Cabo Frio upwelling on the Brazilian coast of the State of Rio de Janeiro. International Symposium on Global Changes in South America during the Quaternary. Special Publ. No. 1. Associação Brasileira de Estudos do Quaternário, São Paulo. Pp. 225-227.
Sá, C.F.C., Araújo, D.S. Dunn de, Cavalcanti, M.J., Alves, T.F., Alvarez-Pereira, M.C., Lima, H.C. de and Fonseca, V.S. (1992). Estrutura da floresta de cordão arenoso da Reserva Ecológica Estadual de Jacarepiá, Saquarema, RJ. Resumos do XLIII Congresso Nacional de Botânica da Sociedade Botânica do Brasil, Aracajú, SE.
Schmitz, P.I. (1990). Caçadores e colectores antigos da região do cerrado. In Novaes Pinto, M. (ed.), Cerrado: caracterização, ocupação e perspectivas. Editora Universidade de Brasília, Brasília. Pp. 101-146.
Stattersfield, A.J., Crosby, M.J., Long, A.J. and Wege, D.C. (1997). Endemic Bird Areas of the World: priorities for biodiversity conservation. BirdLife Conservation Series. BirdLife International, Cambridge, U.K. 860 pp.
Ule, E. (1901). Die Vegetation von Cabo Frio an der Küste von Brasilien. Bot. Jahrb. Syst. 28: 511-528.
This Data Sheet was written by Dra. Dorothy
Sue Dunn de Araújo (FEEMA, Serviço de Ecologia Aplicada, Estr. da Vista Chinesa 741,
20531-410 Rio de Janeiro, RJ, Brazil).
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