Bromeliaceae species from coastal restinga habitats, Brazilian states of Rio Janeiro, Santo, and Bahia.

: Bromeliaceae is one of the most representative plant families in restinga habitats. We analyzed the species richness and composition of Bromeliaceae in 13 restinga habitats along the Brazilian coast. We found a total of 41 species distributed along the restinga habitats studied. The restinga of Praia do Sul, in the state of Rio de Janeiro, had the highest number of species (15), whereas the restinga of Abaeté, in the state of Bahia, had the lowest (4). Our data are suggestive that the Doce River may represent the limit of distribution for some bromeliad species, with some species occurring only south of that river and others occurring only to the north of it. The differences in Bromeliaceae species composition among restinga habitats probably are not only due to differences in local environmental conditions, but also due to the geographic distribution pattern of each species and to the present degree of disturbance at each restinga .


Introduction
Restingas are considered to be marginal habitats of the Atlantic Rainforest Domain (Scarano 2000;Oliveira-Filho and Fontes 2000) and about 80 % of the Brazilian coast is covered by those habitats, which occur from the states of Pará to Rio Grande do Sul (Araújo 1992;Lacerda et al. 1984;1993;Cogliatti-Carvalho et al. 2001;Rocha et al. 2004b).
Restingas are coastal habitats characterized by relatively harsh environmental conditions (i.e. high temperatures and insolation, low water availability, high salinity), and by sandy soils covered with xerophyllous arbustive and herbaceous vegetation (Zaluar and Scarano 2000;Scarano 2002). Along the Brazilian coast the restinga habitats present differences in physiognomy, structure and floristic composition (Lacerda et al. 1984;Rocha and Bergallo 1997;Araújo 1992;. The Bromeliaceae is one of the most representative plant families of restinga habitats Freitas et al. 2000;Araújo 2000;Rocha et al. 2004a;b), where these plants have an important role in facilitating the establishment of other plant species (Zaluar and Scarano 2000) and in providing resources to various animal groups 2004a). As the species in the family Bromeliaceae respond differently to environmental variations (Benzing 1980), and since each restinga habitat presents different environmental conditions , we could expect that each restinga would have a distinct set of bromeliad species. In the present study we aimed to verify the bromeliad species composition of 13 different restinga habitats at three Brazilian states: Rio de Janeiro, Espírito Santo, and Bahia.

Material and methods
Study Site -From November 1999 to March 2000, we studied the bromeliad communities of 13 restinga habitats, along approximately 1,500 km of the Brazilian coast, in the states of Rio de Janeiro (Praia do Sul, Grumari, Barra de Maricá, Massambaba, Jurubatiba, and Grussaí), Espírito Santo (Praia das Neves, Setiba, and Guriri), and Bahia (Prado, Trancoso, Abaeté, and Baixio) (Table 1; Figure 1).  Data Collection -To analyze the bromeliad species composition at each restinga we sampled 100 plots, each measuring 100 m 2 (10 x 10 m), established at transects performed perpendicularly to the beach. Due to the different sizes of the restingas, the transects had different lengths, and were distant 50 m or more from one another, with the parcels being 10 m apart [for details of the method used see Cogliatti-Carvalho et al. (2000) and Freitas et al. (2000)]. We carefully checked the entire area inside each plot looking for bromeliads and all individuals found were identified and recorded. The specimens which were not identified in the field were photographed and collected, and the material was later sent to specialists for identification. Voucher material was housed at the Herbarium of the Museu Nacional do Rio de Janeiro (R).

Results and discussion
We found a total of 41 species of Bromeliaceae along the 13 restinga habitats studied ( Table 2). The restinga of Praia do Sul, in southern Rio de Janeiro, had the highest number of species (15), whereas the restinga of Abaeté, in Bahia, had the lowest (4 species) ( Table 2). According to Rocha et al. 2004b, the restinga of Praia do Sul presented the lowest habitat disturbance level whereas Abaeté had the highest one. The other restinga habitats that also had relatively high numbers of species (Setiba = 13, Grumari = 12, and Praia das Neves = 11 species) also had comparatively low habitat disturbance levels, which suggests that the degree of disturbance may negatively affects bromeliad richness in restingas (Rocha et al. 2004b). Bromelia antiacantha and Tillandsia stricta were the commonest species, occurring in eleven and in eight localities, respectively, while 21 species occurred at only one restinga habitat.
The species composition varied among localities and the differences tend to increase with the distance among areas. Our data are suggestive that the Doce River, which has been recognized as a geographic barrier for some animal groups (Rocha 2000), may represent the limit of distribution for some bromeliads. We conclude that, as expected, the restingas studied differ in the bromeliad species composition and that such differences are probably due not only to differences in local environmental conditions, but also to the geographic distribution pattern of each species and to the present degree of disturbance at each restinga.