Habitat utilization and CAM occurrence among epiphytic bromeliads in a dry forest from southeastern Brazil

Abstract

-(Habitat utilization and CAM occurrence among epiphytic bromeliads in a dry forest from southeastern Brazil). We studied the community and habitat occupation of epiphytes to understand how these plants cope with a supposedly stressful habitat: i) how general epiphytes occupy tree trunks, ii) how epiphytic bromeliads, occupy their supportive trees, iii) how CAM bromeliads are spatially distributed. The study was done in the dry forest of Jacarepiá, State of Rio de Janeiro. Data collection on epiphytes, phorophytes, and trees was based on the point-center quarter method. The photosynthetic pathway of the bromeliad species was determined using isotope ratio mass spectrometry. The presence of Gesneriaceae, Araceae, and Cactaceae indicates that some humidity is present in the area allowing the presence of supposedly less-specialized epiphytes. There was no correlation between epiphyte abundance and phorophyte diameter, and phorophytes had larger sizes than trees that do not host epiphytes. There was correlation between tree diameter and bromeliad abundance, and lack of correlation between diameter and bromeliad richness. Only one species was typical of the understorey and one was typical of the canopy, while intermediate heights were occupied by different species. The only C 3 bromeliad species (Vriesea procera (Mart. ex Schult.f.) Wittm.) was signifi cantly more exposed than the other species. If CAM occurrence is related to water economy, the fact that a C 3 species is subjected to more exposed conditions is remarkable. Further comments are presented on the proportion between CAM bromeliad species and abundance in dry forest. Regarding life forms, holoepiphytes, as opposed to hemiepiphytes, showed not to be restricted by the phorophyte's diameter suggesting a more successful establishment of this life form.Key words -Atlantic rainforest, Bromeliaceae, canopy, restinga vegetation RESUMO -(Utilização de hábitat e ocorrência do metabolismo CAM entre bromélias epífi tas em uma fl oresta seca do sudeste do Brasil). Investigamos a comunidade e a ocupação de epífi tas da fl oresta seca de Jacarepiá, Rio de Janeiro para entender: i) como epífi tas em geral ocupam troncos das árvores; ii) como bromélias epífi tas ocupam árvores suporte; iii) distribuição espacial de bromélias CAM. A coleta de dados sobre epífi tas, forófi tos e árvores foi baseada no método ponto quadrante central. A via fotossintética das bromélias epífi tas foi determinada por espectrometria de massa. A presença de Gesneriaceae, Araceae e Cactaceae indicam umidade sufi ciente para permitir a presença de epífi tas supostamente menos especializadas. Não houve correlação entre abundância de epífi tas e diâmetro dos forófi tos, e forófi tos possuíram maior tamanho que árvores sem epífi tas. Houve correlação entre diâmetro das árvores e abundância de bromélias e falta de correlação entre diâmetro e riqueza de bromélias. Somente uma espécie foi típica da submata e outra do dossel. Estes resultados diferem do padrão de ocupação de microsítios por epífi...

Variation in nitrogen use strategies and photosynthetic pathways among vascular epiphytes in the Brazilian Central Amazon

“…the epiphytic habitat is generally the driest niche within tropical forests and many species use the photosynthetic water-conserving caM-pathway, including epiphytes from Bromeliaceae, cactaceae and orchidaceae , 1989, Fontoura & Reinert 2009). Moreover, morphological adaptations (water-storing phytotelmata, succulence, xeromorphic leaves, poikilohydry, deciduousness, and general reduction of the shoot) also allow many c 3 -species to live under these extreme conditions (Benzing 1990, Hietz et al 1999.…”

Leaf structure of Tillandsia species (Tillandsioideae: Bromeliaceae) by light microscopy and scanning electron microscopy

“…This characteristic is also present in the subgenera Diaphoranthema and Phytarrhiza (Tables 2 and 3). The presence of amphistomatic leaves indicates adaptations to the dry environment, as the higher density of stomata in the leaves favors CAM photosynthesis inside these species (Benzing, 2000;Fontoura & Reinert, 2009). Fahn and Cutler (1992) surface of the leaves by SEM (Figures 2c and 8a,b).…”

“…The trichomes also perform the luminous intensity regulation and, consequently, of the internal temperature of the tissues, favoring photosynthetic processes (Scatena & Segecin, 2005). These characteristics favor CAM photosynthesis because the trichomes can function as a physical barrier for stomata protection (Benzing, 2000;Fontoura & Reinert, 2009;Scatena & Segecin, 2005). Other functions are attributed to the trichomes, such as protection from predators and the attraction of pollinators by forming dense indument, reflecting light, and secreting digestive enzymes (Benzing, 1976(Benzing, , 2000.…”

The Reserva de la Biosfera Barranca de Metztitlán (Hidalgo): An illustrated checklist of bromeliads and orchids and their high levels of Mexican endemisms

“…Some species of bromeliads and orchids grow in drier habitats (Gentry and Dodson 1987) which is related to CAM metabolism and economy of water (Benzing 1990, Fontoura and Reiniert 2009). For example, T.mauryana and T.ionantha grow in xerophytic areas and are adapted to water stress conditions (Benzing 2000).…”