ABSTRACT The microclimatic gradient established from the forest understory to the canopy provides a range of different conditions for the establishment of bryophytes along the height of a tree. We investigated epiphytic bryophyte communities of four fragments of Atlantic Forest with the aim of describing their vertical zonation and assessing differentiation among the communities of the different fragments. In each fragment, five host trees were selected from which bryophyte samples were collected in four height zones from the base to the canopy. Furthermore, 10 plots were demarcated in each fragment where bryophytes were collected from the understory. In total, 114 bryophyte species were found on the 20 sampled phorophytes, plus an additional 51 species in the understory, for a total of 165 species. Species composition of height zones differed significantly between communities of the trunk base and the canopy. The samples from the understory included 77% of all species. Among all species found, 10 showed a significant preference for a specific height. Around 70% of the bryophyte species grew as mats; this life form occurred in all trees and height zones. The results showed a weak, yet significant, vertical gradient, which differs from what is usually found in the Atlantic Forest.

Epiphytic bryophyte communities in terra firme forests of the Amazon region were investigated for the first time through standardized sampling across the Amazon basin. The sampling was carried out at nine localities, where bryophytes were collected in five height zones, from the forest floor to the canopy of eight canopy trees per locality. The sampling generated 3104 records, identifying 222 species and 39 morphospecies, within 29 families. The most common families were Lejeuneaceae (in 55%), Calymperaceae (in 8%), Leucobryaceae (in 4%) and Sematophyllaceae (in 4%). Richness and species composition did not show any geographical gradient. The bryoflora was significantly richer in the localities of Saül, in French Guiana, and Tiputini, in Ecuador, than in the other localities, probably due to differences in local climatic conditions. Among the 155 species recorded for more than one locality, 57 were classified as specialists. A total of 29 species (among which 3 were unidentified) were sampled only in the canopy, which reinforces the importance of canopy sampling for the study of epiphytic bryophytes in the Amazon.

A freqüência de reprodução sexuada através da produção de esporófito foi determinada para musgos acrocárpicos, coletados no Estado de Pernambuco e depositados no Herbário UFP. Cada exsicata foi observada ao estereomicroscópio para verificação da ocorrência e do estádio de desenvolvimento do esporófito. Às informações obtidas acrescentaram-se dados de coleta e outros específicos pesquisados em literatura. Examinaram-se 770 exsicatas, pertencentes a 11 famílias e 59 espécies. Destas, 26 são monóicas, 27 dióicas e as seis restantes têm sistema reprodutivo desconhecido. A ocorrência de esporófito por amostras foi de 3:1, de monóica em relação à dióica. Apresentaram esporófito 88% das espécies com maior riqueza de amostras, havendo tendência, entre as dióicas, de produção ocasional ou rara de esporófito. A análise do estádio de desenvolvimento dos esporófitos por ocasião da coleta demonstrou que a produção ocorre principalmente durante o período chuvoso. Confirma-se então a importância da umidade e da autofecundação na reprodução sexuada destes musgos.

The frequency of sexual reproduction in acrocarpous mosses collected in Pernambuco State, and subsequently deposited in the UFP Herbarium, was determined based on sporophyte production. Each voucher was observed under a dissecting microscope for recording the presence of the sporophyte and its developmental stage. The data obtained from literature was also registered. 770 voucher, distributed in 11 families and 59 species, were examined. 26 species have a monoecious reproductive system, 27 a dioicous one, and the six remaining ones have an unknown breeding system. The rate of fruiting specimens was higher in monoicous (3:1) than dioicous ones. Sporophytes were found in 88% of the best represented species. The frequency of fruiting specimens of dioicous species is either occasional or rare. The analysis of the developmental stages of sporophyte throughtout the year demonstrated that the production of sporophytes mainly occurs during the rainy season. Finally, humidity and self-fertilization play an important rule in the sexual reproduction of the acrocarpous mosses.