Composição florística e distribuição de epífitas angiospermas na região do rio Urucu, Coari-AM

Abstract

In this study we conducted a floristic survey in 1,5 hectares of terra firme forests in the Municipality of Coari, Amazonas State, Brazil. The objective of this study was to characterize the composition and floristic diversity of epiphyte communities and their host plants, with the goal to determine the phytosociological associations among the species and verify the floristic similarity between the areas studied. In order to collect these date we sampled using plot methodology, where lowland, slope and upland environments where included in the analyses. All of the angiosperm epiphytes were inventoried from trees with DBH ≥ 10 cm. Three thousand five-hundred twenty eight individual epiphytes distributed in 13 families, 48 genera and 164 species were sampled during the course of the study. The epiphytes occurred on 727 individual phorophytes distributed in 40 families, 123 genera and 324 species. Monocots were the most well represented group (68,90%), and the hemiepiphytes represented the predominant life form (57,31%). Araceae was the family with the greatest epiphytic species richness, followed by Melastomataceae, Orchidaceae and Bromeliaceae. The families which represented the greatest abundance were Araceae, Bromeliaceae, and Cyclanthaceae. The genera representing the greatest diversity were Philodendron, Clusia, Heteropsis and Miconia. The epiphytic species with the greatest diversity are Guzmania lingulata (Bromeliaceae) and Philodendron linnaei (Araceae), representing together 53,20% of all individuals. The families of the phorophyte community which represented the greatest diversity include Fabaceae, Sapotaceae and Chrysobalanaceae, and the most abundant was Lecythidaceae. The phorophyte genera with the greatest richness were Pouteria, Licania and Eschweilera. The phorophyte species exhibiting the most abundance were Eschweilera wachenheimii (Lecythidaceae), Licania micrantha (Chrysobalanaceae) and Oenocarpus bataua (Arecaceae). One individual of Guarea convergens (Meliaceae) harbored the greatest number of epiphytic species and individuals, with a full- height of 36 m and diameter of 45,3 cm. The JAZ region represented the greatest richness (78,04%) and abundance of epiphytes (72,53%), as well as phorophytes (74,07% e 61,89% respectively). Among the three environments studied, the lowlands were the most favorable for the development of epiphytic communities, where 84,14% of the species and 48,24% of the individuals were present, as well registering the greatest richness and abundance of phorophytes (52,16% and 39,75% respectively). In the phytosociological analyses of the epiphyte communities as quantified by the Family Importance Value Index (FIV). Araceae highlighted in all of the community parameters. This was followed by Bromeliaceae, Cyclanthaceae and Orchidaceae. The phorophyte families which attained the greatest FIV were Sapotaceae, Lecythidaceae and Fabaceae. In the estimates of the Index of Species Importance (ISI), within the 15 species which present the greatest ISI, 11 belong to Araceae. The calculation of this index G. lingulata e P. linnaei were greater than the other species in all the parameters involved, that together 27,75% of the total. The Index of Species Importance (ISI) for phorophyte, highlighted E. wachenheimii, L. micrantha E. tessmanii. The greatest diversity estimated through Shannon s Index was registered in the lowland environments, where for epiphytes the index H = 3,40, and for the phorophytes was H = 4,47. The floristic similarity, estimated by the Morisita Coefficient, among the sampled areas was low for both the epiphytic and phorophytic communities. However, for the epiphyte communities the similarity was high among the upland and slope habitats, but low in comparison between the lowlands and all other habitats.