Epífitas vasculares: relações com forófitos e a influência dos atributos físicos da casca das árvores nos padrões de riqueza e abundância em florestas de igapó da Amazônia Central

Abstract

Understanding the relationships between epiphytes and their arboreal supports (phorophytes) is fundamental for designing conservation strategies that allow a broader look at the forest structure. We studied the vascular epiphyte community and epiphytephorophyte relationships in six igapó forests in central Amazon, where 54 plots of 25 x 25m were inventoried in an extension of approximately 517 km along the Negro River basin. All trees with DBH ≥ 10 cm within the plots were sampled and identified, and all vascular epiphytes present were registered and identified. In addition, two bark samples (approx. 5x6 cm) were collected from the most representative tree species in the environments for the measurement of physical attributes. We specifically tried to answer the following questions: 1) How many and which tree species are phorophytes in igapó forests and which concentrate greater richness and abundance of epiphytes? 2) Do the richness and abundance of trees influence the richness and abundance of vascular epiphytes? 3) Is the size of the phorophytes related to the richness and abundance of vascular epiphytes? 4) Do the physical attributes of tree bark influence the occurrence, richness, and abundance of epiphytes? Our results evidenced 969 individuals, 29 families and 186 phorophytic species that hosted 4,692 individuals, 17 families and 106 epiphytic species. The tree species Pouteria elegans (A.DC.) Baehni and Duroia velutina Hook.f. ex K.Schum were the most representative phorophyte and the species that showed high epiphyte richness and abundance were Aldina latifolia Spruce ex Beth. and Eschweilera ovalifolia (DC.) Nied. Orchidaceae presented the highest number of epiphyte species and individuals and Codonanthopsis crassifolia (H. Focke) Chautems & Mat. Perret colonized the largest number of phorophytes. We also found that epiphyte richness and abundance correlated positively with increasing numbers of tree species, and the mean values of bark physical attributes (thicknesses, weights, water-holding capacity, moisture content, water loss) measured were significantly higher on trees that had epiphytes compared to trees that did not have epiphytes. In addition, richness (r2m= 0.32; r2c=0.41) and abundance (r2m = 0.36; r2c=0.90) were strongly influenced by forophyte diameter and saturated bark weight of the forophytes. The results obtained in this study provide new information and contribute to understanding of the factors that drive vascular epiphyte diversity, distribution and interactions in igapó forests of Central Amazon