Distribución de epífitas vasculares sobre cuatro especies arbóreas en un bosque xerofítico del Chaco Húmedo, Argentina.

In numerous forests, the vascular epiphytes contribute substantially to species diversity. Studies about vascular epiphytes in the Wet Chaco region are very scarce. We carried out a description of the epiphyte community in four deciduous tree species, representative of a quebrachal of the Cuña Boscosa Santafesina: two of them from the upper stratum (Schinopsis balansae and Sideroxylon obtusifolium) and two from the lower one (Acacia praecox and Prosopis spp.). Eight individuals of each tree species were selected, and each individual was divided in four zones (Zone I-II: main trunk; Zone III: basal branches; Zone IV: middle branches; Zone V: thinnest branches). For each zone, all the vascular epiphytes were counted and identified at species level. In Zone V, living and dead branches were differentiated. Data were analyzed with general linear mixed models and multivariate analysis. Fourteen species of vascular epiphytes were recorded (nine holoepiphytes, two facultative and three accidental epiphytic species) of four families (Bromeliaceae, Cactaceae, Polypodiaceae and Anacardiaceae). The richest family was Bromeliaceae, with seven species of the genus Tillandsia and Aechmea distichantha. The most abundant species was Tillandsia recurvata. Prosopis spp. had the highest abundance of epiphytes and S. obtusifolium the highest richness. Zone V had the highest average abundance and richness of vascular epiphytes. There were quantitative differences in species composition between phorophytes: A. distichantha and T. loliacea were positively associated with S. obtusifolium. Prosopis spp. had the highest abundance and richness in dead branches and the phorophytes of the upper stratum in the living ones. The differences in abundance, richness, specific composition and vertical distribution of vascular epiphytes between phorophytes could be attributed to their morphological characteristics and the microhabitats conditions in the trunk and branches. [ABSTRACT FROM AUTHOR]