EPIPHYTISM IN THE MONTANE FORESTS OF EL-REY NATIONAL-PARK IN ARGENTINA - FLORISTIC COMPOSITION AND DISTRIBUTION PATTERN

In the Montane Forest of El Rey National Park in Northwest Argentina, between 800 and 1700 m.a.s.l., epiphytism is conspicuos both in flora and structure, comprising at least 47 species of vascular epiphytes: 18 species of fern, 11 Bromeliaceae, 9 Orchidacea, 4 Piperaceae, 4 Cactaceae and 1 Begoniaceae. Percentage of trees with vascular epiphytes was 52% for the Basal Forest (900 m.a.s.l.) and more than 78% in the Myrtaceae Forest (1100 m.a.s.l.). These species are distributed in no less than ten biotopes in which the phorophytes may be divided, forming five ecological groups according to kind of substrate and light intensity. The stability of the substrate is an important factor for epiphyte distribution promoting a succession from the distal to the basal extremes of branches. This succession starts in a smooth and highly unstable substrate exposed to high watery stress and ends in a rough, rugose substrate where accumulation of water, nutrients and organic matter allow the settling of bigger epiphytes with longer life cycles.