FATORES AMBIENTAIS AFETAM A ABUNDÂNCIA DE BROMÉLIAS EPÍFITAS EM FLORESTA TROPICAL SAZONAL SECA

Epiphytes can have both your richness and abundance altered by environmental conditions. In this study, we tested whether host plant characteristics (phorophyte) and other environmental factors contribute to the increased abundance of vascular epiphytes. Seventy-five fixed 20 × 20 m plots were sampled, distributed among three fragments of Dry Seasonal Tropical Forest (Caatinga) in three municipalities of Sergipe, Brazil: Poco Redondo (area 1), Porto da Folha (area 2) and Poco Verde (area 3). The hypotheses tested were: I. the greater the structural complexity of the phorophyte, greater the abundance of epiphytes in response to a greater diversity of fixing sites; II. Epiphyte abundance will be positively related to environmental factors that favor photosynthetic activity and nutrient absorption. Thus, a positive relationship between abundance and light, air relative humidity and altitude is expected, as well as a negative relationship between abundance, air temperature (possible water stress) and canopy cover (greater shading). 2,728 epiphytes were observed belonging to six species of Bromeliaceae, registered in 514 phorophytes of 29 species and 15 families. The abundance of epiphytes responded to some characteristics of the phorophytes and some of the abiotic factors. Thus, trunks with larger diameter and number of branches, smooth rhytidome and higher temperatures positively influenced the abundance of epiphytes, while increases in altitude and humidity affected the abundance negatively. It is concluded that the abundance of epiphytes in Caatinga fragments is directly associated with factors such as phorophyte structure and microclimatic conditions. Keywords:  Caatinga, Interaction epiphyte-phorophyte, Microclimate.