Document: CAT-3-40-35

Effects of microenvironment and tree characteristics on canopy vascular epiphyte distribution.

CARDELUS, C.*

University of Connecticut, Storrs CT 06269 ¹

Abstract:
To understand how biotic and environmental factors influence vascular epiphyte distribution, I measured tree characteristics, microenvironment and vascular epiphyte abundance in the canopies of three tree species: Lecythis ampla, Terminalia amazonia and Hyeronima alchorneoides at La Selva Biological Station, Costa Rica. Sixteen 0.5m by 0.5m quadrats were established on canopy branches of two individuals of each species. Atmospheric humidity, photosynthetically active radiation, temperature, soil moisture, soil pH, branch diameter, branch angle and branch height, vascular epiphyte cover and species composition were recorded for each quadrat. Epiphyte species composition differed among these three tree species, with no species overlap observed between Terminali a and Hyeronima. Significant differences in microclimate were also recorded among tree species, mostly with respect to relative humidity and light. Humidity in Hyeronima is maintained at 97% diurnally, whereas Terminalia and Lecythis have more variable humidity, probably due to their more open canopies. Canonical correspondence analysis of epiphyte communities within the canopy revealed clear groupings, with the first and second axes most stongly influenced by humidity and light. Results indicate that tree characteristics and microclimate strongly influence vascular epiphtye distribution.

Keywords: vascular epiphyte, La Selva, microenvironment, canopy biology, distribution

This abstract is being presented at: 10:30 AM in session:
Oral Session #5: Mutualisms.