effects of cypress dome size on epiphyte diversity in southern Florida

Epiphyte richness and abundance were observed in 18 cypress domes spanning two regions in South Florida that were classified by annual low temperature differences of 4.05°C. Using the Preston model of island biogeography and linear regression, the following hypotheses were tested: (1) Larger domes have greater epiphyte diversity because they moderate temperature extremes better than smaller domes. (2) The effect of cypress dome size is reduced in subtropical compared to more temperate regions. (3) A measurable temperature gradient exists within cypress domes. The analyses indicated that epiphyte distribution in cypress domes fits the Preston model. In addition to an increase in diversity with area, there were regional differences that were correlated to temperature, however, these differences diminished as dome size increased. Within the domes, an increase in diversity was correlated to significant differences between dome edge and center temperatures, indicating the occurrence of factors that were influenced by area.