Monday, August 3, 2009

PS 6-65: Climate change effects on Lepanthes rupestris subpopulation dynamics

Paola Olaya, Elvia Melendez-Ackerman, Raymond Tremblay, and Maria Eglee Perez. University of Puerto Rico, Rio Piedras and Center for Applied Tropical Ecology and Conservation (CREST-CATEC)

Background/Question/Methods Climate variation may affect the physiology of epiphytic plants in tropical environments. If so, epiphytic plants may serve a potential bioindicators of climate change and useful tools to study the response of plant populations to atmospheric and/or climatic changes. We evaluated the long-term changes (33 years) in temperature and precipitation dynamics between 1975 and 2007 and demographic responses of an epiphytic (on trees) and litophytic (on rocks) orchid Lepanthes rupestris to those changes, between 2000 and 2007.

Results/Conclusions Mean annual precipitation showed changes in inter-anual variability with a dry period between 1991 and 1994 and a higher frequency of events where the mean annual precipitation for the wet season below to the 33 yr means after 1992. Also, the mean maximum and minimum annual temperature increased 2 degrees from 1975 to 2007. Several significant correlations were found between variability in orchid demographic stages and variability in mesoclimatic variables but these correlations were more common on rock substrates than on tree substrates. Overall results suggest that plant responses are mostly associated with changes in temperature and changes in precipitation uncertainty (mean number of dry intervals).These associations may have important consequences within the context of expected climate changes in the Caribbean.