May 1 2013

12:00 LSB 2320

Gretchen North
Department of Biology, Occidental College

Resistance is Not Futile: Water Use by Tank Bromeliads


Tank bromeliads are widespread, ecologically important epiphytes in the Neotropical family Bromeliaceae that obtain virtually all of their water and mineral nutrients from the contents of their tanks. Because they lack stems and absorptive roots, their leaves are the organs of both supply and demand. Epiphytes such as bromeliads also provide excellent models in which to investigate how external factors such as light affect leaf hydraulic conductance due to environmental variation within the rainforest canopy. At La Selva Biological Station in Costa Rica, we have measured light availability and several plant and leaf properties associated with hydraulic conductance for five species of tank bromeliad that vary in their light requirements and photosynthetic pathways. Based on height in the canopy and leaf anatomical traits such as tracheid number and diameter, we report a positive correlation between light and leaf hydraulic conductance for some, but not all, tank bromeliads. We also report some of the lowest measured values for leaf hydraulic conductance in an angiosperm for a shade tolerant tank bromeliad and discuss evidence from a model and from leaf anatomy that help explain such a high resistance.















































































































































































































































































































































































































































































































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