Differential Tolerance to Super-Elevated Temperatures in Corticolous Lichens Associated with Oregon Oak Ecosystems
Presented by: Tim Nam
Mentor: Mark Patterson
Department of Botany & Plant Pathology

Two integral parts of the Oregon oak savanna ecosystem are periodic
wildfires and a diverse array of lichen epiphytes. The interaction between these two parts is being investigated. It is presumed that in real fire conditions, the most sensitive component of lichens is the photobiont component. Thus, photosynthetic health, in terms of variable fluorescence, is being used as the primary indicator of lichen health. Variable fluorescence is the ratio between normally occurring fluorescence, ft, and the fm, a peak amount of fluorescence following a saturating pulse of light. Lichens were harvested from a field site located in NW Corvallis. The maximum variable fluorescence was measured (3x) and averaged for 12 different species of varying morphology. Exposure to heat was made at 100 degrees C. for varying durations and variable fluorescence was measured again to determine if and how much damage occurred to the lichen. Other possible indicators of lichen health considered are electrolyte leakage and gas exchange rates. The experiments are currently in progress.