Recent Topics Posters
Kouwenberg, Lenny , McElwain, Jennifer .
The effect of light intensity and temperature changes on the stomatal and epidermal morphology of Quercus kelloggi: implications for paleoelevation reconstructions.
RECENTLY a new method to reconstruct paleoelevation has been developed, based on the adjustment in number of stomata on leaves to the predictable decrease in CO2 partial pressure with altitude. The first time application of this method focuses on determining the altitude of growth of early Miocene Quercus pseudolyrata leaves from the northern Sierra Nevada. Calibration of the fossil stomatal numbers to altitude is based on the stomatal response of the modern day California black oak (Quercus kelloggi), whose leaves are indistinguishable from Q. pseudolyrata and grows in the same region.
The clear correlation between increasing stomatal density and index vs. increasing altitude of growth found in (Quercus kelloggi can for a large part be attributed to the predictable decrease in CO2 partial pressure. Many plants, among which several Quercus species, show this increase in stomatal frequency with decreasing CO2 and CO2 is the only environmental parameter that globally and predictably changes with elevation.
However, several other climatic variables can also change with elevation and potentially influence stomatal density. The most important two are light intensity and temperature. In a natural setting, the relative influence of all environmental parameters on the stomatal change over altitude transect is extremely difficult to pry apart. Therefore, saplings of (Quercus kelloggi were grown under controlled conditions in growth chambers, varying the levels of light and temperature. We will present preliminary data on the effect of both light levels and temperature regimes on stomatal frequency and epidermal cell morphology of (Quercus kelloggi leaves. An experiment with lower (high-elevation) and ambient CO2 levels will be carried out in the near future. The data obtained from the growth experiments will greatly contribute to the accurate use of stomatal frequency analysis as a tool for paleoelevation reconstructions.
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1 - Field Museum of Natural History, Department of Geology, 1400 South Lake Shore Drive, Chicago, Illinois, 60605, USA
Presentation Type: Recent Topics Poster
Location: Auditorium/Bell Memorial Union
Date: Tuesday, August 1st, 2006
Time: 12:30 PM