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Marianela Mercado - CO2 Lab

University of Puerto Rico - Rio Pedras

My summer internship took place in the CO2 laboratory site at the Kennedy Space Center in Florida sponsored by Smithsonian Environmental Research Center and NASA.  During June and July months of summer 2005 I worked to find Photosynthetic responses of Quercus myrtifolia and Quercus geminata to elevated CO2 in a Florida scrub-oak ecosystem. My investigation was first to find if, scrub oaks response to increasing CO2 in photosynthesis; second if scrub oaks acclimate to elevated CO2 in photosynthesis and finally if elevated CO2 affect the light response curve of scrub oaks. To find this answers I followed different procedures. I used the LI-COR, LI-6400 machine to measure the photosynthesis rate of the two species in ambient and elevated CO2 concentrations for both months. I measured it once a month in the elevated and ambient chambers during 8:00am to 12:00pm. Comparing the species at the different CO2 concentrations I found that photosynthesis rate was higher in elevated than in ambient CO2 for both species. To find if the species acclimate to elevated CO2 I measured photosynthesis against the CO2. While CO2 was changing from the LICOR, I was obtaining the rates of photosynthesis. I measured it once a month in the ambient and elevated chambers between 8:00am to 12:00pm too. I found that Q. myrtifolia acclimate but Q. geminata didn't. Finally to know if elevated CO2 affect the light curve response I measured photosynthesis again but changing the intensities of light from the LICOR.  I made the measurements once a month and in the mornings too. I sampled leaves in shade and leaves in sun to compare the light curves of the two species in the elevated and ambient CO2 concentrations. While the light was changing the photosynthesis rate was changing too until reach a stable rate. I found that leaves in shade made less photosynthesis than the sun leaves.

Funding provided by the National Science Foundation - REU